Analysis of Drainage Channel Performance in Catchment Area Greges River City of Surabaya

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33

Analysis of Drainage Channel Performance in Catchment Area Greges River City of Surabaya

Rafiq Ardiansyah Nur, Adi Prawito, Hendro Sutowijoyo Faculty of Engineering, Civil Engineering Study Program

Narotama University Surabaya

[email protected] , [email protected] , [email protected]

Abstract

The drainage channel is designed to safely accommodate the planned discharge based on rainfall data, land use, and channel dimensions. The drainage channel in the catchment area along Kali Greges is one of the infrastructures that supports the functioning of an urban system in the city of Surabaya. The change in land use change from green land to residential land has caused surface runoff in several locations in the city of Surabaya.

The problem of surface runoff that often occurs during the rainy season due to the increase in drainage discharge in the rainwater catchment area along the Kali Greges, causes the need for studies to analyze the performance of the drainage channels.The data used in this study are secondary data, namely: rainfall data for the last 10 years is obtained from rain stations (silver rain station, simo, and hut) and drainage channel data. While the method used is hydrological analysis, methodsarithmetic, and the gumbel method. The data obtained are then analyzed to determine the discharge plan and drainage capacity.

Keywords :

Arithmetic method, Channel dimensions, Discharge plan, Drainage capacity, Gumbel method, Rainfall.

1. Preliminary

1.1. Background

The city of Surabaya is the second largest city after DKI Jakarta which is the capital city of East Java province. Surabaya is geographically located at 07˚09`00 "- 07˚21`00" South Latitude and 112˚36`- 112˚54`

East Longitude. The area of Surabaya covers land with an area of 326.81 km² and oceans covering an area of ??

190.39 km². The city of Surabaya has developed quite rapidly in the last few years as an effort to fulfill its role and function as a central area for trade, industry and education.

The Kali Greges primary channel is a channel that passes from the upstream side of the Viva restaurant on Jalan Kedungdoro to the downstream of Boezem Morokrembangan along 4.55 km, in the rainy season there is often puddles in the catchment area of Kali Greges, which causes disruption of population activities.

Drainage channels along Kali Greges are one of the basic facilities designed as a system to meet community needs and are an important component in urban planning. In order for the channel performance along the Kali Greges to work optimally, it is necessary to conduct a study to overcome the problems that often occur with the hydrological analysis method. Hydrological analysis is used to predict the incoming water discharge at a certain return period, namely 2 years, 5 years or 10 years, and to determine channel capacity.

Thus, it is necessary to analyze the performance of the drainage channels in the catchment area along the Kali Greges, to determine the performance of the drainage channels, then the data from the analysis of channel performance is used as a reference to find solutions to problems of standing water in the drainage channels along Kali Greges. So that the drainage channel can work optimally to accommodate surface runoff.

1.2. Problem Formulation

1. What is the maximum design flood discharge for Kali Greges drainage channel?

2. What is the size of the existing drainage for Kali Greges?

3. How does Kali Greges channel perform?

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34 1.3. Research purposes

1. Calculating the discharge of the Kali Greges drainage plan.

2. Evaluating the existing drainage channel against the planned flood discharge of Kali Greges.

3. Analyzing the performance of Kali Greges drainage channels.

2. Literature Review

2.1. Hydrological Analysis

In the preparation of this final project, the results of the data that have been obtained are then processed using the methods that have been studied and taught, or other methods that may be needed to complete this final project.

