خلاصة:
Drought as a natural phenomenon characterized by a significant decrease of water availability during a period of time and over a large area. In recent years, droughts and its frequent in arid and semi-arid regions like Iran on the one hand, and water demand has been rising on the other hand and, as a result, their impacts are being aggravated. Therefore, the meteorological and hydrological droughts are receiving much more attention. This research focused on the Standardized Precipitation Index (SPI), Streamflow Drought Index (SDI) and Groundwater Resources Index (GRI) to investigate the correlation between these indices and overlapping periods of 3 to 48-months in the centeral Iran over the period of 1970–1971 to 2014–2015. Furthermore, the driest year based on the SPI were 2007–2008 and 2011-2012, while they were detected to be 1999–2000 and 2003-2004 based on the SDI and GRI, respectively. The decreasing time series trends using Spearman’s rho and Kendall’s tau tests were more evident for the all three indices at most of the years. SPI on time scales of 18, 24 and 48-months, with SDI and GRI showed a significant relationship in 0.01 and 0.05 percent levels that it can be confirmed directly affected by a groundwater drought in the plains. The Spearman correlation analysis indicated a strong correlation between SPI on time intervals of 18, 24 and 48-months, with SDI and GRI that showed a significant relationship in 0.01 and 0.05 percent levels that it can be confirmed directly affected by a groundwater drought in the plain. In general, the results showed that the study area suffered from the meteorological drought more than the other two types of droughts. Moreover, the results revealed that the study area has become drier over the last three decades.
ملخص الجهاز:
This research focused on the Standardized Precipitation Index (SPI), Streamflow Drought Index (SDI) and Groundwater Resources Index (GRI) to investigate the correlation between these indices and overlapping periods of 3 to 48-months in the centeral Iran over the period of 1970–1971 to 2014–2015.
Therefore, main objectives of this research are ccomparative analysis of the SPI, SDI and GRI based on the data from selected rain- gauges, hydrometric station and piezometers in the study area, then applying two nonparametric approaches to detect the meteorological, groundwater and hydrological drought trends and their relationships over the last decades, after that analysis of overlapping periods of 3, 6, 9, 12, 18, 24 and 48-months in each year over a 35 years period (1970–1971 to 2014–2015), and finally assessing the correlation coefficient between the indices.
Based on the cumulative streamflow volumes Vi,k, the Streamflow Drought Index (SDI) is defined for each reference period k of the i-th hydrological year as follows: precipitation (or rainfall surplus), negative values represent less than mean precipitation (or i ,k k s (View the image of this page)deficit rainfall) (Patel et al.
1. Reconstruction of data Monthly rainfall, streamflow and groundwater depth data for the period of 1970- 1971 to 2014-2015 from 27 rain-gauge, streamflow stations and 28 piezometers of Kerman Meteorological Department (KMD) and Kerman Regional Water Authority (KRWA) was used for severity and frequency of occurrence of droughts in this area.