Monitoring spatiotemporal variability of water quality parameters Using Landsat imagery in Choghakhor International Wetland during the last 32 years

Abstract

Use of Landsat is of importance in monitoring and assessment of long-term changes of water quality in freshwater ecosystems, especially in small water bodies. In this study, over a 32-year period (1985-2017), the changes in water surface temperature (WST), secchi disk transparency (SDT), and chlorophyll-a (Chl-a) concentration were estimated at the Choghakhor wetland using Landsat imagery. Based on WST three detectable temperature zones can be observed within the wetland aquatic environment where the highest amount was observed in thermal strips. The results showed Chl-a concentration volatility in different periods in the wetland as well as its long-term increasing trend. The western part of the wetland, as compared to other areas, was affected by these changes, which could be due to the human activity concentrated in this area. In contrast (SDT) showed a decreasing trend during this period that was consistent with the observed changes in Chl-a concentration. This could be due to an increase in organic matter load and suspended solids in the water body of wetland during this time. Comparison of the extracted satellite data with the field data showed the least RMSE and high R2. Also, ANOVA results showed significant spatiooral differences between the studied parameters in Choghakhor wetland (p < 0.05). The present study can help to detect long-term changes in Choghakhor wetland and help toward moving to optimal management and protection of this wetland.