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| Effects of Land use change on runoff in Rouyuanchuan small basin |
| (1.Research Institute of Forest Ecology, Environment and Protection, CAF,Key Laboratory of Forestry Ecology and Environment of State Forestry Administration, 100091, Beijing;2.Agricultural College, Henan University of Science and Technology, 471003, Luoyang, Henan:China |
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Abstract The annual runoff had decreased dramatically during last several decades in NW China. This led that the water shortage in this region was more serious. However, ongoing climate change and land use change (i. e. forestation and afforestation) were found not to be key reasons of this runoff reduction.Thus, it was speculated that land use intensity increasing and veqetation structure variation were the main reasons of this runoff reduction. In present paper, Rouyuanchuan, a small basin located in NE, was chosen as research area and its land use intensity was analyzed according to its image data recorded by QuickBird in 2009, and DEM. Results showed that: 1) In Rouyuanchan small basin, grassland andcropland were the key types of land use as 69.8% and 21.7% of basin area, respectively. But forests only accounted for 3.4% of basin area. 2) Forest were open forest with average crown density of 0.1,average tree density of 260 trees/ hm2, average canopy width of 3.4 m. 3) Three types of artificial grassland, i. e. alfalfa plantation, grassland within ditches and grassland within small pits, occurred with 6.2%, 4% and 1.8% of basin area, respectively; however, natural grassland was still key type of grassland which accounted for 57.8% of basin area. Grassland with medium level of coverage (20% -50%) accounted for 44.2% of basin area. Grassland with high level of coverage ( >50%), which was consisted of alfalfa plantation, amounted to only 2.8% of basin area. 4) The landform was changed strongly by cropland terracing. Terraces, which accounted for 11.1% of basin area, were more than traditional sloping cropland in Rouyuanchuan small basin. These indicated that land use intensity was increasing and vegetation structure was changing e. g. terracing farmland and grass plantation, which would strongly affect on the runoff.
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Received: 05 July 2012
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