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THE USE OF RETENTION POND TO PROTECT THE LAND FROM FLOODING IN LAMASI RIVER LUWU REGENCY SOUTH SULAWESI INDONESIA

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osInternational Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 2129-2140, Article ID: IJCIET_10_04_220
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
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THE USE OF RETENTION POND TO PROTECT
THE LAND FROM FLOODING IN LAMASI
RIVER LUWU REGENCY SOUTH SULAWESI
INDONESIA
Ali Malombassi
Doctoral Program in Environmental Science, Graduate School, Brawijaya University,
Malang, Indonesia
Pitojo Tri Juwono
Faculty of Engineering, Brawijaya University, Malang, Indonesia
Muhammad Bisri
Faculty of Engineering, Brawijaya University, Malang, Indonesia
Ratna Musa
Faculty of Engineering, Indonesia Moslem University, Makassar, Indonesia
ABSTRACT
Luwu Regency, South Sulawesi Province is an area, encountering a lot of flood
problems because in particular the rivers in downstream are relatively flat increase
sedimentation in the lower reaches of the Lamasi River. In this study one of the rivers
in Luwu district, which often experiences flooding every year and has a length of 76.43
km and an area of river basin 432.80 km2. The flooding caused losses of nine villages
in the area surround the Lamasi river. The objective of this study is to determine the
optimal capacity of the retention pond and the dimensions of the retention pool used
based on the analysis using the Gumel and Nakayasu methods. The type of research
based on the data is done by using a quantitative approach by collecting secondary
data from the Central Office of the Pompengan and Jeneberang River Region in South
Sulawesi province. The result showed that the optimal capacity of the retention pond is
1,600,000 m3 at 9.3 m elevation while the pool volume in the pond at the 10-year return
period was 901,131.78 m3 and the water elevation in the pond is at plus 8.43 m. The
dimensions of the retention pond are 3,069 m long and vary from 100 m to 300 m and
within an average of 3 m, the height of the embankment is 1.50 m with the width of the
embankment 5 m with an optimal reservoir of 1,500,000 m3. The age of the retention
pool functions effectively because of the sedimentation of 4,481.01 m3 per year
estimated for 133 years.
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Ali Malombassi, Pitojo Tri Juwono, Muhammad Bisri and Ratna Musa
Keywords: flood, reservoir, retention pond, river.
Cite this Article: Ali Malombassi, Pitojo Tri Juwono, Muhammad Bisri and Ratna
Musa, The Use of Retention Pond to Protect the Land From Flooding in Lamasi River
Luwu Regency South Sulawesi Indonesia. International Journal of Civil Engineering
and Technology, 10(04), 2019, pp. 2129-2140
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=04
1. INTRODUCTION
Flood is one of the disasters that often destruct various countries. Indonesia is one of the
disaster-prone countries including floods. Regularly, Indonesia often experiences floods,
earthquakes, landslides, cyclones, tornadoes and droughts. In the past decade, Indonesia often
faces flooding every year in various cities [1,2]. The overall current flood disaster management
may lead to more recurrent events and cause severe impacts. Sustainable actions are needed to
solve these problems that include environment-based flood integrated countermeasures [3]
Luwu Regency is located in South Sulawesi Province, Indonesia. This regency is often
encountered with flooding problems because it is crossed by several river routes. Because of
this process, the river channel in the downstream section has sand and clay material which is
easily eroded and the river channel is easily moved during floods. Siltation of mud also the
other problem along with the flood that lead to river capacity decreasing.
The Lamasi River is one of the rivers in Luwu Regency which frequently causes flooding
every year. The floods were often reported to have an environmental damage. The Regional
Disaster Management Agency, Luwu Regency reported that in the Eastern Lamasi sub-district
there were more than 9 flood points that cause environmental damages.
Based on the field conditions in the Lamasi River, the flood control in accordance with the
conditions of the field is chosen by the payment method using dead rivers as retention ponds.
