Table 5 The significant drought events (SPI/SPEI ≤ − 1) duration, magnitude, intensity, and peak value in the northern part of OGRB from 1981 to 2017
Sub-basin | Stations | Accumulation periods | Duration | Magnitude | Intensity | Peak value |
|---|---|---|---|---|---|---|
Northern | Ambo | SPI-4 | Apr 1991–Dec 1991 | − 10.4 | − 1.16 | − 2.76 |
SPI-12 | May 2002–Sep 2004 | − 30.20 | − 1.68 | − 2.32 | ||
SPEI-4 | Apr1990–Dec1991 | − 10.18 | − 1.3 | − 2.37 | ||
SPEI-12 | Jul 2002–Feb 2005 | − 35.92 | − 1.12 | − 2.61 | ||
Butajira | SPI-4 | July1997–Jun1988 | − 17.34 | − 1.58 | − 3.39 | |
SPI-12 | Oct 1990–Jun 1992 | − 30.96 | − 1.35 | − 2.83 | ||
SPEI-4 | Oct1990–Jan1992 | − 20.23 | − 1.26 | − 2.22 | ||
SPEI-12 | Oct 2014–Mar 2017 | − 21.81 | − 1.21 | − 2.43 | ||
Gedo | SPI-4 | Nov 2010–Nov 2011 | − 21.14 | − 1.42 | − 2.72 | |
SPI-12 | Sep 1995–Jul 2000 | − 84.88 | − 1.44 | − 2.36 | ||
SPEI-4 | Nov 1998–Dec 1999 | − 19.86 | − 1.42 | − 2.11 | ||
SPEI-12 | May 2011–Jun 2012 | − 22.2 | − 1.59 | − 1.84 | ||
Gibe Farm | SPI-4 | Dec 1999–Dec 2000 | − 17.6 | − 1.35 | − 2.98 | |
SPI-12 | Jul 2002–Feb 2005 | − 45.53 | − 1.42 | − 3.41 | ||
SPEI-4 | Dec1999–Dec 2000 | − 16.05 | − 1.23 | − 2.17 | ||
SPEI-12 | Jul 2000–Apr 2005 | − 40.31 | − 1.19 | − 2.23 | ||
Wolkite | SPI-4 | Feb 2000–Nov 2000 | − 13.25 | − 1.2 | − 3.38 | |
SPI-12 | Sep 1999–May 2001 | − 31.93 | − 1.52 | − 2.74 | ||
SPEI-4 | Mar 1999–Dec 2000 | − 13.25 | − 1.2 | − 3.58 | ||
SPEI-12 | Sep 1999–May 2005 | − 76.24 | − 1.10 | − 1.95 |