Hydrogeological characteristics of waterlogged areas in Natore District,Bangladesh

Waterlogging (WL) refers to the process by which water flow is resisted in vertical and horizontal directions and thus water stagnates for a short or long span of time; it is induced by a combination of human and natural factors. In the southwestern region of Bangladesh, including Natore District, WL is a significant issue that needs to be addressed if agricultural activity is to be successful. This study aimed to identify surface WL in Natore District and to characterise the WL scenario in the study area in terms of hydrogeology. Waterlogged areas were identified with a geographic information system using satellite images corresponding to the premonsoon and postmonsoon periods. Using groundwater level data (1990–2017), the pre- and postmonsoon scenarios of the waterlogged areas were indicated by seasonal and perennial types of WL. Groundwater recharge scenarios were classified as long and short lag times. Most of the study area was characterised by thick clay or silty clay surficial layers with low water penetration rates, resulting from low porosity and low hydraulic conductivity. The cross-correlation between rainfall and groundwater level revealed the response of groundwater to rainfall, with a lag time of 1–5 months. Long lag time areas exhibited slow groundwater recharge and significant groundwater level fluctuation, with lower hydraulic conductivity values of 49.37–76.24 m/day. In contrast, short lag time areas displayed rapid groundwater recharge and small groundwater fluctuation due to a good proportional relationship with rainfall and higher hydraulic conductivity values of 74.74–117.79 m/day.