UserMicrosoft Word - JAEBS-1622-11-revisedJ. Appl. Environ. Biol. Sci., 7(3)59-64, 2017 |
© 2017, TextRoad Publication |
ISSN: 2090-4274 |
Journal of Applied Environmental and Biological Sciences www.textroad.com |
Water Resources Conservation on Cidurian Upstream as Flood Reduction in |
Cidurian River |
Bambang Bodro Ismoyo* and Mas Agus Mardyanto |
Post Graduate Program Environmental Sanitation Engineering, Environmental Engineering Department, Sepuluh |
Nopember Institute of Technology (ITS) Surabaya, Indonesia |
Received: November 11, 2016 |
Accepted: January 22, 2017 |
ABSTRACT |
Flood always happen in every heavy rain at Serang District and Tangerang District. Flood is caused by overflow from |
Cidurian River. That makes gives a very detrimental impact to the local community activities. Not a few villages and infrastructure in Serang District and Tangerang District is disrupted by flood. Flood is occurred from 2010 up to now. Based on the data of the BBWS-Cidanau-Ciujung Cidurian River, increase of fllod discharge occured from 2010 up to now. Improvement of flood discharge is estimated by changes in land cover conditions. For anticipation of these conditions, the need for a concerted effort to stifle the flow rate of the surface. The effort made is mechanically conservation by making dam. With the reduction effort of this conservation are expected to reduce flooding in the Serang District and Tangerang District. |
KEYWORDS: Flood, flood discharge, mechanical conservation, Cidurian River |
INTRODUCTION |
Flood became a natural phenomenon that occurs almost routinely each year. Almost all districts of the city |
in Banten Province there are dots flood-prone. Floods can occur naturally or is caused by human error. Wild logging in upper watersheds will impact fatal to the survival of ecosystems and the forest environment and will have an effect on the increase in the rate of runoff. |
An increase in the maximum discharge in Cidurian river occurs reach 600%. From the results of the recording shows that the maximum debit debit Cidurian River from 2002 up to the year 2009 of 236.92 m³/sec. While from 2010 up to now increases to 1,214.05 m³/sec. It is estimated that the impact of any change in the existing land cover Watershed of Cidurian[1]. |
Closures of land use in watershed Cidurian and surrounding areas covering 12 types i.e., secondary forest land, forest plants, agricultural settlements, plantations, dry land, dry land agricultural mix, rice fields, shrubs, ponds, open land, surface water and the airport. The condition of changing land closure is forest crops, orchards, neighborhoods, bushland and open land. Cidurian forest plants decreased by 26% after the year of 2006. Broad plantations decreased by 9% after the year 2003. Extensive settlements experienced growth from 2000 up to 2003 amounting to 16.7%, while in 2003 up to 2006 amounted to 13.7%, dry land farming mixed has decreased from 2000 to 2006, but the increase occurred in 2009[2]. |
Based on these conditions need for water resource conservation efforts to reduce the flow rate that will have an impact on the continuity of forest ecosystems and the environment at the same time can prevent disaster for the downstream area. |
METHODS |
This study operates on the reduction of flood discharge in river Cidurian with mechanical method (Dam). |
Dam is planned as a flood control and as ground water storage[3]. Broad river basin study region is 322.742 km2. |
