Impacts of the Urmia Lake Drought on Soil Salinity and Degradation Risk: An Integrated Geoinformatics Analysis and Monitoring Approach

Abstract

Recent improvements in earth observation technologies and Geographical Information System (GIS) based spatial analysis methods require us to examine the efficiency of the different data-driven methods and decision rules for soil salinity monitoring and degradation mapping. The main objective of this study was to analyze the environmental impacts of the Lake Urmia drought on soil salinity and degradation risk in the plains surrounding the hyper-saline lake. We monitored the impacts of the lake drought on soil salinity by applying spatiotemporal indices to time-series satellite images (1990–2020) in Google Earth Engine environment. We also computed the soil salinity ratio to validate the results and determine the most efficient soil salinity monitoring techniques. We then mapped the soil degradation risk based on GIS spatial decision-making methods. Our results indicated that the Urmia Lake drought is leading to the formation of extensive salt lands, which impact the fertility of the farmlands. The land affected by soil salinity has increased from 2.86% in 1990 to 16.68% in 2020. The combined spectral response index, with a performance of 0.95, was the most efficient image processing method to assess soil salinity. The soil degradation risk map showed that 38.45% of the study area has a high or very high risk of degradation, which is a significant threat to food production. This study presents an integrated geoinformation approach for time-series soil salinity monitoring and degradation risk mapping that supports future studies by comparing the efficiency of different methods as state of the art. From a practical perspective, the results also provide key information for decision-makers, authorities, and local stakeholders in their efforts to mitigate the environmental impacts of lake drought and sustain the food production to sustain the 7.3 million residents.

Water Balance Analysis of Hulun Lake, a Semi-Arid UNESCO Wetland, Using Multi-Source Data

“…Lakes are closely related to the biosphere, atmosphere, and lithosphere, and have the special functions in the regulation of regional climates, the recording of regional environmental changes, the maintenance of the balance of regional ecosystems, and breeding biodiversity [4,5]. In recent years, many lakes have experienced salinization and/or eutrophication, shrunk, or even dried up [6][7][8][9][10]. The shrinking of lakes in arid and semi-arid regions leads to their salinization, climate deterioration, the expansion of desert land, vegetation decline, and the inhibition of fish-resource proliferation.…”

Health effects of shrinking hyper-saline lakes: spatiotemporal modeling of the Lake Urmia drought on the local population, case study of the Shabestar County

“…In recent years, changes in the water level of Lake Urmia have caused salt release centers in the southern and southwestern areas of Shabestar County. The Lake Urmia drought has led to dry soil, deforestation, an increase in airborne dust, and the dispersion of allergens, which potentially compromise respiratory and circulatory health 27 . Early studies for analyzing the lake drouth and its respective environmental issues pointed out the integrated impacts of intensive anthrophonic factors and climate change for lake drouth.…”

“…The predominant wind direction in Shabestar is westward. Considering the extensive exposed salt lands resulting from the lake drought and the direction of the wind, the coastal and even inland areas of Shabestar are in serious danger of salt intrusion 27 . There is a direct relationship between the scatter of salt particles in the air and the drying lake.…”