Abstract:
Karamoja region is situated in north-eastern Uganda. Over 80% of the population in
this region is moderately food insecure, and this has oftenly prompted relief agencies
to engage in humantarian relief especially food aids for atleast the last three decades.
The main objective of this study was to apply geospatial techniques in determining
supplemental irrigation requirements for Maize and Sorghum production in this
region. To achieve this goal, a land suitability analysis employing the use of spatial
Multi-Criteria Evaluation (SMCE) tool in Integrated Land and Water Information
System (ILWIS) was carried out. This involved the development of relevant
geospatial datasets for the study area. The generated datasets were structured,
standardized and weighted in ILWIS, from which the respective suitability maps for
Maize and Sorghum production were calculated. The SMCE results showed 85.3%
and 45.4% of the area in the region as being at least moderately suitable for Maize
and Sorghum production, respectively. An irrigation suitability analysis was then
conducted by initially establishing the average decadal effective rainfall maps for
each of the designed three (3) seasons across the set scenarios i.e. wet, normal and dry
scenarios. Average decadal net irrigation requirement (NIR) maps, as a deficit of the
respective calculated average decadal crop water requirements and the effective
rainfall maps earlier developed, were then determined and classified using set NIR
ranges and logical-IFF condition commands in ILWIS. Finally cropping and irrigation
alternatives to guide effective land utilization were determined following an
inferential approach in which statistic information summarizing specific acreages and
percentages at varying suitability index for each crop across all scenarios was
collated. It was observed for Season-1 (running from March to June) that significant
areas are highly suitable for both crops particularly in the wet year scenario. This is
majorly attributed to the relatively higher effective rainfalls in the region around this
time of the year, thus eliminating the need for irrigation. Season-2 (running from July
to October) showed significant areas falling in the marginally suitable class. The
region was particularly observed to have up to 57% of the area marginally suitable for
Sorghum production in the dry year scenario. The increase in marginal suitability is
majorly attributed to the relatively high NIR during this season. Season-3 which runs
from November to February coincides with the driest spell in this region with average
decadal rainfall ranging from 0-26 mm as compared to the 10-54 mm in Season-1.
This statistic calls for relatively more irrigation water supply across all three scenarios
of Season-3 in order to guarantee effective crop production. The results of this study
show the extent of supplemental irrigation required to sustain effective crop
production in the various areas of Karamoja region. The study recommends that a
more detailed soil water balance analysis, at a relatively higher spatial resolution be
conducted in the future in order to ascertain the specific contribution of other ambient
factors to supplemental irrigation estimation within the study area.