Retention ponds are an effective and general way of dealing with floods and can produce
optimal solutions both from the cost and control the overall flood, besides the retention pool
benefits from the others as follows: (1) The speed of the river flow can be increased so that
erosion on river banks can be avoided; (2) The bottom sediments from upstream can be
accommodated in the pond so that the bottom sediments are downstream; (3) Environmentally
friendly because it does not damage the cliffs and trees on the edge of the river and asks for the
quality of water downstream of the pond; (4) The retention pool that is designed does not fit
the needs Debit flow from the pool must be owed because the discharge is the same as the
capacity of the river so there is no overflow or flooding downstream of the pond [4].
The use of retention ponds has been carried out in various countries, such as Belgium [5],
Scotland [6], Portugal [7] and Taiwan [8] to deal with flood and mud sedimentation. This pool
is designed as a tub or pond that can hold or absorb water temporarily in it. The retention pond
is divided into 2 types depending on the wall coating and the bottom of the pool, namely natural
ponds and artificial ponds. Natural ponds are retention ponds in the form of basins or infiltration
tanks that have been formed naturally and can be utilized either in their original conditions or
made adjustments.
Artificial ponds or non-natural ponds are retention ponds that are made deliberately
designed with certain shapes and capacities at locations that have been planned in advance with
stiff material layers, such as concrete. The retention pool referred to in flood control research
is an artificial retention pool that has the following functions:
1) Replacing the role of recharge land that is used as closed land, housing, offices, then the
recharge function can be replaced with a retention pool. The function of this pool is to collect
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The Use of Retention Pond to Protect the Land From Flooding in Lamasi River Luwu Regency
South Sulawesi Indonesia
direct rain water and flow from the system to be absorbed into the soil. So, this retention pool
needs to be placed in the lowest part of the land. The number, volume, area and depth of this
pool is very dependent on how much land is converted into residential areas.
2) As a controller that functions as a temporary shelter during the flood and the water is
released and when the surface conditions on the river return to normal so that the peak of the
flood can be reduced.
There are three types of retention ponds, namely one retention pool next to the river,
the two retention ponds are on the riverbank and the third is a retention pool elongated storage
type.
The three types of retention pools mentioned above are selected as the second type because
they are in accordance with the conditions of the study area.
The objective of this study is to determine the optimal capacity of the retention pond and
the dimensions of the retention pool used based on the analysis using the Gumel and Nakayasu
methods.
2. METHOD
The study was conducted on the Lamasi river in Luwu district, South Sulawesi Province. The
type of research based on data is done by using a quantitative approach by collecting secondary
data from the Central Office of the Pompengan and Jeneberang River Region (COPJRR) in the
form of topographic data, longitudinal and transverse river profiles and hydrological data.
2.1. Retention Pool Capacity
The capacity of the retention pool can be optimized by taking into account factors such as
hydrology and topography, to be able to clearly see the functions of the following:
Hydrological analysis to determine the amount of the flood discharge plan will affect the
amount of maximum discharge to be accommodated. Then in the above analysis, rainfall data
are needed in all the regions concerned.
Hydraulic analysis to determine the water level that will be accommodated and the capacity
of the river downstream of the pool pond
Plans for discharge and overflow door openings to maintain the stability of the water that
comes out and keeps over topping the pond embankment if the incoming water discharge
exceeds the planned discharge.
Based on the things mentioned above, the capacity of the pool storage volume can be
determined using the topographic map of the location of the pool that is equipped with elevation
and contours using the general equation as follows:
V = A. H
(1)
With A = the area of the reservoir and H = the depth in the pond, but in the implementation
of this formula it cannot be used directly because of the uneven topographic conditions, so the
calculation of the area of the pool is layered according to the height of the contour formula
used as follows:
A = (The upper area between the contour + The area under the contour) / 2
Hydrological Analysis
Hydrological analysis aims to determine the amount of flood discharge based on debit
records manually or automatically from AWLR (Automatic Water Level Record) or with
empirical equations based on using rainfall data. The use of empirical formulas with rainfall
can be done if data on recording debits is insufficient, or both methods are used to control each
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Ali Malombassi, Pitojo Tri Juwono, Muhammad Bisri and Ratna Musa
other Determining the amount of river discharge based on rain needs to review the relationship
between rain and river flow. The size of the river flow is largely determined by the amount of
rain, rainfall intensity, area of the watershed, duration of rain, and characteristics of the flow
area.
