Assessment of Hydroclimatic Variability Using Observations and MERRA-۲ Data for Sustainable Kalamu Dam Management

Water resources stored in small reservoirs and intake dams are essential for ensuring a reliable water supply, particularly in regions exposed to strong hydroclimatic variability. Climate change and increasing fluctuations in precipitation and evaporation patterns are creating new challenges for the sustainable management of water infrastructures. In Boma, Democratic Republic of the Congo, the Kalamu intake dam experiences recurrent seasonal water shortages due to reduced river discharge during the dry season, reservoir eutrophication, and growing pressure on available water resources. This study aimed to assess the hydroclimatic variability of the Kalamu catchment and evaluate its implications for water availability, reservoir performance, and long-term water resource sustainability. Monthly precipitation and evaporation observations collected at the Boma meteorological station were combined with MERRA-۲ reanalysis data covering the period ۱۹۹۲–۲۰۲۳. Statistical analyses, including Pearson correlation, coefficient of determination (R²), Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and bias, were used to evaluate the agreement between observed and reanalysis datasets. Hydroclimatic variability was investigated through water balance analysis, Z-score classification of hydrological years, and trend detection using the Mann–Kendall test and Sen’s slope estimator. The results showed that MERRA-۲ satisfactorily reproduced general precipitation patterns but moderately overestimated rainfall and smoothed extreme events. In contrast, evaporation estimates exhibited poor agreement with observations, characterized by a strong negative bias and weak correlation. The hydroclimatic analysis revealed alternating wet and dry years, a cumulative water deficit of ۴۹۸۲.۰۵ m³, and a required storage capacity of ۲۰۹.۸۸ m³ compared with the current reservoir capacity of only ۱۶۰ m³. Trend analyses indicated no statistically significant long-term changes in precipitation, evaporation, or water balance, although substantial interannual variability was observed. The study concludes that the Kalamu dam remains vulnerable to seasonal water shortages. Increasing storage capacity, improving reservoir management, strengthening hydroclimatic monitoring, and applying bias correction to reanalysis datasets are recommended to enhance water supply reliability. Furthermore, current hydroclimatic conditions suggest that the installation of a mini-hydropower plant is not presently feasible because water availability remains insufficient to guarantee sustainable energy production without compromising the primary water-supply function of the dam.

کلیدواژه ها:

Hydroclimatic Variability ، Water Balance ، MERRA-۲ Reanalysis ، Reservoir Management ، Kalamu Intake Dam