Long Short-Term Memory (LSTM) and SWAT+ Hybrid Models for Assessing Hydrological Water Balance Components under Climate Variability and Land Use/Land Cover Change in the Gumara Catchment, Lake Tana Sub-Basin, Ethiopia.

Understanding the dynamics of basic hydrological water balance components in the Gumara Catchment, Lake Tana Sub-Basin, Ethiopia, is crucial for climate change-resilient agricultural planning and regional water resource management. This research presents a novel hybrid approach that integrates deep learning with process-based hydrological modelling to evaluate the key components of the water balance under climate variability and changes in land use/land cover (LULC). Using the Quantum GIS (QGIS) interface, the Soil and Water Assessment Tool Plus (QSWAT+), and Long Short-Term Memory (LSTM) networks, a framework is developed that leverages calibrated SWAT+ outputs as additional input features to an LSTM model. This LSTM was trained on observed historical data to estimate direct runoff, actual evapotranspiration, groundwater recharge, and total runoff flow for the historical years 1973, 1995, and 2016, as well as for future projections in 2050 and 2080 under both the intermediate shared socioeconomic pathway (SSP 245) and high-emission shared socioeconomic pathway (SSP 585) scenarios. A Random Forest classifier was used to map LULC for the years 1973, 1995, and 2016. The results revealed that the hybrid model significantly outperformed the standalone LSTM and SWAT+ models over both the calibration and validation periods, as measured by Nash–Sutcliffe Efficiency (NSE), Coefficient of Determination (R²), and Root Mean Square Error (RMSE) performance evaluation metrics.

The analysis indicated a significant increase in direct runoff in both the historical period (1973–2016) and the future period (2016–2080), particularly under high-emission scenarios. Actual evapotranspiration showed a slight increase over the study period, while groundwater recharge declined markedly.

Total runoff flow forecasting varied by scenario, with decreases under an intermediate pathway (SSP245) and increases under a high-emission scenario (SSP585).

These findings underscore the improved predictive ability of hybrid modelling and highlight the Gumara Catchment vulnerability to ongoing environmental change. The approach offers a sound framework to enhance water balance predictions and provides meaningful insights for sustainable water resource planning in climate-sensitive regions like the Gumara Catchment.