DROUGHT PREDICTION AND MAPPING UNDER CHANGING CLIMATE: A CASE STUDY OF EAST HARARGE ZONE, ETHIOPIA

Abstract

Drought is a short lived period of abnormally dry weather long enough to cause a hydrological imbalance. The intensity and frequency of droughts are expected to change earth’s climate. Climate change and climate variability has been experienced in Ethiopia and exposed the country to recurrent droughts and decline in agricultural production and productivity. The impacts of drought are more severe in areas where rain-fed agriculture dominates all agriculture. The pastoral and agro-pastoral areas are the most frequently drought affected areas of all time. This study was designed to assess and map the drought areas in East Hararge zone based on the data obtained from satellite and global climate model. The spatial and temporal characteristics of historical drought in East Hararge zone was analyzed and mapped from remotely sensed climate hazard infrared precipitation with station (CHIRPS) and moderate resolution image spectroradiometer (MODIS) vegetation data. The coupled model inter comparison project phase 6 (CMIP6) based CanESM5 data under shared socio economic pathway (SSP2 4.5) scenario was used to track drought areas under changing climate. The study was used standardized precipitation index (SPI), agricultural standardized precipitation index (aSPI), normalized difference vegetation index (NDVI), and NDVI anomaly index to achieve its general objectives. The result obtained from drought indices were validated with crop yield anomaly. The validation result for drought indices were shown as r = 0.72, 0.74 and 0.78 for SPI, NDVI, and NDVI anomaly respectively. It was also shown from the combined drought risk that 29.8% and 26.7% of the areas were witnessed moderate and slight drought respectively in the last 12 years. The drought assessment under changing climate in this study was based on SPI and aSPI calculated from 2015 to 2100 under SSP2 4.5 scenario. Accordingly, drought trend analysis based on SPI_6 shows significantly increasing trends of drought with a changing rate of -0.003 and P value of 0.046 as confirmed by Man-Kendall trend test. The spatial drought analysis based on aSPI shows general decreasing trends of drought risk areas with a changing rate of 0.466. Frequency analysis of drought in East Hararge zone shows the occurrence of drought once every 2 years under SSP2 4.5 scenario. Generally, the study provides valuable baseline information and future predictions that will help to monitor the real time situations in the future for different adaptation options in the area.