Long term analysis of international wetlands in Iran: Monitoring surface water area and water balance

Abstract

Wetlands have rich biological diversity and productivity, and support unique ecological functions. However, wetlands worldwide are under threat owing to the pressures of development and climate change. We analysed the extent and water balance of 21 important wetlands in Iran from 1990 to 2022 based on Landsat 5, 7, 8, and 9, and Sentinel-2 satellite images and ERA5-land in the Google Earth Engine (GEE) platform. We performed morphometric analyses using NKU-MAN and the Mann-Kendall test to estimate the trends for wetland water bodies. Most seasonal water balance maxima occurred in January, followed by February and, in some cases, in the adjacent months, whilst the minima primarily occurred in May (nine wetlands) and June (five wetlands). Most importantly, the results revealed a gradual decrease in the size of the water bodies over the course of the study period, although this trend was not statistically significant for all water bodies. The findings of this study provide information that can be used by policymakers, planners, scientists, and residents to assess and manage sustainable water usage in wetland watersheds in a changing climate.