Agricultural Drought in Ethiopia - Monitoring and Predicting Agricultural Drought: A Global Study - page 228

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seeds) has been facing serious shortages due to recurring droughts. People's
purchasing power determines access to food in the market-dependent food
supply system.

D rought Frequency
In Ethiopia, an agricultural drought is assessed using the concept of the
le ngth of growing period (LGP). The growing period is defined as the
pe riod (in days) during a year when rainfall exceeds half the potential
ev apotranspiration (PET), plus a period required to evapotranspire water
fr om excess rainfall stored in the soil profile (FAO, 1978). One-half of the
PE T has been considered sufficient to meet the crop water requirement
(F AO, 1978; Doorenbos and Kassam, 1979). A year with an LGP less
th an 90 days is considered to be a drought year. Because most crops in
Et hiopia, with the exception of some pulses and very low-yield varieties
of tef ( Eragrostis tef ) and wheat, require a growing period of at least 90
da ys (Henricksen and Durkin, 1985). The number of this below-90 day-
L GP-years divided by the total number of years gives the severity level of
dr ought. Based on this ratio, Reddy (1990) classified drought severity as
ra nging from low to very high. There are two rainy seasons in Ethiopia:
be lg (the first rainy season, from February to May) and Kiremt (the second
ra iny season, from June to September), which do not apply equally for the
w hole country.
The results of assessing agricultural drought (figure 17.1) based on the
ab ove explanation indicates that during the first season the frequency of
ag ricultural drought is low (below 15%) for most parts of the Amhara
R egional State, with the exception of eastern and southern parts, west-
er n parts of Oromiya, Benshangul Gumuz; Southern Nations Nationali-
tie s Peoples Region (SNNPR) and, with the exception of parts of South
O mo, Gambella Regional State, the highlands of Sidammo, Arsi, Bale, and
H ararghie. The frequency of drought is between 15 and 40% (moderate)
fo r northern parts of north Gonder, southwestern parts of south Tigrai,
w estern parts of eastern Amhara, most parts of north Shoa, parts of east
Sh oa, parts of east and west Hararghie, northern parts of Bale, northern
an d western parts of Borena, and parts of South Omo. However, drought
is very frequent in most parts of Tigrai, Afar, eastern Oromiya, Somali, and
so uthern Borena. The area with high drought frequency has decreased and
is limited to the eastern parts of Tigrai, most parts of Afar, most parts of So-
mali, southern Borena, and parts of South Omo during the second season.
Most parts of Amhara, western parts of Tigrai, most parts of Oromiya,
and SNNP have a low frequency of drought during the second season, as
shown in figure 17.1. The other parts of the country that experience two
rainy seasons experience medium drought risk (15-40% frequency) during
the second season.

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