Spatiotemporal change in groundwater sustainability of Bangladesh and its major causes

Abstract

Groundwater is gradually becoming scarce in Bangladesh, like many other countries around the globe, due to various climatic, hydrological, and socio-economic changes. This study aimed to assess the spatiotemporal changes in groundwater availability and sustainability in Bangladesh. The study employed weekly groundwater table (GWT) data from 844 groundwater observation wells of the Bangladesh Water Development Board from 1995 to 2019. The modified Mann–Kendall test at the 5% significance level and the Sen slope estimator were used to assess the spatiotemporal changes in GWT, and the reliability–resiliency–vulnerability (RRV) approach was applied to evaluate the sustainability. In addition, the trends in annual RRV indicators and sustainability were estimated. The results revealed lower GWT in the northwest and central regions. The GWT is declining almost all over the country, particularly in the areas where it is already low, by 0.84–1.555 m/year. The groundwater showed remarkably poor sustainability for most of the areas. It also showed a declining trend over a large area in the central north. The analysis of results through the scrutiny of irrigated land, population distribution and rainfall changes in the country revealed higher abstractions of groundwater for irrigation and domestic supply are the major cause of declining groundwater sustainability in the central region, while the increase in rainfall is the cause of increasing sustainability in the intensively groundwater irrigated northwest region of the country. The study provided an understanding of the changes in groundwater and its sustainability, which can be used as a guide for sustainable groundwater management and drawing up future groundwater policies for Bangladesh.