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|Title:||INTEGRATED WATER MANAGEMENT MODELLING IN URBAN FRINGE USING REMOTE SENSING & GIS|
|Authors:||Jat, Mahesh kumar|
|Keywords:||CHEMISTRY;INTEGRATED WATER MANAGEMENT MODELLING;URBAN FRINGE;REMOTE SENSING & GIS|
|Abstract:||Steady progress in urbanization and industrialisation leads to concomitant stresses on the entire ecosystem, including water resources. A striking feature of current water management practice in developing countries, especially in India, is the fact that the supplies and discharge increase with an increase in population either from excessive groundwater use or transferring water from distant places. Thus, there is a growing dependency on adjacent systems. In this way, the external source and sink problems of one system become the internal problems of other systems. Such practices create implications for the management of water resources and lead to a variety of problems i.e., floods, drought, shortage, pollution, conflicts and depletion of groundwater. These problems are largely due to lack of management and coordinated planning and utilisation of water resources. Although various forms of single or multi-purpose water management schemes are being practiced in many areas, however a comprehensive approach to water management, referred to as the integrated water management, is still relatively uncommon. The concept of integrated water management is not commonly applied in urban areas unless there is a shortage of supply and severe conflicts among the users competing for limited water resources. It includes integration of various possible sources and their optimum utilization considering, at the same time, the demands of different users, environment protection, and land and urban planning. Integrated approach to water resources planning/management requires a comprehensive consideration of water requirements and characteristics (hydrological & hydraulic) of different available sources (such as availability, cost, and reliability). There are a variety of management models reported in the literature for rural areas and canal commands, however very few have been reported for the urban areas. Water resource system of urban areas is quite different and complex as compared to canal commands on account of dynamic nature of various hydrological processes (affected by dynamic land use/cover), different type of conflicting water demand (in quantity and quality), different environmental aspects (water pollution and wastewater generation) and more human interference. There is a lack of studies, including Indian context, which consider the major components of water resources system (all the sources of surface water like local surface runoff, groundwater and other unconventional sources of water i.e., treated wastewater) of an urban fringe along with various economic considerations, within an integrated decision-making tool, like optimisation. Therefore, in the present study an integrated water management model has been developed using system engineering (optimisation) and geospatial techniques (remote sensing and GIS), considering major components of an urban water resources system, like multiple sources of water (import of water from number of sources, number of groundwater sources and multiple local surface sources, treated wastewater from different facilities), 11 multiple users (domestic, industrial and institutional) and some demand management measures with associated physical and operational characteristics. The model developed in this research has been formulated so that data from the City of Ajmer (Rajasthan, India) could be used to illustrate a practical application of the model. Geospatial techniques i.e., remote sensing and GIS have been used for the parameterization of various hydrological/hydraulic processes (rainfall-runoff and groundwater simulation) involved in the study. Remote sensing technique has been used to address the effect of dynamic land use/cover processes in urbanized catchments while estimating the quantity of water to be available from local surface sources. To estimate the quantity of water available from local surface sources, a distributed rainfall-runoff model i.e., SWMM, has been used. Initially, model has been conceptualised for urbanised catchments enclosing the Ajmer fringe and subsequently, the model is calibrated to obtain the catchment parameters. Runoff responses have been generated for monsoon season of eight years (1977, 1989, 1991, 1994, 1997, 2000 and 2002) using the calibrated model, which are further used to formulate the empirical rainfall runoff model. If local surface sources are to be integrated in the water supply system of an urban area, dynamic nature of surface runoff to be generated from urbanised catchment should be incorporated into the water resources planning process. An empirical rainfall-runoff model has been developed in present study, which incorporates the effect of dynamic hydrological behaviour of urbanised catchments in the form of impervious area which changes with time. Empirical rainfall runoff is based on some easily available meteorological parameters i.e., seasonal rainfall depth and number of rainy days and catchment characteristics, like percentage of impervious area and percentage topographic slope. Developed model is suitable for the estimation of runoff from the urbanised catchments, and can be used for planning level applications. The groundwater flow simulation model can be used to quantitatively determine the change in water table elevations as a result of pumping or recharge. These models are always distributed in time, and may be lumped or distributed in space. A distributed groundwater model of the area has been developed using the Visual MODFLOW package and calibrated to study the response of groundwater system against the withdrawal and recharge within the study area. Groundwater model of the area and optimisation model are externally coupled through an iterative procedure to determine the behaviour of groundwater system in response to different water utilisation scenarios. The costs of providing water from various sources are important for any economicengineering study, which include actual capital investment as well as operational cost. Cost analysis has been carried out for different sources i.e., imported source, groundwater, local surface sources and treated wastewater re-use, using the actual cost data collected from the field and organisations. Cost function has been developed for the unit cost of groundwater pumping for the fractured aquifers. Nonlinearity of groundwater pumping cost has been accounted in the optimisation model through successive linearization technique. Unit cost of in water treatment is estimated using the cost functions developed from the data of treatment plants already in operation at various locations in the country. Further, these unit costs of water supply from different surface sources are incorporated into management model. For the water deficient urban areas, where conventional sources are either limited or not available, use of water conservation/demand management is the need of the hour. In the present study, two demand management options; rationing and treated wastewater re-use, have been integrated in the management model. Re-use of treated wastewater has been investigated in two ways; for potable and non-potable uses. Non-potable uses have been explored through a dual water supply system. Detailed representation of physical water resources system, considering spatial and temporal variability of different processes involved, enhances overall planning and management of water resources by reducing the uncertainties involved. Spatial and temporal variability of different topographical and catchment characteristics, like land use/cover, slope etc., have been incorporated into the management model through the coupling of GIS and various hydrological models, which provided various important inputs for the management model. Formulated integrated water management model (optimisation model) has been found to be successful to obtain the optimum water use policies of water resources system of Ajmer. The model minimizes the overall cost of water supply system, satisfying various demand and system constraints. Model has been found to be appropriate to determine (i) least cost integration of various sources of water into the water supply system of an urban area, (ii) quantity of wastewater to be reclaimed and reused, (iii) optimum integration of various demand management strategies with the conventional water supply system and (iv) sustainability of the water resources system over a period of time. Model has been used to investigate the different situations of optimal integration of various sources into water supply system. Results of various scenarios are compared and management scenario, in which present water supply system is integrated with groundwater, local surface and treated wastewater (for non-potable uses through dual water supply system), has been found to be the most optimum strategy for the water resources system of Ajmer, considering cost and sustainability criteria. Study concluded that present deficient water supply system of Ajmer can be converted into a sustainable system with the suitable integration of supply augmentation (use of local available sources) and demand management measures (re-use of treated wastewater for non-potable uses). Present study has demonstrated the effective use of geospatial techniques i.e., GIS and remote sensing in managing the water resources and hydrological processes, and providing a useful reference to water resource professionals. The study has successfully demonstrated the integrated spatial technologies, hydrological/hydraulic models and system engineering techniques within integrated water management concept, which may help water resources planners and decision makers in better planning and optimum utilisation of available water resources of urban areas.|
|Research Supervisor/ Guide:||Khare, Deepak|
Garg, P. K.
|Appears in Collections:||DOCTORAL THESES (chemistry)|
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