Assessment of vulnerability of water resources to climate variability in Mara river basin, Kenya
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Date
2014-09-09
Authors
Waithaka, Reuel Kamau
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Abstract
Africa's water resources are at risk due to climate variability further aggravating the
water scarcity and also ability to cope with other external pressures and calamities.
Climate variability on intra-seasonal and decadal time scales has had significant
impact on water resources. The main objective of the study is to assess the
vulnerability of water resources to climate variability in Mara River Basin. To
achieve this, study analysed rainfall, river flow and satellite imagery data. The
rainfall data spanned from1980 to 2011 and satellite imagery from the years 1985-
2010. The study relied on secondary data (rainfall, temperature, river gauges
measurements and satellite imagery) various empirical tools such as key informant
interviews and field observation guides. Numerical tools for data analysis comprised
descriptive statistics and non-parametric test. Satellite imagery were ana lysed by use
ILWIS and Arc GIS software's and climatic data analysed through Microsoft excel.
The study results showed great inter annual variability of rainfall and corresponding
river flow. Temperature data trend line analysis showed an annual increase of 0.2oC.
Rainfall showed an increase of 0.02mm/yr at Narok station while Ilkerin weather
station showed a decreasing trend of 0.002mm/yr. The rainfall showed uneven
distribution both in spatial and temporal scales with cyclic nature of high intensity
followed by drought periods. The inter-annual variability in rainfall is more sporadic
and unpredictable, and this affects water supply both to the ecosystem, domestic and
agricultural use. The study predicts that this will have detrimental effect on the basin
water resources at a local level and regional. Vegetation cover type and trend over
time was utili sed as an indicator of water resources vulnerability. The analysis of
NDVI, NDWI and LULC thematic maps from 1985-2010 provided compelling
analysis of vegetation density and distribution in the basin. Forest/shrubland reduced
by 38% while cropland/shrubland increased by 28% and surface water aerial
coverage reduced by 10.7% within the same period. There is direct relationship
between vegetation cover change and reduction of aerial coverage of surface water.
Majority of the respondents interviewed were farmers (24.4%) planting mainly maize
and pastoralists (45.5%). Drought and crop failure were the many effects of climate
variability. The respondents (45.2%) experienced more than 5months of food
deficiency. Majority associated the insufficiency to climate variability. Distance
travelled to access water averaged 2-5km,while most of the water resources were
seasonal (56.7%), apart from distance other challenges affecting water accessibility
include ,dirty water and conflicts with neighbours. To overcome these challenges
there is need to develop basin management strategies geared towards increased forest
conservation. The need for education and awareness creation on crop diversification
and investment in both household and community water harvesting strategies. There
is need for integrated waters resources management especially on education on
efficient water use mechanisms both for domestic and agriculture.
Description
Department of Environmental Planning and Management, 137p. 2014