Journal of Modern Science and Technology

Vol. 6. No. 1. March 2018 Issue. Pp.63-77

63

Design of Storm water Drainage Network with Limited Data Using GeoSWMM: Case Study for Bogra City

Mushtari Maliha* and Md Sabbir Mostafa Khan

Significant progress in urban growth and infrastructural development has been observed in Bogra city and as a result, provision for adequately planned drainage network has become mandatory. Several types of data are required to design a drainage system but in Bogra city, all the data are not available. This study focuses on designing an adequate drainage system with limited data. In conclusion of this study, minimum cross-sectional area of each stream has been calculated from the stream discharge obtained from the model GeoSWMM output. The minimum cross-sections for 5 year return period in the C4 , C6 , C16 , C17, C27, C28 streams are 30.24, 52.6, 48.08, 51.1, 73.56, 42.15 �

� and for 10 year return period in the C4 , C6 , C16 , C17, C27, C28 streams are 66.23, 99.10, 109.66, 102.06, 105.33, 89.33 �

�. It has been found that as the intensity of rainfall for 10 year return period is higher than that of 5 year return period, more area might be required for the runoff to be discharged safely in the river.

Keywords and Field of Research: Urbanization, Bogra city, Storm water drainage management system, GeoSWMM.

1. Introduction The 1st objective of this study is the determination of runoff of different sub-catchment. Previously no study on drainage management of Bogra has been carried out and hence we cannot compare the results of this study with other studies. Rapid urbanization has increased the volume of storm water runoff by increasing imperviousness. Managing the drainage system to safely and adequately drain this excess runoff is a major issue. Moreover, scarcity of data makes it even more difficult to make provisions for designing adequate drainage system. Very few studies on designing drainage system with GeoSWMM have been performed and in case of Bogra, this study is the very first one. This study provides an overview of the storm water runoff situation in Bogra and proposes the design of drainage network with the limited data. This paper is organized as follows – the first section describes the introduction which is followed by study area, methodology, data collection and data processing, calculation, result and analysis, pseudo calibration in the following sections and conclusion in the final section. _________________________ *Mushtari Maliha, Corresponding Author, Department of Water Resources Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh, Email: mushtarimaliha10@gmail.com

Dr. Md Sabbir Mostafa Khan, Department of Water Resources Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000, Bangladesh

Maliha & Khan

64

Major metropolitan areas are characterized by continuous increases in imperviousness due to urban development. Higher levels of impervious surfaces result in a higher volume of runoff with higher peak discharge, shorter travel time, and more severe pollutant loadings. Urban imperviousness is a very important parameter to manage for urban watersheds and the relatedwater environment. Direct connectivity to the drainage system is an important attribute of urban imperviousness. (Lee et al 2003) The idea of efficient storm water management is based on the requirement to protect the health of the public, welfare and safety of the public, conservation of water, need to strive for sustainable environment etc. Basic considerations in a storm water catch basin design are functional requirements, technical requirements, and social and economic considerations. (Dieter, 2013) Bogra city is located in the North-Western region of Bangladesh. Since 2009 with the advancement of urban planning, there has been a significant development in the infrastructure of Bogra including, restructured and widened town roads, improved telecommunications, and the instillation of underground gas connections. There is no proper storm water drainage system in here. There are a number of natural drainage channels which are responsible for the drainage of storm water to the Karatoya River. These natural drainage channels are being filled up due to unplanned land development and encroached by people. Percentage of impervious area and directly connected impervious area is increasing due to widening of existing pavements, development of new pavement roads and construction of commercial and residential buildings. Therefore, it is necessary to plan for an integrated storm water drainage management of the city for the efficient management of storm water quantity and quality. Urbanization causes extensive changes to the land surface beyond its immediate borders, particularly in ostensibly rural regions, through alterations by agriculture and forestry that support the urban population. (Lambin et al, 1999) The creation of impervious surfaces that accompanies urbanization profoundly affects how water moves both above and below ground during and following storm events, the quality of that storm water, and the ultimate condition of nearby rivers, lakes, and estuaries. (Needhidasan et al, 2013) The magnitude of population growth is an important variable affecting urban environmental problem because it directly affects the spatial concentration of people, industry, commerce, vehicles, energy consumption, water use, waste generation, and other environmental stresses (Bartone et al, 1992). Storm water runoff is water, from rain or snowmelt that flows over the land surface, and is a major component of the water cycle. Typically, storm runoff is produced by any one of two methods- the first occurs if the precipitation falls on the soil surface more rapidly than the soil can absorb it, causing the excess precipitation to run over the surface of the land. (Booth D.B, 1991) The peak rate, volume, and timing of runoff are important characteristics in the planning and design of storm water management practice. Runoff rate and volume generally increase after urbanization and this development alters the characteristics of runoff. (Needhidasan et al, 2013)

