Analysis of land use and cover change in the Naoli river watershed during 1954–2006

Using land use and cover change (LUCC) transition matrix techniques and land use change rate analysis, this study characterized current land use patterns and quantified land cover change from 1954 to 2006, and discussed major drivers and environmental effects in the Naoli river watershed (NRW), Sanjiang plain, northeast China. LUCC analysis indicated that cropland (54%), woodland (25%) and wetland (14%) dominated in the watershed and the magnitude of the LUCC was generally high; however, the change percentage of various land types relative to the total area was quite different. From 1954 to 2006, cropland, built-up land, and water body increased by 40.12, 2.29, and 0.04 percent of the total area, respectively; in contrast, wild wetland, woodland and grassland decreased by 30.39, 8.66 and 3.40 percent, respectively. LUCC transition patterns showed that wild wetland converted to cropland is the main type of land use transition. From 1954 to 2006, the area of wild wetland decreased from 103.82×10⁴hm² (44%) to 32.12×10⁴hm² (14%); in contrast, cropland increased from 32.98×10⁴hm² (14%) to 127.63×10⁴hm² (54%). Natural wetland shrinkage and degradation are major ecological and environmental issues in this watershed, resulting in water and soil quality deterioration, drought and flood disaster expansion, and biodiversity reduction, etc. The anthropogenic activities, including increasing population, political and economic policy, have mainly been driving LUCC in the NRW during the past 50 years.