Analysis and prediction of streamflow and precipitation data by Alfred Benjamin Cunningham A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Civil Engineering Montana State University © Copyright by Alfred Benjamin Cunningham (1971) Abstract: The double mass analysis and a related method of data synthesis are used to develop a computerized data analysis and generation model. Total monthly volumes of precipitation and streamflow are the types of data for which the model is designed. The double mass analysis is used to check the consistency of the data at a particular station. Then, using the equation of the double mass curve, periods of missing record are synthesized for the station in question. A comparison can be made to determine if cyclic variations exist between the synthetic and actual data. In the event that cyclic variations do occur, correction factors can be applied to improve the accuracy of the synthetic data. Although the data analysis and generation model was developed for use on the streamflow and precipitation data in Montana, its general structure does not restrict its use to any one geographic region. Statement of Permission.to Copy In presenting this thesis in partial fulfillment of the requirements for an advanced degree at Montana State University, I agree that the Library shall make it freely available for inspection. 'I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by my major professor, or, in his absence, by the Director of Libraries. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission. Signature Date ANALYSIS AND PREDICTION OF STREAMFLOW AND PRECIPITATION DATA by ALFRED BENJAMIN CUNNINGHAM A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Civil Engineering -yappro; d: Head, Major Deparment Chairman, Examining Committee Graduate Dean / MONTANA STATE UNIVERSITY Bozeman, Montana December, 1971 • ACKNOWLEDGMENTS The author wishes to extend his thanks to the faculty of the Civil Engineering and Engineering Mechanics department of Montana State University for their willing assistance, and especially to Professor T. T. Williams for Ais help and guidance in preparing this thesis. Thanks are also extended to the author's wife who, along with Mrs. Neta Eckenweiler prepared and typed this thesis. XV TABLE OF CONTENTS Page Number VITA.................... ............................ . ACKNOWLEDGEMENTS. . . . . . I .................. ii .... iii LIST OF FIGURES AND TABLES............................ vi ABSTRACT. . ............................. ix INTRODUCTION.......... ............................ I STATE WATER PLANNING MODEL........ .................... I SUMMARY OF PROBLEMS WITH EXISTING DATA. . . . . . . . . 4 STATEMENT OF OBJECTIVES .............................. 4 LITERATURE REVIEW........................................ 6 MODELING TECHNIQUES FOR HYDROLOGIC STUDIES............ 6 Mechanical Analog.......................... .. 6 Electric Analog.................................... 6 Digital Computer ...................... .......... 7 STREAMFLOW SYNTHESIS.......... ........................ 7 PRECIPITATION SYNTHESIS . . ............'.............. 8 CONSISTENCY CHECK FOR STREAMFLOW AND PRECIPITATION DATA 8 DEVELOPMENT OF TECHNIQUE FOR DATA ANALYSIS AND GENERATION. 10 \ DATA A N A L Y S I S ........ ■............................... 10 Consistency Check.................................. 10 Correction of Inconsistent Data........ .. 11 V DATA GENERATION Page Number 15 Criteria Necessary for SyntheticData Generation ^ Double Mass Extension.......... ^ Multiple Regression........................... MODEL STRUCTURE.................................. DATA ANALYSIS SUBROUTINE..... .................... 22 22 Discontinuity Detection.............. ......... Evaluation of the Data Analysis Subroutine...,. 2b DATA CORRECTION AND GENERATION SUBROUTINE......... 27 Data Correction............................... 27 Data Generation............... 27 Evaluation of the Data Correction and Generation Subroutine......................... 28 PRESENTATION OF RESULTS................................. 30 ' DESCRIPTION OF RESULTS.... ......................... 30 SIGNIFICANT PARAMETERS............................. 30 DISCUSSION OF RESULTS............ 50 ACCURACY VS. CORRELATION........... 50 EFFECTIVENESS OF DOUBLE MASS ANALYSIS..... 52 CYCLIC VARIATIONS.................................. 54 OPERATION PROCEDURE FOR DATA ANALYSIS AND GENERATION MODEL................ 56 vi Page Number SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH........... APPENDIX A. LITERATURE CONSULTED........................... APPENDIX B . PROGRAM LISTING................................ 58 ' 61 62 . vii LIST OE FIGURES AND TABLES Figure I Title . Page Number ADJUSTMENT OF INCONSISTENT DOUBLE MASS POINTS. . . . 12 I 2 DOUBLE MASS EXTENSION............. 18 . 3 MULTIPLE LINEAR REGRESSION ......................... 20 1 4 DETECTION OF DISCONTINUITIES IN DOUBLE MASS ANALYSIS 23 5 GENERATION OF SYNTHETIC DATA BY DOUBLE MASS EXTENSION 29 6-A DOUBLE MASS DIAGRAM - HYALITE CREEK AT RANGER STATION VS. GALLATIN RIVER AT GALLATIN GATEWAY . . 35 COMPARISON OF DATA FOR HYALITE CREEK - ACTUAL DATA VS. SYNTHETIC DATA ............................. . 36 6-B 7 PER CENT ERROR VS. CORRELATION COEFFICIENT . . . . . 37 8-A DOUBLE MASS DIAGRAM - POWDER RIVER AT LOCATE VS. YELLOWSTONE RIVER AT SIDNEY. . . . . . . . . . . . 38 8-B 9-A DATA COMPARISON FOR POWDER RIVER - ACTUAL DATA VS. SYNTHETIC D A T A .............................. 39 DOUBLE MASS DIAGRAM - GALLATIN RIVER AT GALLATIN GATEWAY VS. MADISON RIVER AT WEST YELLOWSTONE. . . 40 !. 9-B IO-A 10-B 11-A DATA COMPARISON FOR GALLATIN RIVER - ACTUAL DATA VS. SYNTHETIC AND ADJUSTED SYNTHETIC DATA........ 41 DOUBLE MASS DIAGRAM -YELLOWSTONE RIVER AT YELLOWSTONE LAKE VS. MADISON RIVER AT WEST YELLOWSTONE............ .......................... 42 DATA COMPARISON FOR YELLOWSTONE RIVER - ACTUAL DATA VS. SYNTHETIC AND ADJUSTED SYNTHETIC DATA. .... 43 DOUBLE MASS DIAGRAM - PRECIPITATION AT WYOLA VS. PRECIPITATION AT SIDNEY........ .. 44 viii Figure 11-B 12-A 12-B 13-A 13-B Table I !H i . i Title Page Number DATA COMPARISON FOR WYOLA PRECIPITATION - ACTUAL DATA VS. SYNTHETIC DATA. ......................... 45 DOUBLE MASS DIAGRAM - PRECIPITATION AT MONTANA STATE UNIVERSITY VS. PRECIPITATION AT TRIDENT. . . 46 DATA COMPARISON FOR MSU PRECIPITATION - ACTUAL DATA VS. SYNTHETIC DATA.......................... 47 DOUBLE MASS DIAGRAM - PRECIPITATION AT PRYOR VS. PRECIPITATION AT BILLINGS........................ 48 DATA COMPARISON FOR PRYOR PRECIPITATION - ACTUAL DATA VS. SYNTHETIC DATA. . . . . . .............. 49 Title Page Number OCCURRENCES WHICH CAUSE DISCONTINUITIES IN DOUBLE MASS ANALYSIS..................................... 14 DATA FOR THE PRECIPITATION AND STREAMFLOW STATIONS WHICH WERE STUDIED . . . ......................... 33 ix ABSTRACT The double mass analysis and a related method of data synthesis are used to develop a computerized data analysis and generation model. Total monthly volumes of precipitation and streamflow are the types of data for which the model is designed. The. double mass analysis is used to check the con­ sistency of the data at a particular station. Then, using the equation of the double mass curve, periods of missing record are synthesized for the station in question. A comparison can be made to determine if cyclic variations exist between the synthetic and actual data. In the event that cyclic variations do occur, correction factors can be applied to improve the accuracy of the synthetic data. Although the data analysis and generation model was de­ veloped for use on the streamflow and precipitation data in Montana, its general structure does not restrict its use to any one geographic region. Chapter I INTRODUCTION In the last several years, the proper development and management of water resources has become an issue almost everywhere. Previously the greatest concern had been to maintain an adequate water supply for large urban areas; however, it is now becoming apparent that proper development and management is needed everywhere if the optimum use of available water resources is to be achieved. The state of Montana, even with its abundant water resources and sparse population, is no exception. In fact, because so many other areas of the country depend on the water originating in Montana, the need for management in Montana is indeed great. Until recently, there has not been a concentrated effort to put water resource planning and management techniques to use in this state. However, with the organization of the Montana Water Resources Board out of the old Water Conservation Board in 1967, and the subsequent increase in public support, water resource development and management has become a top priority issue. STATE WATER PLANNING MODEL In 1968 the Departments of Civil Engineering & Engineering Mechanics and Industrial & Management Engineering at Montana State University contracted with •'the, Montana Water Resources Board to -2develop a statewide water planning model. Although there are several types of modeling techniques in use, the approach taken was to develop a mathematical model for use on the digital computer. This is accom­ plished by deriving mathematical expressions to represent the inter­ action of certain hydrologic parameters and programming these ex­ pressions for a computer solution. Once these expressions have been derived, it is possible to determine the distribution of the ground and surface water throughout the state for any specified time interval. Having this capability, it will then be possible to evaluate the effects of proposed projects on the state's water resource system. . To accomplish this objective, the state water model will utilize large quantities of hydrologic and geologic data - most of which have never been collected on a regular basis. It is apparent, therefore, that a key to a successful model lies in developing accurate methods of estimating missing data. Two types of data which are vital to the model are.