ارزيابي تغييرات مكاني شدت دوره هاي خشكسالي هواشناسي در مقياس هاي زماني متفاوت در استان كردستان

خشكسالي به عنوان كمبود طبيعي بارش در طي دوره اي از زمان است كه يك بحران مخاطره آميز براي محيط زيست و حيات گونه هايزيستي محسوب مي شود. بنابراين در زمان وقوع بحران خشكسالي، عدم وجود فرصت و منابع كافي موجب صدمات جدي مي گردد. مديريت بحران در برگيرنده مجموعه اي از اقدامات واكنشي مي باشد كه مي تواند موجب كاهش با تعديل اثرات خشكسالي ها گردد. لذا تحليل نمايه هاي اندازه گيري خشكسالي براي پيش بيني و ارزيابي مكاني و زماني اين پديده به منظورمديريت آن ضروري به نظر مي رسد. در اين پژوهش، وضعيت خشكسالي و تحليل زماني و مكاني آن در ايستگاه هاي استان كردستان با استفاده از شاخص بارش استاندارد شده (SPI)، توسط نرم افزار DrinC درمقياس هاي زماني 3، 6 و 12 ماهه انجام شده است. براساس حداكثر طول دوره ي آماري موجود، آمار سال هاي 2000 تا 2014 در 9 ايستگاه هواشناسي استان كردستان براي تحليل ها مورد استفاده قرار گرفت. نتايج حاصل ازبررسي شدت خشكسالي طي دوره مورد مطالعه نشان داد در سراسر استان كردستان در بين هر سه مقياس زماني شديدترين خشكسالي مربوط به ايستگاه دهگلان در سال 2006- 2005 اتفاق افتاده است. هم چنين طولاني ترين دوره خشكسالي(بسيارشديد) دوره 17 ماهه مربوط به ايستگاه قروه مي باشد. نتايج تحقيق تغييرات وقوع خشكسالي با درجات متفاوت را در مقياس هاي مختلف زماني و مكاني در منطقه مورد مطالعه مورد تائيد قرار مي دهد. هم چنين بر اساس نتايج، ايستگاه دهگلان اولويت اول را از نظر شدت خشكسالي در بين ايستگاه ها و ظفرآباد (ديواندره) آخرين اولويت را دارد.در نتيجه پيش بيني و مديريت بحران خشكسالي مي تواند يكي از اقدامات موثر در كاهش خسارات اين پديده اقليمي خصوصاً در مناطق حساس باشد.

Drought as a natural deficiency of precipitation over a period of time is a serious hazard to environment and the life of living species. Spatio-temporal variability of wet and dry spells will affect availability of water resources and management plans. Therefore, the lack of opportunity and sufficient resources causes serious damage in the time of drought occurrence. Drought disaster management includes a set of reactive responses which can reduce or mitigate the consequences of drought events. Thus, the analysis of drought indices is necessary to predict and assess the spatial and temporal variability of this phenomenon. The Standardized Precipitation Index, as a well-known meteorological drought indicator, is the capability of estimating various drought characteristics and can be used to analyze past droughts and predicting future droughts return periods. The Standardized Precipitation Index was selected due to its simplicity, ability of calculating the severity and duration of drought events of drought and mildew. Materials & Methods In this study, drought condition and its spatio-temporal variations was investigated through Kurdistan province, Iran, using the Standardized Precipitation Index (SPI) calculated by DrinC software in different 3, 6 and 12 months’ time scales. Toward this attempt, the monthly precipitation data of nine synoptic stations of Kurdistan province were obtained at 9 synoptic stations including Sanandaj, Saghez, Zafarabad, Marivan, Baneh, Ghorveh, Bijar, Kamyaran and Dehgolan. The maximum available recorded were used for analysis. The maximum and minimum values of the SPI index in the 3, 6, and 12-month scales were defined in the study period. Also, spatial distribution of drought condition based on the 12-month index was presented alternately in some years of the study period. Then, the most important characteristics of wet and dry periods, including the total number of wet and dry months, were determined in different drought classes. In this research, the inverse distance weighting method was used to determine the spatial pattern of drought characteristics in the study area and zoning maps. Results & Discussion The results of the study indicated that the severe drought in the three time scales has been occurred across Dehgolan station in 2005-2006 year. The longest period of drought occurrence with high severity level with 17-month length has been related to Qorveh station. The results of the study approved the variability of drought occurrences across the study area in different time scales. Finally, the zoning maps of the study area indicate that in the North and West regions, there is a higher wet spell occurrence. While the Eastern parts of the province experienced more severe droughts. Accordingly, Dehgolan station has the first priority in terms of drought severity between stations and the lowest drought severity was defined in the Zafarabad (Dyvandreh) station. Conclusion Also, it can be concluded that, the Dehgolan and Divandare stations assigned as highest and lowest priority in term of drought hazard occurrence in considered temporal time scales. As a result, drought crisis management and prediction can be one of the effective measures in reducing the damages of this climatic phenomenon, especially in drought prone areas. It is suggested that other drought indicators used to identifying drought characteristics and the results compared to obtain a comprehensive understanding on the drought severity and extent over the syudy area.