Maliha & Khan

65

A storm drainage system is a system receiving, conveying, and controlling storm water runoff in response to precipitation and snowmelt. Such systems include: ditches, culverts, swales, subsurface interceptor drains, roadways, curb and gutters, catch basins, manholes, pipes, attenuation ponds and service lateral lines. (EPWDR, 2011) The major drainage system comprises the natural streams and valleys and manmade streets, channels and ponds. The main purpose is to essentially eliminate the risk of loss of life and property damage due to flooding. (Needhidasan et al, 2013) DPHE (1968), the first master plan was prepared to protect the developed area of 75��

� from floodwater and to drain internal storm water. BWDB (1975), following the previous master plan, prepared detailed scheme for an area of 145��

�. In 1976 another scheme for internal drainage system was prepared by DPHE. Due to difficulty in financing both the proposals were not approved. Instead a crash program for removing standing water from Dhaka City, Internal Scheme was recommended and has been implemented by DPHE since 1976.In 1981 “Dhaka Metropolitan Integrated Urban Development Project” was completed in which a framework for the future Urban Development of Dhaka was prepared and future detailed study for the drainage system improvement was recommended. As the existing storm water drainage system is still inadequate for coping with the recurring heavy storms and flood. JICA (1887) carried out a study on storm Water Drainage System Improvement Project in Dhaka City from November 1986 to October 1987 to solve the water logging problem. The study proposed improvement of 39.7 km of khals. In October 1988 the Govt. of Bangladesh formed a committee for flood control and drainage of greater Dhaka in the wake of the floods of 1987 and 1988. Afterwards the Government of Bangladesh established a committee for flood control plan for Greater Dhaka Metropolitan region which predicted mostly on the 1987 JICA study storm drainage system improvements for Dhaka city and the 1988 “Jansen Report” on causes of the flood and recommended solutions. Apirumanekul and Mark (2001) highlighted the urban flooding in September 1996 when residences experienced ankle to knee- deep water on the streets. The study has depended on a combined approach of physically based modeling and GIS. The urban drainage is structured by MOUSE for the basis of two networks, one simulating the free surface flow over the streets and one for the sewer pipe system. There is no existing study on drainage management of Bogra city. This study fills the knowledge gap by providing the design of an adequate drainage management system with limited data using GeoSWMM. This study adds to the body of knowledge by contributing an effective drainage management study to the field of hydrology of Bogra. In this era of rapid urbanization and increasing imperviousness, the importance of effective drainage management is undeniable. The paper is organized as follows- Section 1 deals with Introduction, Section 2 focuses on Study Area, Section 3 contains Methodology, Result Analysis is provided in Section 4 followed by Pseudo Calibration in Section 5 and finally Conclusion in Section 6.

Maliha & Khan

66

2. Study Area

Bogra is a major city located in the Bogra District, Rajshahi Division, Bangladesh, and acts as the major commerce hub in the Bogra District. Described by some as the "nerve center of Northern Bangladesh", Bogra is a bridge between the Rajshahi Division and Rangpur Division. Bogra is also known as the industrial city of the North Bengal. Bogra Sadar Upazilla is an upazila of Bogra District in the Division of Rajshahi, Bangladesh. Bogra Thana was established in 1821 and was converted into an upazila in 1983. The upazila takes its name from the district and the Bengali word sadar (headquarters). It is the sub district where the district headquarters, Bogra town, is located. Bogra Sadar Upazila lies at 24°51′N 89°22′E. It borders Shibganj Upazila to the north, Gabtali Upazila to the east, Shajahanpur Upazila to the south, and Kahaloo Upazila to the west. The Karatoya River flows south through the upazila.

