Stream Flow Responses to Land Use/ Land Cover Changes in Kimondi Watershed, Yala River Basin, Nandi County, Kenya
Loading...
Date
2010
Authors
Shikuku, Evans Tsabuko
Murimi, Shadrack
Macharia, Anthony
Journal Title
Journal ISSN
Volume Title
Publisher
www.iiste.org
Abstract
The global terrestrial land surface has been affected by the changing land cover/land
use over years. The continuous changes in land cover/land use have also affected the
water balance of major watershed by changing the magnitude and pattern of the
stream flow of major rivers in Kenya. Land use and land cover changes in Kimondi
watershed has caused serious hydrological changes on Kimondi River thereby
affecting the entire hydrological regime of the whole of Yala Basin. The study was
necessary to evaluate the stream flow responses to land use/land cover changes in the
upstream of Yala River.These findings provides invaluable insights to the Yala
watershed conservationists, the Nandi county and the government of Kenya in
conserving the water resources, monitoring of watershed conservation and ensuring
environmental sustainability. This is will provide effective upstream response
measures in ensuring reduced magnitudes and frequency in surface runoff and
increased groundwater recharge in Kimondi watershed. The extent of land use and
land cover changes in the watershed was examined through analysis and
classification of SPOT images using ENVI 5.3. Descriptive analysis of data collected
from KII and questionnaires was done using SPSS and Ms Excel. The evaluation of
variations and responses in river flow and rainfall was done using linear regression
and correlation methods. Weibull’s method was used in the analysis of extreme
(MaxQ and MinQ) hydrological data as well as determine the return periods. The
Flow Duration Curve examined the historical variability of observed stream flow.
The study revealed that there were major land use and land cover changes in
Kimondi watershed such as uncontrolled human encroachment in King’wal wetland
due to search of land for agriculture and settlement, decrease in natural forests, and
increase in growth of eucalyptus as well as rainfall variability. The study revealed an
increase in agricultural area (4.8%), bare ground (3.97%), settlement (12.46%), planted forest (9.59%) and shrubs (1.66%), and decrease in area under natural forest
(28.94%) and shrinking in size of King’wal Swamp (3.63%). Trend analysis of the
hydrographs revealed, for annual and monthly daily stream flows, as statistically
significant at p-value ≤ 0.05 with monotonic trend. Trends and variations in river
flow indicated periods of low dry season flows and peak wet season flows between
the 1990 and 2015 mainly attributed to both land use/land cover changes and climate
variability. The Flow Duration Curve revealed an 11.3% exceedance for Q25 and 0.74%
exceedance for Q95. Weibull’s analysis showed a 1.8% and 2% return period in 53
years for maximum discharges and minimum discharges respectively.
Description
Article
Keywords
Land use, Land cover, Stream flow, Climate variability, Flow duration curves, Return period, Low flows, Peak flows