Sushil Ade1,Harshal Pathak2, Pravin Chaudhari3

Transcription

1 International Journal of Modern Trends in Engineering and Research e-issn No.: , Date: 28-3 April, 26 Best Management Practices (BMP s) Used for Flood MitigationOn Mitthi River Sushil Ade,Harshal Pathak2, Pravin Chaudhari3 Civil and Environmental Engineering, Civil and Environmental Engineering, V.J.T.I.College, 3 Civil and Environmental Engineering, V.J.T.I. College, Mumbai, 2 Abstract An increase in storm water runoff occurs when urban and commercial development converts pervious surfaces into impervious rooftops, driveways, roads, and parking lots. These land use changes are often made with little or no consideration for managing the increased volume of water discharged during storm events. This storm water runoff increases stream flows that cause property damage because of flooding and bank erosion. To avoid these losses it is necessary to mitigate such runoff which causing flood. By using traditional methods floods should be mitigated but it can be found that it is not applicable for the urban areas. In most cities in India, the runoff from roads, buildings and other urban areas is directed to conventional drains / conveyance systems. During the rainy season it can be found that these drainage systems are exceeded hence that causes flood. Keywords- Best Management Practices; SWMM, Rain Barrel; Flood control; Urbanization; Rain Garden; I. INTRODUCTION Storm water management BMP s are control measures taken to mitigate changes to quantity of urban runoff caused through changes to land use. Generally BMPs focus on water quantity problems caused by increased impervious surfaces from land development. BMPs are designed to reduce storm water volume and peak flow. Accelerated storm water runoff creates environmental problems in many urban communities. This might be thought of as a water resources problem because the increased flow can yield physical damage. Unfortunately, the problems of greatest concern are generally associated with the environmental effects that increased flow can have on aquatic ecosystems. Methods for managing accelerated runoff are available, but most do not work well for residential properties with poorly drained soils. II. PROBLEM DEFINITION The sharp rise in urban development has led to an increase in impervious areas and a decrease in vegetated surfaces. The thrust toward this development caused drought and overflow problems to occur, elevating the storm-water runoff volume to the level of emphasis usually associated with water quality.

2 Volume 3, Issue 4, [April 26] Special Issue of ICRTET 26 III. CASE STUDY The river originates from the overflow of Vihar lake and also receives the overflows from the Powai lake about 2 km later. It flows for a total of 5 km before it meets the Arabian sea at Mahim creek flowing through residential and industrial complexes of Powai, Saki Naka,Kurla, Kalina, Vakola, Bandra-Kurla Complex, Dharavi and Mahim. The river has an average width of 5 m in the upper reaches, has been widened to 25 m in the middle reaches and up to 7 m in the lower reaches after the 26 July 25 deluge (944 mm in 24 h on 26 July 25). Mithi River catchment which is located between north latitudes of 9 '36"and 9 '9" and east longitudes of 72 49'59" and 72 56'33".The location of the Mithi River has been shown in Fig. Fig. Mithi river catchment area The river originates from the overflow of Vihar Lake and also receives the overflows from the Powai Lake about 2 km later. It flows for a total of 5 km before it meets the Arabian Sea at Mahim Creek flowing through residential and industrial complexes of Powai, Saki Naka, Kurla, Kalina, Vakola, Bandra-Kurla complex, Dharavi and Mahim. IV. METHODOLOGY 4. General Rainfall runoff plays important role in surface urban flooding. The runoff data describes the characteristics of the ground surfaces in the system, and the rainfall-runoff model used for each. This defines how much of the rainfall falling on the catchment becomes runoff and how quickly it enters the drainage system. 4.2 Hydrological Runoff model The watershed map, Google Earth data is used to define land use pattern. Rainfall data, and attributes from the land such as pervious, impervious area is used as an input to runoff model. The methodology adopted in the computation of runoff using SWMM 5. is as follows:- 563

