Determining the Monthly Wet and Dry Regimes Using Angot Precipitation Index in Ardabil Station

Subject Areas : Water and Environment

Roghayeh  Asiabi-hir ¹ (M.Sc in Watershed Management, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran.)
Raoof  Mostafazadeh ² (Associate Professor, Dept. of Natural Resources, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran. * (Corresponding Author))
Saied  Nabavi ³ (Ph.D Student in Watershed Management, Faculty of Natural Resources, University of Tehran, Karaj, Iran.)

Received: 2016-08-24 Accepted : 2016-10-31 Published : 2022-09-23

Keywords: Temporal precipitation variations, Climatic index, Dry month, Drought, Precipitation regime,

Abstract :

Background and Objective: Drought is the main causes of socioeconomic and environmental issues and the spatial and temporal variability of precipitation has a great influence on water resources availability. The Angot Precipitation Index (ratio between the average values of multiannual of precipitation over wet and dry periods) is an indicator to determine the precipitation variations. The API highlights the climate significance of every month to detect dry or rainy regime.Material and Methodology: This study aims to assess and calculation of API in analysis of dry-wet periods of monthly precipitation in Ardabil station. The API values were calculated based on average daily values of precipitation in a year. Based on API values, dry and wet months were identified and the relationship between API and monthly precipitation characteristics according to Pearson correlation coefficient.Findings: According to the results, the value of API was 2.33 for the May month as a wet month and the November and April months are determined as normal precipitation regime (1.65 and 1.57 values, respectively) and other months have been classified into dry months as the API is less than the unity. Also, the API had a negative correlation with precipitation coefficient of variation (R2=0.408), and a positive correlation is exist between average monthly precipitation amounts and the API (R2=0.998).Discussion and Conclusion: The maximum API index value was observed in November and May months. The results indicated that the amount of Angot index was inversely correlated with coefficient of variations; while a direct relationship is exist with average monthly precipitations. Application of Angot index allows the determination of monthly precipitation regime on the basis of the vale ranges of the calculated index. Comparing the results of other drought indices in determining wet and dry months in climatic zones of Iran needs further investigations.

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