(I) records of the precipitation which falls on the state and (2) records of the streamflow which occurs within the state. Although these data are collected for Montana by the National Weather Service and the U.S. Geological Survey, the records at many locations are presently inadequate. This is primarily because precipitation and streamflow records in Montana range in length from one or two years up to fifty or more years. Also, the data for some locations nave not been -3continuously collected throughout the lifetime of the station. In . fact an examination revealed that missing record periods are present in approximately 80% of the available precipitation and streamflow records for Montana. Thus if a method could be developed whereby periods of missing record could be synthesized accurately, a signifi­ cant improvement to the State Water Planning Model would be made. " Another inadequacy in the data that must be recognized is that some periods of record are "inconsistent It is important here to realize what is meant and not confuse the term "erroneous" with the term "inconsistent." The record for a particular station is "erro­ neous" if the gage inaccurately measures the true quantity of pre.cipitation falling or streamflow passing. The record is "inconsistent" if some, natural or man-caused occurrence (such as the physical fe:location of a gage to a different site) causes a shift or discontinuity 'in the data. v For example, consider a stream gaging station at which data .’have been collected for a long period of years. If this station "were then to be moved upstream past a major tributary .to the river, ' ■the streamflow record after the move would be inconsistent with the i• ! record before the move. That is, the recorded flow would then be less I • j compared to what it would have been if the gage had not been moved. . Notice in this example that the gaging station is assumed to record 'the true flows at each location. But if the record from this station is assumed to consist of the two segments of data collected from the -4two sites without adjusting the data from one, then the record would be said to be "erroneous." It is easily seen that if the presence of inconsistent records is not detected, any attempt to use these records in a watershed model or to synthesize missing data could result in serious error. Therefore a necessary prerequisite for data synthesis is that existing data which is to be used, first be tested for consistency. I SUMMARY >OF PROBLEMS WITH EXISTING DATA The problems associated with the streamflow and precipitation data for the State Water Planning Model can be summarized in the following way. The primary problem with the data is that periods of data are missing from about 80% of the existing records. Therefore a way must be found to generate synthetic data in order to have complete records at all desired locations. The second problem which is less significant (though still important) is that some existing records are inconsistent and must be corrected before being used for data generation or any other purpose. Therefore a way must be found to test existing streamflow and pre­ cipitation data for consistency. STATEMENT OF OBJECTIVES Based on the foregoing statements concerning the need for the development of a "Data Analysis and Generation Model,"' the following objectives are stated. -5(1) . Construct a computerized "Data Analysis Model" which will check the consistency of existing precipitation and streamflow data. (2) . Construct a computerized "Data Generation and Correction Model" capable of synthesizing missing periods of monthly streamflow and precipitation volumes - as well as correcting existing data which are inconsistent. (5). Describe the operation procedures for these models which will yield the best possible results. i ,'i ■$> Chapter 2 LITERATURE REVIEW A survey of pertinent literature was conducted to analyze the I various hydrologic modeling techniques as well as the various methods I of data analysis and generation. MODELING TECHNIQUES FOR HYDROLOGIC STUDIES Three types of modeling techniques which are currently being used in hydrologic studies are given by M'ount, (1965). These three types are (I) the mechanical-analog model, (2) the electire-analog model, and (3) the digital computer model. Mechanical Analog JS An example of applying a mechanical-analog model to a hydro- i logic study would be to use a stretched membrane to represent the ; effect of pumping water from a well. As the well is pumped, the water table assumes the shape of an inverted cone with the apex at the well. ; The same shape occurs in a membrane when it is pressed with a sharp instrument. In this case the elastic properties of the membrane are : analogous to the water transmitting properties of the aquifer and . the magnitude o'f the point force applied to the membrane is analogous to the rate of withdrawal from the aquifer. Electric Analog Electrie-analog models, however, appear to have greater utility than mechanical-analog models because electric properties have -7analogs in many- physical systems. However, in hydrologic studies, electrical systems can be used to model certain aspects of the . hydrologic cycle. For example, an electrie-analog model could be constructed to depict the changes in ground and surface water condi­ tions for a given area. Here, the ground and surface storage would be ''represented by capacitance streamflow, precipitation, and ground water movement would be represented by current; and soil.transmissibility would be represented by resistance. Digital Computer Although the electrie-analog and the mechanical analog models are useful in many cases, the digital computer model is more versatile and therefore used more often. The application of digital computer modeling to hydrology involves determining mathematical relations which represent the interaction of hydrologic parameters. For example, consider the Stanford Watershed Model which is described by Linsley . and Crawford, (1966) . In this model virtually every aspect of the hydrologic cycle has been represented mathematically and programed for a computer solution. Once the required hydrologic data have been obtained for a particular watershed, the Stanford Watershed Model can be used to predict the outflow hydrograph resulting from any theoreti­ cal storm which could occur on the watershed. STREAMFLOW SYNTHESIS A computer solution for estimating periods of missing streamflow record was developed by Beard, (1967). The procedure was to -8make the existing data at a particular gaging station a function of the data from a group of surrounding stations. The method of least squares is used as the basis for this analysis and results in the development of a linear relation between the data for the particular station and the data for the surrounding stations. Once this equation is determined, Beard's program can then fill in any periods of missing record for the particular station. PRECIPITATION SYNTHESIS '■ . ■Linsley, Kohler, Paulhus, (1950) presented a method which graphically determines the distribution of rainfall from a particular storm over a given area. This is done by first plotting the recorded ,3 rainfall at each of the gaging stations for the area in question. >. Then, isohyets or "rainfall contours" are drawn to indicate how the rainfall was distributed over the area. Thus the rainfall could be \ estimated for any station which was not operating at the time of the storm. Though it would be . quite time consuming, an entire period of , record at a given station could be estimated by repeating this proi cedure for each storm that -occurred" during the time the gage was not operating. • CONSISTENCY CHECK FOR STREAMFLOW AND PRECIPITATION DATA A survey of available literature revealed that the standard method for testing the consistency of hydrologic data is the "double mass analysis" (DMA). literature. In fact no other method was found in the A development of the DMA for use in testing the consistency of precipitation data is presented by Linsley, Kohler, & Paulhus, (1958). Although the DMA is primarily used for precipitation data, it is pointed by Linsley, Kohler, Paulhus, (1949), that the DMA can be used to test the consistency of streamflow data as well. It is because of this capability for testing the consistency of both types of data that the double mass analysis was chosen as the basis 'for the data analysis and generation model. R. Singh (1968) developed a computer solution for the double mass analysis. However, his program was deemed inappropriate for this study because it could not detect the presence of more than one period of inconsistent data. V Chapter 3 DEVELOPMENT OF TECHNIQUES FOR DATA ANALYSIS AND GENERATION Based on the results of the literature survey, techniques were developed for both the analysis of existing data and generation of synthetic data. DATA ANALYSIS As previously stated, the double mass analysis is used by hy­ drologists to test the consistency of both precipitation and streamflow data. Consider now how the DMA is applied to precipitation data1. Consistency Check The consistency of precipitation data is checked by comparing the accumulated precipitation at a given station with the accumulated precipitation for a group of surrounding stations. .The procedure is to plot the accumulated rainfall values at the particular station as the dependent variable and the concurrent accumulated rainfall for the surrounding stations as the independent variable. If the records from the stations are well correlated, as they should be if the stations are in the same hydrologic unit, the points should plot approximately on a straight line. However if a slope change is necessary to fit line segments through the points, it is highly probable that an inconsistency exists in the data for the dependent station. If a slope change is detected, it is important to check the history of the dependent station to confirm the existence of the -11data inconsistency. If the gage history reveals the occurrence of art event which could cause a slope change in the data, then it is almost certain that an inconsistency in the dependent station record exists. If the slope change cannot be substantiated from the gage history, it is a judgment decision as to whether the slope change does in fact indicate a discontinuity in the data. Care must be taken in this case not to interpret the natural scatter of the points as an inconsistency in the data. The possible reasons for discontinuites in both precipi­ tation and streamflow data are discussed later in this chapter. The above discussion is an explanation of the procedure involved in performing the double mass analysis. Although this procedure was discussed with respect to precipitation data, it is important to note that streamflow data can be analyzed in exactly the same manner. The only difference is that these two types of data will have different units. The streamflow data used in this study will have the units of acre-ft/month while the precipitation data will be in inches/month". Correction of Inconsistent Data Once the DMA has detected a discontinuity in the record of the dependent station, correction of the erroneous data is easily done. The procedure is to multiply each erroneous double mass ordinate by the ratio of the slopes of the two line segments constructed through the double mass points.. To illustrate, a double mass curve is shown in Figure I. individual data values are shown along with the resulting double The -12- L - 1 .0 2 .5 1 .0 .5 2 .0 .5 3 -0 1 .0 2 .0 2 .0 CUMULATIVE D E P E N D E N T ^ STA T | O N DATA 25 X X 2.0 2 .0 7 .0 9 .0 1 0 .0 i4 .o 1 5 .0 1 6 .5 