Trend analysis of ground-water levels and rainfall to assess sustainability of groundwater in Kamrup Metropolitan District of Assam in Northeast India Monomoy Goswami Civil Engineering Department, Central Institute of Technology, Kokrajhar, Assam, India Email: m.goswami@cit.ac.in; Mobile: +91 8383862879 Dolly Rabha Civil Engineering Department, Assam Engineering College, Guwahati, Assam, India Email: dollrabha123@gmail.com; Mobile: +91 9101453549 Abstract Although categorised as “safe” in respect of ground water development and management, the state of Assam in northeast India is found to possess the “highest depleting potential” of usable ground water storage in the country, and to exhibit falling trends of pre-monsoon ground water levels in about 55% of the monitoring Stations. With the second highest population density in the state and with ground water being the major source of water-use, the Kamrup Metropolitan District of the state has already started witnessing water stress, and has been characterised by the maximum falling trend of ground water level in the state. In this study, seasonal and annual trends of ground water level and rainfall in the Kamrup region were analysed from monthly water-level data of 39 stations and concurrent rainfall data from January 2007 till June 2019 by using nonparametric Mann-Kendall test and Sen‟s Slope estimator. The trends indicate cause of concern, and provide scientific basis for strategizing ground water development and management for sustainable water-use in the region. Keywords: Groundwater level; rainfall; trend analysis; Mann Kendall; Sen‟s slope; Kamrup Metropolitan District INTRODUCTION Groundwater is a major element for sustenance of life and livelihood in many parts of the world, particularly where the use of surface water is constrained either due to inadequacy of quantity and/or quality or for lack of infrastructure for providing supply from surface sources. However ramifications of increasing population and alterations in the dynamics of groundwater recharge have started exerting pressure on the availability of groundwater in many regions where complacency about continued availability of groundwater have, until recently, masked the need for scientific analysis and assessment for sustainably managing this precious resource. The state of Assam in the north-eastern part of India is one such region, all 28 districts of which had been designated “safe” by the Central Ground Water Board (CGWB) of India in its National Compilation of Dynamic Ground Water Resources (CGWB, 2017). Here the category “safe” indicates a stage of groundwater extraction that is less than 70% in the area