Author:
Bernard Nuoleyeng Baatuuwie
Year:
2017
Doctoral or master thesis:
Doctoral thesis
University:
KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY
Supervisor:
Dr. Quang B. Le; Dr. Wilson A. Agyare; & Prof. Eric K. Forkuo
Website:
Excerpt text:
Abstract
The White Volta Basin (WVB) is
located within the Savanna Ecological Zone shared by Ghana, Burkina Faso
and Togo. It is of national importance to the development of these
countries through agriculture, urban water and hydro-electric supply,
transportation, tourism and others. Despite its benefits and potentials,
it is currently under threat due to land degradation (LD) driven by
both anthropogenic and natural forces. A multidimensional approach was
employed to assess the degradation at two spatial scales (i.e. Basin and
sub-basin scales) and propose mitigation measures. Spatial data from
remote sensing historical land cover (1990-2007); existing GIS database
of soil erosion obtained from RUSLE was integrated to determine LD
hotspots in the area at a basin scale. Sub-basin scale assessment was
also done to complement the basin scale analysis to ensure information
complementarities.
Observable indicator system developed from
literature and expert consultation was used in conjunction with FAO
field protocol for mapping land degradation in the sub-basin.
Additionally, data on socio-ecological determinants of land degradation
and mitigation measures were also gathered through interviews and group
discussions. The results indicated that land degradation is persistently
occurring in the basin and can be effectively mapped using these
indicators. Soil loss through erosion and negative land use/cover
conversion (NLUCC) were common indicators identified and used to map
land degradation at both basin and sub-basin‘s scales. About 82% of the
basin is degraded due to negative land use/cover conversion or soil
erosion. Of this, 33% of the basin‘s area is experiencing severe
degradation. Degradation hotspots were found around areas where
urbanization was on the increase. A cross-scale analysis of the
different indicators at the two scales showed that, there exist matches
and divergences between some indicators. The best indicator matches was
between the net soil loss at the basin scale with that of soil erosion
state at the sub-basin scale (92.6%) and erosion extent (92 %). There
exists a vi great divergence between negative land use/cover conversions
at the basin scale and erosion severity at the sub-basin scale with a
divergent value of 87 %. Poor agricultural soil and rangeland
management, deforestation as well as climate change were perceived to be
the direct drivers of LD in the basin. Increased in human population,
change in demand and consumption for food and fuel wood, poverty and
inadequate labour were the main indirect drivers responsible for the
degradation in the basin.
Identified possible mitigation
measures to combat the degradation in the basin include: controlled bush
burning or no burning, minimum tillage and crop rotation. Others were
stone bunds, organic manures and mineral fertilization. The study
revealed that land degradation is occurring in the basin and can be
mapped using both proxy and observable indicators. Thus, this will
reduce the cost and time involved to assess land degradation at the
sub-basin or field levels using traditional methods.
It is
therefore recommended that the appraisal of land degradation should
embrace these three pillars (multi-scale, multi-indicators and
actor-based) as proposed in this study for effective and accurate
results as well as development of appropriate mitigation interventions.
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