Sand mining and agricultural activities have contributed significantly to the amount of sediment in the Nzhelele River. The link linking the development of sinkholes with various land use activities determines the amount of sediment load.
INTRODUCTION
- Background to the study
- Statement of the problem
- Research aim and objectives
- Research Aim
- Research Objectives
- Research Questions
- Delimitation of the study and description of the study area
- Delimitation of the study
- Description of the study area
- Definition of key terms
- Structure of the Dissertation
This will improve understanding of the nature of land use and ditch development in South Africa. It will explain how land use has influenced and caused gully development and sediment loading in the Nzhelele River Valley.
LITERATURE REVIEW
- Introduction
- Land use and land use change
- Impact of land use on river ecosystem
- Functional aspects of land use
- Past land use and climate changes
- Present land use changes
- Dictating land use and land cover change using GIS
- Land use and land cover dictation
- Soil structure and Sediment load
- Soil composition and geomorphology
- Sediment production
- Human impacts on soil erosion
- Overgrazing trails and footpaths by domestic animals
- Different farming activities
- Road construction
- Gully erosion process
- Development of gullies
- Gully classification
- Contribution of rainfall on gully erosion
- Impact of rainfall intensity on gully development
- Slope and critical drainage area
- Conceptual framework
Land cover is related to the type of features present on the land surface by (Lillesand et al., 2007). Sediment load introduces the concept of the need to quantify the contribution of land use to gully development.
RESEARCH METHODOLOGY
- Introduction
- Research design
- Type of research design
- Sampling method and unit of analysis
- Ethical considerations
- Data collection
- Familiarising with the environment
- Land use change of the Nzhelele valley
- Role of human activities on land degradation
- Relationship between gully development and land use
- Relationship between land use and sediment load
- Data analysis
In order to determine the compactness of the soil, a steel ring with a diameter of 4.4 cm and a depth of 10 cm was used to determine the bulk density. The radius of the soil core was also measured to find the core volume. After obtaining the volume of the samples taken, the researcher weighed the samples with an electronic balance to determine the mass of the soil, which was used to determine the bulk density.
Soil particles in Nzhelele village were also analyzed to determine soil degradation. The soil from each sieve used was weighed to determine the mass from each sieve. The samples were pre-weighed before heating in the oven in order to obtain the initial weight of the soil sample before heating.
Measurements were made of the amount of total suspended sediment (TSS), flow rate and soil load. The DH-48 samples were collected in a vertically integrated manner in the center of the channel. Supervised classification was performed to familiarize the study area with training sites of land use types.
DATA PRESENTATION AND ANALYSIS OF RESULTS
Introduction
Different land use and Spatial pattern changes
- Different land use categories description in Nzhelele Valley
- Change detection for the study period (2007-2012)
The following are the main types of land use found in the Nzhelele Valley and indicate the spatial distribution pattern. Most of the houses located within the study area are far away from the Nzhelele River. Vegetation becomes less dense near residential areas, indicating a sign of high land use activity in the area.
Land for agricultural purposes is very crucial to society and is therefore the second highest land use practice after residential area. However, some of the open areas are mainly used as open playgrounds by local people and church gatherings in some cases. Most of the areas are paved within the business center resulting in high runoff resulting in soil erosion.
For the purpose of the study, the 2007 picture was considered as pre-change land use pattern and the 2012 picture was considered as the picture of changes occurring after a 5-year interval, as shown in Figure 4.2 and Figure 4.3. The Kappa coefficient of supervised classified images, which is 0.87, indicates that the classification method largely captured the land use and land cover dynamics of the area of interest in the Nzhelele River Valley. However, the water body showed the lowest value change (0.3%), with the settlement showing the greatest land use change from 10.3 to 39.8.
Influence of human activities on land degradation
- Bulk density
- Soil particle size
- Soil organic content
- Soil pH
- Land use activities and land degradation
Organic matter contributes to productivity through its effect on physical, chemical and biological properties of the soil. Different land use activities increase or decrease the levels of organic matter in soil over time. Properties such as soil structure and moisture holding capacity are highly influenced by organic matter which affects the susceptibility of soil erosion (Wenming et al., 2014).
From the analysis made within the land use zone on the banks of Nzhelele, an average of 2.3% of organic matter is indicated, indicating a relatively low amount of organic matter in the soil. The two sites also have the least amount of organic matter, showing that the areas are highly susceptible to erosion and gully development. This shows a lower percentage of organic matter due to a different type of land use within the area.
In general, the entire area has a low percentage of organic matter, which could be attributed to the different types of land use over time, which resulted in higher rates of soil erosion and the development of sinkholes. Statistical analysis was done using Pearson's correlation coefficient between organic matter and calculated soil moisture content. Site 1, 2, and 3 have more organic matter than soil moisture content, while site 4 and 5 have more soil moisture than organic matter content.
Gully development in different land use
- Surveying of gully development in the Nzhelele riparian zone
- Internal structure of gully
- Spatial distribution of gully development
- Land use and gully development
The trench is located in the agricultural area in the riparian zone of the Nzhelele river valley. The vertical plane of the trench shown in figure 4.1.0 is 4.7 meters deep and is stratigraphically grouped into 5 horizons with reference to the soil profile. From the lower lower horizon "C", the soil is categorized as dark brown homogeneous loamy loam.