Analysis of planned rainfall or frequency analysis was using the Gumbel and Log Pearson
III method based on rainfall data obtained from the Central Office of the Jeneberang and
Pompengan River Region. This office provided data from three stations namely, (1) Rante
Damai (119 OP) rainfall recording station between 2000 – 2015; (2) Lamasi rainfall recording
station (120 OP) between 2000– 2017; and (3) Makawa (51 H) rainfall recording station
between 2000 – 2017.
Table 1 The maximum daily rainfall at the three rainfall stations
Year
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
Maximum daily rainfall (mm)
Batusitanduk
Lamasi
Rante Damai
100
250
95
115
145
95
120
70
96
200
193
95
120
100
95
134
177
160
130
129
95
80
106
95
125
94
99
75
86
98
55
98
99
70
131
99
50
125
90
92
92
95
50
135
38
50
107
36
39
81
39
61
-
Average
148.33
118.33
95.33
162.67
105.00
157.00
118.00
93.67
106.00
86.33
84.00
100.00
88.33
93.00
74.33
64.33
60.00
50.00
Source: COPJRR
2) Distribution Suitability Test
Calculation of rainfall plans with the two methods (Gumbel and Log Pearson Type III) above
will give different results, so that results suitability tests are needed. Conformity test carried
out by Chi-Square method (X2 - Test).
The Chi-Square Compliance Test is a measure of the difference between the observed and
expected frequencies. This test is used to test perpendicular deviation, which is determined by
the formula:
The testing steps are as follows:
a. Plotting rain / debit data.
b. Drag the line with the help of rain data points that have a certain return period.
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South Sulawesi Indonesia
c. Price X2cr is searched from the table, by determining the level of significance (ïĄ) and
the degree of freedom (DF), while the degrees of freedom can be calculated by the equation:
Information:
DF = degree of freedom
n = Amount of data
m = Number of parameters for X2cal (m taken 2).
d. If the price of X2cal <X2cr (according to the table), it can be concluded that the
deviations that occur are still within the permitted limits.
Rainfall data from the Log Pearson III method and the Gumbel Method after being tested
with Chi Squares are selected which have the smallest X2cal value.
3) Analysis of Flood Debit Plans
The river drainage data required for the analysis of flood discharge are planned between the
area of the Cacthman Area (Km2), the main river length L (Km), the elevation of the highest
point Hmax / H2 (+ m), the lowest elevation of Hmin / H1 (+ m). needed. If viewed from the
morphometry data of the watershed / watershed, the method of calculating the planned flood
discharge from rainfall data can be used the hydrographic method in the Nakayasu synthesis
unit and the Gamma my method because the river with analysis has a watershed area> 100 ha.
Data on the characteristics of the Lamasi River Basin can be seen in table 2 below.
Table 2 Characteristics of the Lamasi River Basin
Characteristics
Data
Catchment Area
432.80
km2
Maximum height of river basin (H max)
+
2,283.00
m
Minimum height of river basin (H min)
+
3.00
m
76.43
km
Length of main river
Source: Identification from topography map
The selection of flood discharge flood discharge plan is based on the discharge of the
analysis results from the above, then compared to the discharge originating from the results of
recording the water level in the field.
Debit analysis based on the recording of the face height uses the curvilinear method.
The study discharge curve is used for analysis using Logarithmic motives, namely by taking
debit Q1, and Q3 from curves made on logarithmic paper based on existing data and Q2
determined by formula:
Q2 = (Q1 x Q3) 0.5 3
Then read on the curves of H1, H2 and H3 based on Q1, Q2 and Q3, then the curves are
converted into a straight line by reducing or adding to the price of Ho obtained from the
formula,
đ»0 =
đ»1+đ»2−đ»22
đ»1−đ»2−2đ»2
(2)
Then the coefficients of K and n are determined by the formula,
(y) – m log K – n (x)
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(3)
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Ali Malombassi, Pitojo Tri Juwono, Muhammad Bisri and Ratna Musa
(xy) – (x) log K – n (x2) = 0
(4)
And the relationship between Q and H is derived from the formula,
Q = K (H – Ho)n
(5)
where :
Q1, Q2 Q3 = water debit from existing data
H1, H2, H3 = height of water taken from logarithmic curves based on
Q
Ho
= water level that straightens the curve
(y)
= sum of log Q scores
(x)
=sum of log (H-Ho) scores
(x2)
= sum of x quadrate
(xy)
= sum of score x multiply by y
M
= number of data
From the above equation, the amount of the debit (Q) can then be calculated for each record
of water level (H), so that the average daily flow data of the river are obtained at the
measurement location. While the maximum annual discharge is used to analyze the planned
flood discharge.
