Spatial-temporal changes of land use and its characteristics in Zigui County under the period of TG dam project

In order to find the detailed changes of land resources during the TG Dam project in areas of the head part of the Three Gorges reservoir, based on TM and SPOT data, this study acquired 1:50 000 land use classification results in 1992, 2002 and 2007 in Zigui County, analyzed land use dynamic changes during these different periods. Geographic Information System (GIS) techniques and land use dynamics methods were utilized to depict the characteristics of land use changes. The results of land use changes mainly indicated that garden area increased about 248.14%, dry land area decreased about 20.32%, forest area decreased about 0.59%, grass area decreased about 8.04%, urban and built-up area increased about 141.84%, water area increased about 90.86% during 1992-2007 mainly due to many influential factors of human activities brought by the Three Gorges dam project. The study also analyzed driving forces with conversion matrix in order to seize the mechanism behind land use changes. There were different trends and change velocities in changes of garden, dry land, man-made area and water area during 1992-2002 and 2002-2007 according to the dynamic indices. The characteristics of land use conversion differed greatly in these two periods by land use extent indices. Compared with land use extent results during 2002-2007, human activities had more impacts on land use changes during 1992-2002 mainly because of immigration project, cities and towns relocation and reservoir inundation. It was necessary to provide countermeasures and suggestions further to support the reservoir management in future in Zigui County.