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FOREST SERVICE HANDBOOK
Portland, Oregon
TITLE 2509.16 - WATER RESOURCE INVENTORY HANDBOOK
R6 Supplement No. 2509.16-92-1
Effective September 25, 1992
POSTING NOTICE. Supplements to this handbook are numbered consecutively.
Check the last transmittal sheet received for this handbook to see that the above
supplement number is in sequence. If not, obtain intervening supplement(s) at once
from the Information Center. Do not post this supplement until the missing one(s)
is received and posted. After posting, place the transmittal at the front of the title
and retain until the first transmittal of the next calendar year is received.
The last R6 Supplement to this handbook was No. 1, July, 1987.
Document Name
Sheets)
Superseded New
(Number of
2509.16,1
7
Page Code
1.21--1 thru 1.22--2
4
Digest:
This is a Technical Supplement to change this handbook into official electronic
format. CONTENT HAS NOT CHANGED except to delete a reference to a
nonexistent exhibit.
/s/ John E. Lowe
JOHN E. LOWE
Regional Forester
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FSH 2509.16 - WATER RESOURCE INVENTORY HANDBOOK
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CHAPTER 1 - WATER RESOURCE INVENTORY PROCESS
1.2 - INVENTORY PHASE.
1.21 - Data and Information Search. The general contents should consider, but not
necessarily be limited to, the following:
1. Introduction
a. Purpose of survey.
b. General methods and techniques.
2. General
a. Watershed map delineating the major land subwatersheds.
b. Area by ownership, in acres and square miles.
3. Watershed History. Fire, logging, grazing, farming, mining,
developments, land treatments, water uses.
4. Climate. A narrative statement discussing the general weather pattern
and climate conditions of the major watersheds and elaboration of the following:
a. Precipitation
An isoheytal map of mean annual precipitation on a water-year basis.
Annual precipitation on a water-year basis for wettest year, driest year, and
average year.
Cumulative and percent of precipitation by months for the average water-year for
each station.
Recurrence interval for equaling or exceeding the mean annual precipitation at each
station.
Maximum precipitation intensities for 15-minute, 30-minute, 1-, 6-, and 24-hour
periods.
Percent of precipitation occurring as snowfall by months for average, maximum,
and minimum snowfall years.
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Average monthly snowpack depth and water equivalent for the average, minimum,
and maximum runoff year, and the maximum snow depth recorded for the average
minimum and maximum year.
A storm isoheytal map for a typical winter storm and where possible a summer
storm.
b. Air Temperatures
Average monthly maximum, minimum, and mean temperatures for each station.
Frost-free periods for each major watershed.
c. Wind. Wind patterns, velocities, average monthly winds, and prevailing
directions by months.
d. Relative Humidity. Seasonal and daily fluctuations, extremes, and
averages.
e. Solar Radiation. Cumulative, instantaneous, and so forth, amount of solar
radiation showing seasonal fluctuations.
f. Evapotranspiration. Average monthly and annual potential.
5. Topography
a. Elevation distribution.
b. Slope class distribution.
c. Aspect distribution.
6. Vegetative Cover. Vegetative cover by major Forest types, and non-Forest
types. The Forest types should be broken down into major timber types, clearcut by
age, and noncommercial. Non-Forest types should be broken down into such
categories as grass, brush, rocks, roads, powerlines, railroads, residential, lakes,
rivers, and so forth. The density, structure, and arrangement of openings of the
timber types may also be included.
7. Soils. A table listing hydrologic soil groups. Define hydrologic soils groups
to represent homogeneous areas particularly in respect to infiltration and storage
capacity at various depths. Basic information should include:
a. Infiltration rate in inches-per-hour for moist soil and dry soil.
b. Water holding capacity (field capacity in inches) for rooting depth for
dominant type of vegetation, entire soil profile down to bedrock, and bedrock, if
fractured.
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c. Available plant water, in inches, for the same depths as item b above.
d. Average rooting depth, in inches, for the various major vegetation types.
e. Average depth, in inches, to water impermeable layers.
f. Percolation rate in inches-per-hour for the various soil horizons.
g. Erosion hazard, in qualitative terms.
8. Geology. Landforms, principle rock types--igneous, metamorphic, and so
forth, kinds--granitic, sandstone, and so forth, relation of geology to water storage,
transport, and quality.