3. RESULTS AND DISCUSSION
3.1. Frequency of Rainfall
As mentioned above, the maximum daily rainfall data used in this analysis is data with the
average method originating from three rainfall stations in table 1 using the Gumbel method and
Log Pearson III and the analysis results as follows. The value of Rainfall in the two-year
repetition period analyzed by the Gumbel method (96.70) was higher than that of the Log
Pearson III method (73.38); while those in the reported period of 100 were higher in Log
Pearson III (201.47) then in Gumbel (194.81) (Table 3).
Table 3. Rainfall data Repeated with Gumbel and Log Pearson III
No.
Method
1
Gumbel
Log Pearson
III
2
2
96.70
5
122.96
Repeated periods (years)
10
20
25
140.35 157.04 162.33
73.38
96.49
125.34
143.00
164.02
50
178.63
100
194.81
178.86
201.47
3.2. Distribution Suitability Test Results with Chi Square Method
Conformity Test Results Distribution with Chi Square Method Conformity test obtained
differences found between the observed and expected frequency or must be X2cal <X2cr and
the results of the analysis, showed the Gumbel method which has a difference X2cal with X2cr
smaller than the Log Pearson III method, then the next analysis used the results of the Gumbel
method frequency analysis.
3.3. Debit Plan
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The results of the planned discharge analysis or return period start 2, 5, 10, 25, 50 and 100
years with the Nakayasu and Gamma I methods. The result showed that Flood Discharge
analysis with Gamma was always higher. It is projected to be 94.40 m3/second in the next 100
year (Table 4).
Table 4 Flood Discharge Repeated Nakayasu and Gamma Methods
Repeated
periods
2
5
10
25
50
100
Projection of Flood Discharge (m³/second)
Nakayasu
Gamma
46.47
52.18
56.33
63.48
62.80
70.96
69.01
78.14
77.05
87.43
83.07
94.40
3.4. Debit Arch
Debit curves were analyzed based on data recording of water level and discharge on the staff
gauge on the Lamasi River (source data for the CPJRR) and described in the following graph,
then regression of the relationship between water level and discharge obtained by the equation
of discharge:
Q = 8.553 (H --0.64)2.1
(8)
Where H is the water level, then this equation is used to analyze daily debits based on
recording water level.
Figure 2. Relationship between debit and water level
Daily debits obtained from equation 8 with a face height from recording the water level in
the Lamasi river are then analyzed by the Gumbel method with the following results. The
projection of water debit calculated by Gumbel Method was 44.83 m3/second in next 2 year
and gradually increase to 88.70 m3/second in the next 100 year (Table 5).
The maximum daily debit obtained from equation (8) with the height levelfrom recording
water level in the Lamasi river was calculated. The result was showed in Table 5.
Table 5. The Lamasi River Maximum Daily Debit
No.
Year
Qmax (m3/sec)
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Year
Qmax (m3/sec)
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1
2
3
4
5
6
7
8
9
1999
2000
2001
2002
2003
2004
2005
2006
2007
30.99
30.99
46.33
46.33
45.46
49.87
49.87
41.27
29.26
10
11
12
13
14
15
16
17
18
19
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
57.86
30.64
49.42
45.46
63.36
33.51
29.95
63.36
74.59
63.87
Furthermore, the discharge results in Table 5 above were analyzed with its frequency using
the Gumbel method. The result was presented in Table 6.