Hydrological data is a collection of information or facts regarding hydrologic phenomena, such as the magnitude of: rainfall, temperature, evaporation, length of sun exposure, wind speed, river discharge, river water level, flow velocity, and river sediment concentration will always change. against time. Hydrological data are analyzed to make decisions and draw conclusions about hydrological phenomena based on some hydrological data collected. (Soewarno, 1995)

A. pearson type III log method 𝑙𝑜𝑔𝑋̅̅̅̅̅̅̅ =^∑^𝑛^𝑖=𝑙^{log 𝑋}

𝑛 (1)

𝑆_𝑥 = √^∑𝑛 (log 𝑋−log 𝑋)²̅̅̅̅̅̅̅̅̅̅

𝑖=𝑙

(𝑛−1) (2)

𝐶_𝑠=^∑^𝑛_𝑖=𝑙(log 𝑋− log 𝑋̅̅̅̅̅̅̅)³

(𝑛−1)(𝑛−2)𝑆_𝑥³ (3)

log 𝑅_𝑇𝑟= 𝑙𝑜𝑔𝑋̅̅̅̅̅̅̅ + 𝐾. 𝑆_𝑥 (4)

B. distribution fit test Chi squared

𝑋_ℎ𝑖𝑡² = ∑ ^{(𝑂𝑖−𝐸𝑖)²}

𝐸𝑖

𝑘1=𝑙 (5)

Smirnov Kolmogorov C. plan discharge calculation

𝑄 = ¹

3.6× β × C × 𝑙_𝑡× 𝐴

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2.2. Hydraulics Analysis

Hydraulics is an applied science and technique that studies the mechanical properties of fluids, and also studies water flow both micro and macro. Fluid mechanics is the basis of hydraulic theory which focuses on the engineering of fluid properties. In fluid power, hydraulics are used for power generation, control, and power transfer using compressed fluids.

In terms of flow mechanics, there are two types of flow, namely closed channel flow and open channel flow. The two types of streams in many ways have similarities but differ in one important condition. The difference is in the presence of a free surface, the open channel flow has a free surface, while the closed channel flow does not have a free surface because water fills the entire channel cross section.

A. Fullbank capacity

𝐴 = (𝑏 + 𝑚. ℎ). ℎ (7)

𝑃 = 𝑏 + 2ℎ√1 + 𝑚² (8)

𝑅 =^𝐴

𝑃 (9)

𝑉 = ¹

𝑛× 𝑅^2/3× 𝐼^1/2 (10)

𝑄 = 𝐴 × 𝑉 (11)

3. Research Methodology

This final project research method contains the work steps to solve the problem by using the method of completion that has been selected. This chapter also describes several aspects of research related to research objectives. Some of these aspects include: research locations, research methods, data sources, data collection techniques and data processing techniques. The data is processed with predetermined data processing stages.

From the results of data processing, it will produce a final conclusion from this research.

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35 3.1. Research sites

The location of this research is in the drainage channel along Kali Greges, Surabaya city. The length of the primary channel of the Greges River reaches 4.55 km, from the upstream of the river on Jalan Kedungdoro beside the Viva restaurant to the downstream of the river in South Bozem Morokrembangan.

3.2. Flow chart

Figure 1. Flow Cart

4. Discussion

4.1. Hydrological Analysis

Hydrological analysis uses rain data obtained from Rain Stations in the Surabaya area. Surabaya has 10 rain stations spread throughout the region, including the Perak Rain Station, Simo Rain Station, Gubeng Rain Station and others. The determination of the selection of the Rain Station in this final project research took 3 Rain Stations closest to the research location, namely the Perak Rain Station, Simo Rain Station, and the Gubeng Rain Station. Rainfall data for 10 years (2010-2019) was taken from the nearest Rain Station to the

Secondary Data

- Channel geometry data - Rainfall data (2008-2017) - Flood data

Processing data 1. Rain Plain (Gumbel) 2.(Rasional)

3. Debit Plan (Q=1/3,6.C.I.A)

No

Start

Data Collection

Primary Data Documentation

Hydrounlic Analysis

- Holding Capacity - Long Flood

Dimention Fullbank Capacity?

Discharge channel plan

Conclusion

Finish

yes

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Greges River. The purpose of the hydrological analysis is to determine the channel discharge along the Greges river in Surabaya.

Table 1. Calculation of discharge plans for 2, 5, and 10 years No.