1 7 .0 1 8 .0 1 9 .0 Y - 1 .0 3 .5 4 .0 6 .0 6 .5 9 .5 1 0 .5 1 2 .5 1 4 .5 1 6 .5 5 .0 2 .0 1 .0 4 .0 1 .0 1 .5 .5 1 .0 1 .0 y = Dependent station data. Y = Ordinates on double mass diagram. x = Surrounding station data. X = Abscissa values for double mass diagram. Slope segment 2 10 ^ Adjusted data points S Segment I lope = .5 1940 5 CUMULATIVE FIGURE I. 10 SURROUNDING 15 STATI ON 20 DATA ADJUSTMENT OF INCONSISTENT DOUBLE MASS POINTS 25 -13mass coordinates to demonstrate how the double mass lines were con­ structed. Plotting the double mass coordinates (Y vs. X), shows that a slope change occurs approximately in 1950. Assuming that the slope change does in fact represent a discontinuity in the dependent station record, the record from 1950 to 1960 can be corrected by multiplying the segment of the ordinates which lie above the discontinuity by the ratio .5/2.0 so as to be consistent with the points on segment I. Thus far it has been assumed that if a discontinuity is found by a double mass analysis the record for the dependent station is auto­ matically in error. However, in the event that only one surrounding station is used as the independent station, it is equally possible that a discontinuity could be due to erroneous data for the independent station. In this case the record for both the independent station and the dependent station must be examined if a slope change is found by the double mass analysis. The most common causes for the occurence of discontinuities in streamflow and precipitation data are listed in Table I. Where precipitation data is concerned, it has been observed by the National Weather Service, according to Linsley, Kohler, and Paulhus (1958) , that a change in gage location can be a significant factor in causing the data to be inconsistent. In some cases a change in location of less than five miles can cause significant error in the gage record. Changes in the exposure of a gage can also be a signifi­ cant factor in affecting the accuracy of the gage record. This happens in areas where trees or vegetation are allowed to grow up around a gage, thus affecting the catch. -14TABLE I OCCURENCES WHICH CAUSE DISCONTINUITIES IN THE DOUBLE MASS ANALYSIS PRECIPITATION DATA 1. Changes in gage location 2. Changes in the gage exposure 3. Changes in instrumentation 4. Changes in observation techniques STREAMFLOW DATA 1. Construction of hydraulic structures 2. Changes in diversion practices 3. Changes in gage location 4. Changes in observation procedure 5. Changes in instrumentation 6 . Erosion or sedimentation in vicinity of gage Variations in observation procedure or changes in instrumenta­ tion can also affect the accuracy of raingage data. For example changing from a simple volumetric recorder to a continuous recorder could change the accuracy of a monthly gage record considerably. Also if the observation procedure for a simple volumetric recorder is -15changed so that the gage is checked every month instead of daily, a decrease in the accuracy of the monthly precipitation values could be observed. It is these types of "accuracy changes" which can also cause inconsistencies in rain gage data. In the case of monthly streamflow data, changes in instrumenta­ tion gage location and observation procedure could affect the accuracy of the record in much the same way as they affect precipitation records. However other possible causes for discontinuities in streamflow data are changes in diversion practices and construction of hydraulic structures. The occurrence of either event above a stream gaging station will almost certainly cause a discontinuity in the record. DATA GENERATION . Once all existing periods of data for a particular station have been checked'for consistency, the next task is to fill in the missing record periods for which there are concurrent records from surrounding stations. Before the various alternatives are explained it is necessary to define the criteria needed to permit missing data to be synthesized. These criteria are presented below. Criteria Necessary For Synthetic Data Generation (I) The data used to obtain a relationship between the de­ pendent variable ( the data for the dependent station) and the independent variable ( the data for the surround­ ing stations) must be tested and found to be consistent. -16(2) The independent variable data which is used to fill in missing periods of dependent variable data, must be consistent. In the light of these criteria two alternate methods for data generation were explored. Double Mass Extension The first method considered was an extension of the double mass curve. The procedure is to substitute known "X" (double mass de­ pendent variable values) values for the period of missing record, into the established double mass curve equation of the form: Y = MX -f b where % “ The independent variable Y = The dependent variable. M = The slope of double mass line. b = The intercept of double mass line. The result is the generation of synthetic values of "Y" for the missing record period. The points on the double mass curve are determined by the relationship: 2 Y'i i=1 Yn= and - Jh where Yn" The ordinate of the n ^ double mass point. y^= The individual base station data values. Xn= The abscissa of the n ^ double mass point. Xi= The individual surround­ ing station data values. -17The actual synthetic missing data values are found by sub­ tracting each "Y" from the "Y" value immediately succeeding it. That is : y^= The ith synthetic data value. ?!= Yi- Yi-1 Yi and i-1 = The synthetic double mass ordinates used to obtain y^, Thus the necessary missing record for the dependent station is generated in this manner. Multiple Regression The second method for data generation which was explored was the method of "multiple regression," which is a direct application of the Theory of Least Squares. Multiple regression in this case would involve using a period of known record to make the dependent station data a function of the data from surrounding stations. This is accomplished by fitting the following type of polynomial to the existing data. y = C0 + C1X1 + C2 x2... Cn Xn where y = data for dependent station X1 = Concurrent data for surI) rounding stations. Cq = coefficients which are determined by the least square fit of the poly­ nomial to the data. The least squares fit of the polynomial to the data results - 18- in the determination of the coefficients C0 , C n. Once these are known, periods of missing dependent station record (y values) can be determined merely by knowing the concurrent "x" values for the surrounding stations. At first glance little similarity is apparent between the two methods for data generation. However, further examination shows that there is in fact, a great deal of theoretical similarity. It can be shown for a special case that theoretically double mass ex­ tension and multiple regression will produce the same synthetic data values. This special case occurs when the data at the dependent station is made a function of the data from only one neighboring station. The proof is as follows : Consider first how synthetic data are generated using an extension of the line of best fit through the double mass points. Y YrmX ♦ b Figure 2. DOUBLE MASS EXTENSION = xi . (i Ii The individual data values for the dependent station Xj^ = .The individual data values for the surround­ ing stations x U •H -- . y± h-» Yn = . Ii In the previous diagram, 1=> -19- I'j••« jn) To estimate any synthetic data value yn , the following pro­ cedure is used. yn = Yn - Yn -1 = (mXn + b > “ <^n-l + b> This can be rewritten as: yn = m(Xn - Xn^ 1) + b - b Since (Xn - Xn_1) = xn yn = mxn where m = slope = y n Xn Now consider how synthetic data are calculated from multiple linear regression. Using concurrent data from the dependent station and the surrounding station, a linear relation is obtained. yn = co + c lxn where yn = Individual data values for the dependent sta. xn = Individual data values for the surrounding sta. This relation is represented graphically as follows: qj -20- Figure 3. MULTIPLE LINEAR REGRESSION To obtain an estimate of the synthetic data value yn the only information needed is the known value for xn . Analysis of the above diagram leads to the following equation. since * • c ^n = y -c slope = _n____o xn - 0 (^n" cq ) But E . I can also be written: 0r: xn + Cq (2) yn = (yn + C q - Cq) xn yn = (yn - cO ) xn + co xn Since E q. 2 and the final form of Eq. I are identical, it has therefore been shown that the synthesis techniques of "double mass extension" and "multiple linear regression" will produce the same synthetic data values - provided that the dependent station is made a function of only one surrounding station. (3 ) -21This proof provided the basis for the decision to use double mass extension for the synthetic data generation portion of the y model. This decision allowed the computer programming to be done such that information from the data analysis section could be very easily transferred to the data generation section. Had the multiple linear regression technique been used for data synthesis, a more complicated program structure would have been required. Chapter 4 MODEL STRUCTURE The data analysis and generation model consists of two distinct units with the output from the first unit (the data analysis sub­ routine) serving as partial input to the second unit (the data correction and generation subroutine). DATA ANALYSIS SUBROUTINE Since the primary purpose of the "Data Analysis Model" is to detect discontinuities in existing data, a method had to be developed whereby the computer would accurately detect both the presence and the location of these discontinuities. Discontinuity Detection The method used is presented below. 1. (Refer to Figure 4) First the coordinates of the points on the double mass curve are calculated by a subroutine of the program. These points would be similar to those plotted in ILgure 4. 2. Using the following least squares^equation Y = Y + M (X where M = i=l(Xi Yi) - NXY 2 (Xi - X )2 i=l the model next calculates the line of best fit through all of the data points (one point at a time). That is the first line of best fit is passed through the first double mass point only, the second line is passed through the Slope Slope Slope = m o, CUMULATIVE DEPEN DEN T^ STATION DATA -23- CUMULATIVE FIRGURE 4. SURROUNDING STATI ON DATA DETECTION OF DISCONTINUITIES IN DOUBLE MASS ANALYSIS -24two points etc. The most important parameter obtained from these calculations is the slope line of best fit. of the This parameter is used in determing if a discontinuity exists in the data. 3. Along with obtaining the slope "Mi", the model simulta­ neously calculates the slope of another straight line. This line passes through the particular double mass point and the origin. For example, when the model fits a line through the first four double mass points, it also calcu. Iates the equation of the line passing through point #4 and the origin. The slope of this two point line is labeled "M2". 