Figure 1: Bogra Sadar Upazila Map (LGED Bangladesh)

Bogra Sadar Upazila has a total area of 176.58 square kilometers (68.18 sq. mi). The elevation ranges from 14m to 40m and almost all of the areas can be categorized as flat to nearly flat topography. The Karatoya River, known as Phuljhur rises in the Baikunthapur jungles in the extreme north-west of Jalpaiguri district (West Bengal, India) and forms for some distance the boundary between Dinajpur and Rangpur districts. It, then, meanders through Rangpur and Bogra. In the south of Bogra district, it receives the Halhalia and the united stream is then known as Phuljhur. It leaves Bogra at Chandakona and flowing in a southerly direction past Raiganj and Shujapur is joined by the Ichhamatiat Nalka.

Maliha & Khan

67

3. Methodology

3.1 Data Collection and Data Processing

For Storm Water Drainage Analysis, Digital Elevation Model data and rainfall data of the study area are required. In order to assess the present drainage condition of the Bogra Sadar Upazila, these data are collected from different sources. A Digital Elevation Model (DEM) is a digital cartographic/geographic dataset of elevations in xyz coordinates. For the collection of SRTM DEM data for this study, SRTM 1 Arc Second Global DEM was collected from the USGS Global Data Explorer website. This elevation data offer worldwide coverage of void filled data at a resolution of 1 arc-second (30 meters). Rainfall data have been collected from Bangladesh Meteorological Department (BMD) stations .These data have been analyzed for annual variation. Land use map is required for hydrological pseudo calibration. With the help of the land use map the surface cover of every catchment can be determined and the runoff coefficients can be calculated accordingly. In this study land use map of Bogra city in 2017 has been generated using Google Earth. The types of land use are divided into the following categories- built ups, vegetation, barren land, waterbodies. These types are digitized as polygon shapefile using the ‘create polygon’ tool in Google Earth.

Figure 2: Clipped DEM

Maliha & Khan

68

Figure 3: Generated Land Use Map

Estimates of extreme rainfall depths or intensities are required for the design of drainage or sewer systems. Therefore, the annual maximum series, which is the set of maximum values observed during a period (minute(s), hour(s) or day) in each year, are analyzed.

Figure 4: Digitized Existing Streams and Agree DEM

Maliha & Khan

69

Several distribution functions can be selected to estimate extreme rainfall during the considered period. The Gumbel distribution which is skewed often gives satisfactory results. The “Extreme value distribution method” was first introduced by Gumbel in 1941 and is commonly known as Gumbel’s distribution. It is one of the most widely used probability distribution function for extreme values in hydrologic and meteorological studies for prediction of flood peaks, maximum rainfall, maximum wind speed, etc. Existing Stream network is digitized from Google Earth for the creation of “AGREE DEM” and for the better examination of the portrayed streams with the actual streams of the study area. Watershed delineation of the study area is done using GeoSWMM software.

4. Calculations

Daily rainfall data at rainfall station at Bogra for years 1948-2014 was collected from Bangladesh Water Development Board. Maximum rainfall value for each year was identified and added in a separate worksheet in Microsoft Excel which is used for rainfall analysis using Gumbel’s Distribution Here,

N = sample size = 67 � ̅ = Mean of the variate = 129.46

��−1 = Standard deviation of the sample = 48.95 Yn= Reduced mean = 0.55

�= Reduced standard deviation of the sample = 1.18

For Return Period T=5 Years

Reduced variate, � = − (0.834+2.303 log�

���)= -(0.834+2.303 log

�

���) = 1.5004

Frequency factor, k=�����

��

= �.������.��

�.�� = 0.8

Value of the variable x with a return period T = 5 years,

� = x �+���−1= 129.46+ 0.8 × 48.95= 168.64

For Return Period T=10 Years

Reduced variate,� = − (0.834+2.303 log log�

���) = -(0.834+2.303 log log

��

���� ) = 2.251

Frequency factor, k= �����

��

= �.�����.��

�.��= 1.44

Maliha & Khan

70

Value of the variable x with a return period T = 10 years,

� = x �+���−1= 129.46+ 1.44 × 48.95= 199.71

5 year return period � = 168.64 means a rainfall of 168.64 mm will occur at least once

in 5 years in Bogra District. For 10 year return period � = 199.71 means a rainfall of

199.71 mm will occur at least once in 10 years in Bogra District.

