Evaluation of Standardized Precipitation Index (SPI) to identify drought in selected station of the Salt Lake watershed

Abstract

Drought is one of the most chronic environmental instabilities that has extensive environmental effects. In this research, the evaluation of standardized precipitation index (SPI) based on precipitation and temperature data in Kashan synoptic station for the statistical period of 2019-1970 has been done. In order to check the trend, Mann-Kendall and Pettie tests were used. According to the results in Kashan station, from 1992 to the first quarter of 1994, with 27 months, it had the longest drought period and from 2015 to 2018, it had the longest drought period. The results of the Mann-Kendall test for the parameter of total monthly and annual precipitation showed a significant downward trend of precipitation in December. For the parameters of maximum temperature, minimum temperature and average temperature, the average temperature showed a significant downward trend in the months of April, August and November.The time series of minimum temperature and maximum temperature parameters showed similar results, so that these parameters had a homogeneous trend in most months. Of course, this trend for the maximum temperature time series in March was heterogeneous and significant at the 5% confidence level. The Pettie test for the average temperature parameter showed different results, and the time series for this parameter in the months of April, June, July, August, September, November and on an annual scale had a heterogeneous trend. In general, it can be acknowledged that the awareness of the process and characteristics of drought plays an important role in the management of dry areas.

Keywords

• temporal analysis
• mann-kendall test
• tarsali
• precipitation data
• dry areas