4. After each calculation of the slope values "Mi" & "M2", the program checks for a discontinuity by calculating the ratio. R1 = M1 ~ M2 Mi If the absolute value of "Ri" is greater than the prescribed tolerance, then a discontinuity is assumed. In Figure 4, line I represents the line of best fit through all points up to point "P•u Line 2 represents the line passing through point."?" and the origin. The slopes of lines I and 2 are "Mi" &-"M2" respectively. Assuming that the value of "Ri" exceeds the tolerance, the -25presence of a discontinuity has now been established. This also establishes that point "P" lies "above" the discontinuity. Discontinuity Location 5. Once the presence of a discontinuity is established, the program next attempts to accurately determine its location. To do this the program first fits a line through the first twenty points above point "P". The slope of this line is defined as "M3 ." Now another "two point" line is calculated through point "P + 20" and the points lying below point "P" one point at a time. The slope of this line is labeled "M4 This process continues until the ratio: 5.2="■ is exceeded. that the ratios It must be noted here & Rg must be set by the programmer prior to the running the program. It was found that values of Rl Sc R 2 in the range .I - .5 were the most satisfactory, taking into account that ^ g should be chosen pro­ portionally with the "scatter" of the double mass points. In Figure ,4' , line 3 represents the line of best fit. through all points between point "P” and point "P + 2.0" the slope of which is"Mg." Point "Q" is the point at which "R" is assumed to exceed the tolerance. -2 6 - 6 . The point of discontinuity is assumed to lie half way between point "P" and point 11Q.'" Break point = P + Q 2 7. Once a point of discontinuity is located, the program now neglects all points below the "break point," thus treating the break point as the new origin of the double mass curve Starting from this new origin, the model now repeats steps I - 6 to check for additional discontinuities. Evaluation of the Data Analysis Subroutine The method used in constructing the data analysis model was chosen because of the following advantages: 1. The method allows the model to detect more than one discontinuity. 2. The method lends itself easily to a computer solution. 3. The logic behind this method is simple and straight forward. This method of data analysis also has certain disadvantages. These include: I. The accuracy with which the program locates slope changes is proportional to the "degree of scatter" of the double mass points. This scatter is measured by computing the standard error of estimate of the points about the line of best fit. -272. The tolerance which determines when a break point occurs must be set by the programmer. It is important to keep these disadvantages in mind, especially when interpreting the results of the Data Analysis Model. DATA GENERATION AND CORRECTION SUBROUTINE Keeping in mind the methodology presented in Chapter 2, the program structure is as follows: Data Correction 1. If discontinuities are detected in the data by the Data Analysis Model, the first step of this program is to correct the existing inconsistent data. To accomplish this, the programmer must first decide how the data is to be corrected based on examination of existing records. Once this has been determined, the proper correction equations are placed in a special subroutine and the data is corrected. Data Generation 2. Having corrected all faulty data, periods of missing records are now synthesized by the data generation section of the model. The procedure used to accomplish this was simply to program the methodology outlined in Chapter 2. Once this was done, the input needed for data generation were (I) surrounding station data for the periods of missing base station record, and (2) the equation of the line of best fit for the correct period of data on the double mass curve. -2 8 - As an example of how the data correction and generation model works, consider Figure 5. . Assuming the data on segment I to be in error, the programmer must first decide how the data is to be corrected. That is, it must be decided to move the double mass points on segment I either vertically, horizontally or in both directions. As stated before, this is a judgment decision based on examination of the records for the stations involved. Once this has been decided the points on segment I are corrected in the proper manner to lie on segment'll. Now assume that the known period of base station record ends _ at point A. Assume also that the equation of line segments II & III is the correct model to be used for data generation. The known abscissa values are now substituted into the correct equation to yield the ordinate value for the missing period. These ordinates are then subtracted in the proper manner to produce the missing data, values. Evaluation of Data Correction and Generation Subroutine The advantages which justify the use of this approach to data generation and correction are: 1. The exact method of data correction is in each case left to the judgment of the programmer. 2. The model provides for the correction and generation of more than one period of data. — 29- 25.0 - 22.5= 2.5 points on segment I to be corrected to on segment II. X =22.0 CUMULATIVE SURROUNDING STATI ON DATA FIGURE 5. GENERATION OF SYNTHETIC DATA BY DOUBLE MASS EXTENSION Chapter 5 PRESENTATION OF RESULTS The effectiveness of the data analysis and generation model was tested using data from various gaging stations in Montana. The test procedure was first to check the consistency of the data, and then after making any necessary corrections, to synthesize a period of data. For the purpose of testing, periods of record were syn- - thesized which in fact were already known. Thus a comparison could be made to determine the effectiveness of the model. DESCRIPTION OF RESULTS The results which follow consist of double mass curves (which check the consistency of a particular set of data) and graphs of the generated synthetic data plotted with the actual data. Both stream- flow and precipitation data are represented in the results. The streamflow data tested came primarily from the Gallatin, Madison, and Yellowstone River drainages, while the precipitation data came from both Gallatin County and Southeastern Montana. SIGNIFICANT PARAMETERS Significant parameters which are used in the discussion of the results are the following: I. Correlation Coefficient defined as: - x) (yj - y) n Sx Sy -31where Xi = known base station data x = mean of x data Sx = STD. deviation of x data = known surrounding station data y = mean of y data Sy = standard deviation of y data n 2. = total number of data points. Per Gent Error defined, as : Mg - Ma I x 100 where Mg = mean of the generated synthetic data Ma - mean of the actual data for the period of synthetic data Per Cent Error is used to estimate the accuracy with which the synthetic data for a given period compares with the actual data for that same period. 3. Monthly Per Cent Error defined as : ' - ms^ ) . ; MaW Ma (■1-' where X 100 (1 . 1,...12) Mg (i) = mean of the synthetic data for a given month of the year. ) -32(i) = mean of the actual data for a given month of the year. e (i) = Average monthly deviations. -33TABLE II DATA FOR THE PRECIPITATION AND STREAMFLOW STATIONS WHICH WERE STUDIED STREAMFLOW STATIONS 1. Hyalite Creek (U.S.G.S. # 6-0500) LOCATION -- At Hyalite Ranger Station 7.3 miles south of Bozeman, ,Montana.. DRAINAGE AREA ---48.2 sq. mi. REMARKS -- Records fair. Flow regulated by Middle Creek Reservoir since 1951. 2. Gallatin River near Gallatin Gateway (U.S.G.S. #60435) LOCATION.-- 7.3 miles south of Gallatin Gateway, Montana. DRAINAGE AREA ---825 sq. mi. '. REMARKS -- Records good. Diversions for about 1400 acres above station. 3. Madison River near West Yellowstone Montana (U.S.G.S. #6-0375) LOCATION-- 1.6 miles east of West Yellowstone iMontana. DRAINAGE AREA ---420 sq. mi. REMARKS -- Records good. above gage. 4. No diversion or regulation Yellowstone River at Yellowstone Lake outlet (U.S.G.S. #6-1865) LOCATION -- .2 miles downstream from outlet of Yellowstone Lake. DRAINAGE AREA -- 1006 sq mi. REMARKS -- Records good except for winter months which are bad. -34PRECIPITATION STATIONS 1. Wyola LOCATION -- On Interstate 90 fourteen miles from Montana-Wyoming border. 2. Sidney LOCATION -- On the Yellowstone River seven miles from Montana-North Dakota border. 3. Bozeman LOCATION -- On campus of Montana State University 4. Trident LOCATION.-- Thirty one miles west of Bozeman,,Montana, . 5. Pryor LOCATION -- Thirty seven miles south of Billings, Montana. 6 . Billings LOCATION. -- Downtown Billings, Montana D e p endent HYAl ITF Surrou ndi ng S tction CPK G (@ Hyalite Ranger Sta.) a l l a t i n r i V f r (@ Gallatin Gateway) F E E T ) X IO5 (ACRE .08IX + 3320 DEPENDENT ST A. STREA M F L O W DOUBLE MASS DIAGRAM ( ACRE S U R R O U N DI N. G FIGURE 6-A. STA. FEET) X 10 ST REAM F L O W DOUBLE MASS DIAGRAM : STREAMFLOW D e p e n d e n t H Y A L IT E C R K C o r re lc itio n ( @ Gallatin Gateway) C o e t t D a t a FEET) x IO 3 Ic Q A U l AT|N— R IVER -3 6 - ( A C R E STREAMFLOW S y n t n e t (@ Ranger Sta.) D a t a A c t u a l MONTHLY RIntinnS S t a t i o n 12 1959 3 4 S 6 7 S 9 10 11 12 I 2 3 4 5 6 7 S 9 10 11 12 I 2 3 4 i960 T I M E (m o n t h s ) FIGURE 6 -B. COMPARISON OF DATA FOR HYALITE CREEK I 1961 5 6 7 S 9 10 11 12 »/ . ERROR CORRELATION COE FFIOfFNT Observed data Vo E R R O R Average observed data for .I inter­ vals of r. ( DIMENSIONLESS) CORRELATION FIGURE 7. COEFFICIENT PER CENT ERROR vs. CORRELATION COEFFICIENT S u r r o u n Li nr L X - ^ c r n L e n t ___ £ . t c t i £ . . Q P o W n F YELLOWSTONE (@ Sidney) 17 R l V F R (@ Locate ). RlVER DEPENDENT X 105 FEET) (ACRE 5 TA. S T R E A M F L OW DOUBLE MASS DIAGRAM 020X - 4.05 s 'i9 6 o DISCONTINUITY C ACRE SURROUNDING FIGURE 8-A. S TA. FEET ) X 10 STREA M F L O W DOUBLE MASS DIAGRAM: STREAMFLOW Dependent LOCATE (p O W D E R RIVER) S ID N E Y D a t a ( YELLOW STONE C o r r e l a t i o n S y n t h e t i c D a t a (Discontinuity Ignored) - - - - X '- ® S y n t h e t i c D a ta (Discontinuity Corrected) RIVER) Coeff. 