Achievements and significance of national hydrograph stations network and 55 years of continuous groundwater level monitoring in India

Groundwater management is not only about technology but also about the governance of the resources. The National Hydrograph Stations Network (NHSN) has been operated by the Central Groundwater Board (CGWB), India for more than 55 years and covers a large geographical area. It has over 25000 monitoring wells, including dug wells, bore wells, tube wells, and springs across India's 18 regional offices, including 28 states and 8 union territories. During the last two decades, the NHSN has gone through a significant modernization process, involving the installation of bore well stations equipped with Digital Water Level Recorders (DWLR). Groundwater level data is collected from the wells in January (winter/non-monsoon), May (pre-monsoon), August (co-monsoon), and November (post-monsoon), and continuously examined quarterly to monitor the groundwater's quantity, quality, and significance changes. The present study aims to understand and provide details about the NHSN that include, 1) data streaming from field hydrograph stations to the regional offices for analysis; 2) automatic and manual publication of the fluctuation in groundwater; 3) chemical analysis of observed data, etc. Additionally, the study analyses the borewells, temporal and spatial changes in the groundwater level, chemical content, and groundwater assessment in the country. The spatial and temporal analysis of bore well stations further indicates the network's capability in recent decades. It is noteworthy that, the total number of assessment units in the safe category has increased after the implementation of the National Aquifer Mapping program (NAQUIM) in year 2012. The exercise spearheaded by the CGWB and the increased involvement of the society is improving the groundwater scenario in India. Groundwater monitoring is important for the conservation of water resources and also essential for the policymakers for sustainable development and management. These results provide valuable understandings for decision-making and strategies to improve the resilience of water resources in the region.