Mahdis Amiri; Hamid Reza Pourghasemi
Abstract
The current study aims to investigate the relationship between hydrological and meteorological droughts in the Maharloo Watershed, Fars Province. In order to assess the hydrological drought, Standardized Water-Level Index (SWI) was used, calculated from piezometric groundwater level data from 60 observation ...
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The current study aims to investigate the relationship between hydrological and meteorological droughts in the Maharloo Watershed, Fars Province. In order to assess the hydrological drought, Standardized Water-Level Index (SWI) was used, calculated from piezometric groundwater level data from 60 observation wells within 15 years (2000-2014). The Standardized Precipitation Index (SPI), calculated from the 15 years of rainfall data from 18 stations was used to assess meteorological drought in the study area. Two geostatistical techniques were employed to create drought zonation maps namely Inverse Distance Weighting (IDW) and simple kriging. Correspondingly, three criteria were chosen to evaluate the results including Mean Absolute Error (MAE), Mean Bias Error (MBE), and Root-Mean-Square error (RMSE). Furthermore, the Mann-Kendall test was used to assess the temporal trends of hydrological and meteorological droughts. As a result, trends in hydrological drought were increasing in a significant manner, while meteorological drought trend was decreasing at first and increasing afterwards so that it did not follow any particular trend. With regard to the results of hydrological drought assessment, the driest period has been occurred in 2000 with the SWI value of about 2.25, while 2003 had the highest SWI value equals -2.66 as the most significant wet period. Moreover, the most intense drought and wet periods have been occurred respectively in northwestern and southwestern to central parts of the study area. The results of meteorological drought assessment indicated that the Komehr station has had the most intense wet period in 2000, however; it turned to have the most intense drought periods later on. As regards the evaluation of interpolation techniques, the IDW method with the lowest MAE value of 0.2688 and the lowest RMSE value of 0.0629was chosen as the best interpolation method compared to simple kriging. Also, the drought map obtained from the SPI method with the lowest values of MAE (0.2688) and MBE (-0.000051) found to be the most desirable method to assess the drought behavior in the study area.
Gholamreza Chamanpira; Gholamreza Zehtabian; Hasan Ahmadi; Arash Malekian
Abstract
Drought is the most hazardous natural phenomenon. Although not preventable, its negative effects can be reduced through taking some measures. One of the systems severely affected by drought while less considered is the groundwater. In this study, drought status and its impact on groundwater resources ...
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Drought is the most hazardous natural phenomenon. Although not preventable, its negative effects can be reduced through taking some measures. One of the systems severely affected by drought while less considered is the groundwater. In this study, drought status and its impact on groundwater resources was investigated in Alashtar Plain using Standardized Precipitation Index (SPI) at monthly, quarterly, and annual scales and the Groundwater Resource Index (GRI) during the statistical period of 1991-2010. After data collection, statistical errors were corrected by subtraction and ratios method. Then, to determine the status, SPI and GRI were calculated with DIP software on an annual, seasonal, and three, six, nine, 12, 18, 24, and 48-month time scales for Alashtar Plain. Then, according to SPI and GRI value, the moisture status were determined for each period. Results indicated that the trend of plain meteorological and groundwater drought is negative. Correlation between SPI at different time scales with and without the time delay and with average groundwater level and GRI was analyzed. Statistical analysis showed that SPI was significant at the level of 0.01, in the 24-month time scale without any time delay with mean groundwater level and GRI and had the highest correlation coefficient, suggesting the impact of drought on Alashtar plain groundwater. Regression relation between the mean level of the water table and SPI_24 showed that 64.4% of the variance at the mean level of water table was affected by SPI_24 and 35.6% was affected by other factors. Drought magnitude (DM) analysis showed that meteorological and groundwater droughts are consistent with winter and autumn, respectively. Undoubtedly, optimized utilization management, especially in spring and summer, may have a critical impact on preventing damages to the groundwater resources of the region.
