Satellite-Based Analysis of Maharloo Lake's Surface Area Trends and Influencing Factors

Maharlou Lake is one of Iran's saltwater lakes, located 10 kilometers southeast of Shiraz in Fars Province. It holds significant economic, social, and environmental importance for the region. Therefore, a comprehensive analysis of the lake's long-term water surface area changes is crucial for informed decision-making by relevant stakeholders. As a result, the primary objective of this study is to analyze the time series data of the lake's water levels.
The study is conducted in the Maharlou Lake basin. By employing Landsat satellite data, the lake's area in each image was delineated within the designated statistical timeframe from 1986 to 2020. Subsequently, alterations in the lake's water level throughout this period were subjected to analysis using the Mann-Kendall test. Additionally, an exploration of the factors influencing the fluctuations in the lake's water level was undertaken. This examination encompassed variables such as changes in rainfall patterns, groundwater levels, basin vegetation coverage, and population dynamics during the stipulated statistical interval.
Result and Discussion:
The outcomes of the time series analysis conducted on the Maharlou Lake area within the study period unveiled a noteworthy declining trend at a rate of 3 km²/year in the lake's expanse. The turning point in the time series was identified in September 2007, signifying a marked plunge in the lake's water level from that point onward. Analyzing of precipitation alterations demonstrated the absence of a significant negative trend in precipitation amount; While the changes in the flow rate entering the lake and evaporation showed a significant negative trend, there was a significant increasing trend in population and vegetation changes. Furthermore, a comprehensive scrutiny of underground water level variations exhibited a substantial adverse trend within this geographical expanse.
Conclusions:
Examining the changes in the Maharlou Lake's level revealed a substantial decrease in its surface area. The investigation into the influencing factors on the lake's surface indicated that there was no significant trend in the precipitation volume within the basin, which serves as one of the main water sources for the lake. The results demonstrated that while rainfall changes did not exhibit a significant trend and the evaporation trend was decreasing, the increasing population and vegetation trends in the basin demanded greater water supply. Consequently, this situation led to an excessive increase in withdrawals from underground water resources and surface flows, resulting in a significant decline in both the underground water level and the inflow rate into the lake. The combined impact of these factors contributed to the negative trend in changes to the lake's surface area. Given the vital importance of Maharlou Lake within the basin, it is imperative that land sustainability planning receives earnest attention from management in order to prevent further declines in the lake's level.