Erosion And Water Runoff In The Mountain Forests-the Arid Valley Ecotone In The Upper Reach Of Minjiang River

Based on the Mountain Forests-the Arid Valley Ecotone in the Upper Reach of Minjiang River, make some experiments by the artificial rainfall equipment (QYJY-501 type),we contrast the different vegetation types and the different slope and the different soil water content to analysis that the recovering of the vegetations took an important effection on the environment of this area. The main conclusions of the study are as follows:(1) Different vegetation types plays an important role on runoff and erosion and sediment yield. The runoff and erosion and sediment yield of the Bare land is the biggest on certain conditions. Mixed grass and shrub land as forest and land cover on surface play an important role of prevention the soil erosion. On different conditions, shrub grassland and mixed forest has played a role in slowing runoff erosion. Gradient of 24°, initial soil water content, rain intensity 10mm.min-1, bare land, shrub grassland, and mixed no runoff and sediment. Rain intensity 20mm.min-1, bare land, respectively the total runoff and sediment runoff real estate increased by 43.11 percent and 28.86 percent total than the shrub and herb. Rain intensity 30mm.min-1, bare land total runoff and sediment runoff and sediment yield total increased by 46.37 percent and 23.95 percent than the mixed. Bare land runoff is 3.23 times as big as the grass land. Bare land sediment yield increased by 88.55 percent than the sediment yield of the shrub and grass.(2) The area of runoff and sediment production situation changes with the slope, bare land within the entire duration of rainfall in 35°, the total runoff increased by 17.89 percent and 41.73 percent than in 24°and 10°. Bare land in 35°of the total sediment increased 73.71 percent than in 24°. The sediment yield of Bare land in 35°is 2.40 times as in 10°.(3) Different soil moisture content causes the different runoff and erosion and sediment yield. All soil types has the bigger runoff and sediment yield on certain conditions. Rain intensity 20mm.min-1, The runoff and sediment yield of the bare land at initial soil water content was increased by 46.91 percent and 14.53 percent. The runoff and sediment yield of the grass land at initial soil water content was increased by 5.17 percent and 17.49 percent. The mixed forest land runoff is 850.00g and sediment yield is 18.42g at initial soil water content. The mixed forest didn't runoff at initial soil water content.(4) Considering all factors, soil erosion runoff and sediment runoff is closely related with rainfall intensity, with the rainfall intensity increases, the runoff and sediment yield increased. Sediment yield and rainfall intensity related coefficient is 0.495, correlation notability, the sediment yield is increased as the rainfall intensity increased. Similarly, runoff and sediment yield and runoff and rainfall intensity are more significant, so the combined affection of various factors, sediment yield and runoff by rainfall intensity the most. And runoff and sediment yield showed significant correlation.