Regional-scale hydrologic modelling for prediction of water balance and variations in streamflow: The case study for the river basins of Afghanistan
摘要
Afghanistan grapples with multifaceted challenges concerning water availability, necessitating a comprehensive understanding of its current water resources. To better understand the country’s water balance, this study utilizes the Soil and Water Assessment Tool (SWAT) to simulate core hydrological processes – precipitation, evapotranspiration (ET), runoff, and recharge across the major river basins. The national average annual precipitation is estimated at 360.56 mm, of which ET is the dominant component, accounting for 257.51 mm, while 113.92 mm contributes to surface yield and 43.51 mm to recharge. During the monsoon (November–May), rainfall is 314.96 mm with ET at 180.72 mm, yield 97.23 mm and recharge 41.46 mm. In the non-monsoon period (June–October), rainfall drops to 45.60 mm, while ET rises to 76.79 mm and yield and recharge fall to 15.99 and 2.05 mm, respectively. The most significant insight from this study lies in the spatial variability among basins, which directly influences the hydrologic efficiency and water management strategies. The Helmand Basin, which spans the largest area (~2.62 million km2), receives just ~208 mm of rainfall annually but loses ~168 mm to ET, producing only ~32 mm of water yield and ~17 mm of recharge. In contrast, the Kabul Basin (~76,900 km2) receives ~466 mm of rainfall, with ET losses of ~370 mm, yet it produces ~172 mm of yield and ~70 mm of recharge – among the highest in the country. The Amu Darya Basin (~90,700 km2) also performs well, with 419 mm of rainfall and relatively efficient yield (175 mm) and recharge (77 mm). In essence, the research outcomes are poised to significantly enhance the scientific comprehension of hydrological processes in Afghanistan. Beyond academia, this understanding promises to guide policymakers, offering crucial insights into potential challenges for sustainable water management, contending with the ramifications of climate change and escalating water demand.