Comparison of the Performance of Six Drought Indices in Characterizing Historical Drought for the Upper Blue Nile Basin, Ethiopia

Yared Bayissa; Shreedhar Maskey; Tsegaye Tadesse; Schalk Jan van Andel; Semu Moges; Ann van Griensven; Dimitri Solomatine

doi:10.3390/geosciences8030081

Geosciences (Feb 2018)

Comparison of the Performance of Six Drought Indices in Characterizing Historical Drought for the Upper Blue Nile Basin, Ethiopia

Yared Bayissa,
Shreedhar Maskey,
Tsegaye Tadesse,
Schalk Jan van Andel,
Semu Moges,
Ann van Griensven,
Dimitri Solomatine

Affiliations

Yared Bayissa: IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands
Shreedhar Maskey: IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands
Tsegaye Tadesse: National Drought Mitigation Center, University of Nebraska-Lincoln, 815 Hardin Hall, 3310 Holdrege St., Lincoln, NE 68583, USA
Schalk Jan van Andel: IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands
Semu Moges: Department of Civil Engineering, Addis Ababa Institute of Technology, King George VI St., Addis Ababa 1000, Ethiopia
Ann van Griensven: IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands
Dimitri Solomatine: IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands

DOI: https://doi.org/10.3390/geosciences8030081
Journal volume & issue: Vol. 8, no. 3
p. 81

Abstract

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The Upper Blue Nile (UBN) basin is less-explored in terms of drought studies as compared to other parts of Ethiopia and lacks a basin-specific drought monitoring system. This study compares six drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evaporation Index (SPEI), Evapotranspiration Deficit Index (ETDI), Soil Moisture Deficit Index (SMDI), Aggregate Drought Index (ADI), and Standardized Runoff-discharge Index (SRI), and evaluates their performance with respect to identifying historic drought events in the UBN basin. The indices were calculated using monthly time series of observed precipitation, average temperature, river discharge, and modeled evapotranspiration and soil moisture from 1970 to 2010. The Pearson’s correlation coefficients between the six drought indices were analyzed. SPI and SPEI at 3-month aggregate period showed high correlation with ETDI and SMDI (r > 0.62), while SPI and SPEI at 12-month aggregate period correlate better with SRI. The performance of the six drought indices in identifying historic droughts: 1973–1974, 1983–1984, 1994–1995, and 2003–2004 was analyzed using data obtained from Emergency Events Database (EM-DAT) and previous studies. When drought onset dates indicated by the six drought indices are compared with that in the EM-DAT. SPI, and SPEI showed early onsets of drought events, except 2003–2004 drought for which the onset date was unavailable in EM-DAT. Similarly, ETDI, SMDI and SRI-3 showed early onset for two drought events and late onsets in one-drought event. In contrast, ADI showed late onsets for two drought events and early onset for one drought event. None of the six drought indices could individually identify the onsets of all the selected historic drought events; however, they may identify the onsets when combined by considering several input variables at different aggregate periods.

Published in Geosciences

ISSN: 2076-3263 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Geology
Website: https://www.mdpi.com/journal/geosciences

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