Analysis of Basin drought for URMIA Lake in Iran with Standardized Precipitation Index method (SPI)
Drought is a natural and reversible feature of climate change and occurs almost in all climatic regimes, and its effects are not restricted simply to arid and semi-arid areas. Drought can also occur in areas with high precipitation in each season of year and cause considerable damages to agricultural and industrial sectors and to cities. Located at subtropical region and having semi-arid climate, Lake Urmia basin experiences drought frequently. Since some cultivations in this region are made in the form of rainfed farming, sudden decreased rain will leave many damages.
In the present study, drought of Lake Urmia basin was investigated according to the total monthly precipitation data obtained from synoptic stations in the area, using Standardized Precipitation Index (SPI) in four time scales (3, 6, 12, and 24 months). The results show that short-term scales response quickly to rainfall changes, while drought is continued more in long-term scales. That's why drought frequencies in long-term series (scales) minimize. In addition, by comparing the time scales, it is found that a region may be in wet conditions in a time scale, while be in dry conditions in another time scale simultaneously.
© 2011 Karaelmas Fen ve Mühendislik Dergisi