Publication

Abstract : Groundwater being the most abundant source of freshwater for the survival of flora and fauna is expected to meet the demands of agriculture, industry, and drinking water requirements. Due to climatic changes and over-exploitation, the total groundwater reserve has decreased. The only way out of this quagmire is to use the resource judiciously and recharge frequently. Not all regions are suitable for recharge due to differences in hydrological settings. As a result, determining the ability of an area to retain water is pertinent. This study proposes a demarcation of groundwater potential zones using eigenvectors on a grid within the Periyar River Basin (PRB) in Kerala, India. The PRB is Kerala’s second largest river basin, serving the domestic, agricultural, and industrial needs of the metropolitan Kochi. Over PRB, the grid of approximately 11.1 km-by-11.1 km in length and points within 1.11 km of each other is considered. The variables used for the analysis are Normalized Difference Vegetation Index, Soil Moisture, Lineament Density, Sand content, Silt content, Clay content, Drainage Density, Slope, Rainfall and Temperature. The eigenvectors are computed for the matrix deformed using the grid point variable values. Satty’s Scale and Analytical Hierarchical Process are used to calculate the weights. The basic method employs several weighting approaches to the layer subclasses, which increases the uncertainty in the final output. This volatility has been morphed using the developed method. On a seasonal scale, the dominant eigenvector that explains the most variability is used to form the groundwater potential zones (GWPZ), namely low, moderate and high during the months of January, April, August and November of 2020. Validation is based on actual groundwater levels (GWL) in the 9 observation wells managed by the Central Groundwater Board (CGWB). Based on the results, seven wells in January and six in November reached the expected potential zone class, while one of the wells encountered over-exploitation at the considered PRB grid point. Overall, the agreement between the groundwater levels and the potential zone delineation is 72.2%. This developed method can be applied in different locations to delineate GWPZs. An accurate potential map aids in source monitoring, assessment and protection.