Abstract:
Rainwater harvesting is the process of intercepting, conveying, and storing rainfall for
future use as an alternative source of water in the drought prone areas of Ethiopia
especially eastern Oromia. The aim of the research was to assess and mapping potential
area of water harvesting site in Daro Labu District. There are various methodologies and
criteria to identify suitable sites and techniques for rainwater harvesting (RWH).
Determining the best method or guidelines for site selection, however, is difficult. GIS is
the recent technology of spatiotemporal data used to assess the factor of influences for
rainfall and runoff depth estimation for identification of potential area of RWH for crop
production and mapping of the potential site. The influence factors for consideration of the
assessment was climate data, soil texture and depth, land use and land cover (LULC) type,
slope difference was used. The SCS–CN for rainfall runoff depth estimation was used to
compute runoff and volume from the land surface depend on the level of antecedent
moisture condition (AMC) and length of wet and dry season of the study area. The total
area of the catchment was about 156064.72 ha with antecedent moisture condition (AMC)
of II, I III by having the values of 82, 67, and 91 respectively. The annual average rainfall
of 20 years was 925.2 mm with maximum and minimum of 1134 mm and 737.3 mm, with
average annual runoff depth estimate of185.3 mm. From the estimated annual runoff the
volume of water harvested was about 289.14 x 106
m
3
. The suitability map of the study
area shows that, extremely potential, highly potential, moderately potential, marginal and
not potential accounts by coverage areas about (12,828.52 ha) 8.22%, (25,220.05 ha)
16.6%, (99,038.67 ha) 63.5%, (11,777.28 ha) 7.54%, and (7120.20) 4.62% respectively.
The runoff in the study area was affected by geomorphological factors, particularly, land
use change, topography, soil texture and depth, slope, and affects the runoff rate and
volume significantly. In order to change the water harvested for crop production and meet
the irrigation requirements of selected crop (tomato, onion, and maize) was 528 mm, 354.3
mm and 558.5 mm respectively was taken. The total cultivated area was about 58.6% and
the area can be irrigated using the volume of water harvested was about 63% of the total
cultivated area for single crop season of the study area. Thus, Rainwater harvesting can be
considered as livelihood income generation and increases with production and
productivity of the communities as well.
