Comparative Study of Meteorological Indices with Hydrological Indices for Drought Monitoring Using Data Mining Method (Case Study: Arazakuseh Station-Golestan Province)

Meteorological drought, caused by deficit precipitation as compared with the normally expected, leads to hydrological drought, causing reduction in the flow of rivers, and as well, fall of the groundwater level. Several indices have been defined To make the drought quantitative. For example the Standard Precipitation Index (SPI) which is obtained as based upon the monthly precipitation data, and is an indicator of meteorological drought, also Standard Stream flow Index (SSI), which is an indicator of the hydrological drought. Each of these indices is classified into categories with each category indicating a state of some drought severity. The aim followed in this research is a comparative study of the meteorological hydrological drought indices in Araz Kouse station, located in Golestan Province, which is done by using some association rules in data searching. Following calculation and classification of SPI and SSI indices within a 12-month-period, and by defining different scenarios, it was concluded that there is no complete accor found between the meteorological vs hydrological droughts and according to drought situation in earlier periods, stream flow shows different behaviors. Also drought as compared with wet year, affects the stream flow with a lower latency.