Hydrological Drought Analysis using Streamflow Drought Index (SDI) in Ethiopia

Abstract

Drought is a natural disaster that has impacts on society, the environment, and the ecosystem. Ethiopia faced many horrible severe drought events in the last few decades. Even though there are some drought-related studies in the country, most of the investigations were focused on meteorological drought analysis. This study was focused on hydrological drought analysis in Ethiopia using the streamflow drought index (SDI). The main objective was to identify drought-prone areas and severe drought events years. Streamflow data were collected from 34 stations to analyze SDI in seasonal (3-month) and annual (12-month) timescales. The analysis implies that seasonal time scale (3-month) hydrological drought has a high frequency of occurrence but short duration, whereas annual (12-month) analysis has a low frequency with a large magnitude. The overall result shows that 1984/85, 1986/87, 2002/03, and 2010/11 were the most severe and extreme drought years in all river basins. The 1980s were found severe and extreme drought years in which most hydrological drought events occurred in the country. The spatial analysis shows that Tekeze, Abbay, and Baro river basins have similar characters; Awash and Rift Valley River basins show relatively the same character, and Genale Dawa and Wabishebele river basins have a similar character. But Omo Gibe River basin has a unique character in which the severe drought occurred in a different year of other river basins.

Hydrological drought forecasting and monitoring system development using artificial neural network (ANN) in Ethiopia

“…In the previous few decades, drought studies were conducted in some parts of Ethiopia with a special focus on meteorological drought assessment [ 49 ]. However, hydrological drought analysis and long-term drought forecasting using the recent data-driven application are still not addressed.…”

Comparing surface water supply index and streamflow drought index for hydrological drought analysis in Ethiopia

“…Figure 1 shows the major river basins in Ethiopia and the spatial location of hydrometeorological stations. Of the existing 12 major river basins ( Figure 1 ), three are dry and one river basin has low flow and low recorded data [ 47 ]. Therefore, comparing of two hydrological drought indices (SDI and SWSI) was conducted only on eight major river basins.…”

“…Ethiopia has many perennial rivers and lakes, but still, those resources are not well utilized [ 46 ]. While hydrological and agricultural drought analysis and monitoring have not been thoroughly explored, meteorological drought analysis has been regularly studied in various parts of the country [ 47 ].…”

“…However, there are also drought indicators used for hydrological drought analysis such as the palmer hydrological drought index (PHDI) [ 49 ], streamflow drought index (SDI) [ 50 ], and surface water supply index (SWSI) [ 12 ]. SDI is simple and required a single input data (streamflow) and is suitable for drought study at the site [ 47 ] whereas, SWSI was developed at Colorado University by Shafer and Dezman (1982) and is used for regional or basin-level hydrological drought analysis by considering the available surface water from different sources [ 12 ]. It requires all forms of surface water sources such as streamflow, precipitation, reservoir level, and groundwater level.…”

Analysis of Discharge Fluctuation Using Modified Streamflow Drought Index (SDI) and Standardized Precipitation Index (SPI) in the Upper Nišava River Basin

“…The SDI is simple to compute and is based on the Standardised Precipitation Index (SPI) used for detecting and characterizing meteorological droughts (McKee et al, 1993). Nalbantis (2008), Nalbantis and Tsakiris (2009), Tabari et al, (2013), Myronidis et al, (2018), Malik et al, (2019), Jahangir and Yarahmadi (2020), Abbas and Kousar (2021), Tareke and Awoke (2022), and others used the SDI for the hydrological drought monitoring and analysis purpose.…”