Assessment of inundation changes of Poyang Lake using MODIS observations between 2000 and 2010

Abstract

China's largest freshwater lake, Poyang Lake, is well known for its ecological and economic importance as well as its rapid changes in lake inundation areas. However, due to technical difficulties, to date long-term records of its dynamic inundation areas are lacking, not to mention how they are affected by climate change and/or human activities. Using Moderate Resolution Imaging Spectroradiometer (MODIS) medium-resolution (250-m) data collected between 2000 and 2010 and an objective water/land delineation method, we documented and studied the short- and long-term characteristics of lake inundation. Significant seasonality and inter-annual variability were found in the monthly and annual mean inundation areas. The inundation area ranged between 714.1km2 in October 2009 and 3162.9km2 in August 2010, and the inundation area during any particular year could change by a factor of 2.3–3.2. During the 11-year period, the maximum possible inundation area was 14 times the minimum possible inundation area, indicating extreme variability. Both the annual mean and minimum inundation areas showed statistically significant declining trends from 2000 to 2010 (−30.2km2yr−1 and−23.9km2yr−1, p<0.05). The changes of the inundation area were primarily driven by local precipitation during non-summer months, while during summer months of July to September when the outflow into the Yangtze River was impeded the effect of precipitation became less significant. These results provide long-term baseline data to monitor future changes in Poyang Lake's inundation area in a timely fashion, for example quantifying the extreme drought conditions during spring 2011.