Gully erosion distributions are reconstructed by analyzing aerial photographs of the Nzhelele River valley taken in 2012. In addition, Figure 4.1.2 shows local communities which include Matanda, Ha-Raliphaswa, Dzanani, Ha-Mandiwana and Ha-Mphaila. From the analysis made using descriptive statistics, the agricultural area has the highest gully development area, which is higher than in any other land use activity with an average gully depth of 1.06 meters.
The area has a sample variance of ±0.13 with the highest gully depth at 1.8 meters and the minimum depth at 0.4 meters. Grazing and agricultural land is the second highest gully development area with an average depth of 1.9 meters. The lowest minimum gully depth of 0.3 meters was observed within the built-up area as illustrated in Figure 4.1.4.
Relationship between land use and sediment load
- Total suspended sediment and bed load
- Six event data totals
- Land use analyses
The highest total suspended sediments (TSS) is recorded in November of 6.13 g in the agricultural area. The sediments are generally higher within the agricultural area than any other area with a total of 4.3 g of total sediments collected. The agricultural area had the highest amount of bed load of 1.24 g than any other area.
From the results obtained, high total suspended sediments were measured along the agricultural area with an average of 3.60 g. However, there is an average small difference between the bridge site and the forest site of 0.11 g. Overall, bottom loading is generally higher along the agricultural area with a mean value of 0.71 g, which correlates the suspended sediments due to presumably some surrounding activities and the gradient of the slope.
The bed load of the forest area was significantly reduced compared to suspended sediments with a mean value of 0.12 g (Figure 4.1.9). Inside the bridge, compared to the forest area, there is a smaller increase in bed load with an average value of 0.15 g. However, the bed load concentration is much higher in the agricultural areas compared to the bridge with a difference of 3.41 g.
DISCUSSION OF THE FINDINGS
- Introduction
- Spatial variations in land use and land cover
- Control of human exploitation on land use
- Gully development and aspects affecting their development
- Perpendicular expression of gully depth
- Land use and sediment load
This is supported by Gumiere et al., (2009) in which he said that clay soil has a high erodibility. Similar results were found by Heng et al. 2011), which suggest that in different soil textures a high proportion of fine particles dominate runoff. Some researchers have demonstrated that excessive tillage and fertilization can seriously degrade soil structure (Elliot, 1986 and Zhang et al., 2007).
Mingxiang et al. (2015) added that infertile soils are highly susceptible to soil erosion leading to development. In addition, Ahearn et al. (2004) states that rainfall is not a sufficient factor to effectively leach nutrients from the soil in long fields. It is known that the formation of erosion on beaches is one of the negative consequences of sand mining on beaches (Mensah 1997 and Esteves et al., 2002).
This is consistent with observations made by Moreno et al., (2014) that intense human deforestation is likely the main driver of the development of the Ribagorda Gully, aided by grazing and agriculture. This is supported by Dohler et al., 2015 who alluded to the fact that a thin "A" horizon (<5 cm) is developed in uplift anthropogenic sediments. Heathwaite et al., (1990) suggested that heavily grazed lands resulted in high production of suspended sediment during the rainy season.
CONCLUSION AND RECOMANDATIONS
Introduction
Conclusion
- Change in land use and land cover
- Land degradation associated with human activities
- Sources of gully development
- Land use and river sediment load
This is mainly affected by various human activities such as building houses and building roads. The different sizes of soil particles range from fine soils to sandy soils that are highly related to different land use activities. However, the size of soil particles may not indicate how human activities have affected their size.
The low content of organic matter in agricultural areas is mainly influenced by the continuation of farming without replacing the manure. Soil moisture content is related to organic matter among different locations, with locations 4 and 5 having the highest soil moisture content. This illustrates the impact of human activity on land use, which can cause soil degradation and hill and inter-hill erosion.
The spatial distribution and extent of channel development in the investigated riparian zone of Nzhelele indicate that intensive channel development has taken place more in high land use area. However, it is unclear how much land has degraded to the point that human activities became problematic. In the Nzhelele Valley, it is clear that today's human activities and possible future land use trajectories are strongly linked to past land use challenges and soil erosion.
Recommendation
- Responsiveness on best agricultural practices
- Essential conservational consciousness
- Management of riparian zones
- Vegetation of degraded environment
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Relationship between land use and soil erosion on communal land near Peddie, Eastern Cape, South Africa. Soil erosion in gully basins affected by land leveling measures in the Souss Basin, Morocco analyzed bt rainfall simulation and UAV remote sensing data. Effect of type of vegetative cover on runoff and soil erosion in different land uses.
Soil erosion in gully watersheds influenced by land leveling measures in the Souss basin, Morocco, analyzed by rain simulation and UAV remote sensing data. Assessment of erosion and soil erosion processes - a case study from the Northern Ethiopian Highlands. Measurement of runoff and soil erosion in three areas with different land use in Sardinia (Italy).
