Inventory of Groundwater Springs in the Hills of Assam, India: An Approach to Springshed Development

Groundwater springs are essential water sources in hilly and mountainous regions. India’s springs are facing water scarcity due to groundwater overuse with increasing population growth and climate change. This study explores groundwater springs in Assam's Dima Hasao district, focusing on spring emergence, spring water chemistry, suitability for drinking and irrigation, and potential groundwater recharge zones, where these parameters are not well documented. Inventory parameters include GPS coordinates, rock type, slope measurement of the catchment, spring type, nature of discharge, and surrounding land use land cover. Instruments used for field observations were a GPS device GARMIN etrex10, a bucket of a specific volume, a stopwatch, and an on-site water testing kit-Hanna instrument. The springs found mainly emerge from fracture zones, joint planes, and contact zones between residual soil and bedrock with varying elevations, classified as fracture and depression springs. All springs that were evaluated at 52 sites are non-thermal springs. Discharge rates ranged from 0 to 12 liter/minute. As per Meinzer's classification, springs are ranked as sixth, seventh, and eighth magnitude. For chemical analysis, the concentration parameters were determined using a flame photometer, spectrophotometer, and volumetric titration methods as required for different parameters. Precipitation is found as the primary factor controlling the water chemistry. Water types identified included Ca-Mg-Cl-SO₄, mixed Ca-Mg-Cl, and Ca-Mg-HCO₃, indicating mixed temporary and permanent hardness. Stable isotope analysis of hydrogen and oxygen using Liquid-Triple Isotopic Water Analyzer (L-TIWA) revealed that recycled moisture contributed to the local precipitation with a few secondary evaporative effects. Water Quality Indices based on chemical parameters showed that 24% of samples needed treatment before consumption. Significant faecal contamination was noted which was determined from the microbial analysis i.e., most probable number determination. Adequate treatment of spring water is essential because of the microbial contamination. All springs are suitable for irrigation as per irrigation indices. Groundwater Potential Zones (GPZs) were created by integrating six layers using AHP and GIS techniques, classified from very poor to very high potential. The occurrence of springs in the area is compared with the GPZs and results have shown that sixth, seventh, and eighth-magnitude springs were located in predicted very high, high, moderate, and poor potential zone areas. The findings from this study were crucial for springshed management. Considering seasonal variations in spring water discharge and quality, mapping groundwater and groundwater springs potential zones, and constructing artificial recharge structures can contribute to effective water management in the hills of Dima Hasao and similar regions facing climate impacts. The study highlights the importance of regularly monitoring spring resources in Assam hills, artificial recharge to maintain spring discharge amidst climate change, and aiding policymakers in crafting sustainable management plans to meet the UN’s sustainable development goals XIII (climate change action).

Keywords: Spring, groundwater, groundwater potential, springshed management, water quality indices