Document Type : Research Paper
M.Sc. Student of Irrigation and Drainage, Department of Water Sciences and Engineering, Collage of Agriculture and Natural Resources, Ardakan University, Ardakan, Iran.
Associate Professor, Department of Water Sciences and Engineering, Collage of Agriculture and Natural Resources, Ardakan University, Ardakan, Iran
PhD Student, Faculty of Natural Resources, Tehran University, Tehran, Iran
Assistant Professor, Department of Water Sciences and Engineering, Collage of Agriculture and Natural Resources, Ardakan University, Ardakan, Iran
drought is one of the phenomena that can affect the quality and quantity of surface water in basins.therefore , investigating the changes and determining thecontributionofthisphenomenononquantitativeandqualitative parameters can help managerstoimproveandmanagewaterresources.accordingly,thisstudywasconducted with the aimofinvestigatingdroughttimestepsonquantitativeandqualitativeparametersofriverwaterinisfahan province . for this purpose , theprecipitation and temperature data of synoptic stations during the period of 20 years ( 2000 - 2020 ) and water quality and discharge data during theperiodbasinlocatedinthewatershed outlet . for drought analysis in the study area , standardized precipitation index and riverhydrologicaldrought indexwereusedinfourtimesteps(6,12,24and24months).theresultsofthestudyofmeteorologicalandhydrological drought indices suggest that drought severityandcontinuityespeciallyhydrologicaldroughtinrecentyears , and the existence of a 12 - month delay between meteorological and hydrological drought has been . in the study of time steps of drought on quantitative and qualitative parameters of river , it was found that there is a positive and significant correlation between the standard precipitation index and the quality parameters of surface water in 6 months time step . as a result , meteorologicalandhydrologicaldroughtcanaffectthequality and quantity of surface water . in the studyoflandusechangesonqualityparametersduringwetandwetperiods , the results indicate a decrease in the quality of water due to decrease of range land use and increase ofurban land use in drought and increase of agricultural land useinwetyear.indroughtperiod,withdecreaseinland use aree
andshrubandincreaseinlandandbarelands,thesechangescanincreaseerosionsedimentyieldandtransferofchemicalresidues ( fertilizers and pesticides ) to the channels and decrease water quality . theresults showed that increasing human activities , climate fluctuations are thefactorsaffectingthequantity and quality of the river , so it is necessary to implement the correct management programs for controlling land use changes and water resources management in drought situatioss .