Temporal trends and spatial characteristics of drought and rainfall in arid and semiarid regions of Iran

Abstract

Abstract:Drought, a normal recurrent event in arid and semiarid lands such as Iran, is typically of a temporary nature usually leaving little permanent aftermath. In the current study, the rainfall and drought severity time series were analyzed at 10 stations in the eastern half of Iran for the period 1966-2005. The drought severity was computed using the Standardized Precipitation Index (SPI) for a 12-month timescale. The trend analyses of the data were also performed using the Kendall and Spearman tests. The results of this study showed that the rainfall and drought severity data had high variations to average values in the study period, and these variations increased with increasing aridity towards the south of the study area. The negative serial correlations found in the seasonal and annual rainfall time series were mostly insignificant. The trend tests detected a significant decreasing trend in the spring rainfall series of Birjand station at the rate of 8.56 mm per season per decade and a significant increasing trend in the summer rainfall series of Torbateheydarieh station at the rate of 0.14 mm per season per decade, whereas the rest of the trends were insignificant. Furthermore, the 12-month values of the standardized precipitation index decreased at all the stations except Zabol during the past four decades. During the study period, all of the stations experienced at least one extreme drought which mainly occurred in the winter season.

Evolution of low flows in Czechia revisited

“…Even if one concentrated only on one year, the list of such literature would be huge. To name some, in 2012 the relationships among trends in river flow and precipitation were investigated by Chen et al (2012), Ehsanzadeh et al (2012), Liu et al (2012), Lorenzo-Lacruz et al (2012), Shifteh Some'e et al (2012), Steffens and Franz (2012), Tabari et al (2012) or Wagesho et al (2012). Since the mid-1990s, the role of serial correlation (autocorrelation) frequently present in hydrometeorological series has been accented.…”

Trend assessment of precipitation and drought index (SPI) using parametric and non-parametric trend analysis methods (case study: arid regions of southern Iran)

“…There have been a number of drought indices such as SPI, standardised precipitation evapotranspiration index, palmer drought severity index, and reconnaissance drought index. In this study, the SPI is applied, because of its good characteristics in drought identification and prediction of drought class transitions (Moreira et al, 2008;Tabari et al, 2012).…”

“…It can have a substantial impact on the ecosystem and agriculture of the affected region. It can be classified as meteorological, agricultural, hydrological or socio-economic drought (Moreira et al, 2008;Tabari et al, 2012). Precipitation is one of the most important meteorological variables which can impact the occurrence of drought or flood.…”

“…Analysis of precipitation and drought data yields important information which can be used to improve water management strategies, protect the environment, plan agricultural production or in general, impact economic development of a certain region. In recent years, a plethora of scientists worldwide have compared and analysed the precipitation trends (Gemmer et al, 2004;Oguntunde et al, 2011;Tabari et al, 2012).…”

Two-year field monitoring shows little evidence that transgenic potato containing ABF3 significantly alters its rhizosphere microbial community structure

“…The monthly %Normal Precip was calculated as actual monthly rainfall (the data from Cheongju Weather station utilized) divided by the monthly long-term normal (Mkhabela et al 2010). The SPI was computed based on the concept of standardized precipitation, which is the difference between total precipitation for a certain period of time and the long-term (30 years) mean total precipitation for that same period, divided by the standard deviation (Tabari et al 2012). …”