An enhanced Budyko-based water balance model simulating monthly runoff in headwater catchments of the Tarim River Basin

the Tarim River Basin (TRB), China Climate warming is rapidly retreating the cryosphere, increasing water yield variability in high mountain catchments and challenging downstream water management. A deeper understanding of water resources involving quantifying runoff components, is crucial for effective adaptation strategies in high mountain catchments. However, data scarcity limits the application of complex physically-based models in high mountain areas. To address this challenge, an enhanced conceptual hydrological model is proposed, integrating glacier and snowpack ablation processes into a classical Budyko framework-based model, using only precipitation, temperature, and potential evapotranspiration as inputs. The novel model was applied to simulate runoff and identify runoff components in the upper TRB. Results indicate that 76 % of the 25 catchments achieved good performance. From 2001–2010, observed and modelled mean annual runoff were 146.2 ± 29.2 mm/a and 143.7 ± 18.2 mm/a. We found that glacier runoff, snowmelt runoff, rainfall runoff and baseflow account for 53.8 %, 3.9 %, 12.7 % and 29.6 % of the total runoff, respectively. Furthermore, the runoff during May to September accounted for 81.4 % of the total runoff, of which glacier runoff accounted for 67.3 %. This finding underscores the importance of glacier water for agriculture irrigation in the TRB. The model provides a novel and efficient tool for runoff simulation in the glacierized basins with scarce data. • A new enhanced Budyko-based monthly water balance model was proposed. • 19 out of 25 catchments demonstrated good performance in monthly runoff simulation. • Runoff components were identified by runoff generation processes and flow pathways. • Glacier runoff and baseflow were the most important contributors to total runoff.