Document Type : Research
Authors
1
Department of Drought & climate change
2
Assistant Prof., Soil Conservation and Watershed Management Research Institute, Agricultural Research, Education and Extension Organization, Tehran, Iran
10.22092/wmrj.2024.364593.1567
Abstract
Introduction and objective
Understanding water in terms of quality, quantity and its supply is an essential step towards optimizing consumption. Severe droughts in arid and semi-arid regions caused by inappropriate human interventions have reduced the quantity and quality of surface water resources . Due to the importance of the drought phenomenon and its effects on the quality of surface water and groundwater, the investigation of this issue has attracted the attention of researchers in Iran and other parts of the world. For this purpose, researchers have used various indices to monitor drought and its effect on water quality. The aim of this study was to identifying wet and dry spells and the occurred droughts using SPI and then to investigate the effect of chemical parameters of surface water in Kashkan basin during drought periods and their changes during a 30-year period.
Materials and Methods
Kashkan with an area of more than 9560 km2 covers about 22% of the total Karkha river basin (KRB). It is located in the middle part of Zagros Chain in 450 Km southwest of Tehran. For this purpose, the chemical quality of the rivers in a period of 30 years in the hydrometric stations with quality data including anions (Cl, SO4, HCO3), and cations (Na, Mg, Ca, K) and other variables including SAR, PH, TH, TDS and EC in the joint statistical period from 1981 to 2016 were considered and analyzed.
Results and Discussion
The results of this research showed the contribution of each formation in the way and the share of drought events of the recent decades on surface water quality.
Conclusion and suggestions
In general, droughts are associated with water crises and a severe reduction in surface water resources. Continuous monitoring and evaluation of surface water and the effect of drought on it is necessary to know the quantitative and qualitative changes and to plan the catchment area. Therefore, conducting studies to investigate the quality of surface water as well as the factors affecting it can provide useful information for the realization of future goals and plans. Therefore, this research was carried out in order to investigate the changes in the water quality of the Lower Kashkan river in the part of Poldokhtar. Also, it proved the quality of surface waters in each sub-basin has changed. Finally, it was shown that although droughts have lowered the quality of surface water (e.g., EC has been increased from 300 μm/cm in 1981 to about 570 μm/cm in 2016) which is still suitable for irrigation in agriculture despite qualitative decline. It is suggested to determine the role of polluting sources such as runoff and sewage in changing the water quality of this river.
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