Predicting the effect f climate change on drought indices (SPI) and (SDI) in Malayer watershed using ARIMA time series model

In recent years, the impact of climate change and drought forecasting on water resources planning and management has received much attention. In the present study, probable climate change on Malayer basin temperature and precipitation over the period 2014-2014 was investigated and monthly, seasonal and annual forecasts for the near future (2030-2011) under three scenarios A2, B1 and A1B using HadCM3 general circulation model The LARS-WG model was used for performing and exponential micro-scale.
Data and

ARIMA multiplication time series and AIC and SBC criteria and Pert-Manto test in predicting precipitation and SPI and SDI indices have been used to predict drought for the period (1397-1418) of Merville, Pihan and Wasjeh hydrometric stations.The results show an increase in precipitation and temperature in all three monthly, seasonal and annual scales in the coming period, and Shows that the largest meteorological drought for the base period in 1998-1999 is -1/96 and In the coming year 1418-1418 there was adecrease of -2/4. Surveys show that moderate and severe droughts will increase in the coming statistical period at the Mervil, Peyhan and Vasge stations.

Drought occurrence reduces discharge and hydrological drought. The results show that due to variability of precipitation and mean air temperature, the trend of drought changes is not the same in different months. Therefore, the duration, severity and frequency of droughts vary from month to year.

Investigation of correlation (r) and mean error (MSE) values ​​between observed and calculated values ​​of discharge and precipitation at the stations under study indicate the high capability of ARIMA model in simulating monthly discharge. And it can be used in other parts of the country.