Effects of Forest Composition and Spatial Patterns on Storm Flows of a Small Watershed1 |
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| Authors: | Shi Qi Yunqi Wang Ge Sun Yubao Xiao Jinzhao Zhu Hailong Yang Xiaojing Hu Bin Wu Yujie Wang Steve G McNulty |
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| Institution: | 1. Respectively, Associate Professor, Assistant Professor, Professor, Associate Professor, Professor, Professor (Qi, Yunqi Wang, Zhu, Yang, Wu, Yujie Wang), Key Laboratory of Soil and Water Conservation and Desertification Combating, Ministry of Education, College of Soil and Water Conservation at Beijing Forestry University, Beijing 100083, China;2. Research Hydrologist, Research Ecologist (Sun, McNulty), Southern Global Change Program, USDA Forest Service, 920 Main Campus Dr. Venture II, Suite 300, Raleigh, North Carolina 27606;3. Engineer (Xiao), Communication Department, Institute of Highway Planning, Survey and Design of Sichuan Province, Chengdu 619941, Sichuan, China;4. Engineer (Hu), Beijing Hydraulic Research Institute, Beijing 100044, China. |
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| Abstract: | Abstract: The PRMS_Storm model was built as a storm event, distributed hydrological model for studying the hydrological effects of forest composition and spatial distribution on storm‐flow volume and peakflow rates in the Xiangshuixi Watershed in the Three Gorges Reservoir Area, in the Yangtze River Basin in southwestern China. We developed three simulation scenarios based on forest composition and their spatial arrangements across the watershed, including all mixed conifer‐evergreen broadleaf forests (Scenario 1), all mixed evergreen broadleaf forests (Scenario 2), and mixed conifer + evergreen broadleaf + shrub forests (Scenario 3). We examined 11 storm events observed during 2002‐2005. Compared with the existing forest covers, modeling results suggested that the amount of overland flow was reduced by 21, 23, and 22%, and the interflow increased by 16, 88, and 30%, for Scenarios 1, 2, and 3, respectively. During the same time, peakflow rates were reduced by 20.8, 9.6, and 18.9%, respectively. The reduction of peakflow rates was most significant when rainfall intensity exceeded 0.8 mm/min and events with a short duration and effect was minor when rainfall intensity was below 0.5 mm/min. In general, we found that Scenarios 1 and 3 were preferred for reducing storm‐flow volume and peakflow rates due to their higher interception rates, large soil water holding capacity, and higher soil infiltration capacity. The modeled results suggested soil properties are important in affecting the flow processes and thus forest composition and forest spatial distributions will affect storm‐flow volume and peakflow rates at the watershed scale. To maximize flood reduction functions of a watershed, high priority should be given to those forest types (Scenarios 1 and 3) in reforestation practices in the study region. This study suggests both forest composition and spatial pattern are important reforestation designs for flood reduction in the Three Gorges Reservoir Area. |
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| Keywords: | forest composition PRMS_Storm Three Gorges Reservoir Area forest hydrology |
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