Pumping and sustainability of groundwater resources: A case study on Mohadevpur Upazila of northwest Bangladesh

Abstract

 Excessive pumping of groundwater is a warning for sustainability of an aquifer. In this research, abstraction of groundwater and its impact on shallow aquifer in Mohadevpur Upazila are evaluated from analysis of exploratory bore logs, historical record of groundwater level, rainfall, river water level and pumping data. A coarse sand aquifer with occasional gravel and a fine sand aquifer, with thickness 15 m to > 55 m and 3 m to 38 m respectively, are revealed from bore log analysis within 100 m depth. The aquifers, prevailing in most of the area, are confined to semi-confined in nature. Annual fluctuation of hydraulic heads of groundwater were almost stable up to 1991. After 1991, these variations has decreased in most of the area. Seasonal variation in hydraulic heads is strongly associated with monsoon rainfall and river water level. Analysis of data reveal that the annual artificial discharge of groundwater from shallow aquifer has gradually increased with the expansion of irrigation since 1980. In 2015, artificial discharge was about 51 times higher than that of 1980. However, the rate of extraction was reduced at the later period. Decadal changes in hydraulic heads from 1990 to 2020 show that groundwater spatially flows from central part towards peripheral area in all seasons except in south central part of the area in dry season of 2010. Declination of hydraulic heads of groundwater is observed in most of the area for both dry and wet seasons within 30 years from 1990 to 2020. The declination rate varies from 0.1 to 0.35 m/yr. Declining trends in average pressure heads of groundwater are alarming in north east and south east parts of the area. Though the decrease in regular vertical recharge of groundwater is deduced in this area, increased rate of declination in hydraulic head is primarily be an impact of long term pumping of groundwater at higher rates, which might be a cause of enduring environmental issues on that area.