GIS  BASED  SURFACE  IRRIGATION  POTENTIAL  ANALYSIS:  A  CASE  STUDY  OF  UPPER  BIRBIR  SUB  BASIN,WESTERN  ETHIOPIA
Creators: name: Fikadu, Ayana
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2015

description: The  study  is  specifically  concerned  with  analysis  of  Upper  Birbir  surface  irrigation  potential 
using  GIS.  The  study  area  is  found  within  rural  communities,  striving  to  overcome  food  self 
insufficiencies  utilizing  natural  resources.  However,  to  date,  there  is  no  appropriate  surface 
irrigation potential data,  for paramount natural treasures  found within the study area  to put over 
practically. For this reason, the writer decided to give away, with application of GIS in line with 
other relevant nearby data.
This thesis, first identify  potential irrigable land and characterize its nature of utility for surface 
irrigation. In a second stage estimate potential surface water resource for irrigation and determine 
crop water requirement for very common crops of the study area. Finally, recommend the storage 
volume  demands  unless  the  available  water  resource  would  meet  the  demand  of  the  potential 
area and crops.
The hydrological, meteorological, Digital elevation model, soil, Land use,  land cover map and 
etc data were gathered from different organization of government  and other  concerned sectors.
First elevation data of the study area were delineated as 90m resolution, then, characteristics of 
flow  direction,  contours  and  radius  of  elevation  noticed.  The  potential  irrigable  land  was 
identified  by  using  slope,  land  use/cover  and  soil  in  arc  GIS  software,  spatial  analysis  tool  to 
analyze their suitability individually, then application of  the weighted overlay tool was provided 
to  condense  overall  suitability  factors  as  specific  outcome,  and  suitability  was  conducted 
implementing FAO criteria for surface irrigation. Analysis of  the  water resource potential of the 
study area was carried out by using hydrological data after filling different gaps observed using 
techniques like  the  average mean method  and distance power method to screen them for further 
application.  Here,  there  was,  flow  duration  curve  developed,  flood  frequency  tested,  low  flow 
analyzed  to  differentiate  between  variability  existed  between  time  series  of  the  records.  The 
reservoir  requirements  of  the  catchment  were  dealt  with  dependable  flow  by  mass  curve 
technique.  Also  crop  water  requirement  of  most  widely  growing  crops  of  the  study  area  viz. 
Potato and Maize were computed from climatic data as an input depending on the preference of 
agro climatic condition of the study area using CROPWAT model, version 8. 
Potential  irrigable  land  was  identified  out  of  the  total  catchment  area  considering  suitability 
outcomes for river catchments and selected crops  agro ecology.  The  Gross irrigation demand of selected  crops for each month is computed for  low flow analysis of 80%, 85%, 90%, 95%, and  a 
100%  exceedence.  The  result  suggests  that  the  irrigation  potential  of  the  area  considering  the
analysis  of  possible  low  flows  and  crop  gross  irrigation  requirement  is  8627.8ha.  The  storage 
requirements  are  700,  105, 35 and 55,55Mm
3
for  Birbir,  Keto,  Iowa, Kuni  and Merdafo  rivers
respectively, so  as to endure  432,776.9ha  total irrigable potential  area.  Generally,  Site specific 
studies with latest technologies will be encouraged to provide more substantial outcomes.