A Multi-Method Hydroclimatic Modeling Framework for the Sustainable Management of Floodplain Aquifer Dynamics in the Lower Atrai Basin

Abstract

Groundwater depletion poses a structural threat to agricultural sustainability and freshwater ecosystem integrity across the margins of the vulnerable Lower Atrai Basin in Bangladesh. This study presents a rigorous assessment of long-term hydroclimatic trajectories and their direct coupling with aquifer dynamics in Singra Upazila, Natore district. Utilizing monthly data for rainfall, mean temperature, total evapotranspiration (ET), and groundwater depth, the study deployed a statistical framework combining parametric multiple linear regression (MLR) with a robust non-parametric trend consisting of standard Mann-Kendall (MK), Sen’s Slope Estimator, and Innovative Trend Analysis (ITA). SPSS diagnostic checks revealed a powerful lag-1 serial correlation, confirming structural hydrological memory within the local aquifer matrix. Parametric sensitivity modeling demonstrated that consolidated climate variables (rainfall, temperature, and ET) account for a restricted portion of the total water table variance (R2 = 0.367), indicating that non-climatic, anthropogenic abstractions principally override natural climate signals during the intensive dry-season Boro rice irrigation. Non-parametric evaluations further exposed severe asymmetries in water table behavior. Annual rainfall exhibited a monotonic decline (β = -10.78 mm/year), whereas mean annual temperatures showed a significant warming trend (+0.018°C/year). Consequently, both pre-monsoon and post-monsoon groundwater depths demonstrated progressive, systematic drawdown trends. Quantile evaluations via ITA confirmed that groundwater depletion is accelerating most severely during peak dry-season extraction stages (Sita =+0.077 m/year). These findings emphasize that Singra's deepening groundwater crisis is structurally driven by human abstraction rather than meteorological deficits, highlighting an urgent need for an immediate transition toward surface water conservation, optimized crop rotation, and managed aquifer recharge policies.