Assessment Of Water Demand Pressure On Surface Water Resources In Burguret River Sub-Catchment Using IS SWAT
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Date
2019Author
Muriuki, Samuel Wambugu
Type
ThesisLanguage
enMetadata
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Assessment water availability and use in any catchment is a preliminary key
requirement for policy administrators and leaders to make an appropriate
decision on water allocation. This ensures utilisation of water resources in a
sustainable way thus understanding the quantity of water resources available
over time. The study aimed at establishing water resources demand and availability
at different seasons.
In order to determine water available at different seasons in the Burguret Subcatchment
as well as filling the missing data for river flow data, SWAT model
was applied. Three-year period was applied to calibrate SWAT. Validation was
done in a two-year period pegged on daily flow data. Calibration outcomes
showed that, an acceptable degree among simulated and observed daily flows
with NSE value of 0.63 while RSR was 0.63. The Performance Efficiency (R2)
value for observed vs simulated daily flow data for the basin was 0.74 and 0.7
for the validation and calibration period respectively.
Assessment of abstractions along Burguret River and analysis of the same was
carried out to determine the water demand. To determine total water demand
for irrigation every user/abstractor, a Demand-Based Estimate Method was
used.
The research showed that most of the water abstracted from Burguret subcatchment
was mainly used for irrigation. There has been a huge increase in
VII
water demand over time. Out of 113 abstractions surveyed along Burguret
River, only eight known abstractors have clear permit records. This indicated
the little level of water utilization legality. It was also observed that 88% of
water abstractors in the sub-catchment were small-scale farmers where most of
them used portable pumps.
The abstraction survey conducted during the dry season (normal flow period),
the total abstracted quantity was found to be 20685 m3 per day. The authorized
abstraction during normal flow is 149 m3 per day. This means water utilization
is approximately 15 times the authorized quantities.
With water demand for irrigation water being the highest and is increasing with
time in the catchment, the situation was found to be worsened by inadequate
water resources management as well as rainfall variability. Unwarranted
abstractions of the river especially `during dry seasons have often resulted in
reduced stream flow and highly affect the downstream users.
The research study found that viable use of available surface water resources
combined with better natural flow management is crucial. This can only be
realised with the serious collaboration of farmers in the catchment for both
communities and individual farmers.
The study recommended that a comprehensive water allocation assessment in
the catchment for all users should be carried out. This will manage demand that
will improve water use thus improving returns from it whilst deterring crisis and
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UoN
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Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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