9. Geomorphology
a. Stream gradients.
b. Drainage density.
c. Watershed shapes.
d. A stream reach location map where the main drainage is divided into
sections with similar hydraulic characteristics (gradient, channel capacities,
conditions, roughness, overflow channels, and flood plains).
10. Sedimentation
a. Monthly and seasonal amounts of total suspended sediment.
b. A table summarizing particle size analysis.
11. Water Quality. Chemical, physical, and biological characteristics of the
water.
12. Water Quality and Timing
a. Average daily runoff and yearly runoff in cfs, csm, for the maximum runoff
year, minimum runoff year, and average year. Include year of occurrence except for
average year.
b. Acres in still bodies of water such as lakes and reservoirs.
c. Cumulative and percent of runoff by months for the average water-year.
d. Ground water resources and fluctuations.
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13. Land Uses. Describe the various kinds and extent of land uses. Include
specific figures for those uses which might have an influence on the water quantity,
timing, and quality. Do not duplicate data recorded in other inventories. Present
the information in a manner to relate it to the survey objectives. Examples of
applicable land use data might be as follows:
a. Acres of clearcut--average annual, cumulative total, and so forth.
b. Acres of slash burned--average annual.
c. Miles of road constructed.
d. Sources of possible water contamination.
14. Climate. Precipitation measurements from Forest Service storage gages
will be reported on form R6-2500-14, Storage Gage Precipitation Measurements, on
a water-year basis--October 1 to September 30. Forward two copies annually to the
Division of Watershed Management by January 15. They will forward the report to
the appropriate State or Federal Agency for information purposes and/or
publication.
Do not include precipitation records from stations which are computed by automatic
data processing.
The observations reported on R6-2500-14 should be the final amounts after any
adjustments necessary have been made. For example, if intermediate observations
are based on stick or tape measurements and annual weigh-out indicates a poor
correlation, some adjustment in intermediate readings may be necessary. Do not
show any observations determined by prorating precipitation amounts based on
another precipitation station.
The use of R6-2500-14 does not preclude the use of form R6-2500-6, Precipitation
Record for Storage Gage, which should continue to be used for bookkeeping
purposes on the Forest or where the storage gage has been partly financed by the
U.S. Weather Bureau.
15. Appendix and Sources of Data
a. Topographic maps.
b. Geologic maps.
c. Soils maps and compilation tables.
d. Slope-class map and compilation tables.
e. Area-elevation map and compilation tables.
f. Erosion hazard map.
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g. Cover-type maps and compilation tables.
h. Daily hydrographs of streamflow for each station.
i. Daily hydrographs of water temperature for each station.
j. Climatic compilation tables for each station.
1.22 - Analysis of Data. A hydrologic analysis can be used to develop:
1. Estimates of water quantity, timing, and quality which can be used to
develop specific prescriptions.
2. Watershed resource improvement.
3. Opportunities and/or limitations in meeting specific watershed
management objectives.
4. Specific recommendations.
The analysis should include, where applicable, methods and techniques used and
reliability of data. Data and estimates should be subjected to recognized statistics
analysis, double sampling, and field checking. Refinements will be made as
necessary.
In addition to, and based on the data included in the water resource inventory, a
hydrologic analysis should consider, but not necessarily be limited to, the following:
Objectives of the analysis
- Water quantity and timing
- A water balance accounting for runoff for the average year, maximum year,
and minimum year by broad vegetative and/or elevation zones.
- Flood frequency.
- Hydrograph flow separation, recession curves.
- Flow duration.
- Regression analysis with prediction equations relating to the various
parameters influencing water quantity and timing.
- Water uses and availability.
Water quality
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- Daily and seasonal fluctuations in physical, chemical, and biological
characteristics.
- Maximum, minimum, and average physical, chemical, and biological
characteristics.
- Regression analysis with prediction equations relating to the various
parameters influencing water quality.
- Influence on water quality.
Water Resource Improvement Projects. An inventory of water resource
improvement needs by specific projects to meet watershed management objectives
should be part of the hydrologic analysis. Contents should be similar to that
outlined in FSH 2509.15 or FSM 2522.21.
Opportunities and/or Limitations. After making an analysis of the data, include a
narrative summarizing the opportunities and/or limitations in meeting the
watershed management objectives. This may involve making preliminary water
yield predictions prior to the preparation of the actual prescriptions.
Recommendation. Include any recommendations pertaining to:
- Objectives of the analysis.
- Collections of additional data.
- Instrumentation.
- Updating of survey and analysis.
- Watershed management techniques.