According to JICA reports, percentage of the rainfall with 5 year and 10 year return period is determined for different time steps.

Table 1: For 5 And 10 Year Return Periods, Percentage of Rainfall for Different Time Steps

Time Step (hour) Percentage 5 Year Return Period

��= 168.64mm 10 Year Return Period

��= 199.71mm

0-4 9 15.18 17.97

4-8 15 25.30 29.96

8-12 44 74.20 87.87

12-16 16 26.98 31.95

16-20 9 15.18 17.97

20-24 7 11.80 13.98

From the rainfall data at 4 hour interval calculated from Gumbel Distribution, 10 year return period rainfall intensity is higher than the 5 year return period rainfall. And the average difference between the 5 year and 10 year rainfall value is around 5mm. For delineating watershed of Bogra City, SRTM DEM files are collected. These DEM files are of 30m resolution. Then this raster is clipped according to the Bogra Sadar Upazilla shape file & the concerned study area. The DEM is clipped taking extra area outside the study area to avoid the missing of some sub-catchments within the study area. The Digitized stream network from Google earth is used for stream burning and an Agree DEM is generated. A stream shape file is generated from the Agree DEM raster file. Then some outlet points are generated automatically. A stream shape file is generated from the Agree DEM raster file. Then some outlet points are generated automatically. The average slope of the sub catchments found from the model is 6.4%. The average width calculated from the model is 186 m. The total sub-catchment area of the study area is 129.69��

�.The N values for imperviousness, perviousness, depression storage imperviousness, depression storage perviousness is assumed to be respectively 0.1, 0.1, 0, and 100. Flow rate (flow units), average water depth (m), flow velocity (m/sec), volume of water (��) of link such as conduit, outlet are obtained from the model simulation. The cross sectional area of the drains are designed using the continuity equation with the help of the maximum conduit flow obtained from model simulation.

Maliha & Khan

71

This study combines the use of geodatabase and hydrological modeling. There were no study on drainage management carried out for Bogra city. Besides, very few drainage studies carried out for other major cities combined geodatabase and hydrological modeling for better results.

Figure 5: Delineated Watershed

5. Result and Analysis

The study area has 9 sub-catchments divided by the cannel network. The runoff values of each sub-catchment are given in Figure-1.2 & 1.3. From the output table it is clear that the runoff coefficients are in the reasonable range 0.5 ~ 0.6 and the values match with the values of runoff coefficient estimated using the land use map. The peak runoff is found for 5 year return period is 87.29 CMS in the W28 sub catchment and for 10 year return period it is 165.24 CMS in the W28 sub-catchment. The total runoff for 5 year return period is around 89mm and for 10 year return period it is around 120mm. The discharge value of 10 year return period is greater than 5 year return period as expected.

Maliha & Khan

72

Table 2: Sub catchment Runoff (T= 5 Years)

Subcatchment Total Precipitation

(mm)

Total Runoff

(m)

Peak Runoff CMS

Runoff Coefficient

W3 168.64 93.67 0.59 0.555

W4 168.64 84.33 32.38 0.500

W5 168.64 93.44 9.75 0.554

W6 168.64 101.48 51.35 0.602

W16 168.64 84.34 49.08 0.500

W17 168.64 87.37 57.84 0.518

W24 168.64 89.47 55.4 0.531

W28 168.64 86.38 87.29 0.512

W29 168.64 88.4 39.77 0.524

Table 3: Sub catchment Runoff (T= 10 Years)

Subcatchment Total

Precipitation (mm)

Total Runoff

(m)

Peak Runoff CMS

Runoff Coefficient

W3 199.71 124.76 0.72 0.625

W4 199.71 115.4 64.14 0.578

W5 199.71 124.52 16.88 0.623

W6 199.71 132.55 82.43 0.664

W16 199.71 115.41 96.7 0.578

W17 199.71 118.44 109.2 0.593

W24 199.71 120.55 95.68 0.604

W28 199.71 117.45 165.24 0.588

W29 199.71 119.47 73.52 0.598

Flow rate (flow units), average water depth (m), flow velocity (m/sec), volume of water (��) of link such as conduit, outlet are obtained from the model simulation.

