tailieunhanh - WETLAND AND WATER RESOURCE MODELING AND ASSESSMENT: A Watershed Perspective - Chapter 13

Tăng nhanh khả năng xói mòn đất là một trong những vấn đề môi trường nghiêm trọng nhất trên thế giới. Ở Trung Quốc, hàng triệu tấn của lớp đất mặt bị xói mòn và vận chuyển mỗi năm, không chỉ làm giảm tài nguyên đất mà còn gây ra hậu quả bất lợi về môi trường. Đất xói mòn ảnh hưởng đến năng suất bằng cách thay đổi tính chất của đất, và đặc biệt là bằng cách phá hủy cấu trúc lớp đất mặt, giảm khối lượng đất và khả năng giữ nước, giảm sự xâm nhập, tăng. | Part IV Wetland Biology and Ecology 2008 by Taylor Francis Group LLC 13 Soil Erosion Assessment Using Universal Soil Loss Equation USLE and Spatial Technologies A Case Study at Xiushui Watershed China Hui Li Xiaoling Chen Liqiao Tian and Zhongyi Wu INTRODUCTION Accelerated soil erosion is one of the most serious environmental problems in the world. In China millions of tons of topsoil are eroded and transported every year which not only degrades soil resources but also causes detrimental environmental consequences. Soil erosion affects productivity by changing soil properties and particularly by destroying topsoil structure reducing soil volume and water holding capacity reducing infiltration increasing runoff and washing away nutrients such as nitrogen phosphorus and organic matter Meyer et al. 1985 Oyedele 1996 . The resulting sediments act as carriers of pollutants including heavy metals pesticides and others. Jiangxi is a province that suffers severely from soil erosion. The total affected area is X l04 ha which accounts for of the total provincial area and is mainly distributed in the upper and middle valley of the Xiu River Ganjiang River Xin River Fu River and around Poyang Lake. The Xiushui watershed discharges water and sediments into Poyang Lake which is the largest freshwater lake in China and an important international wetland with considerable ecosystem functions. Regional economic development deforestation and soil erosion in the Xiushui watershed have degraded the wetland ecological environment of Poyang Lake. Before effective management measures can be taken the amount and location of soil that has been eroded must be quantified. There are many models available for erosion estimation. Some of these models are based on physical parameters such as the WEPP Water Erosion Prediction Project and some are empirically orientated such as the universal soil loss equation 153 2008 by Taylor Francis Group LLC 154 Wetland and Water Resource .