MODELLING OF URBAN WATER MANAGEMENT

Abstract

India is facing a rapidly increasing trend in urbanization, which has laid stress on water resources and leads to adverse impacts on urban hydrosphere. Within the urban water domain, these concerns have motivated research on three sectors mainly water supply, wastewater and stormwater management related to optimal allocation, treatment and disposal water. Management of stormwater needs urgent attention as the generated heavy surface runoff in urban areas will flood the metropolitan cities, create havoc, affect the economy and disturb normal of peoples in the cities. The recent example of Chennai, Mumbai and Delhi in India puts a hard pitch to prove the case. Urban stormwater is major irritant for municipal development authorities, urban local bodies. Management of surface runoff involve troublesome exercise of identification, planning and design of Low Impact Development type of Best Management Practices. Involvement (LID-BMPs) of software modelling at initial phase of project initiation will make this job a lot easier This dissertation work presents the application of SWMM modelling software in reduction of surface runoff from the study area. SWMM in Haridwar city in Uttarakhand state of India. Study area has a catchment of 6.41 km2 area with an average elevation varying between 275m to 350m with mild slope covering most part of the region. Most of the rainfall occurred in four months from June to September, with an average depth of 240 mm and 6 thunderstorm days.The texture of soils in the catchment has Sandy Loam texture having average infiltration capacity of of 2.03 cm/hr Most of the natural drains flowing through catchment are either encroached or blocked due to silt coming from the hills from the north direction of the catchment. Data necessitate for the dissertation work has been collected from the field and the Uttarakhand Peyjal Sansthan. Soil samples are collected from four sites and analysed for the texture identification. Watershed is delineated with the help of ArcGIS software. Regions of water accumulation has been marked & loaded in background of SWMM modelling software, sub-catchments are delineated according to the natural slope and local topography and provided with necessary parameters. Flow is routed through the catchment to the outfall. A design storm of 168.92 mm depth, duration 30 minute, and 5 year of return period is estimated using Gumbel Extreme Value method is used as rainfall input in SWMM. Model is Page | IV calibrated for a rainfall event with runoff of 0.24 MLD from the area served by Bhagirathipuram pumping station. The calibration curve fits well within 5% error range. Sub catchment SC25, SC26 and SC11 are analysed in detail. These sub-catchment generates peak runoff of approximately 90,1000 and 700 MLD respectively. Node J17, J56 and J24 are identified as flooded. LID-BMPs of green roof, bio-retention swale, permeable catchment, roof disconnection and infiltration trench are proposed as management practice for surface runoff reduction from the sub catchment. After application of management practice flooding a reduction in range of 10 to 15 percent is obtained at the flooded nodes J17, J56 and J24.This study can be further extended in assessing the cost effectiveness of LID-BMPs with design suitable to the region