Maliha & Khan

73

Table 4: Conduit Flow Summary (T= 5 years)

Link Type Maximum Flow

(CMS)

Time of Max Occurrence days:hr:min

Maximum Velocity (m/sec)

C3 CONDUIT 82.431 0:20:26 2.93

C4 CONDUIT 24.195 0:20:15 1.29

C5 CONDUIT 161.425 0:21:29 1.97

C6 CONDUIT 42.084 0:16:25 1.94

C16 CONDUIT 38.462 0:16:49 1.31

C17 CONDUIT 40.883 0:20:20 1.28

C23 CONDUIT 138.409 0:21:33 1.05

C27 CONDUIT 58.846 0:20:45 1.36

C28 CONDUIT 33.72 0:16:21 1.88

Table 5: Conduit Flow Summary (T= 10 years)

Link Type Maximum Flow

(CMS)

Time of Max Occurrence days:hr:min

Maximum Velocity (m/sec)

C3 CONDUIT 122.452 0:17:05 3.30

C4 CONDUIT 52.978 0:16:28 1.67

C5 CONDUIT 233.51 0:19:23 2.17

C6 CONDUIT 79.285 0:16:14 2.48

C16 CONDUIT 87.731 0:16:16 1.74

C17 CONDUIT 81.645 0:16:40 1.56

C23 CONDUIT 199.693 0:20:54 1.18

C27 CONDUIT 84.257 0:17:52 1.43

C28 CONDUIT 71.463 0:16:09 2.47

From the above output tables of link flow the peak flow is found 161.425 ��/s for 5 year return period and 233.51 ��/s for 10 year return period in the stream link C5. Using this max flow for each stream link the corresponding cross-section areas for those streams are measured.

Maliha & Khan

74

According to Continuity equation,

Q = AV

A=Q/V

Here,

Q = Stream Discharge (cumec)

A = Stream Cross-Section Area (��)

V = Stream Velocity = 0.8m/s (Non-silting, non-scouring velocity)

Table 6: Stream Cross-Section Design (T=5 year)

Link Discharge Q (��/s)

Velocity,V (m/s)

Area, A(��)

C3 82.43 0.8 103.04

C4 24.19 0.8 30.24

C5 161.43 0.8 201.79

C6 42.08 0.8 52.60

C16 38.46 0.8 48.08

C17 40.88 0.8 51.10

C23 138.41 0.8 173.01

C27 58.85 0.8 73.56

C28 33.72 0.8 42.15

Table 7: Stream Cross-Section Design (T=10 year)

Link Discharge Q (��/s)

Velocity,V (m/s)

Area, A(��)

C3 122.45 0.8 153.06 C4 52.98 0.8 66.23 C5 233.51 0.8 291.89 C6 79.28 0.8 99.10 C16 87.73 0.8 109.66 C17 81.65 0.8 102.06

C23 199.69 0.8 249.61 C27 84.26 0.8 105.33 C28 71.46 0.8 42.15

Maliha & Khan

75

Pseudo Calibration According to the Ohio Department of Transportation Hydraulics Manual,

Table 8: Runoff Coefficients for Different Land use Type Given by ODOT

Type Runoff Coefficients

Apartment Dwelling or Residential Builtups

0.6

City Business Areas or City Builtups 0.85

Cultivated Land or Vegetation 0.55

Barren Lands 0.3

Water Bodies 0

Depending on the land use, the runoff coefficient for a catchment is obtained by, Runoff Coefficient= {(%RB × 0.6) + (%CB × 0.85) +(% V × 0.55) + (%BL × 0.3) + (%WB × 0)} ÷ 100

Here, RB= Residential Builtups

CB= City Builtups

V= Vegetation

BL= Barren Lands

WB= Water Bodies

Table 9: Calculation of Runoff Coefficients for Different Catchments based on Land Use

Catchment

Built-up(Residential)

Built-up(City)

Vegetation

Barren land

Waterbody

Runoff coefficient

W3 0 0 100 0 0 0.55

W4 25 15 30 20 10 0.50

W5 40 20 20 10 10 0.55

W6 70 15 8 4 3 0.60

W16 30 10 35 15 10 0.50

W17 15 25 30 17 13 0.52

W24 15 25 35 12 13 0.53

W28 15 5 55 25 10 0.51

W29 20 13 45 15 7 0.52

Maliha & Khan

76

Adjusting the roughness coefficient ‘n’, the runoff coefficients obtained from model simulation for rainfall of 5 year return period are matched to the estimated values to perform calibration.