Channel

Segments C Β I (mm) A (km2) Q plan (m2 / sec )

2 Years 5 Years 10 Years 2 Years 5 Year 10 Years 1 0.0 0.95 0.995 44,347 50,395 53,141 1,326 15,440 17,546 18,502 2 0.100 0.95 0.995 45,802 52,048 54,884 1,638 19,694 22,380 23,599 3 0.200 0.95 0.995 46,161 52,457 55,315 1,949 23,626 26,848 28,311 4 0.300 0.95 0.995 56,246 63,917 67,400 2,261 33,389 37,943 40,010 5 0.400 0.95 0.995 47,588 54,078 57,025 2,572 32,143 36,526 38,517 6 0.500 0.95 0.995 51,458 58,476 61,663 2,884 38,968 44,282 46,695 7 0.600 0.95 0.995 54,213 61,606 64,963 3,196 45,489 51,693 54,509 8 0.700 0.95 0.995 53,022 60,253 63,536 3,507 48,828 55,487 58,510 9 0800 0.95 0.995 54,282 61,685 65,046 3,819 54,429 61,852 65,223 10 0.900 0.95 0.995 57,111 64,899 68,436 4,130 61,939 70,386 74,221 11 1,000 0.95 0.995 56,298 63,976 67,462 4,442 65,664 74,619 78,685 12 1,100 0.95 0.995 54,694 62,153 65,540 4,754 68,267 77,578 81,805 13 1,200 0.95 0.995 57,806 65,689 69,269 5,065 76,882 87,367 92,127 14 1,300 0.95 0.995 64,656 73,474 77,477 5,377 91,282 103,731 109,383 15 1,400 0.95 0.995 59,233 67,311 70,979 5,689 88,472 100,538 106,016 16 1,500 0.95 0.995 62,245 70,734 74,588 6,000 98,064 111,438 117,510 17 1,600 0.95 0.995 60,855 69,155 72,923 6,312 100,854 114,608 120,853 18 1,700 0.95 0.995 65,946 74,940 79,023 6,623 114,686 130,327 137,429 19 1,800 0.95 0.995 63,760 72,455 76,404 6,935 116,101 131,935 139,124 20 1,900 0.95 0.995 64,853 73,697 77,713 7,247 123,397 140,226 147,867 21 2,000 0.95 0.995 59,548 67,669 71,356 7,558 118,176 134,292 141,610 22 2,100 0.95 0.995 65,009 73,874 77,900 7,870 134,331 152,651 160,969 23 2,200 0.95 0.995 63,280 71,910 75,828 8,181 135,936 154,475 162,892 24 2,300 0.95 0.995 63,250 71,876 75,793 8,493 141,048 160,284 169,018 25 2,400 0.95 0.995 56,339 64,023 67,512 8,805 130,247 148,010 156,075 26 2,500 0.95 0.995 57,574 65,426 68,991 9,116 137,811 156,606 165,139 27 2,600 0.95 0.995 54,702 62,162 65,549 9,428 135,412 153,879 162,264 28 2,700 0.95 0.995 58,892 66,924 70,570 9,739 150,603 171,143 180,468 29 2,800 0.95 0.995 58,704 66,709 70,345 10,051 154,924 176,053 185,646 30 2,900 0.95 0.995 60,329 68,557 72,292 10,363 164,151 186,537 196,702 31 3,000 0.95 0.995 57,924 65,824 69,411 10,674 162,346 184,487 194,540 32 3,100 0.95 0.995 54,463 61,890 65,263 10,986 157,101 178,526 188,254 33 3,200 0.95 0.995 57,638 65,499 69,068 11,297 170,976 194,293 204,880 34 3,300 0.95 0.995 61,559 69,954 73,766 11,609 187,642 213,233 224,852 35 3,400 0.95 0.995 63,728 72,419 76,366 11,921 199,470 226,673 239,025 36 3,500 0.95 0.995 60,900 69,206 72,977 12,232 195,602 222,278 234,390 37 3,600 0.95 0.995 62,288 70,783 74,640 12,544 205,156 233,135 245,839 38 3,700 0.95 0.995 62,422 70,935 74,800 12,856 210,702 239,437 252,484 39 3,800 0.95 0.995 65,357 74,270 78,317 13,167 225,958 256,773 270,765 40 3,900 0.95 0.995 66,780 75,888 80,023 13,479 236,342 268,574 283,209 41 4,000 0.95 0.995 68,361 77,683 81,916 13,790 247,528 281,286 296,613 42 4,100 0.95 0.995 70,366 79,962 84,319 14,102 260,546 296,079 312,213 43 4,200 0.95 0.995 70,297 79,884 84,237 14,414 266,043 302,326 318,799 44 4,300 0.95 0.995 70,018 79,567 83,903 14,725 270,718 307,638 324,401 45 4,400 0.95 0.995 72,420 82,297 86,781 15,037 285,929 324,924 342,629 46 4,500 0.95 0.995 73,395 83,404 87,949 15,348 295,782 336,120 354,435

