tailieunhanh - WETLAND AND WATER RESOURCE MODELING AND ASSESSMENT: A Watershed Perspective - Chapter 4

Nằm ở phía bắc tỉnh Giang Tây, các vùng đất ngập nước của hồ Poyang đã đóng một vai trò quan trọng trong kiểm soát lũ lụt, cung cấp ở, thanh lọc chất độc, và điều chỉnh khí hậu. Nguồn tài nguyên có giá trị này đã bị cạn kiệt trong những năm gần đây do khai thác quá mức, dẫn đến sự suy giảm chức năng của đất ngập nước và khả năng tự phục hồi (Zhang, 2004 Zhu et al 2004). Bất khả tiếp cận của khu vực này làm cho nó khó khăn và tốn kém để. | 4 Carex Mapping in the Poyang Lake Wetland Based on Spectral Library and Spectral Angle Mapping Technology Shuisen Chen Liangfu Chen Xiaobo Su Qinhuo Liu and Jian Li INTRODUCTION Located in the northern Jiangxi Province the Poyang Lake wetlands have played an important role in controlling floods providing habitation purifying toxicants and adjusting climate. This valuable resource has been severely depleted in recent years due to excessive exploitation resulting in the decline of the wetland s functions and self-restoration ability Zhang 2004 Zhu et al. 2004 . The inaccessibility of the area makes it difficult and expensive to monitor and assess the dynamics of this freshwater lacustrine system. Thus remote sensing technology has become a necessary and efficient tool for this task Nepstad et al. 1999 . Remotely sensed data have been extensively used to map land cover including wetland areas for the purpose of environmental conservation for example identifying areas demanding protection and monitoring important habitats Steininger et al. 2001 Turner et al. 2003 . Remotely sensed data has previously been used for acquiring information about the environment and resources of the Poyang Lake wetland including specific characteristics analysis of healthy vegetation Xiaonong et al. 2002 and multitemporal analysis of land cover changes. However the wetland mapping in Poyang Lake was not completely automatic Jian et al 2001 Zhao et al. 2003 which hindered quick acquisition of the biological resource information necessary for utilization and protection of the wetland. The purpose of this study is 1 to develop an automatic method for mapping the wetland using Landsat ETM or TM images and 2 to map the distribution of Carex based on the spectral library and the spectral angle mapping approach and 3 to assess the accuracy of the presented approach. 29 2008 by Taylor Francis Group LLC 30 Wetland and Water Resource Modeling and Assessment FIGURE Location of reference .