0/o Error .6 1 7 1 1 .8 # FEET) x I O 3 -------- e Stnt inn S w ( A C R E -39- STREAMFLOW A c t u a l MONTHLY S u r r n i i nrii ng S ta tio n /Z r 12 3 4 1 9 5 0 FIGURE 8 -B. S 6 7 8 9 10 11 12 I 1 9 5 1 ' 2 J 3 4 1 5 6 7 S (V) £ COMPARISON OF DATA FOR POWDER RIVER ( 9 10 11 12 I M O N T H S ) 2 3 4 5 6 7 8 O 10 11 12 Surrou n rfi nn Ga I I ATf N RIVER M ADISO N Stot i n n s PiVFn X IO6 FEET) (ACRE DEPENDENT 5TA. ST R EA M F L O W (@ Gallatin Gateway) (@ West Yellowstone) DOUBLE MASS DIAGRAM (ACRE S U R R O U N DI N- G FIGURE 9-A, FEET) STA. DOUBLE MASS DIAGRAM: X 101 ST RE AM F L O W STREAMFLOW Dependent Ga t e w a y o — •® Siirrnu nrl i ( Ga l l a t i n r i v e r ) Actual Synthetic Data C o r r e l a t i o n Data -c ® ^ AD j LISTED S yn th et i c WEST YELLOWSTONE (M ADI SO N R I V E R ) C o e f T °/o E r r o r D at a •Apr. -2.4 ■May 3 .0 •W \ ■ Aug. -1.8 Nov. -1.9 Dec. -2.8 12 3 4 1950 FIGURE 9-B . 5 6 7 8 9 10 11 12 I 2 3 4 5 6 7 8 9 10 11 12 I 1951 J i M E ( months ) COMPARISON OF DATA FOR GALLATIN KlVEK 2 3 4 1952 5 6 7 5 9 10 11 12 ^ -If?- acre FEET) x IO5 Average Monthly Deviations ( MONTHLY STREAMFLOW — Stntlfin -42D c p cnct e r t S tction Surrounding Stct ions * Y ELLOW STONF I7IVFP MAniSON (@ Yellowstone Lake) Ri \/ F n (@ West Yellowstone) x 1Q6 FEET) (ACRE DEPENDENT STA. STREA M F L O W DOUBLE MASS DIAGRAM 5.0 ( ACRE S U R RO U N D I N.G FIGURE IO-A. 7.5 F E E T ) X 10* STA. DOUBLE MASS DIAGRAM: I STREA M F L O W STREAMFLOW S y n t h e t i c A dj ust ed < (YELLOWSTONE RIVER) WEST YELLOWSTONE C o r r e l o t i o n D a t a FEET) ( M A D I S O N RiVE R ) C o e ft. D a t a Synthetic Dat a Average monthly Deviations Jan. -2.15 x 10 x 1Q 5 e ( A C R E MONTHLY b T REA M F L O W YELLOWSTONE R. Actual Ft ntinnS S t a t i o n 12.1 x 10 Jul. 13.9xlOj Aug. 6 .IxlOj Sep. .ExlOj Oct. -.8x10, - 1 .8 x 10 -E+f- D e p e n d e n t D ep en d en t S rrtin n S u rro u n d in g W Y O L A <,tat i n n s S ID N E Y DOUBLE MASS DIAGRAM I.IOX + 2.20 ( I N C H E S ) SUR RO U N Dl N-G S TA. PRECl Pl TATl ON FIGURE Il-A. DOUBLE MASS DIAGRAM: FRECITIIATIOU S u r r n u nrti nn S ta tio n WVQ LA 0 A c t u a l ® S y n t n e t i c Si n + i n r , ^ S I D NEY D a t a Coett C o r r e l a t i o n D a ta -U-JO 1 5 .5 # °l» E r r o r 6 ( I N C H E S ) MONTHLY PRECIPITATION Dependent I 2 3 4 I 958 FIGURE 11-B. 5 6 7 8 9 10 11 12 I 1959 2 3 4 T I M E 5 6 7 8 9 10 11 12 I ( MONTHS ) 2 3 4 296O COMPARISON OF PRECIPITATION DATA FOR WYOLA, MONTANA 5 6 7 8 9 10 11 12 4» D ep end ent S trtin n Surr MONTANA STATF UNIVF RSl T Y PU ndi nn Stct inn <; TRI DENT DOUBLE MASS DIAGRAM 726 x + .8l4 ( I N C H E S ) S U R R O U N d i n . G STA. FIGURE 12-A. DOUBLE MASS DIAGRAM: PRECI PITATION PRECIPITATION D e p e n d e n t S u r r n i i nrii ng S t a t i o n Actual __ 6 S y n t n e t i c T R ID E D a t a NT C o r r e l a t i o n D a ta %> C o e f t E r r o r MONTHLY PER CENT ERRORS - Z t 1- ( I N C H E S ) MONTHLY PRECIPITATION B O Z E M A N 9,1 12 3 4 1948 FIGURE 12-B . S 6 7 S D 10 11 12 I 1949 2 3 4 T I M E 5 6 7 S 9 10 11 12 I ( m o n t h s ) 2 3 4 1950 COMPARISON OF PRECIPITATION DATA FOR BOZEMAN,MONTANA 5 6 7 8 9 10 11 12 -48D e p e n d e rt S tation S u rro u n d in n ^ lo t io n s W BH u Nn < PMYnn DOUBLE MASS DIAGRAM Z O t - < 200 HCL U LU 1 5 0 CL _ CL to LU 1.12X + 1.42 / 1938 ( I N C H E S ) SURRO UNDI N- G FIGURE 13-A. S TA. DOUBLE MASS DIAGRAM: PRECIPITATION PRECIPITATION Snrrnii S t a t i o n PRYOR A c t u a l D a t a © S y n t h e t i c SMnt i n n s LL I N G S C o r r e l a t i o n D a t a 0Zo C o e f f E r r o r ~6+H (IN C H E S ) m e BI nr l i n g ^ MONTHLY PRECIPITATION D e p e n d e n t 12 3 4 19 5 0 FIGURE 13-B. 5 6 7 8 9 10 11 12 I 2 3 4 1951 T I M E 5 6 7 8 9 10 11 12 I ( MONTHS ) 2 3 4 1952 COMPARISON OF PRECIPITATION DATA FOR PRYOR, MONTANA 5 6 7 8 9 10 11 12 Chapter 6 DISCUSSION OF RESULTS The results obtained from an analysis of data from Hyalite Creek and the West Gallatin River (see Figures 6-A and 6-B) are typical of the type of results obtained for both streamflow and precipitation data. The double mass curve (Figure 6-A) shows that no significant discontinuities exist in the data from 1935-1954, and therefore correction of data for this period is not necessary. On the basis of this double mass curve, the period of monthly streamflow record from 1955-1962 was synthesized and compared with the actual data for that same time period (Figure 6-B). The results for the remaining test data are presented in a similar manner in Figures 8-13. ACCURACY VS. CORRELATION The most obvious conclusion from these results is that the accuracy of the synthesized data is dependent directly upon the degree of correlation of the real data. That is, the correlation between the real data used to construct the double mass curve, can be used as a reliable indicator of the accuracy to be generated. For example, the synthetic data in Figure 6-B was generated using real data which highly correlated (r=.955). The accuracy of this generated data is expressed by a per cent error value (4.1%) which was one of the lowest obtained. Examination of the rest of the results proves conclusively that there is an inverse relationship between the -51correlation coefficient (for the dependent station data and the surrounding station data) and the per cent error values for the generated synthetic data. This is demonstrated in Figure 7 in which per cent error is plotted against correlation coefficient. To better illustrate this relation, the possible correlation co­ efficient values (0.0-1.0) were divided into ten equal intervas and all observed per cent error values falling in each interval were averaged. This result is also shown in Figure 7, and serves to reinforce the existence of the relationship between correlation coefficient and per cent error. From the preceding discussion it is apparent that it is de­ sirable, when generating synthetic data, to find the combination of surrounding stations which have the best correlation with the de­ pendent station. In this study it was found in every case that the correlation coefficient was always highest between the dependent station data and a single surrounding station. In other words, when dependent station data was correlated with every possible combination of data from a group of surrounding stations, the result was that the highest correlation always came from the dependent station and a single surrounding station. This observation is not meant to imply that the above result will always hold true. However, this informa­ tion may be useful for any hydrologic study in which it is desirable to find the combination of sets of similar data which has the highest correlation. -52EFFECTIVENESS OF THE DOUBLE MASS ANALYSIS The curve in Figures 8 -A and 8.-B demonstrates the effectiveness of using the double mass analysis as a consistency check. This curve shows that a discontinuity occurred in the data around 1950, thus causing a significant slope change. Examination of the U. S . Geological Survey records revealed that the discontinuity was caused when the gage at the dependent station (Locate, Montana) was changed in 1947 from a "staff gage" to a "continuous recorder;" To obtain .the average daily flow using a staff gage, the observer 'will read, the gage twice a day and average the readings. However, if -a large daily fluctuation in the streamflow is characteristic at the particular location, the staff gage is not likely to provide a good estimate of the average daily flow. In fact, depending on the time of day at which the readings are taken, it is possible to either con­ sistently overestimate or consistently underestimate the average •daily streamflow. The continuous recorder, because it does provide a continuous .record, allows a more accurate estimate of the average daily streamflow to be made. In this case it was assumed that since the continuous recorder provides a more accurate record, it is the period of record taken using the staff gage (1939-1947) which needs correction. Figure 8 -B shows the results of predicting synthetic data with­ out first checking the consistency of the existing data. The syn- -53thetic data was obtained by using the line of best fit through all the double mass points in Figure 8 -A. Synthesizing data using this line, which disregard's the discontinuity in the double mass points, caused the synthetic data values to be consistently high. In this case the double mass line segment which should be used for data generation is the line in Figure 8 -A which passes through only the double mass points above the slope change. When this line '..was used for data generation, the resulting synthetic data was definitely more accurate, as can be seen by comparing the different sets of data in Figure 8-B. It is also evident in this case, that in early summer large quantities of water are sometimes diverted above the Locate gage. This is illustrated by the actual data plotted in Figure 8-B, which : ■ shows that several years of record have very low flows recorded for the high runoff months of May, June, and July. Since diversion records for Montana are practically non-existent, the accuracy with which synthetic data can be generated for rivers subject to diversion is adversely affected. However, it should be noted that the procedure for estimating synthetic data for these river's is no different than - it is for rivers with no diversion. That is, an attempt should still be made to find the combination of surrounding stations whose data show the best correlation with the data from the dependent station. It might happen that a particular surrounding station (stations) measures a flow which is subject to. the same diversion pattern as the -54flow measured by the dependent station. If so, it may be that a rather high correlation exists and thus, synthetic data may be generated' which is fairly accurate. Another observation that can be made from the results is that in some cases the deviation of synthetic data from actual data follows a definite pattern. (See Figure 9 -B). Specifically, it appears that rniany synthetic data values are consistently higher than the actual .data during some months and consistently lower during other months. In cases where this "cyclic variation" appeared to be well defined, it ,was found the accuracy of the synthetic data could be greatly improved by the following procedure. I. First, a period of synthetic data is generated and compared with the actual data. '2. Next, the deviations of.the synthetic data from the actual data were computed for each month throughout the period of synthetic data. The deviation values for each month are then averaged to produce an "average monthly deviation" value for each month of the year. 3. An additional period of synthetic data is then generated, and the average monthly deviation values are added alge­ braically to each monthly synthetic data value. In instances where cyclic variations were well defined, the above procedure resulted in altering the synthetic data to more -55accurately compare with the real data. 9 -B. An example is shown in Figure First, the average monthly deviations for this data were de­ termined by comparing actual and synthetic data for the ten years previous to 1950. Next the synthetic data shown in Figure 9 -B was generated (dashed line). Then, by applying the average monthly devia­ tions , the adjusted synthetic data (dotted line) was found. When these data are compared with the actual data from 1950-52 (solid line), it is obvious that the adjusted synthetic data is a significant im­ provement over the original synthetic data. This fact can be expressed numerically by comparing the per cent error value of 7.1% for the synthetic data with 3.2% for the adjusted synthetic data. Another example of increasing the accuracy of the synthetic data can be seen in Figure 10-B. In this case the per cent error value for the original synthetic data was 13.2% and the value for the adjusted synthetic data was 5.1%. After examination of all the results, it was apparent that cyclic variations are much more likely to occur in streamflow data than in precipitation data. Several attempts were made to increase the accuracy of synthetic precipitation data, but because of the erratic nature of the particular data, none were successful. This does not suggest however, that cyclic variations do not exist in precipitation data. Rather, the point to be made .is that unless cyclic variations do exist in the data (either streamflow or precipitation data), any attempt to use average monthly deviations -56 to improve the accuracy of the synthetic will be unsuccessful. If it is necessary to further quantify the accuracy of the syn­ thetic data, monthly per cent error values can be calculated by the data generation model. An example of a set of these values is listed in Figure 12-B.