4.2. Hydraulics Analysis

Hidrolika is an applied science and technique that studies mechanical propertiesfluida, and also study Genreairsboth micro and macro. Fluid mechanics is the basis of hydraulic theory which focuses on the engineering of fluid properties. In fluid power, hydraulics are used for power generation, control, and power transfer using compressed fluids.

That From flow mechanics, there are two types of flow, namely closed channel flow and open channel flow. The two types of streams in many ways have similarities but differ in one important condition. The

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37

difference is in the presence of a free surface, the open channel flow has a free surface, while the closed channel flow does not have a free surface because water fills the entire channel cross section.

Hydraulic analysis is performed to determine whether the drainage system is technically planned in accordance with the technical requirements. This analysis includes the calculation of channel capacity and channel planning.

Table 2. Calculation of the existing channel capacity of the Greges Kali primary channel No. Channel

Segments

channel cross

section L (m) b (m) h

(m) A (m²) P (m) R (m) V (m / sec)

Existing Q (m³ / sec)

1 0 + 00 Trapesium 4550 7.6 1.1 8,663 9,868 0.878 2,174 18,836

2 0 + 100 Trapesium 4550 10.17 1.13 11,811 12,500 0.945 2,284 26,975 3 0 + 200 Trapesium 4550 7.25 1.25 9,453 9,827 0.962 2,311 21,848 4 0 + 300 Trapesium 4550 8.08 2.11 19,497 12,896 1,512 3,124 60,914 5 0 + 400 Trapesium 4550 9.21 1.26 12,414 12,039 1,031 2,421 30,052 6 0 + 500 Trapesium 4550 6.68 1.72 12,998 10,542 1,233 2,727 35,449 7 0 + 600 Trapesium 4550 7.23 1.98 16,080 11,572 1,389 2,953 47,486 8 0 + 700 Trapesium 4550 7.89 1.76 16,519 12,510 1,321 2,855 47,157 9 0 + 800 Trapesium 4550 6.56 1.99 16,420 11,784 1,394 2,959 48,587 10 0 + 900 Trapesium 4550 8.47 2.15 21,677 13,845 1,566 3,198 69,323 11 1 + 000 Trapesium 4550 8.79 2.06 20,441 13,492 1,515 3,129 63,953 12 1 + 100 Trapesium 4550 7.38 1.98 17,161 12,103 1,418 2,993 51,367 13 1 + 200 Trapesium 4550 11.66 2.08 25,983 16,140 1,610 3,258 84,647 14 1 + 300 Trapesium 4550 11.58 2.9 37,367 17,940 2,083 3,868 144,537 15 1 + 400 Trapesium 4550 11.94 2.26 28,261 16,599 1,703 3,382 95,571 16 1 + 500 Trapesium 4550 11.45 2.67 32,354 16,954 1,908 3,649 118,054 17 1 + 600 Trapesium 4550 10.7 2.45 29,516 16,292 1,812 3,525 104,035 18 1 + 700 Trapesium 4550 10.83 3.16 38,716 