Assessment of the Impact of Meteorological Drought and Wetness Trends on the Parishan Lake Water Level Decline

In recent years due to increase of drought frequency, lakes water levels, in arid and semi-arid regions of the Iran, have dropped significantly. Therefore, in addition to ecosystem degradations, drought challenges socio-economic sectors as well. The purpose of this study was to evaluate the water level fluctuations of Parishan Lake during the wet and dry periods, and the impact of drought indices on lake water balance. By help of the SPI, CZI, MCZI and ZSI drought indices, the impact of drought on the lake water level fluctuations were investigated using meteorological data of 5 stations close to the lake. Three time scales of 3, 12 and 48 months were used for this purpose. There were significant relationships (P &le 0.05) between the lake water level fluctuations and drought indices of SPI, CZI, MCZI and ZSI for all evaluated stations. Long-term time scale SPI and ZSI indices had better relationship (r = 0.6) with lake water level fluctuations compared to other indices. With removal of phase lag between drought and water level fluctuations, regression relations for 4 drought indices of short- term time scales were improved. Findings of this research indicated that drought was the more effective and important factor on decline of the lake water level during the 2000 decade.