Spatio-Temporal Variability of Drought in Pakistan Using Standardized Precipitation Evapotranspiration Index

Abstract

Featured Application:The following research has a potential to provide a scientific basis for the management of drought mitigation strategies. The trends in drought characteristics in each zone throughout the study period can help decision-makers with more information on resource planning. The identification of contiguous zones with similar drought characteristics across Pakistan is the first step towards developing an integrated and holistic policy to minimize the impacts of droughts. This study will help achieve this goal.Abstract: Pakistan is among the top ten countries adversely affected by climate change. More specifically, there is concern that climate change may cause longer and severer spells of droughts. To quantify the change in the characteristics of droughts in Pakistan over the years, we have evaluated spatio-temporal trends of droughts in Pakistan over the period 1902-2015 using Standardized Precipitation Evapotranspiration Index (SPEI). Additionally, the Spatial "K" luster Analysis using Tree Edge Removal (SKATER) method was employed to regionalize droughts into five contiguous zones. The run theory was then applied to each zone to identify drought events and characterize them in terms of duration, severity, intensity, and peak. Moreover, the Modified Mann-Kendall trend test was applied to identify statistically significant trends in SPEI and drought characteristics in each zone. It was found that the southern areas of Pakistan, encompassing Sindh and most of Baluchistan, have experienced a decrease in SPEI, indicating a drying trend. Central Pakistan has witnessed a wetting trend as demonstrated by an increase in SPEI over time, whereas no statistically significant trend was observed for the northern areas of Pakistan. On a zonal basis, the longest duration drought to occur in Pakistan lasted 22 months in zone 5 (Sindh) from 1968 to 1970. In addition, the droughts of 1920 and 2000 can be said to be the worst drought in the history of the region as it affected all the zones and lasted for more than 10-months in three zones.

Exploring the Evolution of Drought Characteristics in Balochistan, Pakistan

“…Therefore, in this study, we have used SPEI as the drought index and extended the study period to 1902-2015. This study also aims to extend the Pakistan-wide work of Jamro et al [26], which concluded that central Balochistan, along with Sindh, is the most vulnerable area to droughts and requires further investigation.…”

“…Regionalization is a popular technique used in hydrology to group stations into clusters showcasing similar behavior when comparing a certain attribute. The regionalization of droughts has been carried out in this study using a Spatial "K"luster Analysis using Tree Edge Removal (SKATER) algorithm [18,26,38] to divide Balochistan into six regions having a similar behavior of SPEI. A 24-month SPEI was used to cluster the 124 grid cells in Balochistan into six spatially contiguous regions, as this timescale was found to reflect the climate of Balochistan better than other timescales of SPEI.…”

“…Tian and Quiring [20] used the objective SPEI drought threshold in Oklahoma, which was −0.7. Liu et al [18] and Jamro et al [26] used −0.5 as their chosen thresholds. Since this study is an extension of Jamro et al [26], when the SPEI crossed the −0.5 mark, a drought was said to occur ( Figure 2).…”

Unsustainability Syndrome—From Meteorological to Agricultural Drought in Arid and Semi-Arid Regions

“…The other two types of drought arise when use of water resources exceeds renewal of surface and groundwater, or when water demand outstrips supply.Many drought indices have been developed to date, such as the Palmer drought severity index [26], decile index [27], standardized precipitation index (SPI) [28], streamflow drought index (SDI) [15], and standard contribution of rainfall to runoff (SCRI) [29]. Of these, SPI and SDI have been widely used in different climate zones to monitor and assess meteorological drought [30][31][32][33][34][35][36] and hydrological drought [37][38][39][40].Although there has been considerable progress in understanding the impacts of drought in terms of engineering, economics, social science, and geography, the complex links between human and natural processes need more attention. In arid and semi-arid regions with high dependency on agriculture, these links are more complicated, as they affect the livelihoods of local people.…”

“…Many drought indices have been developed to date, such as the Palmer drought severity index [26], decile index [27], standardized precipitation index (SPI) [28], streamflow drought index (SDI) [15], and standard contribution of rainfall to runoff (SCRI) [29]. Of these, SPI and SDI have been widely used in different climate zones to monitor and assess meteorological drought [30][31][32][33][34][35][36] and hydrological drought [37][38][39][40].…”