17,760 2,180 3,987 154,377 19 1 + 800 Trapesium 4550 11.33 2.77 35,604 17,653 2.017 3,786 134,800 20 1 + 900 Trapesium 4550 12.3 2.96 38,598 18,402 2,097 3,886 150,002 21 2 + 000 Trapesium 4550 10.95 2.3 27,566 15,994 1,723 3,409 93,978 22 2 + 100 Trapesium 4550 13.93 2.74 44,475 21,087 2,109 3,901 173,476 23 2 + 200 Trapesium 4550 11.57 2.69 35,103 17,710 1,982 3,742 131,369 24 2 + 300 Trapesium 4550 9.46 2.94 31,270 15,793 1980 3,740 116,940 25 2 + 400 Trapesium 4550 11.48 1.97 23,586 15,541 1,518 3,132 73,874 26 2 + 500 Trapesium 4550 11.11 2.06 25,221 15,812 1,595 3,238 81,657 27 2 + 600 Trapesium 4550 10.6 1.8 20,862 14,709 1,418 2,994 62,461 28 2 + 700 Trapesium 4550 26.2 1.88 51,624 30,726 1,680 3,352 173,039 29 2 + 800 Trapesium 4550 26.3 1.88 50,328 30,176 1,668 3,335 167,867 30 2 + 900 Trapesium 4550 28.66 1.98 59,687 33,610 1,776 3,478 207,595 31 3 + 000 Trapesium 4550 23.76 1.84 44,565 27,553 1,617 3,268 145,635 32 3 + 100 Trapesium 4550 22.24 1.57 36,987 26,341 1,404 2,974 110,001 33 3 + 200 Trapesium 4550 19.26 1.85 37,856 23,673 1,599 3,243 122,775 34 3 + 300 Trapesium 4550 16.78 2.26 41,243 22,171 1,860 3,587 147,951 35 3 + 400 Trapesium 4550 25.84 2.31 63,159 31,350 2015 3,783 238,941 36 3 + 500 Trapesium 4550 27.2 2.04 58,193 32,066 1,815 3,529 205,344 37 3 + 600 Trapesium 4550 26.59 2.17 60,290 31,543 1,911 3,653 220,226 38 3 + 700 Trapesium 4550 29.26 2.16 65,301 33,997 1,921 3,665 239,313 39 3 + 800 Trapesium 4550 31.02 2.41 79,289 37,133 2,135 3,933 311,822 40 3 + 900 Trapesium 4550 31.8 2.54 85,611 38,150 2,244 4,065 348,026 41 4 + 000 Trapesium 4550 33.2 2.69 96,038 40,547 2,369 4,214 404,723 42 4 + 100 Trapesium 4550 31 2.96 93,950 37,102 2,532 4,406 413,961 43 4 + 200 Trapesium 4550 34 2.91 101,057 39,999 2,526 4,400 444,602 44 4 + 300 Trapesium 4550 34.6 2.85 102,265 40,851 2,503 4,373 447,173 45 4 + 400 Trapesium 4550 34.2 3.12 111,084 41,043 2,707 4,606 511,674 46 4 + 500 Trapesium 4550 32.78 3.26 111,114 39,802 2,792 4,702 522,480 4.3. Comparison of Existing Channel Capacity with Planned Discharge

Comparison of Existing Channel Capacity with Plan Discharge is a way of comparing channel capacity with planned discharge. If the existing channel capacity is greater than the planned discharge, then the channel is

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declared safe. But if on the other hand, if the existing channel is smaller than the planned debit, the channel cannot accommodate the channel discharge.