The rain data used in this paper from 1998 until the year 2013, topographic map, map of soil types and soil permeability from BBWS-Cidanau-Ciujung-Cidurian. For a map of land cover in the study area obtained from the office of Citarum Watershed Management Area by 2014. |
To determine the average rainfall of the region is using the Thiessen Polygon method. Debit flood plan using Synthetic Hydrograf Nakayasu Units[4]. Calculation of the volume of the spooler required reducing flood discharge method Flood Routing with spillway[4]. |
*Corresponding Author: Bambang Bodro Ismoyo, Post Graduate Program Environmental Sanitation Engineering, Environmental |
Engineering Department, Sepuluh Nopember Institute of Technology (ITS) Surabaya, Indonesia. email: bbodroismoyo@yahoo.com |
Ismoyo and Mardyanto, 2017 |
ANALYSIS |
The method used in calculating the average rainfall of the region is the Thiessen Polygon[5]. To calculate the average |
rainfall regions using the formula: |
n m |
An Am |
Rave = L A Rn + L A Rm |
An = Influence Area of Rain Station (Ha) |
A = Total area of watershed (Ha) |
Rn = High of rainfall (mm) |
Figure 1. Influenced Area of Thiessen |
Table 1. Calculation of Precipitation Using Thiessen Method |
No. | R (mm) |
1 | 187,00 |
2 | 139,13 |
3 | 135,00 |
4 | 133,00 |
5 | 129,47 |
6 | 110,78 |
7 | 92,90 |
8 | 89,81 |
9 | 88,89 |
10 | 75,81 |
11 | 73,75 |
12 | 68,34 |
13 | 59,93 |
14 | 58,81 |
15 | 53,60 |
16 | 38,93 |
The calculation of precipitation is using a Log Pearson Type III [5]. The formula as follows: |
LogRt = L o g R + K. Sd |
LogRt = is the flood discharge value of some specified probability |
L o g R = Is the average of the log R discharge values |
Sd = Is the standard deviation of the log R-values |
K = Is a frequency factor. The frequency factor K is a function of the skewness coefficient and return period and can be found using the frequency factor table. |
J. Appl. Environ. Biol. Sci., 7(3)59-64, 2017 |
Table 2. Calculation of precipitation plans with Log Perason Type III method |
Rain of Year | R (mm/24 hour) |
2 | 89.06 |
5 | 125.86 |
10 | 151.18 |
25 | 182.51 |
50 | 205.77 |
100 | 228.87 |
The type and area of each land cover in the study area can be seen in table 3 |
Table 3. The Wide of Each Type Of Land Cover |
Type of Land Use | Wide (Ha) |
Primary terrestrial forest | 1399,11 |
Secondary terrestrial forest | 2458,46 |
Crops forest | 3172,25 |
Plantation | 4341,38 |
Settlement | 1196,55 |
Dryland farming | 6411,49 |
Dryland mixed farming | 9936,65 |
Paddy field | 2978,06 |
TOTAL | 32274,81 |
The magnitude of the coefficient stream in the area of study is calculated based on the slope of the land and soil type |
as in the following table 4. |
Tabel 4. Calculation Of Stream Coefficient (C). |
Type of Land Use | Wide (Ha) | C | C x A |
Primary terrestrial forest ( >20% ) | 1399.11 | 0.38 | 531.66 |
Secondary terrestrial forest (8% - 20%) | 2380.56 | 0.29 | 698.30 |
Secondary terrestrial forest ( >20% ) | 197.00 | 0.38 | 74.80 |
Crops forest ( <8% ) | 1948.23 | 0.24 | 467.58 |
Crops forest (8% - 20%) | 534.95 | 0.32 | 171.18 |
Crops forest ( >20% ) | 950.83 | 0.42 | 399.35 |
Plantation ( <8% ) | 4101.24 | 0.24 | 984.30 |
Plantation (8% - 20%) | 240.14 | 0.32 | 76.84 |
Settlement | 1196.55 | 0.40 | 478.62 |
Dryland farming ( <8% ) | 2241.77 | 0.24 | 538.02 |
Dryland farming (8% - 20%) | 4169.72 | 0.32 | 1334.31 |
Dryland mixed farming ( <8% ) | 7201.85 | 0.24 | 1728.44 |