Table 6. Debit Calculation Results for Gumbel Method Repeat
Repeated period
2
5
10
20
50
100
3
44.3
56.58
64.35
71.81
81.46
88.70
Debit (m /second)
3.5. Flood Debit Analysis Plan
The planned flood discharge analysis is determined by comparing the Nakayasu method and
the Gumbel method with the flood discharge resulting from recording in the river and then
drawing the conclusion that the method closest to the recording discharge in the river will be
used in subsequent planning. The results of the re-flow analysis in Table 3 compare with Table
5. It can be concluded that the results of Table 5 which approach table 3 are Nakayasu method
analysis, so that the planned planning for retention pond optimization is used as a result of
Nakayasu synthesis unit hydrographic method.
3.5. Optimization of Retention Pool Volume
Optimization of the pool volume will be adjusted to the volume of water to be accommodated,
in this study the planned flood discharge is used for a 10-year return period and the river
discharge flow capacity in the downstream pond was 25 m3 / sec (source data for COPJRR).
The amount of water to be accommodated in the retention pond was analyzed by Nakayasu
synthesis unit hydrographic method and pool volume based on counts from the Lamasi river
topography measurement data and the results of the analysis of the relationship between the
water level and volume of retention ponds can be seen in Table 6 and then pond capacity
calculated to obtain optimal storage. Figure 6 curvature of the basin showed that the optimal
reservoir of 1,600,000 m3 in the elevation of the water is + 9.30 m.
Table 7. Relationship between Elevation and Volume in the Retention Pool
No.
Elevation
1
2
3
4
5
4.00
4.50
5.00
5.50
6.00
Volume (m3)
Wide
m2
Perelev
Total
0.00
1,370.73
8,217.24
37,397.35
46,195.60
0.00
0.00
4,793.99
22,807.30
41,796.48
0.00
0.00
4,793.99
27,601.28
69,397.76
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6
7
8
9
10
11
12
13
14
15
6.50
7.00
7.50
8.00
8.50
9.00
9.50
10.00
10.50
11.00
91,431.62
153,462.45
197,415.83
249,449.60
315,423.31
391,032.85
512,387.53
595,300.23
680,667.78
730,167.03
68,813.61
122,447.04
175,439.14
223,432.72
282,436.46
353,228.08
451,710.19
553,843.88
637,984.01
705,417.41
138,211.37
260,658.40
436,097.54
659,530.26
941,966.71
1,295,194.79
1,746,904.98
2,300,748.86
2,938,732.87
3,644,150.27
The volume that must be accommodated is analyzed based on the Nakayasu unit
hydrograph in Q10 years, amounting to 901,131.78 m3 and water elevations in the pond at
+8.43 m (pool bottom elevation +4.00 m). The results of the analysis of the volume contained
in the pool each hour can be seen in tables and figures.
The dimensions of the retention pool are 3,069 m in length, varying between 100 m to 300
m and in an average of 3 m, the height of the embankment is 1.50 m with the width of the
embankment 5 m. The size of the retention pond depends on the flood discharge plan to
increase the planned discharge, then the height of the water in the pond and the pool inundation
area increases in this study the amount of the planned discharge being used for 10 years.
This retention pool serves as a stabilizer to drain down water without exceeding the
capacity of the river so that it does not occur or flood. In order to function properly this pool
must be equipped with a release door for regulating the outflow and preventing the level of
water bellow the maximum level.