A more detailed analysis of the comparison of the existing channel capacity with the planned discharge in the Greges River primary channel can be seen in the table below. With a comparison of the discharge plan 5 th.

Table 3. Comparison of planned debit and existing debit

No. Channel

Segments

Q plan (m³ / sec)

Existing Q (m³ /

sec) difference Information

1 0.0 17,546 18,836 1,290 Secure

2 0.100 22,380 26,975 4,595 Secure

3 0.200 26,848 21,848 -5,000 Flood

4 0.300 37,943 60,914 22,971 Secure

5 0.400 36,526 30,052 -6,474 Flood

6 0.500 44,282 35,449 -8,833 Flood

7 0.600 51,693 47,486 -4,206 Flood

8 0.700 55,487 47,157 -8,329 Flood

9 0800 61,852 48,587 -13,265 Flood

10 0.900 70,386 69,323 -1,063 Flood

11 1,000 74,619 63,953 -10,666 Flood

12 1,100 77,578 51,367 -26,210 Flood

13 1,200 87,367 84,647 -2,720 Flood

14 1,300 103,731 144,537 40,807 Secure

15 1,400 100,538 95,571 -4,967 Flood

16 1,500 111,438 118,054 6,616 Secure

17 1,600 114,608 104,035 -10,573 Flood

18 1,700 130,327 154,377 24,050 Secure

19 1,800 131,935 134,800 2,865 Secure

20 1,900 140,226 150,002 9,776 Secure

21 2,000 134,292 93,978 -40,314 Flood

22 2,100 152,651 173,476 20,825 Secure

23 2,200 154,475 131,369 -23,106 Flood

24 2,300 160,284 116,940 -43,344 Flood

25 2,400 148,010 73,874 -74,136 Flood

26 2,500 156,606 81,657 -74,948 Flood

27 2,600 153,879 62,461 -91,419 Flood

28 2,700 171,143 173,039 1,897 Secure

29 2,800 176,053 167,867 -8,185 Flood

30 2,900 186,537 207,595 21,057 Secure

31 3,000 184,487 145,635 -38,852 Flood

32 3,100 178,526 110,001 -68,525 Flood

33 3,200 194,293 122,775 -71,518 Flood

34 3,300 213,233 147,951 -65,282 Flood

35 3,400 226,673 238,941 12,268 Secure

36 3,500 222,278 205,344 -16,934 Flood

37 3,600 233,135 220,226 -12,909 Flood

38 3,700 239,437 239,313 -0.124 Flood

39 3,800 256,773 311,822 55,048 Secure

40 3,900 268,574 348,026 79,452 Secure

41 4,000 281,286 404,723 123,437 Secure

42 4,100 296,079 413,961 117,882 Secure

43 4,200 302,326 444,602 142,277 Secure

44 4,300 307,638 447,173 139,535 Secure

45 4,400 324,924 511,674 186,749 Secure

46 4,500 336,120 522,480 186,360 Secure

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39 4.4. Inundation Handling

Handling of inundation in the catchment area along the Greges River, by revitalizing and normalizing the primary channel system at the Greges River. Handlers must also look at existing field conditions. Activities that must be carried out are:

1. Optimizing the existing capacity, this activity includes repairing and increasing the capacity of existing channels and complementary buildings.

2. Construction of complementary buildings, namely: pump house building, floodgate building, etc. to optimize the function of drainage channels to run optimally. Pump housing also plays a major role in reducing runoff discharge.

