Morphological and Socio-Economic Effects of Sand Mining on River Tyaa in Kitui County, Kenya
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Date
2020-10
Authors
Muiruri, Philip Gathogo
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Current global rate of sand mining in river channels is unsustainable, and in Kenya the activity
going on unregulated. This study established the morphological and socio-economic effects of
sand mining in river Tyaa by addressing the following objectives: To determine the: extent of
sand mining; morphological factors influencing abundance of sand; effects of sand mining on
the morphology of River Tyaa and Socio-Economic effects of sand mining in river Tyaa.
Random sampling technique came up with an active sand mining site. Systematic sampling
was used on this section to select the areas to collect data. Stratified sampling was used to
select respondents using the records from M.S.M.C.S. This sample size comprised of 100
households, 50 sand miners and 5 land owners. Data on channel depth, width, vegetation
cover, erosion status, sand volume status, channel slope angles, and bank position were
obtained through physical measurements in the field while data on sand quantity mined per
year for a decade was obtained from secondary sources. Structured questionnaires were used
to obtain socio-economic data. ArcMap GIS was used to map the spatial extent of sand mining
along river Tyaa. Descriptive statistics was used to analyse the quantitative data and the results
presented in graphs and percentages. The binary logistic regression analysis was employed to
show factors influencing abundance of sand in river Tyaa’s channel. The multiple logistic
regression analysis was used to examine the effect of sand mining to the river Tyaa channel
morphology. Finally, chi-square test was used to test the hypotheses. Chi-Square test indicated
that there were significant sand mining activities in river Tyaa (Df = 1, χ2= 9, P=0.003). The
study established that river channel width (P=6.47e-05), depth (P=7.00e-07), slope angles
(P=3.36e-06) and bank position (P=2.2e-16) were significant in influencing sand abundance in
the river channel as indicated by the respective marginal effects and p-values. Additionally,
sand mining had modified the river channel morphology through causing increase in depth
(P=7.19e-02), width (P=9.95e-03) and slope angles (P=9.37e-03) at the active mining sites,
compared with the control sites as shown by the respective p-values. Finally, sand mining had
caused positive economic effects (Df = 3, χ2= 201.65, P=0.000) such as reduced school dropout rates, infrastructural developments, enhanced livelihoods as well as affordability of
medication. On the other hand, sand mining got associated with destruction of the riparian
vegetation, lowering of water table in the sand reserves, prostitution, community conflicts and
drug and substance abuse (Df = 3, χ2= 42.33, P =0.000). The study concluded that sand
mining had over stretched on temporal, spatial and quantity basis; that sand abundance in a
river channel is a factor of channel width, depth slope angles and the type of the bank. Further,
the study concluded that sand mining had caused increased river channel depth, width and
slope angle and that sand mining had caused significant Socio-Economic effects. The study
recommended reduction in quantities of sand mined from river Tyaa through curbing illegal
mining and closure of some mines; siting of mines on convex banks by regulatory authorities
such as NEMA; Regular EIA as well as EA was recommended as a way of monitoring the
activity. Lastly, the study recommended placement of an elaborate revenue collection system
from sand mining industry by the county government to help give back to the community, and
increasing involvement of the local area members in the sand mining industry to help resolve
resultant conflicts.
Description
A Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Arts in Geography (Geomorphology) in the School of Humanities and Social Sciences of Kenyatta University. October, 2020
Keywords
Morphological, Socio-Economic Effects, Sand Mining, River Tyaa, Kitui County, Kenya