800
700
600
Wide m2 (x 1000)
500
400
300
200
100
0
12.00
Elevation (M)
10.00
8.00
6.00
Volume
Elevation Arch
4.00
Wide Elevation
Arch
2.00
0.00
0
1,000
2,000
Volume
m3 (x
3,000
4,000
1000)
Figure 3. Retention pond capacity
Table 8. Flood Volume Per Hour for 10 Years with the of the Nakayasu synthetic unit Hydrographic
Method in the Retention Pool
Time
(hours)
0
1
Debit
Discharge
m3/second
10.56
12.49
Outflow
m3/second
25.00
25.00
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m /second
0.00
0.00
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Collected
m3/hour
0.00
0.00
m3
0.00
0.00
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2
3
4
5
6
7
8
9
10
11
12
13
14
15
21.23
40.46
62.19
62.80
60.79
57.62
53.37
47.60
41.08
36.23
32.35
29.20
26.63
24.51
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
25.00
0.00
15.46
37.19
37.80
35.79
32.62
28.37
22.60
16.08
11.23
7.35
4.20
1.63
0.00
0.00
55,672.07
133,869.14
136,083.50
128,829.84
117,435.37
102,137.63
81,359.37
57,886.42
40,417.40
26,445.78
15,125.07
5,870.20
0.00
0.00
55,672.07
189,541.21
325,624.71
454,454.55
571,889.92
674,027.55
755,386.92
813,273.34
853,690.74
880,136.52
895,261.58
901,131.78
901,131.78
A previous study of flood design discharge at Bonai River, Kunto Darussalam Residence,
Rokan Hulu Regency reported that the maximum discharge entering the maturity period for the
100-year return period was 224.401 m3/s. This method was used to analyze the Nakayasu
synthetic hydrograph by rainfall units at Kampar Market Station in 2000 to 2009. Analysis
using the Nakayasu synthetic hydrograph unit showed that there was rainfall with 100 years
return period and produced a flow rate of 1,833,594 m3/s. Another study in the Upper Komering
Basin showed that the peak discharge in several hydrographs methods are Nakayasu 607.32
m3/s [9].
70.00
60.00
Flooding debit (m³/dtk)
50.00
40.00
Debit
Keluar
Outflow
debit
QTampung
Q capacity
30.00
20.00
10.00
0.00
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Time (hours)
Figure 3. Nakayasu synthetic unit hydrograph at Q10
One method that can be used to predict flood discharge is the basis of the hydrograph
(Results from the Nakayasu synthetic unit hydrograph analysis at Q10 indicate that peak
discharge at 3 hours, while capacity peak at 4 hours. Estimated flood discharge is needed to
determine the optimal discharge size which is related to the dimensions and age of the structure
being built in. The purpose of this estimation is to plan the optimal structure to overcome the
flooding effectively and efficiently [10].
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3.6. Sedimentation
The amount of sediment is calculated based on observations made by the water resources
department, copyright works and spatial planning of the South Sulawesi Province on the
Lamasi River, then a sedimentary curve is made between the Q discharge and the sediment
discharge with a method similar to that used in making curves. Here was a picture of the curved
sediment.
200.00
180.00
Sediment debit (Qs) ton/day
160.00
140.00
120.00
hasil
Qs result
100.00
Qs Exist
80.00
60.00
40.00
20.00
0.00
0.00
10.00
20.00
30.00
40.00
50.00
60.00
Debit (Q) m3 /second
Figure 5 Sediment Arch
Based on the sedimentary curve above, a regression equation for the discharge relationship
with sediment is obtained
Q = 1.06 (H - 28.61)0.69
(9)
The annual sediment rate can be calculated using the regression equation from the sediment
curve above, the magnitude is as follows:
1) Average Sediment Production of 22.71 tons/day
2) If the sediment density is assumed to be 1.85t / m³, the sediment rate will be 7,725.25
tons / year or 4,481.01 m³/year for return of 133 years.
4. CONCLUSION
1. The planned flood discharge used in the planning of retention ponds is the result of
2.
3.
4.
5.
analysis of the Nakayasu synthesis unit hydrograph method because the results are
close to the discharge conditions of observations in the field.
The optimal capacity of the retention pond is 1,600,000 m3 at 9.3 m elevation while
the pool volume in the pond at the 10-year return period is only 901,131.78 m3 and
the water elevation in the pond is at +8.43 m.
Overflow elevation at + 8.43 m
The dimensions of the retention pond are 3,069 m long and vary between 100 m to
300 m and in an average of 3 m, the height of the embankment is 1.50 m with the
width of the embankment 5 m.
The age of the retention pool functions effectively because of the sedimentation of
4,481.01 m3 / year so the effective age of the retention pond is projected for 133
years.
5. ACKNOWLEDGEMENTS
The author would like to thank the Head of the Central Office of the Pompengan and
Jeneberang River Region in South Sulawesi Province, the Rector of the Indonesia Moslem
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editor@iaeme.com
Ali Malombassi, Pitojo Tri Juwono, Muhammad Bisri and Ratna Musa
University, and Dr. Amin Setyo Leksono, Brawijaya University who assisted in revising the
initial manuscript.
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