3 Volume 3, Issue 4, [April 26] Special Issue of ICRTET 26 Fig. 2 Methodology flow diagram 4.3 Land Use Pattern Land uses are categories of development activities or land surface characteristics assigned to sub catchments. Examples of land use activities are residential, commercial, industrial and undeveloped. Land surface characteristics might include rooftops, lawns, paved roads, undisturbed soil etc. MITHI river sub catchment is divided into number of different land uses such as urbanized area, grassy area open ground, roads, forest area. To identify discharge from each land uses. Urbanized area Grassy area Open ground Roads Forest area Fig.3. Land use pattern V. MODELING BY USING SWMM The mithi river sub-catchment was modelled for the rainfall event of 3th July 29 to 5th July 29 by using SWMM. From that water depth of the river can be simulated. It was observed that the peak water depth at powai site is about.8m. 564

4 Volume 3, Issue 4, [April 26] Special Issue of ICRTET 26 Figure 4. Depth simulation by using SWMM. VI. CALIBRATION AND VALIDATION OF THE MODEL Model calibration and validation can be done by dividing it into two events st event is from 3th july 29 at 8:pm to 4:am. 2nd event is from 6:am to :pm.so by calculating the corelation coefficient for the both the event. The co-relation coefficient for the event was found to be.68 and for the event 2 is.6 so it is validated. The results obtained shows that the simulated water surface depth closely matches with observed depth. This SWMM model can be used as an effective tool for flood estimation in the Mithi River. Figure 5. Calibration and validation of Mithi River model at Powai site. VII. RESULT AND DISCUSSION So for all the reduction in the runoff depth and its sensitivity analysis is checked for 3th july 29 to 5th july 29 rainfall after the application of the different BMP S is checked. Following are the different cases 7. Effect of rain garden in open area Sub Basin Sub Basin 2 Before BMP Sub Basin 3 Susb Basin 4 After BMP 7.2 Effect permeable pavement system on road area 565

5 Volume 3, Issue 4, [April 26] Special Issue of ICRTET Basin Basin 2 Peak water depth Without BMP (m) Basin 3 Basin 4 Peak water depth With pavement system on road area(m) 7.3 Effect of Rain barrel in urban area Basin Basin 2 Peak water depth Without BMP (m) Basin 3 Basin 4 Peak water depth With Rain Barrel on Urban area(m) 7.4 Effect of infiltration trench in open area Basin Basin 2 Before BMP Basin 3 Basin 4 After BMP VIII. CONCLUSION The SWMM models have been used to demonstrate the simulation of water surface depth at Mithi river sub-catchment, The water depth has been obtained at Powai site with and without considering the effect of BMP.Among those all rain barrel system for urban area is the best technique to slow down the runoff.the water depth at the Powai site for four cases was found to be.66m for rain garden,.64m for the permeable pavement,.44m for the Infiltration trench,.56 m. Also the sensitivity for all the four cases was carried out by variation of manning s with increase of 5%, % and 5% also by decreasing order 5%, %, 5%. The SWMM models have been used to demonstrate the simulation of flow and water surface depth at Mithi River sub-catchment. REFERENCE [] Aaron A. Jennings, Ata A. Adeel, Alex Hopkins, Alexandra L. Litofsky & StevenWellstead, Rain Barrel Urban Stromwater Management Performance, ASCE,Journal of Environmental Engineering, (23) Page [2] Cristina Perez-Pedini, James F. Limbrunner, and Richard M. Vogel, Optimal Location of Infiltration Based Best Management Practices For Strom Water Management ASCE, Journal of Water Resources Planning and Management, (25),Page [3] K.L. Katsifarakis, M. Vafeiadis and N. Theodossiou, Sustainable Drainage and Urban Landscape Upgrading Using rain gardens. Site Selection in Thessaloniki, Greece Science direct Elsevier Proceeding Agriculture and Agriculture Science. (25), Page [4] Marcio H. Giacomoni, Emily M. Zechman and Kelly Brumbelow, Hydrologic footprint residence: Environmentally friendly criteria for Best Management Practices ASCE, Journal of Hydrologic Engineering, (22), Page [5] Maya P. Abi Aad, Makram T. Suidan and William D. Shuster, Modeling Technique of Best Management Practices: Rain Barrel and Rain Garden Using EPASWMM-5 ASCE Journal of Hydrologic Engineering, (2), Page [6] Gogate Nivedita G and Rawal Pratap M, International Conference on Advances in Design and Construction of Structures ASCE, Journal of Hydrologic Engineering, (22),Page [7] Urban Storm Drainage Criteria Manual Volume 3, Best Management Practices. 566

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