3. Normalization of the channel, it is necessary to normalize the channel and deepen the channel using an excavator.

Q> Q plan 23,243 m³ / sec> 20,190 m³ / sec (OK)

The calculation of the channel dimensions can be seen in table 4:14 below:

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Table 4. Comparison of discharge plans for the 5 year Greges return periode

No. Channel

Segments Q plan (m³ / sec) Existing Q (m³ /

sec) Information

1 0.0 17,546 37,073 Secure

2 0.100 22,380 52,492 Secure

3 0.200 26,848 35,005 Secure

4 0.300 37,943 39,924 Secure

5 0.400 36,526 46,693 Secure

6 0.500 44,282 50,268 Secure

7 0.600 51,693 55,621 Secure

8 0.700 55,487 62,123 Secure

9 0800 61,852 62,967 Secure

10 0.900 70,386 87,718 Secure

11 1,000 74,619 91,960 Secure

12 1,100 77,578 80,212 Secure

13 1,200 87,367 130,848 Secure

14 1,300 103,731 129,747 Secure

15 1,400 100,538 134,707 Secure

16 1,500 111,438 127,960 Secure

17 1,600 114,608 117,695 Secure

18 1,700 130,327 142,694 Secure

19 1,800 131,935 151,000 Secure

20 1,900 140,226 167,242 Secure

21 2,000 134,292 144,683 Secure

22 2,100 152,651 194,855 Secure

23 2,200 154,475 155,004 Secure

24 2,300 160,284 160,586 Secure

25 2,400 148,010 153,501 Secure

26 2,500 156,606 159,697 Secure

27 2,600 153,879 156,336 Secure

28 2,700 171,143 409,593 Secure

29 2,800 176,053 411,371 Secure

30 2,900 186,537 453,413 Secure

31 3,000 184,487 366,298 Secure

32 3,100 178,526 339,432 Secure

33 3,200 194,293 287,058 Secure

34 3,300 213,233 243,865 Secure

35 3,400 226,673 403,194 Secure

36 3,500 222,278 427,387 Secure

37 3,600 233,135 416,529 Secure

38 3,700 239,437 464,123 Secure

39 3,800 256,773 495,581 Secure

40 3,900 268,574 509,542 Secure

41 4,000 281,286 534,625 Secure

42 4,100 296,079 495,223 Secure

43 4,200 302,326 548,973 Secure

44 4,300 307,638 559,740 Secure

45 4,400 324,924 552,561 Secure

46 4,500 336,120 527,097 Secure

4.5. Inundation handling using a pump

Inundation handling can also use a water pump to reduce the discharge from rainwater runoff. pump housing plays an important role in handling floods which often occur during the rainy season with the pump house can accelerate removing excess water that has stagnated in the cathment area of the drainage channel.

Therefore, the calculation of the pump capacity is carried out using the following methods:

a. Greges times pump calculation Regional data:

- Drain line length (L) : 4550 m

- Water catchment area (A) : 15.72 km²

- Run off coefficient : 0.95 (kawasa urban)

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- b : 6.6

- h : 1.14 m

- m : 0.71 m

- n (cemented masonry) : 0.02

The results of hydrograph calculations can be seen in Table 4:16 and accompanied by a hydrograph graphic image:

Figure 2. Hydrograph Graph 4.6. Pump capacity calculation

Calculation of pump capacity using long storage volume

Calculations using the maximum pump in the greges water pump With the following pump capacities:

- Pump capacity 3 m³ / sec : 5 units - Pump capacity 2 m³ / sec : 1 unit - Pump capacity 0.25 m³ / sec : 2 units

- capacity : 17.5 m³ / sec

With volume calculations

- Pump capacity 3 m³ / sec : 1800 m³ - Pump capacity 2 m³ / sec : 1200 m³ - Pump capacity 0.25 m³ / sec : 150 m³ Storage volume:

𝑉 = (𝑏 + 𝑚. ℎ)ℎ × 4550 𝑉𝑡𝑎𝑚𝑝𝑢𝑛𝑔𝑎𝑛 = 38432 𝑚³

Calculation of pump operating capacity can be seen in table 4.16 Calculation of Pump Capacity below : Time (minute)

