Morphologic Response of a River Channel to Sand Mining in River Tyaa, Kitui County, Kenya
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Date
2020
Authors
Muiruri, Philip Gathogo
Obando, Joy A.
Mahiri, Ishmail O.
Journal Title
Journal ISSN
Volume Title
Publisher
BPC
Abstract
Over 40 billion tons of sand is mined worldwide every year which is
estimated to be higher than the natural replacement rates. In Kenya, the
rate of sand mining is raising concerns over its environmental effects since
it is not regulated. This paper presents findings on the geomorphic effects
of sand mining in the ephemeral River Tyaa channel in Kitui County. The
study adopts the concept of feedback response mechanism of a natural
geomorphic system. Through purposive sampling River Tyaa was selected
for the study, where rampant sand mining was reportedly taking place.
Random sampling on the five sand mining sites identified came up with a
representative site namely Kanginga on which systematic sampling was
applied while collecting data at both the active and control sites. Data
on channel width, depth and slope angles was obtained through physical
measurements while data on quantity of sand mined was obtained from
Mwingi Sand Mining Cooperative. Multiple logistic regression analysis
was used to analyse data whereby the model compared active and control
sites. Test results indicated that sand mining had significantly increased
river channel’s width (O.R. =1.531), depth (O.R. =1.527) and slope angles
(O.R. =1.634) at active mining sites compared to control sites as deduced
from the respective Odds Ratios. It concluded that sand mining had altered
channel’s morphology resulting to adverse environmental effects such as
loss of riparian vegetation and channel incision. It recommended curbing
of illegal sand mining through licencing operators and reducing quantity of
sand mined by closing some mines. Furthers, it recommended monitoring
through regular Environmental Impact Assessment (E.I.A) and Audit (E.A)
to inform protection of the river system from degrading.
Description
Article
Keywords
Channel incision, Ephemeral stream, Morphologic response, Sand mining, Sustainable development
Citation
Muiruri, P. G., Obando, J. A., & Mahiri, I. O. (2020). Morphologic response of a river channel to sand mining in river Tyaa, Kitui County, Kenya. Journal of Environmental & Earth Sciences, 2(2).