Analysing the Master Recession Curve of daily River flow in Nirchai River, Ardabil Province

Analysis of river flow master recession curve is a way to assess the occurrence of hydrological drought.The purpose of this study was to inverstigate the master recession curve preparation of daily flow discharge.The master recession curve represents the nature of flow discharge,flow contribution sources,flowrecission through the river. The shape of master recession curve used to analyse the hydrologic regime,watershed response,groundwater contribution in river flow discharge. The daily flow river of Nirchaiwatershed have been used in this study through a 36-year of recorded data. The MRCs in different regressionequations (Linear,Exponential,Logharithmic,and Multinominal types) were extracted using a Visual Basicprogram (Posacev 2006) in excel environment,The constant coefficients,curve slope were defined andthen,the coefficient of determination of different MRCs were calculated. Based on the results,the bestMRC regression were selected (R2,0.91). The curve slope,constant values were estimated to be -0.07and 0.443,respectively. These coefficients,indicates,its comparisons in different rivers can be usedto investigate the hydrologic regime of the watersheds in different conditions.