Dryland mixed farming (8% - 20%) | 2604.57 | 0.32 | 833.46 |
Dryland mixed farming ( >20% ) | 130.23 | 0.39 | 51.22 |
Paddy field | 2978.06 | 0.31 | 923.20 |
TOTAL | 32274.81 | | 9291.35 |
C ( (C x A)/ Total Area ) | | 0.288 | |
(Source: Land use map 2014 From BPDAS Citarum Ciliwung dan Google Earth 2016 and analysis) |
Based on the area, the magnitude of the coefficient stream in the area of study is about 0.288. Calculation of flood |
discharge using Hydograf Nakayasu. The formula as follows: |
C. A. Ro |
Qp = 3.6(0.3T |
+ T0.3) |
Qp = Function of peak discharge (m³/sec). |
Ro = Unit rainfall (mm). |
C = Watershed characteristic coefficient. |
A = Peak discharge of watershed area (km²) |
Tp = Time lag (hour). |
T0.3 = Time required to discharge reduction up to 30% peak discharge |
(Source: soemarto [4]) |
Ismoyo and Mardyanto, 2017 |
Characteristic of watershed and rainfall |
Watershed area (A) = 322,70 km². |
Length of main river (L) = 69,20 km. |
Precipitation (Ro) = 1 mm. |
Characteristic coefficient watershed (α) = 3 |
Stream coefficient = 0,288 |
Table 5. Recapitulation of the flood discharge using Nakayasu method. |
Year Flood | Discharge (m³/sec) |
2 | 126.20 |
5 | 178.35 |
10 | 214.23 |
25 | 258.63 |
50 | 291.58 |
100 | 324.32 |
RESULTS |
The magnitude of the reduction of flood discharge in river Cidurian is amounting to 150 m³/dt. The |
magnitude of these reductions based on conditions on the field. Serang District and Tangerang District predicted the flood would happen if discharge in Weirs Rancasumur ≥ 150 m³/dt. Therefore it needs to be done with mechanical conservation efforts to stifle the flow rate of the surface. |
Conservation with mechanical in this paper is to manufacture dam. In addition to controlling floods, dam also serves as a place of saving water that will make the increase of the ground water [6]. In this study, dam is planned as a flood control and saving the ground water. In this study, the making of dam based on flood discharge 5 year plan (Q5). The amount of the required dam is a calculation result needs spool volume. The magnitude of the volume of the spooler required reducing flood discharge calculated by search flood (flood routing). The search method of the flood (flood routing) that is used is the search through flood reservoirs. |
I – Q = Ds / Dt |
I (rt2) ΔT – (Q1+Q2)/2. ΔT = S2 – S1 |
( I1 + I2 ). ΔT/2 + ( S1- Q1. ΔT/2) = ( S2 + Q2. ΔT/2) |
Where: |
/l , /2 = Inflow tl , t2 Ql , Q2 = Outflow tl , t2 |
Sl , S2 = Storage Volume whentl , t2 |
(Source: Soemarto, 1999) |
Try with the spooler is 1,172, 000 m ² ≈ 117.20 Ha, pelimpah 40 m wide. |
Table 6. The connection between outflow (Q5) and storage. |
Elevation | H | S | S/Δt | Q2 | S2 | S1 |
m | m | m3 | m3/sec | m3/sec | m3/sec | m3/sec |
1,00 | 0,00 | 0 | 0 | 0 | 0,000 | 0,000 |
1,20 | 0,20 | 234400 | 130 | 6118 | 133281 | 127163 |
1,40 | 0,40 | 468800 | 260 | 17304 | 269096 | 251792 |
1,60 | 0,60 | 703200 | 391 | 31789 | 406561 | 374772 |
1,80 | 0,80 | 937600 | 521 | 48943 | 545360 | 496417 |
2,00 | 1,00 | 1172000 | 651 | 68400 | 685311 | 616911 |
2,20 | 1,20 | 1406400 | 781 | 89914 | 826290 | 736376 |
2,40 | 1,40 | 1640800 | 912 | 113305 | 968208 | 854903 |
2,60 | 1,60 | 1875200 | 1042 | 138432 | 1110994 | 972562 |
2,80 | 1,80 | 2109600 | 1172 | 165183 | 1254591 | 1089409 |
Description: |
S : Storage (depth x area) |
H : Depth of water above spillway. |
Q2 : Discharge use storage, Q2 = 1.71 x B x H^ (3/2) (m³/sec). Q1 : Discharge not use storage (m³/sec). |