- These monthly per cent error values provide an indica­ tion of how accurately the synthetic data values compare with the actual data for each month of the year. By analyzing both the per cent error value and the monthly per cent error values for a set of syn­ thetic data, it is possible to better judge how well additional syn­ thetic data can be generated for missing periods of real data. PROCEDURE FOR OPERATION OF THE DATA ANALYSIS AND GENERATION MODEL The final objective of this study is to determine the optimum operation procedure for the analysis of existing data and the estima­ tion of synthetic data. The procedure is developed on the basis of the results obtained in this study and if followed, should yield the best possible results from the data analysis and generation model. I. First, determine which combination of data from surrounding stations exhibits the highest correlation with the data for the dependent station. The results of this study indicated that the accuracy of the synthetic data is proportional to this correlation coefficient. Also it was found that a single surrounding station will probably have the highest correlation. -572. Using the data analysis model, check the existing data for consistency and make necessary corrections. 3. Next, generate synthetic data for a period for which the real data is known. Determine the accuracy of the synthetic data by calculating the per cent error value and also the monthly per cent error values. It was found necessary to have about ten years of actual data for proper data analysis and an additional five years of actual data (concurrent with the synthetic data) for the true accuracy to be determined. Results which are obtained using shorter periods of actual data should be used with caution. ■4. Analyze the synthetic and actual data to determine if the variations of the monthly values tend to be cyclic. If cyclic variations are suspected, then the average monthly deviations should be calculated and applied to the synthetic data. If the application of these deviations increases the accuracy of the synthetic data, only then is their use justified. 5. ■ Estimate synthetic data for the periods of missing record. The per cent error and monthly per cent error values determine the confidence to be placed in this synthetic data. If cyclic variations exist, then add the average monthly devia­ tions to the synthetic data to obtain the best possible accuracy. Chapter 7 SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH Since 1968 the departments of Civil Engineering & Engineering Mechanics and Industrial & Management Engineering at Montana State University have worked to develop a state-wide water planning model. When completed, this "state water model" will be capable of determine the distribution of ground and surface water throughout the state for any specified time interval. At present, about 80% of the existing precipitation and streamflow data for Montana have periods of missing record and are, there­ fore, unsatisfactory for use in the state water model. Also, all inconsistent periods of record must be found and corrected before they can be used in model studies. To solve these problems with the existing data, a computerized data analysis and generation model was developed. This model utilizes the double mass analysis to check the consistency of the existing data, and then after making any necessary corrections, the moded. uses the double mass equation to fill in periods of missing record. The following represents the procedure used to test the effect­ iveness of the data analysis and generation model. First a group of 20 precipitation and streamflow stations in South Central and South Eastern Montana were selected. These stations were chosen so that a -59 variety of topographic and precipitation conditions were represented. Next, a period of data from each station was analyzed to determine if inconsistencies were present. At this point any necessary corrections were made and then a period of synthetic data was generated. This synthetic data was always generated for a time period for which the actual data was known. In this way a comparison could be made to determine the accuracy of the synthetic data. The results indicated that the correlation coefficient (between the dependent station data and the surrounding station data) could be used to predict the expected accuracy of the synthetic data.. In this study the "accuracy"'of the synthetic data was defined as: accuracy = •— ---Hs.1 = E M= Where, M s = The mean of the . synthetic data. Ma = The mean of the actual data. Also .present in the results was evidence which demonstrated the necessity for testing the consistency of existing data before syn­ thetic data is generated. In addition it was found that in some cases, especially with streamflpw data, the synthetic data differed from the actual data in a definite cyclic pattern. When these "cyclic variations" were well defined, it was possible to improve the accuracy of. the synthetic -60- data values by adding to them "average monthly deviations." These average monthly deviation values represent the average of the differences between the actual and synthetic data for each month of the year. After reviewing the results of the cases' which involved cyclic variations, it became evident that further research in this area is indeed warranted. The first step should be to determine and analyze the natural phenomena which cause cyclic variations to occur - both in streamflow as well as other types of hydrologic data. Also, additional analytic techniques should be developed to take advantage of the cyclic variations in predicting synthetic data. One such method might be to fit a cyclic function to the double mass points by use of Fourier series. If this could be done success­ fully, the synthetic data obtained from this cyclic function could be much more accurate than if a straight line equation had been used. APPENDIX A. LITERATURE CONSULTED 1. Beard. Regional Frequency Analysis, (Sacramento, California: U. S. Army Corps of Engineers Hydrologic Engineering Center, 1967). 2. Chow, V. T. Handbook of Applied Hydrology, (New York: 1961). 3. Cochran, G. F. Optimization of Conjunctive use of Ground and Surface Water for Urban Supply, (unpublished thesis; Reno, Nevada; University of Nevada Library, ]968). 4. Crawford, N . H., R. K. Linsley. Digital Simulation in Hydrology: Stanford Watershed Model IV, (Report //39, Department of Civil Engineering, Stanford University, 1965). 5. Cross, W. D. Johnstone. Koland Press, 1949). Hill, Elements of Applied Hydrology, (New York: 6 . Fiering, M. B., Barbara B. Jackson, Synthetic Streamflows, (Geophysical Union Washington D. C. , Water Resources Monograph //I, McGregor and Werner Inc., 1971). 7. Foster. Rainfall and Runoff, (New York: Macmillian Press, 1948). 8 . Linsley, Kohler, Paulhus. Applied Hydrology, (New York: McGraw-Hill, 1949). 9. Linsley, Kohler, Paulhus. McGraw, 1958). Hydrology for Engineers, (New York: 10. Meyer, A. F. The Elements of Hydrology, 2nd Edition, (New York: John Wiley and Sons, 1946). 11. Mount-,- J. R. Manual of Computing and Modeling Techniques and their Application to Hydrologic Studies, (Texas Water Com­ mission report #100165, Austin, Texas, 1965). 12. Sing, R. "Double Mass Analysis on the Computer." Journal for Hydraulics Division, January 1967.. 13. Wisler, C. E., F.' Brader. Hydrology, 2nd Edition, (New York: John Wiley and Sons, Inc., 1965). A.S.C.E. APPEIiDIX B. . PROGRAM LISTING ceVV£»N x(o:?»0), Y(i:3so), xsu'Konso), y s u m (o ;3s o ), I X > (130), XYSUM(3S3),XY(380),SjMnIF(380), SLOPEf380), 1YINT (33?), SUV3ir(?PO), S S - D E V (330), D E V (330), SLSy T (0: )':ATl3(3aO), E S w O P E (333), B D E V (350),S L 2 C W K (380), Y TJ T B(3 lXX(ji",r),YY(33:,2), ?II(3P0), XXX(383),YYY(3«0), I X 'Os?), YBAfOsn),YAR(P), STDEV(P) , SKEW (2), I C5-E9, N, v, L> A\, IT, JJ, I YSI\|( 12,31,5), YSJVSt 380, 5), DEVMGf 12,50), AVMGDE (12 ) E D V a "SlpN TySI'Tf330), I=NTl(3S0), I=NTP(330), IBREAKfO I XiSV(330), RAD=V(380), XCALC(320), P(380,2),JXY(IO) I, IYR (31 ), IDO) C C RrAC IN' N,r,L,NX N= NUMBER C STA. Ms* P= Y DATA CARDS, REAr . (105,1 ) \, m ,L 1 = p R “ AT(3llP) R t rE (IOS,30=) =03 Fp:'-T{IN = TMr MJMS=R r r BAS= STATIONS...M,NQ, GE Y 1.., L =XP- '1E PTS• PV m a s s CURVE',//) V R T ^ r (103,191) ID1 Epx 'AT (1OX, ":',13X, 'M *, I OX, fL l ) IlRITrt 10%, I 92) N , M ,L 193 F O R " A T (3110,//) C C READ IN ALL Y DATA IN ORDE^ C PUTdUT « ' PJT=JT ' TD NJM =ERS 9r SUtTRGUvDING STAT IGNS ' PUTr JT ' ' =P 10 J = I,N iy 11 = 1 ,M TC(J), IYRf I I),(YSIN(K,I I,J), < = I, 12) 2 FpPwiA T ( I4, I3, FS • I, 11F6 • I ) dp REAC(105,2) 15 CBNt INUEPUTdUT ID(J) 10 CPNTI NUE CP 361 J = I,N II = I K = O —6 3 “ 4 r = i,L r K + I VSI'C(IyJ) = VSTMfX, I I, J) ir(- ■ .F-, 1 P) I I 'Ti' •3 N-• I2 ) < = C u-r L RN/ Is RF 161 CL RT I' RE II re 362 r r RE AD I • X : ATA F"=R STAT ISN IN d u e s Y iSN c re 2o U = IyV REA : (I CS,B ) ICx, IYR(II) / (XSlNGfK,I I ) S FQpl A"I C TH 13,FE. I, MFfe. I ) Pr CQNT IN Lr II = I 3 H O = H -O C N 3C I = O L < Z I.