Analysis and evaluation of hydrological drought indicators in Kurdistan Province

In recent years, Kurdistan Province has faced a dramatic decline in groundwater levels. In this research, the time interval between the occurrence of meteorological drought and hydrological drought was determined for the necessary measures to cope with the drought caused by the lack of surface water and underground water resources. Therefore, the hydrological drought situation in Kurdistan Province was evaluated using Groundwater Resources Index (GRI) and Streamflow Drought Index (SDI) and compared with meteorological drought indicators. The GRI and SDI time series for the 30 years of studied period of 1982-2014 was inter-compared. The GRI showed the highest percentage of frequency of normal period. According to the results of Man-Kendall test, in all time scales, SDI has a higher variability than the meteorological drought indicators. Knowing the interval between the occurrence of meteorological drought and hydrological drought will help managers to cope with the drought caused by a shortage of surface water resources in the interior ministry, The Markov chain model used to predict the current state of a system with regard to the previous state in the statistical period showed good performance. According to the results of the study, on average, the probability of dry, wet and normal periods in the stations was 31, 29, and 40 percent, respectively. This means that in most cases, the region is in normal climatic condition, while the likelihood of wet and dry conditions is very similar. Also, SPEI with12 and 24 months’ time scales have the highest correlation with GRI index at 3 months lag-times, which showed the effects of meteorological drought on groundwater level even after two years or more. By considering the results of this study, the executive directors of water in the province can mitigate the effects of the crises caused by the hydrological droughts.