Evaluation of the effect of land use change in Mehran plain on surface water quality parameters in wet and drought periods

In recent years, with the increase in population, the quantity and quality of surface water resources due to human activity have changed. By studying the effects of land-use change on surface water resources, we will be able to understand the interactions between land use and water quality. Therefore, the purpose of this study is to evaluate the surface water quality in the Mehran plain watershed affected by land use. In this study, after extracting land use, the percentage of each land use area in the region for four time periods of 2000, 2007, 2016, and 2020 was determined, then the effects of land-use changes in both wet and dry periods on water quality parameters including anions, cations, SDR, TDS, EC were examined. Finally, Schuler and Wilcox's diagrams were used to determine the drinking water quality parameter. The results showed an increase in barren and urban lands compared to agricultural, rangeland, and forest lands. So barren and urban lands have increased by 13.2% over 20 years and the number of anions compared to the long-term average of 10 years is 14.82% and cations are 21.23% and soluble salts of SDR, TDS, EC is 36.9%, respectively, Increased by 18.35 and 18.30 percent. In most of the studied applications, the trend of changes based on the Mann-Kendall test showed an increase, and based on Pearson correlation between river flow and quality parameters with all parameters has a negative and inverse relationship, which with decreasing river flow, the trend of quality parameters increased. Is. According to Schuler and Wilcox's diagrams, water is in the salinity range for the study area. The results showed that the increase in human activities and climate fluctuations are factors affecting the water quality of the Gavi River, therefore, there is a need to manage programs to control land-use change

Hydrological Response of Burned Soils in Croplands, and Pine and Oak Forests in Zagros Forest Ecosystem (Western Iran) under Rainfall Simulations at Micro-Plot Scale

The post-fire hydrological processes depend on both land use and soil condition (burned or not). This study aims at understanding the variability of the water infiltration, surface runoff and erosion in burned soils under different land uses (forestland and cropland) in comparison to unburned sitesTo this aim, infiltration, runoff and soil losses after a wildfire in two pine and oak forests, and a cropland are evaluated in Zagros forests (Western Iran) using a portable rainfall simulator. This area represents one of the lands with the highest biodiversity and naturalistic value of the entire Middle East, but no similar hydrological evaluations have been conducted so far. The difference in infiltration between the burned and unburned sites under the three land uses was not significant (on the average less than 10%). The runoff and erosion due to the wildfire noticeably increased in the forestland (+95% and 60%, respectively) and slightly decreased in the cropland (−16% and −20%) in comparison to the unburned sites. In the burned croplands erosion requires much attention, because the soil loss is on an average 30-fold compared to the values measured in the forestland. This increase may be even higher, since the rainsplash erosion could be underestimated and the rill or gully erosion was not considered due to the use of a portable rainfall simulator. Therefore, the study suggests the adoption of suitable strategies in croplands of the Zagros forests, in order to limit the negative impacts of high-intensity fires and hydrogeological events. Overall, the study has provided an insight to improve the knowledge on soil hydrology under different land uses and soil conditions. This evaluation helps landscape planners to select the most suitable anti-erosive actions against erosion in fire-affected areas without any needs of long monitoring field campaigns or model implementation