PhD (Environmental Sciences) / Department of Hydrology and Water Resources / Luvuvhu River Catchment (LRC) exhibits diverse land use and land cover patterns that are
influenced by seasonality and socio-cultural practices of the local communities. From 1950, the
catchment has been undergoing land cover changes caused by expanding villages, new urban
centres and clearing forest land for agriculture. Conversion of natural landscape for agricultural
and urban purposes degraded the catchment by negatively affecting the hydrologic processes.
This study was therefore conducted to evaluate the impact of land cover and land use change on
the hydrology and water resources of LRC. Geographical Information Systems (GIS) and remote
sensing techniques were applied to evaluate the impact of the changes on the catchment.
Remotely sensed imagery was used as the primary sources of data for classification and detection
of changes. Digital Elevation Models (DEMs) were used for hydrologic and geomorphic
modeling in combination with information from remotely sensed imagery. Field data sets for soil
and meteorology were obtained from selected sampling segments, based on the area frame
sampling. The method of direct expansion was used to quantify land use classes. Flood
frequency was analysed using probability distribution methods at recurrence intervals of 2, 5, 10,
20, 25, 50, 100, and 200 years. The FAO CROPWAT software based on Penman-Montheith
equation was used to assess the impact of land cover changes on evapotranspiration regimes. To
study the hydrological response of land cover change in the catchment, the Soil Conservation
Services-Curve Number (SCS-CN) method was first used independently to simulate surface
runoff and investigate the impact of land use change on runoff under historical land cover
regimes. The Soil and Water Assessment Tool (SWAT) model was then applied in the
Tshakhuma-Levubu subcatchment to assess the impact of land management practices on the soil
and water bodies in the catchment.
The results indicated that changes were having negative impacts on the hydrology of the
catchment. The impact of land use and land cover change on hydrology of LRC was manifested
in stream flow, surface runoff, suspended sediment and flood frequency and magnitudes. There
was significant land cover and land use change from forestland, woodland and open grassland to
medium size farms, subsistence agriculture and built-up land. These developments were
concentrated on hillsides and hilltops in the catchment and they were of concern as they were
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impacting on the hydrological processes. Throughout the 2000’s, land use change revealed a
decrease in natural forest from 32.15% to 20.67%, giving rise to agriculture which rose to
38.57% in 2010. Runoff was observed to be highly variable during the month of February with
maximum runoff records of 1.63 m3 and 3.84 m3 upstream and downstream, respectively. Flood
frequency results showed that an increase in the peak discharges was to be expected, especially
for the discharge range corresponding to smaller and medium flood magnitudes. The use of
imagery and DEMs within GIS was found to efficiently represent ground surface and allow
automated extraction of features, thus bringing advantages in terms of processing efficiency, cost
effectiveness, and accuracy assessments. This technique could therefore be adopted to improve
land use planning, water management, and rapid identification of slopes and elevations in
consideration for their functional and structural requirements. Analysis showed that the SWAT
model was suitable for predicting the location and extent of pollution in the catchment. It
assumed sheet and rill erosion as the dominant erosion type contributing to siltation and water
pollution in rivers. The study recommends close monitoring and sustained enforcement of the
rural land use regulations to prevent the conversion of land to urban land use. / NRF
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:univen/oai:univendspace.univen.ac.za:11602/1215 |
| Date | 21 September 2018 |
| Creators | Singo, Lutendo Rhinah |
| Contributors | Kundu, Peter Musula, Odiyo, John Ogony |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 1 online resource (xiv, 326 leaves : color illustrations, color maps |
| Rights | University of Venda |
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