+1 = YSI N 3 ( k , I I ) 4 X(T-I) H D IF I' •C . I") I I = I I*! IF (• .E f . T E 5 < = O CS-* I(■'u E 5iir\T ' ' K Trv i I n N U M B E R RlR BASF FUTf- L T IEX FLTfjL-T ' ' C l Tr L T - STATIRNi '' C CALCL LATf Y SRDILAtE Fee* SUPR&UT I\E QRDSEN,' > F I7 E ( *CS i I B S ) CTF-N AT (//, 1 CX, lL T S T T x a Sr X(I) AND Y(I) WHI CH AR[ THE If a Ih S CE? Te CQNSTRUCT t h e DBUBLE v a 5S CURVE I , / / ) *r ITE ( U ' r , I Cfe ) ]c C S R A I ( I - X/ 1 * ******* + * » * * * * * * * , ******* + * t * * * * * * * * * * * * * * A R I T r (I r s , in=) I 99 5x , 1X ( IYEAR = IYR(I) .i RSR A lc / / , P I)' , 2- X ,IY(I)I,/) —64— TH = I ^ 1= 1 ,L D? , . r !:.=:(I r ? , ^OC) ECT F 9 FV A T ( 1CX, X ( I ) , Y ( T ) , I , I v 9 N T H , IYEAR ?E2C*5,3I7) IE (I"t* TH .Er. 12) IV9VJM =Gj IYEAR = IYEAR + l = T V9KTV + I I TE CffYTlNi jE I“ S ' 1TH C C C CALCULATE. THE X(O) = V ( O) = r.o X AVD CpVT I CALCULATE E9 R STAT C.C DO £ " ; 5 I = I , L XX(1 ,1 ) = X (I) X X(IiE) = Y (I) C Y -X ( T - I) - Y ( I - I ) KVE STATISTICAL DATA r R 5 M SUBROUTINE STAT C Cr ir t’-lti. r i » ?* tf t( * * Vit * <!Htt . *■ii# Ut *■*■**■# Kit Utl a Hfftt Hite *i AN = L CALL BTAT »RIT E (IC S , laH) 19=5 F3R Ca T(//,10X, 'OUTPUT OE STATISTICAL DATA F 9R X(I) ,-R I Tc ( l o g , I AND 96 5 I °6 EQRviAT (I OX, 1**************************************** I, a W I T £ ( Ic?-, S ) 4 E 9 RV A T ( / / , 1 C X, ' Y E A K ' i l C X , »V A R I A N C E ' , 1 0 X , ’ STD c 9 J = I ,E DEV ,IO X ,' DO , - R I Tc ( 1 0 < , 1 ) X V.R ( J ) i V A R ( J ) , S T D E V( J ) , SXEW( J ) a E 9 Rv A T (E S C ,I ,E I 5 , I,E E O •I,E I C •I ) CO XT I N JE • ’? I T r ( I c 3 , 1.1 ) ii E9 Rv' a t t / / , 3 f j X, ' C s r r e l a t i nE I T e i l c ? , I ? ) C9 RCQ qn coeee. 1) IE EQRY a T (E45.5,//) W R IT e (lcs,197) I ° 7 (T9 Rv AT ( I D X , ' * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * C* <i& tf u ti t; z H tin H t;it it tH $ 11#Uttttait# a IHitiftMtt ttfttt tta twit itit^ttU H T*-MHtmatittti X unit C —65— C CALCULATE* TL E* "1 BF ST^AJ g ^T LINE THRBU g H PTg. C XE.U (C) =C •D YSU-(C) = : .o XYSL-I(U) = 0.0 CALCULATE ApAR AvD YBA r O O H = C KK = 0 INET = I 17 De -6 I = KK = K U l XSUv (I) = YSUv (I) = AK = KS XE A R ' I ) = YpA-M I ) = calculate IN P T i L X S UIM I- I ) + X(I) YSUIM 1-1) + Y(I) /SUK(I)ZAf Y S U f ( I )Z AK SU *'1 ac" X(I) AND Y(R) XY(I) = X( D *Y( I ) XYSU y ( I ) = XYSUv (I-I ) f XY(I) C CALCULATE SUM X-XBAR SQUARED S U r- Mr = C . r XP = X ‘-Ad ( I ) PB SR , = T'■PT /I /r [Fr = > ( M -X : DI-Sl r XDirr*XDTFF SLMIr = SUOIE + D IrsQ SC CE »TTN-.-E SL1 --IF (I) s SUDIF C C CALCULATE SLBdE P f LlNr SLSciE d ) = (XVSJM( I )-( (A<)*XEAR( I )*YBAR( I ) ))/(SUMDIF ( I ) XM(I) = X B A R ( D t S L B P E d ) —66— Y I N T (I) = YBAR(I) . XM(I) scY^r = 0,3 YB = Y --ARt I ) De 13 K = IXPT,! YCIpr = Y(KT)-YB YC IprSU = Y-'Ir + YDTF S V Y D I = SUV)! + YlTFSS 1:3 CONTINUE S L Y D IF" ( I ) = SUYDI SSSD f V(I) = S J Y D I F (I)-(((XYSUYt I) -AK*XB a R ( I )*YBAR(I > > I/ (GL-YU IC(I))) L = (SSSnEY(I)ZAK)+*.5 ICD = S S S D r V ( I ) r ^ GET Th: ST". EST. cE VERTICAL DEVIATIONS C rI Y v p M CARDS UE-(T) = (vSCDE V ( I )/(A <))**,5 IFt 11D *L T » ')) DEV(T) = 0.000)39 T9 19 In S C - T ( I ) = ( Y ( I ) - Y T M ( I ) ) Z X ( I ) RAilDt I ) = CSLB3 Et I I-SLB d T (I ))ZSLQpE (I ) R - P AT 19 ( I ) IF ( I •L T • IN = TtO) 39 T° 56 IF ( I.EO.L) 99 T 3 70 IF tAp.S (P AT I9 ( I ) ) .L T , *3 ) 38 T9 56 IF CA B S (RAT IP(I)) .GT. .35 G& TO 40 >U VJ C'-EC< C l OP p 03 LIVr BrvgNl BREAK POINT rgR DEVIATIONS 40 II * I OUTp UT I I 41 CALL SLCHCK(CSLO d E, B D EV,X,Y<I I,Y IN TS j XXX,YYYi I I I ) -R IT e ( 1C3, 7? ) 7C reP-iATtz/Z.lOX, 'BACK SLOPE M O X , 'DEVIATION', 10 X, IY INTE I '.*.( I ) ', IOX, 'Y ( I ) ', 5X, 'POINT' ) Df' U I = 1 1, I If PO -RIt P (109,73) 3S L B P E (I ',BDEV(I),Y l N TB(I),XXX (I),Y Y Y (I), 73 FC-Pv AT £BRlS »2, I4 ) 14 CeNTINUF U U DETERMINE POINT I-HFRr SECOND SLOPE TOLEtU N C E IS M£T -67- C PKr 'Pe ;' T FIRST TpLEr;AVCF FA5 MET C CAL'- LIf-EC-< •VI Tr (I o s , - 7 ) Tj F7 FCT ( / / / , I C X , ' XY WHE=E FIRST TOLERANCE WAS M E T ' , 14) WRITE( : r S , 4 C ) JJ 6 :. Pf V a T(///, l e x , 'XY /MEr3E S^C' T9LERANCE WAS MET', J4) I VFr = (JJ + I I )/2 WR IT E ( IC ^ - 1 3 ) INFT Pis PER AT(//,lOX,'NEW PFCCIN AFTER SLPFE CMANSE IS ASSUMED X S v •" ( I 1' F T - I ) = Y g L ' (I'P T - I ) = X Y S 1. V t T k F T - I ) KK * sc Tq 0,0 0,0 = 0 . 0 O e : B a ccv rIN,r SC rP /I Y C v[ ^ 17 A 1 ' CALCULATE LINE EQ, FRpk- r-n T t P L C 8 C M = L-+1 JBr-! AMt ) = IN- T GC 'S 17 C<C<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 70 TL ( Ik.PT. NE, I > 5 P TR 90 ..RI fE ( I r F i -iI ) 31 FOR Al ( //,rx, ,Y r i ,2 x , 'PRINT' ,5X, fSLRFE', 8 X, 'F o I, 'YlNTERCFPT t, EX, •STD. CEV ',5x, 'SLRRE r3A ',2X, 'X D E V ) IYE Ar = IVR(I) -I IMt'TH a IS ,k2 I = I , L VCA 1 -C(I) = (T(I)-YJNT(L-P) )/ S L S F E d -3) XCE' (I) = V(J) - X C A L C U ) n 11 DC CALCULATE t h e STC' DEVIATION R f X DEVIATIONS S = 0*0 DR <3 I I = 1,1 DSC = V C E V ( I J )+ X D E V (11 5 S = S+CSQ —6 8 — 61 CC-v r If')-'' Air = T SN. = s/4 I I I cr.V ( i ) S'. * *■« s s IP q Jv-T ( I ) = T -\ U T T 4 7 T | / j Z c ^ ; | " - * * ' I * 9 r T ( I ) , S L q P E ( n , S L 2 P T ( I ) , * (I ) I- ry a rA T (C Is ,: r I h .P, Sr t 4 .P ,F IO •2 ) ir ( / 0 ' rw «E » 1 2 ) I mOVJH = C; I VEAP IYEA2+1 Iv r ' I H : I 10 \ I M + 4 4^ CpN T IfNu1E ALL SI' ''c ^ = 0 ' " CO ( 6 I = • ,L SC ' X = I )»XDrV( I ) Si ' I = Su "SC 4. SCuAP f*O ‘ • 'ICvC SI • v = C J m ^ c z a l l r i~ . C V = S " 5 * * % ” T T ' ' /K J £)'; T- 'j s;><-v-vS T ^ ,r)E:VrArieN 0F ALL IU| X DAT A D E V I A T I O N output ' ' •'U t" .1T 1 *T<6$ » * * $ $ $ $ $ * $ ■ $ : $ i P! 1Et l' S,226) SLO c5E(L)^VIVT(L) 3 3 ^ AT U C X , . NO SIGNIFICANT SLGPE CHANGE... .► / • Ji j X f" * j F~"7f ' I ) PU' : JT 1 * v|;rS$.r.$«F$5$s$$«r s$-6 t SC 7O 928 9 V M -t E ( I - T j II) BEST EQ. IS ''-ESrElFessissi1-"2"':A R & R I V Th = 11 IBr1NAk (C ) = I DO 03 V = I,H DO °1 I = IUSE a M H h - I ),(IBRrAK(HH)-I) IPv-t H I ) I < 0 E ' - t n ,/ x ( i i i J c l L c I n 8REAK<H,),’3,,/SL,,PE<IB* E A K , w o *'1 — 69 — C C C r I CUL A TE THE c TD, DEVIATION Ar X DEVIATIONS S = CD ND DS7 Ti = I, I NS = NDEV(Ti),/OEV(II) q = o + c ;’ O f CO', TI' h :-r T a 11 : SK = S / A l I T DEV(I) = SN**.5 RAr -Fv(I) = XDEV(T)ZDCV(I) f-H e (Ir * / 1 4 ) I'"RNTH. IvEARj I • S L O P E (I)/ S L E P T (I ) I )/ r-A T ID-( I ), yDEv ( I ), DAr-EV(I) 34 ^ - V a H e TS, I4,E-10.?j2r V . ? , 3 r ' 5 . 2 } I R d - O Th .[0. IE) Im o n t h = C ; IVEAR = IV E A P + 1 p. = - TH = I "OK T m + I SI CO"" I N .E R P E l - r a J TP ) T- t O Al (/Zj : D y , f :**#*•**•<$*<«•4;$SFt.$r SLSPF C-jANlE I - '/ZZ) 9' Sf N" [N -L HH = H .0 Sc I = ( TPPEA<(Hu)),L IF ( I TH .ED. 12) !MONTH =C #*IYEAR = IVrAR +1 I('Dr Th = IvfjNT^ + I TPNTp(I) = I XCAL C ( I ) = ( V ( I ) - Y p iT(L))ZSLDPir(L) X C E V (I ) = y ( I )- x C A L C (I 5 CALfLLr TF 'HE STD. DEVIATION OF X DFVIATIDNS S = C •D CD E SM U = I j I DSD = XD E V ( I I )*XDEV<1 1 ) S = S + ESO C G N t IKLE Ain = r SC « SZA I I I D C I (T) - SN**.5 R ADCv(I) = XDEV ( D Z D C V d ) NRI7Et ICS/DR) IMONTH/ IvFARj IP N T E (I )/ S L O P E (I )/ S L E P T (T > I I )Jt-ATI = ( I ) , XDEV ( I ), RArEVt I ) —70— 3 cp..;' \ T ( r ? ? , T t , 3 r i o , ? , 2 r i 4 . 2 , 3 F i 5 . 2 ) P- CO'.1 J\\ c ;iT- T ’* * * < ***■## * 4 # » * * # * * * # * » * # * # * * # * * * ♦* ****# *#*# ##*< " IT- c I o’a ) •I „ Cf ..'I '//, ::' t »t.-FS ?$*$::-**$*.?*s /MXARY O U T P U T IPC = I $$s »$$$$$$*« -/"I?) !P E 3 / 13 - r *x (i ) I V 7 r(V<--AT (//, 1~X, 'CPR PO I .TS F P S M '/ 13/ ' TO' / 13) •P ITr (< "-, " I") SLOPE ( I =1PEA X ( I ) - I )/ V I\'T ( IPPEAK ( I ) - D 114 F C :\ AT ( iCX/ 'Y = '/ C7»3» 'X + '/-7.0) MjT-'JT ............................................... ' CO 37 T iU t 1J s J. / - 1 - 1 -P I’P ( :rS,32C) TPPCi<( -IK), I n R E A K ( H 1-Hl) CQT 'AT ( In X, 'Pb ■? n P T siTS trnP -1' /13/' T O ' , I 3) IH ■ “ I : 'E.A < (u H 1 ) -2 JkDEC i;v Cf- at -/I??) S L O nP ( H H K ) , Y INT (UHH) (; :x, 'Y = ',ci.3 , ' x +',F7»O//) JUT' IT •. . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . ' — • <- 3I T T Jr" 'I T l I is, H O ) IlRCAK(A) ,L 13' CO v \ 1 («-x, 'FOi POINTS F R B X ' , 13,'T9',13) /I-:: L ( I - 3/135 ) SLPnE ( U , V J N T t u 333 FBk 1A T ( IEX/ ' Y = ' ,C7.3> 'X *',r7.0) C C c c a l c u l a t e “Bn t h l y m E a n s a n d s t d d e v i a t i o n s C t -;* m cl - -s>.; *$*■ ^ I $ ' t *$■-$*$*'?$$$*$ i£ s $ f s t i & » $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ C ?9'T I I = I < = 9 DB '7 D I = I,L < = <+l DEA11BCK, II) = X1DEV(I) ire cr. A ? T C B vl D C 1 2 ) < = o; 11 * 11*1 • A S S J m E DE-Vm K I, I I ) = O C T e i E S o o n NIC- AH = I I C Calculate monthly ANYr AS = NjYEAS -f a n s -71- DO ^<9 '< = 1,1? T = O • .) Dt5 4OO II = I / v J Y E a R t = I + J r v Y J ( K ^ I I ) *1 ) 4 0 D Jt v . ' ,r •'.V- :L (> ) = I / A VYE a P 4«0 Ce V IVvE CALCULATE STD, CE V ce ^oi K = 1,12 T = 0*0 CO iOH TI = I,XJYEAP TSC = Jr v/ijo (Y , I I )* Cr YYO T - T+Tgl 4O :■ C e 1-T IXv:. 3T / 4(<) = ( T / ( 4 N Y [ 4 R . 1 . 0 ) ) * * . 3 >qi CexrINvv -.jT- r K T iXjt 1 • 1 vTAN SyvDEV Oji**-' .-r f I DO livI1* K = 1,12 -'CItE ( lc8,49?) <, AVMfiCE(K), STCMfi(K) T 2 - 4T(i ox, I ? , l 5 X , F i o * 1 # l o X , r i j . l ) 404 CQXf Ii NL1E Ct-HST*** + C C CALCULAtE TvE PARAMETERS NECESSARY Tfi PLfiT V VS Y X = L Cfi CvH I = I, N =(I<1) = X(I) =(IxH) = Y(T) 3S2 Cfi-r IXd; fivT'^jT ' ' OUTn UT ' ' OLTn JT ' v EAXS CF Y AvC X ' S L1T-vU T XPAR(L) OUTnJT YfiAR(L) CUT=JT ' ' fiLT-vT 1 ' tMO %+ $$ + ' -72- SU-'' )UTI\'E SL C H : < ( S s L e ^ r , D D E V , X , Y, I I,YINTS,XXX, YYY.» I n <> ;I■ -I•■S In'• Y ? M (Ci3®^)> YSUvU O : 3S0)/ XYSl'M (OI 380 ), X 3 I Y 3 ( 1 ),XY(SyO), XM(SSO)/ SU m D I F (380) • : U , XXt(SSO), vYY (SSO ), IIIfSfj''), X( 0:380),Y YIVt I( ? " O ) . YS- M i ­ I ) n i - .1-) SLYDTr ( 3 5 0 ' , SSODEv (3 8 0 ) = CM /SU* = O M x Y3 . v i i - I ) = 3 . 0 SMCuLxTr XPAP AN;D Yr-AP C X = D DB 56 I = 11/I I+SO .XX(I) = X M ) Y Y Y ( T ) = Y(I) IIJ(I) = I .. 3 <+ 1 Si/' ( I ) = \3;> (T-I) YS1 - ( I ) = YSL-U T - D + X(I) + V(T) X = < XL-"' (I) = /S l v (I)X a x h V- (I) = YSuM(I)ZAK C ^ a l CJL A tF SuM ^F X(I) AMD Y( 2 ) AY(I) = X(I) * Y (I ) XYSV--K M = XYSJM(I-I) + XY(I) C C CALCjLATF SLm Dr X-A3As SQUARED r GL-Orr = O M X 8 = X ;A x ( T ) rU- £2 AHl-F rK r So SUDIF J = = = = I I/I X(J)-XS X D T r FtXDIFF SiJ-KF + OIr SO 82 CO'-tINJE SUv-L IF(I) = SLDIF C : -ALCULAOc SLSPE SF LINE -73- •SL' H = (X Y S J M ( D - ( U K ) *XSA4( T ) YSAP(I))) -M ! ! ) = X P a p ( D ^‘ S s l ? pE H > l'I '(I) = vlVAR ( J ) . XV(T) -L VSr = YP = Y S A R t D ''r J Hj v>» !!,I YO l t- = Y (K O - Y P YCIcrSQ = YC IP* YC TF SJYCi n = SUv D l + YDiFSS cbntinue SUYCTF- ( J ) = SUYD? SS ' CYfT ) = S J Y n i n I )-(((XYSUMt I ) - A K*XBAC(I )# !/(SUjUIF(T))) '-Df ' ( D r r S-CRVt I ) / ( A D )** ,5 r. C N \ 1 TNiUf UETv p n o fn —74— Stiif U T T V F L I N E C H K ^ a IS SSP AN# Y .''( 12, 31, 5 ) / I I/ D T l-' SIPN %4SL(3S0) YB/Sr r XP a S a - Y(H) JJ1 Y S I NS ( SgQ, 5) D E V M p (1?,50)> AVMPDEC Y(TI) SL ' E - K ( I ) = C. Q "f r" J = 3,|_ w 'NCw-) = ( Y3 a SE - v (J ) )/ (XP A S - ■ X (J ' ) “F < ^ s ^ , Ct ~ ’N -F Ju - J u[T ,S\ ENC jT '1! ’/ 3 ' L 9 P ' 11' l2£ -75- Sample o u t p u t fro m d a t a a n a l y s i s p ro g r a m . L = Number of data points. 