Table 10: Summary of Calibration

Estimated Runoff coefficient

Runoff Coefficient from Model Simulation

0.550 0.555

0.503 0.500

0.550 0.554

0.604 0.602

0.503 0.500

0.519 0.518

0.531 0.531

0.510 0.512

0.523 0.524

6. Conclusion

Unplanned urbanization in the Bogra Sadar Upazilla has an adverse effect to the runoff generation and storage pattern and drainage system of the whole area. Implementation of the project may introduce drainage problem the study area. So Maintenance of the drainage system is the prime concern of the study area. Area is also subdivided with many cannels connecting the surrounding rivers. Therefore, the required cross-sectional areas of the canals are measured here. The ideal shape of the canal cross sections are taken as open rectangular .The required cross section areas are measured for 5 year and 10 year return period. Some of the calculated cross section areas for 10 year return period are 66.23, 99.10, 109.66, 102.06, 105.33, 89.33 ��and for 5 year return period the cross sections are 103.0375, 30.2375, 52.6, 48.075, 51.1, 73.5625, 42.15 �� . Observing the data, it is clear that the required cross section for 10 year return period storm water runoff is greater than the calculated cross-sections of 5 year return period. The limitation of this study is existing drainage system was not incorporated in this modeling. Future steps needed to be implied could have been predicted more effectively if existing drainage system data were incorporated. Again, the existing canal cross-sections can be modified and can be made garbage free to increase the capacity. Short duration rainfall data of Bogra City is necessary for more accurate rainfall- runoff analysis. 24-hr rainfall data of Bangladesh Water Development Board has been used in this study. Bangladesh Meteorological Department (BMD) used to collect 3-hr rainfall data. Rainfall- runoff analysis for Bogra on the basis of 3-hr rainfall data of BMD will be recommended for future study.

Maliha & Khan

77

References Apirumanekul, C. and Mark, O. 2001, ‘Modeling of Urban Flooding in Dhaka City’, 4th

DHI Software Conference. Bartone, Carl R., Janis Bernstein, and Josef Leitmann 1992, ‘Managing the

Environmental Challenge of Mega-Urban Regions,’ International Conference on Managing the Mega-Urban Regions of ASEAN Countries: Policy Challenges and Responses, Bangkok: Asian Institute of Technology.

Booth D.B 1991, ‘Urbanization and the Natural Drainage System-Impacts, Solutions and Prognoses’, The Northwest Environmental Journal, Vol. 7, No. 1, Pp. 93-118.

Dieter H. Lindner 2013, ‘Surface water drainage design considerations practices’, Canadian Water Resources Journal, Vol. 12, No. 3, Pp. 67-78

Lee J. G, Heaney J.P 2003, ‘Estimation of Urban Imperviousness and its Impact on Storm water Systems’, Journal of Water Resources Planning and Management, ASCE, Vol. 129, No. 5, Pp. 419-426.

Needhidasan. S, Nallanathel, M 2013, ‘Design of Storm Water Drains by Rational Method – an Approach to Storm Water Management for Environmental Protection’, International Journal of Engineering and Technology (IJET), Vol. 5, No. 4 Pp. 3203-3214.

BWDB 1975, Annual Report of Bangladesh Water Development Board, 1975 DPHE 1968, Annual Report ofDepartment of Public Health Engineering, 1968 EPWDR 2011, Storm Water Design Criteria Manual for Municipal Services, Engineering

and Public Works Department, Riverview JICA 1987, ‘Study on Storm water Drainage System Improvement Project in Dhaka

City’, Main report, DPHE, GOB, Dhaka. Lambin, E.F., Baulies, X., Bockstael, N., Fischer, G., Krug, T., Leemans, R., Moran,

E.F., Rindfuss, R.R., Sato, Y., Skole, D., Turner, B.L. II, and Vogel, C. 1999, ‘Land-use and land-cover change (LUCC): Implementation strategy’, IGBP Report No. 48, IHDP Report No. 10, Stockholm, Bon.

SRDI 2005, Annual Report of Soil Resource Development Institute