Hydrological analysis of streamflow thresholds and their implications for water management in Tangi Gharoo watershed, Kabul river basin

Abstract

Identification of flow thresholds (high, intermediate, low) is among the main concerns of water engineers engaged in water and flood management while maintaining environmental security. In this study, 33 years (1960-1980 and 2006-2018) streamflow data of the Tangi Gharoo watershed in the Kabul River basin have been studied for inconsistency checking and streamflow threshold determination. Thresholds are established through the assessment of the consistent streamflow segments and the average slope of the flow duration curve. The results of data checking revealed minor irregularities, while the data gap between 1980 to 2006 affected the shape of the flow duration curve. The findings indicated a descending trend in annual streamflow, with the highest streamflow during spring in 1965 and the lowest streamflow during summer in 2018. The low flow threshold is determined to be 87.3% with a corresponding streamflow magnitude of 0.09 mm/month (0.44 m3/s) while the high flow threshold is 7.84% with a corresponding streamflow magnitude of 7.01 mm/month (34.7 m3/s), in a monthly temporal resolution. These findings have significant implications, providing valuable insights for designing sustainable water extraction plans and environmental strategies based on flow thresholds while effectively managing water resources in the area.