J. Appl. Environ. Biol. Sci., 7(3)59-64, 2017 |
Δt : Time Interval (take 30 minute). |
S1 : S/Δt - Q S2 : Q + S1 |
Tabel 7. Discharge calculation after with storage (Q2). |
T | Q1 | Q (average) | S1 | S2 | H | Q2 |
(minute) | (m3/sec) | (m3/sec) | (m3/sec) | (m3/sec) | ( m) | (m3/sec) |
0 | 0,000 | | | | | 0,000 |
30 | 0,170 | 0,085 | 0,000 | 0,085 | 0,001 | 0,004 |
60 | 0,944 | 0,557 | 0,081 | 0,638 | 0,006 | 0,029 |
90 | 2645 | 1794 | 0,609 | 2403 | 0,014 | 0,110 |
120 | 5555 | 4100 | 2293 | 6393 | 0,026 | 0,293 |
150 | 9929 | 7742 | 6099 | 13841 | 0,044 | 0,635 |
180 | 16009 | 12969 | 13206 | 26175 | 0,068 | 1202 |
210 | 24023 | 20016 | 24974 | 44990 | 0,097 | 2065 |
240 | 34188 | 29106 | 42925 | 72031 | 0,133 | 3306 |
270 | 46716 | 40452 | 68724 | 109176 | 0,175 | 5011 |
300 | 61809 | 54262 | 104165 | 158427 | 0,243 | 8189 |
330 | 79653 | 70731 | 150238 | 220969 | 0,336 | 13340 |
360 | 100404 | 90029 | 207629 | 297658 | 0,445 | 20314 |
390 | 124200 | 112302 | 277344 | 389646 | 0,577 | 30007 |
420 | 151169 | 137684 | 359639 | 497324 | 0,734 | 43006 |
450 | 166314 | 158741 | 454317 | 613059 | 0,900 | 58355 |
480 | 173274 | 169794 | 554704 | 724498 | 1057 | 74380 |
510 | 176874 | 175074 | 650118 | 825192 | 1199 | 89746 |
540 | 178352 | 177613 | 735445 | 913058 | 1324 | 104215 |
570 | 178135 | 178244 | 808843 | 987087 | 1427 | 116627 |
600 | 176450 | 177293 | 870460 | 1047752 | 1513 | 127303 |
630 | 173428 | 174939 | 920450 | 1095389 | 1579 | 135686 |
660 | 169139 | 171283 | 959703 | 1130986 | 1629 | 142156 |
690 | 163617 | 166378 | 988830 | 1155208 | 1663 | 146669 |
720 | 156872 | 160244 | 1008539 | 1168784 | 1682 | 149198 |
750 | 149944 | 153408 | 1019586 | 1172994 | 1688 | 149982 |
780 | 143283 | 146614 | 1023012 | 1169626 | 1683 | 149355 |
810 | 136918 | 140101 | 1020272 | 1160372 | 1670 | 147631 |
840 | 130836 | 133877 | 1012742 | 1146619 | 1651 | 145068 |
870 | 125024 | 127930 | 1001550 | 1129480 | 1626 | 141876 |
Q (m³/sec) |
t (minute) |
Figure 2. The results of the flood discharge deduction with the storage |
Ismoyo and Mardyanto, 2017 |
The flood search results showed that with storage of 1,978,106.22 m³ can reduce flood discharge period of 5 |
year (Q5) 178.352 m³/sec be 149,982 m³/sec. When the storage volume made dam lying scattered in the area of study, if a dam: |
Areas : 3 Ha |
Depth : 5 m |
Volume : 150.000 m³ |
Sum of dam : 1.978.106,22 m³/150,000 m³ |
: 13,187 ≈ 13 dam. |
Tabel 8. Recapitulation of the flood discharge deduction with the storage |
No. Discharged use storage(m³/sec) Volume of demand(m³) |
1. 149.982 1.978.106,22 m³
(13 dams) |
CONCLUSION |
To reduce discharge in Cidurian River, spool volume required is 1,978,106.22 m³. Conservation of water resources with a mechanical can reduce the flood discharge of 16%. |
REFERENCES |
1. Balai Besar Wilayah Sungai Cidanau-Ciujung-Cidurian,(2009),Studi Komprehensif Sistem Pengendalian |
Banjir Sungai Cidurian Serang. |
2. Balai Besar Wilayah Sungai Cidanau-Ciujung-Cidurian, (2015), Penyusunan Rancangan Rencana Pengelolaan Sumber Daya Air Wilayah Sungai Cidanau – Ciujung – Cidurian Tahap II Serang |
3. Budinetro H.S., Praja T.A., Rahayu S., (2009),Evaluasi Kemampuan Pengendalian Banjir pada 37 Embung di Hulu Kota Semarang. |
4. Soemarto. CD, (1999), Hidrologi Teknik. |
5. Suripin, (2004), Sistem Drainase Perkotaan Yang Berkelanjutan |
6. Subagyono K, Hartati U, Tala’ohu S.H., (2004), Teknologi Konservasi Air Pada Pertanian Lahan Kering. |