Evaluating the Trend of Ecological Changes in Shadegan Wetland Using MODIS Imagery (2003-2017)

Abstract

Nowadays, the risk of degradation of wetlands is one of the main environmental challenges in the world, so continuous and long-term monitoring of ecological changes in wetlands can play a key role in their protection and proper management. In the present study, the trend of monthly changes in some of the most important ecological indicators of the aquatic environment of Shadegan wetland including WST, NDVI, MVWR, VWR, LSWI, MNDWI and Chlorophyll-a concentration (during 2003-2017) was evaluated using MODIS satellite imagery. The Mann-Kendall and Sen’s slope tests were used to analyze the trend and its magnitude, respectively. Results showed a significant increasing trend in the volume of water in Shadegan wetland, while the vegetation of the wetland had a significant decreasing trend during the study period (p <0.05). Also, the change in the monthly trend of NDVI, MVWR, MNDWI and LSWI time series was observed around October 2012, which approximately coincided with the development of aquacultural facilities in the northern part of this wetland. In addition, a strong inverse correlation (about -0.86) was observed between vegetation and water indices. Results further provided evidence of an inverse sequence and critical conditions in Shadegan wetland. Integrating remote sensing techniques and statistical methods in this study (to provide continuous time series of ecological indicators) can help to better understand the dynamics of wetland ecosystems (at different temporal and spatial scales). This approach is also applicable in evaluation, modeling and prediction of ecological changes in Shadegan wetland.

Keywords

• shadegan wetland
• ecological changes
• modis imagery
• chlorophyll