جستجوی مقالات مرتبط با کلیدواژه « شاخص خشکسالی هواشناسی » در نشریات گروه « آب و خاک »

The present study was proposed to evaluate severity of drought in Eghlid region where in Fars province. For this purpose, standardized water level index (SWI) and rainfall anomaly index (RAI) were used during a 10 years’ statistical wet period (1384 to 1393) by using monthly water table depth data of 107 pezometric wells and monthly precipitation data of 10 meteorological and synoptic stations. In order to resolve defects of precipitation data, using SPSS software, the correlation coefficient through stations was analyzed and restored with ratios approach method. For determining severity of drought both of data sets of drought indexes were calculated by Excel software in 3, 6, 12, 24 and 48 monthly periods. Five of the biggest occurred droughts were determined in each index and its mutual index and droughts zoning were accomplished using inverse distance weighted (IDW) in ArcGIS program. The results indicated that severity of droughts were increased in recent years. Furthermore, the results are implicating which there is a time delay between hydrological and meteoric drought indexes, in fact it was observed that by calculating the correlation coefficient between the indexes for south and west of Eghlid, the time delay is 2 to 4 years.

Application of meteorological indicators has extensive use in drought monitoring. However, hydrological indicators can also play an effective role in this task. In this research, one of the rare approaches in drought monitoring with hydrological indicators namely Chang method has been applied and assessed for the Tehran basin using daily time step. The results have been compared with the unique meteorological drought index, EDI (effective drought index) and show the capabilities of the hydrological method and its more sensivity to water resources deficit. For instance, application of these procedures for the 1998 to 2000 drought spell in Tehran province revealed that Change method declares 31.1 % of times in very severe drought whereas it is 3.7 in EDI. Because of applying different indicators (e.g. reservoir and ground storage), a combination of both procedures is an ideal approach for drought monitoring in which the water inputs to the system as well as storage and consumptions are considered. The applied methodology makes it Possible to distinguish droughts due to rainfall deficit from the ones, which are resulted from water resources miss management.