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Table 5. Pump calculation

No. Hour Second

Inflow Volume Outflow volume V which

must be controlled

storage Q (m³ /

sec) V (m³) V

cumulative

Q (m³/

sec) V (m³) V

cumulative

1 0.00 0 0.000 0 0 0 0 0 0.00

2 0.10 360 4,341 2604.81 2604.81 3.5 2100 2100 504.81

3 0.20 720 8,683 5209.62 7814.44 8.5 5100 7200 614.44

4 0.30 1080 13,024 7814.44 15628.87 12.5 7500 14700 928.87

5 0.40 1440 17,365 10419.25 26048.12 17 10200 24900 1148.12

6 0.50 1800 21,707 13024.06 39072.18 17.5 10500 35400 3672.18 7 0.53 1915.2 23,096 13857.60 52929.78 17.5 10500 45900 7029.78 8 0.60 2160 21,707 13024.06 65953.84 17.5 10500 56400 9553.84 9 0.70 2520 17,365 10419.25 76373.09 17.5 10500 66900 9473.09

10 0.80 2880 13,024 7814.44 84187.52 17 10200 77100 7087.52

11 0.90 3240 8,683 5209.62 89397.15 17 10200 87300 2097.15

12 1.00 3600 4,341 2604.81 92001.96 5 3000 90300 1701.96

13 1.06 3830.4 0.000 0 92001.96 2.8366 1701.96 92001.96 0.00

14 1.10 3960 0.000 0 92001.96 0 0 92001.96 0.00

Figure 3. Pump Operation Graph

The plan to operate the water pump in the Kali Greges drainage channel is as follows:

1. In the 6th minute, 1 unit of 3 m³ / sec flood pump operated with an additional 0.25 m³ / second 2 units of pump, to stabilize the channel discharge.

2. In the 30th minute, a maximum operation of the pump with a flood pump of 3 m³ / sec is 5 units, a flood pump is 2 m³ / sec 1 unit, and a pump 0.25 m³ / sec 2 units. To reduce drainage discharge.

3. In the 48th minute the channel discharge gradually decreases and the pump is gradually reduced for operation, until at 66 minutes the pumps are all ready because the flow rate decreases,

4. The pump operation is in accordance with the procedure by reducing the incoming flow rate, the pump capacity can handle the volume that must be controlled by the reservoir.

5. The required volume of capacity is 9553.84 m³ while the existing storage capacity is 38432 m³, so the existing storage can accommodate safely.

5. Closing

5.1. Conclusion

From the analysis of the performance of the drainage channels in the rainwater catchment area along the river greges in Surabaya, it can be concluded that:

1. Based on the calculation, it is found that the planned discharge for 5 years which flows in the primary channel of Kali Greges, it is found that the existing Q <Q plan causes water runoff. Segment AB was found to exist Q: 18,660 m³ / sec <Planned Q: 20,190 m³ / sec.

PUMP OPERATION

Time (Minute)

(11)

43

2. Based on the calculation of the existing Q <Q plan, it is necessary to normalize the channel to restore channel function and optimize channel performance.

3. Based on the calculation of Q after normalization is obtained, the existing AB segment Q: 23,243 m³ / sec>

Q plan: 20,190 m³ / sec. Then the existing Q has filled the reservoir.

4. Based on the calculation of the storage capacity of the drainage channel, the reservoir volume of Kali greges is 38432 m³ and the cumulative volume that can be accommodated is 9553.84 m³. So the volume of the Kali greges reservoir still fills the reservoir V Kali Greges: 38432 m³> V cumulative that can be accommodated: 9553.84 m³.

From the above conclusions, the Kali Greges drainage channel needs normalization to meet the 5-year plan discharge, for the river greges storage capacity is still able to accommodate a volume of 9553.84 m³.

5.2. Suggestion

1. It is necessary to normalize the channel so that the performance of the Kali Greges drainage channel can work optimally.

2. There needs to be regular maintenance on the pump so that it can function optimally when it is operated.

References

Soewarno. (1995). Hidrologi Aplikasi Metode Statistik Untuk Analisa Data. Penerbit Nova.