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| Yield process and its characteristics in different kind of small watersheds in Huanglong mountainous area |
| Wu Qinxiao, Li Yangyang |
| Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Northwest SciTech University of Agriculture and Forestry, 712100, Yangling, Shaanxi, China |
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Abstract Using the method of measuring weir, the runoff yield and its process are studied in forested watershed, cutting watershed and rangeland watershed during the period from 1999 to 2003 in Huanglong mountainous area. The results show that the runoff variations of interannual and seasonal are various. The runoff in forested watershed is yielded during a whole year and its amount is mainly connected with precipitation. The runoff in rangeland watershed is yielded only in storm season and its amount is mainly connected with storm intensity. Except the rare storm year, the annual runoff yield amount in forested watershed is more than that in rangeland watershed and the former tops the latter by 3 times on an average of 5 years. The different kind of small watersheds have also different functions on the regulation of the precipitation. The annual flood runoff amount in forested watershed has decreased by 94.9% over the rangeland watershed, up to 5.2?mm on an overage, and the runoff in dry season in the former has increased 0.5?mm over the latter, amounting to 8.7 percent of annual runoff amount, which results in the runoff yield in the watershed relatively well distributed. Cutting forest can change the runoff distribution in watersheds. The runoff yield during a whole year is replaced by that only formed in storm season, but its amount is less than that in rangeland watershed. The process of runoff yield in different kind of small watershed is various. In forested watershed it is comparatively gentle and its fluctuating range is comparatively smooth, while the curve of runoff yield in rangeland watershed is steep, the flood peak is formed rapidly, and it falls after a rise more quickly.
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Received: 10 January 2005
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