Identification of Suitable Hydrologic Response Unit Thresholds for Soil and Water Assessment Tool Streamflow Modelling

• 作者: JIANG Liupeng ZHU Jinghai CHEN Wei HU Yuanman YAO Jing YU Shuai JIA Guangliang HE Xingyuan WANG Anzhi
• 来源期刊: 中国地理科学（英文版）
• 年，卷（期）: 2021,（4）
• 页码范围: 696-710
• 页数: 15页
• 语种: 英文

摘要

Use of a non-zero hydrologic response unit(HRU)threshold is an effective way of reducing unmanageable HRU numbers and simplifying computational cost in the Soil and Water Assessment Tool(SWAT)hydrologic modelling.However,being less repres-entative of watershed heterogeneity and increasing the level of model output uncertainty are inevitable when minor HRU combinations are disproportionately eliminated.This study examined 20 scenarios by running the model with various HRU threshold settings to un-derstand the mechanism of HRU threshold effects on watershed representation as well as streamflow predictions and identify the appro-priate HRU thresholds.Findings show that HRU numbers decrease sharply with increasing HRU thresholds.Among different HRU threshold scenarios,the composition of land-use,soil,and slope all contribute to notable variations which are directly related to the mod-el input parameters and consequently affect the streamflow predictions.Results indicate that saturated hydraulic conductivity,average slope of the HRU,and curve number are the three key factors affecting stream discharge when changing the HRU thresholds.It is also found that HRU thresholds have little effect on monthly model performance,while evaluation statistics for daily discharges are more sensitive than monthly results.For daily streamflow predictions,thresholds of 5％/5％/5％(land-use/soil/slope)are the optimum HRU threshold level for the watershed to allow full consideration of model accuracy and efficiency in the present work.Besides,the results provide strategies for selecting appropriate HRU thresholds based on the modelling goal.