Integrated Ground Water Recharge Based Physical Planning Framework for Urban Areas

Abstract

A comprehensive conception of the intricate aspects of groundwater recharge and storage is critical for managing groundwater resources in a country like India, where it has always been classified as a limiting resource under the influence of a diverse and complex urban environment. In this context, the Groundwater Recharge Potential Zone (GWRPZ) has emerged as a critically vital area of research and has attracted the scientific community's attention. Several tools and techniques can be employed to explore and delineate the possibilities of GWRPZ. The present study deliberates on GW's existence and spatiotemporal dynamicity in the physical environment of the urban region. In the process, the state-of-the-art review of tools and techniques used to explore and delineate the GWRPZ at the urban scale. The parametric studies on GW-governing parameters at the urban and semi-urban scale from selected cases of the International and Indian scenario steered the study to suggest a conceptual framework involving stages of urban complexities for GW management. With the help of a literature review, it has been found that there is a lack of suitable framework at the physical planning level required as a base instrument. In this context, a well-conceptualized analytical framework, as presented in Figure 3.1, is formulated and proposed, which will be able to facilitate and lead the spatial, temporal and statistical analysis to a conclusive deliberation for the delineation of the GWRPZ for urban and semi-urban scale by augmenting the physical planning process. The process will be instrumental in the dynamically complex and growing urban region's future GW security. The study uses nine parameters based on the macro and micro levels of physical, hydrological, hydrogeological and urban complexities and challenges. The selected parameters are LULC, geomorphology, geology, lithology, slope, DD, LD, GW table and rainfall. All the parameters are discussed and analyzed individually and on a mutual basis to observe their cumulative impact in the delineation of GWRPZ. A reliable set of tools and techniques, statistical models, working methodologies, and spatial and temporal data sets are systematically required to conceptualize, derive, and validate the desired output through the formulated framework. Although the proposed framework is generic, it can be adopted and customized for urban and semi-urban cases at different scales. In the process, geostatistical tools such as IDW and EBK are recommended for the interpolation of rainfall and GW table data on a spatiotemporal basis on an urban scale. Calculating normalized weight for the thematic layers is vital to performing the Weighted Overlay Analysis in ArcGIS. In this context, the MCDA, combined with the AHP, is recommended to calculate the normalized weight of the thematic layers. Also, the 9-point scale, as suggested by Saaty, is used to allocate ii | P a g e the relative importance in a pairwise comparison. RS and ArcGIS are applied to process, analyze, and develop satellite imagery for LULC mapping and the analysis of the spatial dynamics of urbanization at micro and macro levels. Similarly, the data of SRTM is recommended for developing the DEM, Slope, Drainage Basin, and DD Map by using spatial analysis and the hydrology tools of the ArcGIS at the urban scale. The framework is proposed to apply to Ajmer City, which is a historic city and continuously growing urban region under a hot and semi-arid climate. Here, water has always been a critical resource in meeting the demands of growing urbanization. From 1991 to 2001, the urban population increased by 20.57%; in 2001, it was 485575. As urbanisation geared up, the population also started growing, resulting in dense urban expansion. In 2011, the population of the urban region was reported as 551101, with a growth rate of 13.50%. The projected master plan for 2033 clearly shows the scope for rapid development in the Ajmer urban region, which will increase the expansion of impervious surfaces and add impermeability to the natural surfaces. This will cause higher water runoff and reduced potential for GW recharge in the region on a spatial basis. In this context, the city of Ajmer offers an ideal opportunity to examine the GWRPZ from a spatial and temporal perspective.