Demarcation of lowered water table zones in a drought-affected area of western Odisha, India
Authors: Ojha Madhusmita 
Published: February 2023

The Nuapada region, which lies in the western margin of Odisha, India, has been suffering from severe drought conditions and critical aquifer-system stress for decades due to the continuous lowering of the water table, erratic rainfall patterns, and the existence of consolidated hard rock terrains of quartzite, gneisses over the region. Unsustainable groundwater management and continuous withdrawal of sub-surface water resources for domestic, agricultural, and industrial purposes bring depletion of the groundwater table a serious threat and drive interest in choosing the study area for the investigation purposes.&#160;This work has focused on locating the potential recharge zones in one of the drought-prone hilly tracts of western Odisha part, India, i.e., the northern blocks of Nuapada district, using GIS tools. Secondary datasets such as local administrative data, topomap, satellite data, forest cover and mineral data, population density, soil, precipitation and field information such as surface lithology, lineaments, structural trends, geomorphological features, drainage patterns as primary datasets were integrated into GIS platform to generate thematic maps such as geology, topography, contour, geomorphology, drainage, Lineaments, NDVI and Land Use Land Cover. Groundwater prospective zones over the study region were formed by integrating the thematic layers in the GIS platform. It&#8217;s been categorized into five zones such as excellent, good, moderate, moderate to poor, and poor. From the observations, it has been found that excellent and good zones account for around 8.428 and 374.906 Km&#178; respectively of the total study area, whereas moderate, moderate to poor and poor zones account for approximately 734.77, 250.272, and 718.548 Km&#178; respectively of the entire study area. The excellent, good, and moderate zones lie mainly in the northern and eastern parts of the study region. These areas are more suitable for attributing groundwater recharge structures such as check dams, percolation tanks, storage tanks, subsurface dyke, nalabund, contour bunding, and rooftop rainwater harvesting structures etc. The poor zones lie in the western half of the study region. Around half of Komna block and few patches of Nuapada block come under the poor zone category. These areas are unsuitable for building recharge structures. The poor zones are composed of hard rocky quartzite. The rest of the study region is covered with granite, granite gneiss, few patches of khondalites, and little alluvium. Accumulated residual, structural hills, steep sloped rugged topography, distribution of drainage pattern, land use pattern and confined to the semi-confined types of aquifers also play critical roles in the categorization of groundwater potential recharge zones. Inconsistent precipitation and climatic factors such as temperature, humidity and evapotranspiration lead to lowering of water table and acute drought conditions in the study region. The declining trend of the water table has been shown here to assess the amount of water resources in the subsurface region.