Abstract
Drought is a serious threat to agriculture in Ethiopia. This study examined the spatiotemporal variability of agricultural drought and its association with climatic variables in the Upper Awash basin. Mann–Kendall (MK) trend test was employed to examine the drought trend while Sen’s slop estimator and pixel-based linear regression model were used to analyze the magnitude of drought changes. The association between agricultural drought and climatic variables was evaluated by the Pearson correlation coefficient (r). High spatiotemporal variability of drought was observed in Kiremit (June–September) and Belg (February–May) seasons. The Belg season spatial average vegetation condition index (VCI) trends were decreased insignificantly from 2001 to 2019 at a 5% significant level, whereas the spatial average VCI trends of Kiremit season were increased insignificantly. The return period of severe droughts during the Belg season was less frequent than the Kiremt season severe drought. The correlation between spatial average VCI and precipitation was positive for Belg and Kiremit seasons. Likewise, the correlation between average VCI and land surface temperature (LST) was negative in Belg and positive in Kiremit season. Moreover, the correlation between mean VCI and Pacific Ocean Sea Surface Temperature (SST) was positive for Belg and Kiremit seasons. The influencing factor of precipitation and LST on VCI during Belg season was higher than Kiremit season. The findings of this study are vital for decision-making systems and preparing plans to adjust sowing time, select drought-resistant crops, practice in situ water conservation, practice small-scale irrigation and diversify the income of smallholder farmers.
Highlights
Drought is one of the most devastating natural hazards [1], which are affecting ecosystem functions and services [2, 3]
To determine the accuracy of the Climate Hazards Group Infra-Red Precipitation with Stations (CHIRPS) satellite precipitation data in the Upper Awash Basin, 19 meteorological gauge station data from the National Meteorological Service Agency (NMSA) of Ethiopia were used as references
The return period of severe drought (VCI < 35%) during the Belg season was less frequent than the Kiremt season
Summary
Drought is one of the most devastating natural hazards [1], which are affecting ecosystem functions and services [2, 3]. In areas such as the Upper Awash basin, which has different ecosystems and heterogeneous topography, VCI is vital to compare the impact of weather in areas with different ecological and economic resources, as the index captures rainfall dynamics better than NDVI, in geographically heterogeneous areas For this reason, it is considered an ideal indicator for large-scale drought monitoring [22, 27, 29]. This study was aimed to examine the spatiotemporal variability of agricultural drought and its association with climatic elements (such as precipitation, LST and Pacific Ocean SST) in the Upper Awash basin of Ethiopia. The objectives of this study were: i) to assess the spatiotemporal variability of agricultural drought, ii) to examine the frequency of agricultural drought, and iii) to evaluate the association between VCI and climatic variables in the Upper Awash basin
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