Lakes are key factors in maintaining ecosystems in semi-arid regions. However, due to data shortage, most studies used remote-sensing data and water-balance models to analyze lake variations in semi-arid ungauged closed watersheds, resulting in the oversimplified assessment of lake variations and their associated hydrologic processes. This study aimed to enhance the understanding of the mechanisms behind the water supplement and consumption of lakes and reveal the influences of hydrological processes on lake variations in such watersheds. Physically based and lake-oriented hydrologic modeling, remote-sensing technology, and results from previous studies were comprehensively integrated to achieve the research objective. The Hongjiannao (HJN) watershed in Northwest China was selected as the study area of this research. The calibration and validation results demonstrated that remote-sensing data and results from previous studies indeed guaranteed the accuracy of the lake-oriented model. Further hydrologic and statistical analyses revealed the linkage between lake variations and their associated hydrologic processes, and the mechanisms behind the linkage. Specifically, rainfall and snowmelt were found to be the most stable sources of HJN Lake, particularly in dry years. Due to the differences in recession rates, groundwater inflow was more stable than upstream inflow and inflow from the contributing area of HJN Lake. The correlations between hydrologic processes and the storage variation of HJN Lake varied significantly at daily and monthly time scales, which can be explained by the generation mechanisms of these processes. This study provided valuable guidance for water resources management and ecosystem protection in the HJN watershed and can be further applied for hydrologic simulations in other similar watersheds.

Understanding the infiltration process and quantifying recharge are critical for effective water resources management, particularly in arid and semi-arid regions. However, factors influencing on recharge process under different land use types in irrigation districts remain unclear. In this study, a Brilliant Blue FCF dye tracer experiment was conducted to investigate infiltration pathways under the cotton field, pear orchard, and bare land conditions in the Kongque Rive Irrigation District of Xinjiang, China. Recharge rates were estimated using the chloride mass balance method. The results show that the average preferential flow ratio was highest in the bare land (50.42%), followed by the cotton field (30.09%) and pear orchard (23.59%). Matrix flow was the dominant infiltration pathway in the pear orchard and cotton field. Irrigation method was a primary factor influencing recharge rates, with surface irrigation promoting deeper infiltration compared to drip irrigation. Under the drip irrigation mode, the recharge of cotton fields ranged from 23.47 mm/a to 59.16 mm/a. In comparison, the recharge of surface irrigation in pear orchards contributed between 154.30 mm/a and 401.65 mm/a. These findings provide valuable insights into soil water infiltration and recharge processes under typical land use conditions in the Kongque River Irrigation District, supporting improved irrigation management and sustainable water resource utilization.