HYDRAULIC PERFORMANCE EVALUATION OF WATER  DISTRBUTION IN GRAVITY IRRIGATION SYSTEM: CASE OF  SIRIMA-DUGDADU MEDIUM SCALE IRRIGATION SCHEME,  OROMIA, ETHIOPIA
Creators: name: GOSA TAYE DEBELA
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2017

description: The  development  of  irrigation  and  agricultural  water  management  holds  significant 
potential  to  improve  productivity  and  reduce  climatic  volatility  in  any  country.  In
Ethiopia  irrigation  development,  has  been  identified  as  an  important  tool  to  inspire
economic  growth  and  rural  development,  and  is  considered  as  a  corner  stone  of  food 
security and poverty reduction. While a lot of effort is being exerted towards irrigation 
development,  little  attempt  was  being  made  toward  the  performance  assessment  of 
already  constructed  irrigation  schemes.  Performance  assessment  is  used  to  identify  the 
present  status  of  the  scheme  with  respect  to  the  selected  indicators  and  will  help  to 
identify ‘why the scheme is performing so’ which in turn imply means of improvement.
This  study  was  conducted  to  evaluate  the  hydraulic  performance  of  off  farm  left  side 
irrigation canal  system of Sirima-Dugdadu Medium Scale irrigation scheme for which no 
such  research  conducted  before.  The  evaluation  includes,  water  conveyance,  water 
distribution,  operation  and  maintenance  of  the  system  using  simple  and  clear  selected 
performance  indicators.  In  order  to  proceed  to  the  evaluation,  weekly  average
measurement  of  discharges  was  collected  for  the  investigation  period  of  September  to 
December 2016. The discharge measurement was performed at  nine  measuring  stations
on branch canal offtake by using SABA universal current meter F1 and three and six inch 
parshal  flumes.  Water  surface  elevation  measurement  was  also  conducted  along  main 
canal  at  fifteen  measuring  location  to  be  used  as  an  input  for  the  calculation  of  water 
surface  elevation  ratio  to  support  for  operation  and  maintenance  activity  for  decision 
makers. 
The selected Hydraulic performance  indicators  for water conveyance and  distribution  are 
adequacy  (PA), efficiency  (PF), dependability  (PD)  and equity  (PE), while the  Operation 
and maintenance based performance evaluation of the system was assessed by parameters
like  water  surface  elevation  ratio  (WSER),  effectiveness  of  infrastructures  (EI)  and
sustainability of irrigated area  (SIA).  After all available data was collected, evaluation of 
hydraulic  performance  assessment  of  Sirima-Dugdadu  left  side  irrigation  canal  was 
performed  by  using  those  selected  simple  and  clear  performance  indicators.  From  the 
evaluation,  the output result was  indicated that the overall  average  adequacy, efficiency, 
dependability  and equity  of the system  were  0.788,  0.801,  0.29 and  0.251  respectively.
This result indicates, the PA, PE and PD of the system have  poor performance, while the 
PF value of the system was fair.  Regarding the operation and  maintenance of the system, 
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the  result  of  the  three  parameters,  WSER,  EI  and  SIA  are  1.01,  0.41  and  0.92 
respectively. This result indicates that, the canal carrying capacity was reduced because of 
siltation  and  scouring,  from  initially  installed  or  constructed  structures  only  41%  are 
functional  and  30ha  of  irrigated  area  was  out  of  production  by  irrigation  from  400ha 
initially irrigated.
Generally,  from  the  evaluation  result  assessed  by  four  selected  hydraulic  performance 
indicators  and three operation and maintenance  parameters,  this study  was  proved  that, 
the  overall  performance  of  Sirima-Dugdadu  left  side  irrigation  system  was  poor.
Therefore,  this  poor performance  was  derived partly  from the management and operation 
and partly  from the physical structures, so all stakeholders must work together in order to 
minimize factors that hinder the good performance of the irrigation system.