1 2 .) 'Br 1'5 r F s V-RbUN OI NG STATI ON' S GO 90 9005 NV11-1F-' - e 2 't: LISTING OASfT S tATISV -T <(I ) AND V ( I ) WHICH ARE TH[ G RDEFrD PAIRS *******<**#^***»******#+***********##****** V(I) X(I) Si *' 0000 70,00900 1?5. O 11OCO :t s , "9000 166,99C C 0 493.90900 g 1-0.99000 I 0 5 A .39 9C 0 1555,00'00 !£^7,90000 2016.OOOCO 6 °lA.COOOr 135s2,90009 18473.0,COOC 2 1 2 4 6 . COOOO 25522,90009 31597.90303 38308.00000 5 4 7 5 9 . “0000 85569.90000 95977.90000 99250,COCOO I 2 3 4 5 6 7 8 9 10 U 10 11 12 I 2 3 4 5 6 7 8 —76- 3 .St?:- :I £ T /) 36tiy, T u'RE CH.\5 XP" TH I ? 3 4 5 6 7 S 9 IC II I9 nEST ES. TS $$ • * vRAN -P24.S -331.3 -471.7 -553.9 -364,9 399.1 -93.7 733.7 477.0 2 3.5 -1.07,2 -271.3 STD.DrV ‘ 1258.0 1313.3 1371,5 1409.0 1234,7 937.4 394.3 "O'). 4 1054.6 1:27.4 1124.7 1183.3 v 29.O33X + -77 Data generation program. CO' 'Oh Ixv Ip X10,P), ImI3PT (lc#2), X(Oi^OC), Y (600 )> IMD(GOO) >I M . / - F r?EA<,NPE=?> I Y S t' (I'',40, = ), vsi\l(5"3,5), 10(10), IYPR ( 5 0 / XSI NG (I?, SC I IX" NtM * O/*’), B E E N , M C T I ’', c > r ' R ( ’OC), VAC(P), STDEV(P), SKE (2),CORED, AN o r -- SII-'' xKM* " ( I " , 2 ) , K^eNf lo), KM^NTW(IO), SAN INT (50/2) #U ''E "'(h. /), y ' A -0(5''')/ XFINAL(^OC), A V ‘ DDE (I 2) > ST D ID (12 ),r - X N * ( ' ? , r o , H F ?(l?),XFrN(l2,20), X ' t o X S (400,2), CE 112), X P (430), X N I (403),E R R M O f 12) I INTt f- , XK'5 N ^ • AL-L Y ''AT A AND C A L C U L A T E O R D I N A T E S n R L a O IN T-3P( I, J) , \ S R E a K, Iu IS3 T (1 1, J) ,NPER ■*-A - , x C - q P Si S 3 E CHANGES, r ,E 'UV-ER 'FRp QP P E R I 8 7 S -L ■ (I 'L ,I ) v SR e a k j VP- p .!CHECK, 'C- AT(?I1 ,rric.o,?!!'1, 14) * m q F d E r IODS QF ' " I S S I NG f X DATA Y ! \ T , SL 9P E, IMS(I),IYP(I)It M IF 'I^1-LCv •vr • ) 5 3° T I 339 OC I ’ = I. M-M E AK ^ RE/"(105,8) ICd ( I N I ) , Id P ( I I ^ p ) dC ' AT(OlD) C O t IN-E READ ( 1 3 5 , 1 0 N , M , L , IDX 'M--v AT (4 H O NVTdvT ’ Cv TdJT n ,m ,w QLTpUT QLtdUT ' * 1 1 1 ID N J v d ERS FQF S U P E Q u MOING S T A T I Q N S 1 1 1 CS H J = I ,V OC 15 T I = H v Cl Td v-T CUt d Jt CL Tp U t • RE A O (I NS,3 ) IC (J ) , Iv R p ( r ! }#(Y S IN (K / II/J )/ K « 1,12) 3 F Q M AT ( T4, 13,FS.I, H F f •! ) Ir- C M t INJE —7 8 - cH ’ c-. T U Il(J ) Cf' " r jr 91 T-' » > I 9L Tri T - H T 1JT (' I 1T V 1 1 I BASE E-TATIq V ID NUMBER * ##** ******* ********** * I ELt' -T ID < -M r ' , 'I Df ' L U II = I < = ; DC 3 ^ 2 I I, V I = I *L < = K + I Y E V C,( I, j) = V 5 IV (Ku I I/ J ) IF .DC. I?) I I = I 1+ 1 Ir ( < "DC. I?) < =" O ?f - Cf ' T V -1E Df " Cf" t I^ C r .'-LCLLf ’"t Y EDDTVATE cr^qv C:J3RCJT?VE 0RDGr V C Cf. -EC" LLC r S S A E Y R f d ISDS S ITH S U B R O U T I N E C S R e CT IF(IChLCK*' E.I ) CS TC 71 CALL CTPECT r T--A- V I 'ISPT ( I I/J) 7 • Df C'-)O T I = I, VRFR AL-H < * C, V ' C ) V IS r T dT , D iI^ IS P T d 1* 2 ) d ": r- D: H T (CIlD) CD: C D -"IVLE v > t. r Ir YDAtA .FEPC TC SE CSRRr CTED OS IT HElE x/xxxA/xxxxxxxx'/xxxxxxxxxyx v/xaxxxxxxxxx'/xxxxxyYxxxxx r D n 300 I I = 1 1 L3FF Of* 24b I = IVIS = K I I, I), IMIS = T C11,?) X(I) = ( Y d ) - YINT)/SLOPE C^c CeNTlNJE 3CD C O N t INJE n n —/ 3 — I X ^ O M = TME if P r I ?. VALUE X N 9 MN XDATA CApDS * /N'9W:N = BpUND^IES PF K N S 1 VK' x DAT A IE p T . NUMBERS IFC n KX .EC, r.) 39 T « 731 DC >?O 7 KK = I,NKX RfAE (1CE> '41) IX99\D( KK, I ), IX99ND (KK, 2 ) Al Ff}RN AT C2110) 2C7 Ce V1 INUE Df " D KK = I, h:<X DC - 7 1 1 = Iv B P N D C K K , I ),IXE6ND(K<v2) RFADc 1 3 5 ,5) T^x,TVp C I P , CX S IN D CK / I I ), <» 1, 6 ) RE A C ( 1 0 5 ,?) IDX,I Yp (I I),CXSIN3(K,I I ), Ks7, 12) "5 rpD-AT (AX, 21 A, 6r8«0) 17 c o n t i n u e I? CONTINUE DO 2 IA KK = IiNKX OEA' (105,215) X K N O V N C K K / I )/XKNOWNCKK, 2) 715 P j Rv AT(EIID) ?V4 CONTINUE n OLTp n r .. .T I ' ^tt=VIr • ' PEST9D ep X(T) I X M8N™ $$$$$$$$$ « « STA.. II ' I it = C CO ?08 KK = IiNKX DO 2D9 I = XK \ 9 K N ( K K i I IiXKNOWN(KKiP) K = K+ l X(I) * XSINSCKi II) + X(J-I) n n "E". 1 2 ) I i = T i+1 IF (“ .ED. 12 ) < = 0 PUTpL1T » » '•p ITE( I C 5/ 2 1 ) <( I ) ,k , IVr( I I ).i, I^x 21 FOR a t (1CX/F10.2/214,5 X , 16) PCD C O N t IN v E 2 CE CONTINUE OUTpUT 1 ' 0 U T ■■U T f • OUT p U t ’ 1 CLTpUT ' LISTING Or UNPANOOMIZED x v a l u e s OUT' uI ' ******* ** ************ * * ***** OU rpUT » pT . RtiTFtiT ' ' 1 1 X (I) X(O) * r *o De 777 I = I,L -80- X 1X (I) = X(T)-X(T-I) 1C8/776 ) IiXX(T) 77» =-eQNAT(iOX, U O i 10X,F10.l ) v.R IT E ( 7 7 7 C O X T IN U F C C "• : O I ? I'ST y 9 N T h OF S P E A K S AND V IS S INS d T R j = DS 7 31 I F d R R E A K .ES. O GO TO 732 DB ??! J = liN3PEA< • REACc1 C 5 >7?2)KXONTH(J) 7 2 2 P t?R ‘ AT ( 1 1 0 ) 721 C O N T I N U E OUTEiT KXONTH(I) 782 DC 7-3 j = I > N d E d T E A d l Si 7 ^ 4 ) < % O N ( J ) 724 rPR AT(IlO) 78 3 Cf n T I N J E OUTrLd KKBN(I) C C - E a D I' '0 T H L Y V A L U E S Br E a NS AND STP.DEV, 755 J = ! • i 2 DB E E A7 ( I C5 i 7 8 6 ) 7?- v A 7 M 9 D F ( JJiSTDYB(J) FgP’ AT (2 2 10 ♦ O J 725 CONT I N U E JC 337 I I = I iY - E A d I'd,A) IDXi IY R ( II )i (X'<NB/, (KiIIJiK=Ii 12) 6 TBRHATt IBi I3,F 3 . I,11p 6 . I ) 537 CONTINUE TI = I . K = O DB 833 I = IiL < = K+l -FIN(KiII) = XdNALf I ) 81 I r ) n =o ; 11 = I r*i — ir(< .[r. P33 r-R\T t n u e r. HJT[ T -if.; At1OrBRAIC AND ABSOLUTE O O C — I = t ^6 E 38 TI = I/ M Db rl9 ur = 1,1? X K I (I ) = X K N 8 W ( K , I I ) I = 1+ 1 ^3° CbN-1 IN 1JFP3? C O N t INUC CC = C *C C = 0*u ■DO '1.1 I = 1^L C = xF In A U M + C CC = XKT(I) + CC "’ll 05'.7 TNUE AL = L .-.VCi-'N = C /AL AVLACT r CC/AL ERROR = 1.0-(A V C S V N / A V E A C T ) O U T p ,1 ' ' OUTp -T ' ACTUAL PEP CENT ERRbR' SLTPjT ' ' Rl lTP' :T rPRHR '0 A 2 3 K = I # 12 RU' = ' •^ Db yD4 11 = I'O jr: = xPT‘!(*r, I I ) - X K N S W ( K i H ) CU" = H F T + SUM ??U C P k-r TNLC AM = M D IE1-1O (K ) = SUM/(AM/2,) %23 CPk- I N U E % CRPHD — 82““ DC 540 K = I , 12 V 1UT DIFMg(K) gU 24 0 CF V IlNiUF C CALClJLATr "4PNTHLV PrR CE NT FFRgRS r XF I' (1,1) = 1.0 Cd = OiC t = 0 .J OD V >2 '<= 1,12 DO 5/+3 I I = I, M B = XF In.(K, I I ) + D PB = X K V R W (K,I I ) + RB 04? CONTINUE AM B M A = R/m‘ AA = B3/AM rrr 'I (<) = 1.0 - ( A/AA) 04 ? C O v-T I N j F 111"'": 'T ' '3FR CENT OUTPUT error VALUES rOR F AC h M O N T H ’ ' ' % Lr RRR' O OtJTr - .IT ' M qi--TH VJ c 44 r ',I? rrTr ( IRS,%4B)<,PRRvg(K) V B rpN‘.-A T ( I 10. "I 0.4) ',44 CONTINUE C C C C C q M p a PE KNOWN dERIOO W ITH SYNTHETIC PrRlSD t T g L ti "'E STAT D 6 "AO '< = 1,12 IEADt I V , S7R) OF(V) 372 “ O 2 AT (r I.O «C') 36G CONTINUE C C I = D Dfc r51 I I = I, M DO F52 K= I, IP I= V l CK(I) = X K N R W (<,I I 5 S50 CS N'T INUF 351 C Q N T [NJE —6 3 — C ( = 10 10 F63 I = I,L <F( I ) = Xrp.'AK T )-ir (K) ]F(K,E3.12) K = 0 < = '<+ 1 CONTINUE C IP -34 1= 1 ,L yC(Izl) = -'-(I) xs(',%) = y<(i> %5'+ LONT IN JE C AN *= L CALL ST a T(XS) C OUTF5UT f I TjTt-LiT ' ' OJTF j T ' vE A+J VARIANCE I SXEN “ J TD jT I i IP F 34 J=I,'1 i'' TT *.(Ir j , -■a 5 ) Xa AS (J ),v AR (J ), 5 TIEV (J ),S<r ,'(J) 16F r s ^ U A T (/,P23.1 -13.1, r ? C » 1 , F 1 0 . I ) ;S'. CP‘»t IN-E O U T 5JT ' ' HUT-JT f C csRSEL a T IF*+' c o e f f i c i e n t ' D U T p UT C ntT D rT c' END —84— S U P tVfirr INE 4? 0 T E N Cn ' ' T * ^ ( 1 0 , P ) , I Y I S P T U C , 2 ) , X ( 0 : 6 0 0 ) , Y ( 6 0 0 ) , I MO( GOO) 4 .:/:•>I./ N3REA<, \PE?, I YS!' (12 ,40 ,3 ), YSIXC-(5C0, 5), ID(IO), IYPR(SO), XSINGf 10, 1 IX" cNO (10,2), I3EE.N, VCTIu , 2 XPA r (4c0), VAP (g ), STDEV(Z), S K E N (2)#C9RC3, / DI M E NS IO N Y ^ (3^ 0 ), v o r i x (330) r C CAUC JLATe t 3T A k PRICIP ESP ALL SURRSUNDINS STATIONS on 5i i = i,L Y P( T) = Q.C J = 1, \ ns YP(I) = Y S r:r>( i,j) + Yri( I ) S-,. CON t TNNC YPFlN(I) = VP(J) 53 CO NTINUE C CALCULATE Y(I) UWICH IS S R D INATE SN DSURLE v4ASS CURVE. C Y(O) = o»o DG 7D I = I >L V(D = YPC-TNf I ) + Y(I-I) 70 CONTINUE PETvPN END -85— :.l ' ‘‘ UT r 'jr T ( 10 ,;»), IMISPTf 13 , 2 ), X (0 : 6 0 0 ) , y (600) , IMS v 9pr An', \-OE3, (I:','+0,3), VSIV3( 503,5), 10(10), IY=R(SO), XSINC ,N l'v, o n o I II X ^ N D (I"',"'), IBEEN, n c T Im , d X: jz 3 (4Q3 ), VAR (2 ), d Jt £ OL a I lows or CORRECTION MERE OP rO I = !I P ( 1 , 1 ) , I3 p (1,2) <(I > = (Y ( t ) - 2 , 5 )/.5 ° C f ' T T N vT 3 ‘ -vO * T = TSR (2, I ), IBR f?, 2 ) f( ’ = (Y(T).2 , E)/,% CO - I W r -Et- RN ENO STOEV(Z), SKEW(Z),CORCf SLlR^UT IME STAT (XR) ,MISOTt»C»2),Xt3!400)<rt600l,JM9t6 IB , 1° 1' 'W R '5 0 1 ' X S I*46( ‘ V 4 R I2>' STDEV(S)j S k e m (S) j CBRCO j Sf Dss i '0= J ^ r '21' S U M X IM C j 5), XX(Ifl) XX,400. 2,,XSI 430,2) = XS(Ifl) XX(TfZ) = XS(IfZ) CBMTjNUE C c-iM 0 U t e t h e ^e a m D0 700 J «1,2 XXS = c.^ 70 IS I = 1,L XXS v = XX ( If J) + YyTU-'1 IS C ? MT I N i 1E XoA- (J) =XXSi.v /i\J Cevr-UTE VATIAMCE AMD STAMQ. 3[V XS3SUM = 0.3 :e °o I = i ,l xsC = xx(Ifj) * Xx(J,j ) XSCRiJM = XRC + XSQRUv 3: CPMT JM-j e XRA-RU = XTAR(J) v AR t j OXPAR(J) ) = (I . /a x )# (Y g c g STQELv( J) CdTrjTE jv = (V A R (J ))««(. F ) THE CQE-R PR S<[\ SUQL E 3 = 0.0 OQ vO I = IfL O l VO = (XX(IfJ)-X 3 A R ( J ) )**3 SU1IOEa = DRVS+ SJMRr3 AO CQMTJNUE (AM#X=3AC?SQ) ) —8 8 — = (l./4\)*(SJX:[3)/( CO ^ V T E STDEV(J) **3) <U9T?SIS C c-rrp e PEAKEgNESS 9F g A TA SJ [4 S 0.D DO 5 D I = I>!_ D^Vv = (XV(IzJ) - x a A R ( j ) )*#4 SV'Dr* = s JVDE4 ♦ D£V4 5" CO'n T IN jcC AKJ-(J) = (I •/AN)»(SUs1DE4)/(STDEV(J)#«4) DO 75 I = I,L S U ' y (I,J) = (X<(r,J) - X O A R ( J ) ) 7S CO >T IN jr 700 C r \TIK Jf r CALCjLATE Sj" O- (X « A R 5■*(Y-YPAR SL D- f s .0." DO 7A 1=1,L PROXy - SU-IX(1,1) * SUW X(I,2) SU *'/ = 3ROXY + S U w XY 7 O C P L t INUC O CALCULATE TWE CORRELATION COEFF, CPRfn =((I ./AN)* SUMX Y ) / ( S T D E V ( I )*5TDEV(2)) RETURN EKD -8 9 - Sample o u t p u t f o r d a t a . g e n e r a t i o n p r o gr a m . U 9 pr (EXCC), (J?) V= * SF S T A , c = o =F y d a t a C a ^d s l = # s f pjs . N = D N = TC L = r NU'-9 FPc Fpi. ?u:-P ?jv''Iki3 P T a t i s m F $*•$*$*$«$ - *!*$+’* t T T ETfT TD(J) ID(J) = 3D IC = 32=5 AFE CTATISh ID vUMBE^ ***» ******* ********** IDY = 326? <^SN(I ) = IC RAN"?"!.ZED. C""PLrTED SBSrPVATISN STATIS' PT, I 2 3 4 5 A 7 8 3 IC MSNTH ID 11 12 I 2 3 4 5 6 7 YEAR 49 49 49 50 50 50 50 50 50 50 RECSPD RECORD 1*00 172.82 98.76 81.06 1 17,16 2 53.30 297,26 313,42 9 21 .80 770.00 —90— A(*Tv'AL rER CFTMT ERR9R -3-0? = ? • 6 8 ' ' : 9 5 4 ? - o2 Ir 15 ™ t '"En SYNTHETIC D a t a is . g t . ACTUAL Xf=NT^LY DEVIATIONS 9F ACTUAL F?9X D IC 1 Ieco s I Hf. J5 5 D I c 1* (V) r I A £ •£ A 3 D I F N O (v ) Cirv (k-) Z IS O C D J C CTrvc r D T C ;■< ) r.( < ) I- D.&39 Z - Li. £ ' I C - 'c ° . 7r r rr • ( DIP'" ) r s * ' 0 7?* -•'7o. 3 : 4 (F) Z D I F N L (V ) Z -6H . r CCp D I F M N ( !< ) S 3 * 6 •f IC DIFNL(K) S IC C • I5^ DlFMN(K) Z 1f T . f V ^ Prp CFNT EPR9R VA l LCS F?? EACH MgNTH vONTH I "I .2 " 19 2 -I .0737 ° -I .C 7 1 4 OMlC 3 E .(-N 7 7 A .CiiOl 7 .IeiEc A .2134 n .1559 I’ ** 11 .0620 12 .0369 SYNTHETIC rsrrv , _ 3