An Assessment of Environmental Impacts of Sand and Gravel Mining In Nzhelele Valley, Limpopo Province, South Africa

Edmore Kori and Humphrey Mathada

Department of Geography and Geo-Information Sciences, University of Venda, Private Pag X5050, Limpopo Province, South Africa

Abstract. Sand and gravel mining refers to the actual process of removal of sand or gravel from a place of occurrence. The increase in demand for sand and gravel for construction purposes has placed immense pressure on the environment where these resources occur. Miners employ different methods of extraction along river channels and their flood plains. Using environmental impact assessment guidelines, a host of environmental aspects were identified along Nzhelele valley, Limpopo Province of South Africa. These aspects include collapsing river banks, habitat destruction, land use changes and floodplain ponding. These aspects have a significant impact on environmental functionality of the valley. It is therefore, concluded that there is need for more environmental regulations and guidelines to be developed and implemented.

Keywords: Assessment, Impacts, Gravel mining, Sand mining, Environment.

1. Introduction Sand and gravel mining refers to the actual process of removal of sand or gravel from a place of

their occurrence (Langer, 2003). The places of sand and gravel occurrence are oceans, rivers, streams, flood plains or hills and mountains. The increase in demand for sand and gravel for construction purposes has placed immense pressure on sand and gravel resources. Sand and gravel mining is a direct and obvious cause of environmental degradation (Kondolf, et al., 2008). The demand for gravel is rising because its importance and role in construction is indispensible. Therefore, the extraction of the two important construction aggregates is bound to have considerable ramifications on the environs of their occurrence.

Rivers and their floodplains are an economical source of sand and gravel. These aggregates are required for a variety of purposes, including making concrete, backfill for houses footings, and maintenance of roads and landscaping. Although these aggregates are of paramount importance, previous studies (Kondolf, 1998; Langer, 2003; Kondolf et al., 2008) show that in-stream mining of these aggregates can reduce water quality as well as degrade the channel bed and banks. The mining of these aggregates on the floodplain can affect the water table and alter the land-use (Langer, 2003).

Rivers flood and shift their courses from time to time, resulting in natural cycles of erosion and deposition of sand and gravel. The river and its banks are home to many fauna and flora species. In this era of rapid land development, however, people have turned to rivers and floodplains as major sources of sand and gravel for construction. Sand and gravel occurs in a variety of natural settings and are common materials used in the construction industries worldwide. The extraction of sand and gravel from rivers and streams, floodplains and channels conflict with the functionality of riverine ecosystems. Some of the disturbance is from the mining methods and machineries used. The most common environmental impact is the alteration of land use, most likely from underdeveloped or natural land to excavations in the ground (Langer, 2003). Social pressures like population growth can cause the environmental impacts of sand and gravel mining.

2012 3rd International Conference on Biology, Environment and Chemistry IPCBEE vol.46 (2012) © (2012) IACSIT Press, Singapore

DOI: 10.7763/IPCBEE. 2012. V46. 29

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The purpose of this paper is to identify and assess the environmental impacts of sand and gravel mining along Nzhelele valley of South Africa. Therefore, following this introduction is an outline of the research methods and the results and discussion. The paper closes with some concluding remarks.

2. Methods This paper follows a qualitative approach in assessing the environmental impacts of sand and

gravel mining in Nzhelele valley. A Global Position System (GPS) was used to capture coordinates for the location of villages along the valley as well as the location of the mining activities. Photographic impressions were of significant importance to this research. Therefore a camera was widely used to capture the environmental aspects identified in the field.

Environmental aspects were identified following the 2000 Environmental Impact Assessment Guidelines for Sand and Gravel mining from the Environmental Conservation Department of Malaysia. The guidelines identify aspects according to their size, complexity and sensitivity. Using these methods, the following are the results of the reserch.

3. Results and Discussion

3.1. Mining Activities and Their Environs Global position points superimposed on a Nzhelele map reveal that 22 villages are within the

environs of the sand and gravel mining activities along the valley (Figure 1). The mining activities are , however, not evenly distribited along the valley and among the villages. To the west and south-west gravel mining dominates. The mining affects five villages which are located between the mining sites and the river. The situation is different on the east.

The eastern parts of the valley are dominated by instream and flood plain sand mining. This is probably because there is less water in the channel in the east as this is the source of the river. In addition, the gradient is gentler on the nothern tributary than the southern one which is characterised by gorges. That make the southern tributary difficult and expensive to exploit. The activities, therefore, affect the rural villagers who rely on the river for water supplies.

3.2. Environmental Impacts During field observation various environmental impacts such as floodplain degradation, habitat

destruction,riparian zone damage, dust, noise, collapsing riverbanks and sedimentation were observed. The following is an overview of the environmental impacts. They do not follow any given order.

3.3. Habitat and Aesthetic Beauty Degradation The extraction of gravel from upland areas involves the clearing of vegetation to expose the

material. This degrades the habitat of many organisms and the aesthetic beauty of the natural environment. Figure 2 shows a landscape scar which resulted from the clearing of vegetation to expose gravel.

Massive clearing of vegetation to expose gravel was observed at Sendedza village. Vegetation clearance from the hill precedes the mining of gravel.This has led to loss of valuable habitat and aesthetic beauty. The mining in the area may result in destabilisation of the hill slope and increased soil erosion as there is no vegetation to bind the soil particles together.

3.4. Land Use Change Sand and gravel mining activities disrupt the ecological functions of natural ecosystems in

various ways such as alteration of food chains. This study complements Langer (2003) who observed that extraction activities change the land use of an area. This reduces the land’s ecological and economic value. Figure 2 shows a hitherto arable piece of land that has turned into a wetland.

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3.7. Riparian Zone Degradation During field observation stockpiles were observed on the riverbanks and these overburden the

banks and alter the channel hydraulics during high flows. The stockpiles increase local erosion thereby increasing sedimentation in the channel. Overburdening of the riverbanks can cause the banks to collapse as a result of the added weight. The dynamic interaction between water, sediment and aquatic–terrestrial landforms creates and maintains riparian areas and controls their characteristic functional processes and biodiversity patterns.

Riparian zone degradation is caused by the need to create space for stockpiles and haul roads. Creation of haul roads results in the formation of bare tracks compacted by vehicle wheels. Figure 4 (right) shows a haul road entering the Nzhelele River at Dopeni village. When it rains water follows these tracks in concentrated flow causing erosion. The eroded material increases sedimentation, turbidity and deposition of pollutants in the river.

Sand mining imposes pressure on the biological communities thriving in the river environments. The riparian zone acts as resting and nesting ground for many migratory birds and the destruction of this valuable area affects those migratory birds (Sreebha, 2010). Local channel changes propagate upstream or downstream and can trigger lateral changes of the stream as well as the riparian zone. Alteration of the riparian zone affects the physical and biological functioning of the stream (Packer et al, 2005).

4. Concluding Remarks The demand for sand and gravel for construction is growing every day. This demand has

resulted in the increased pressure on the natural environment where these resources occur. This paper has shown that there is significant environmental degradation in Nzhelele valley as a result of unregulated sand and gravel mining. The balance of nature is disturbed and this has a multiplier effect on the ecosystem. Sand and gravel mining is largely unregulated by any legislation in South Africa. Therefore it is recommended that the government develops and implements policies and regulations designed to protect the environment around sand and gravel mining areas.

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associated potential environmental impacts, and methods to control potential impacts,” USGS Open-File Report OF-02-153.

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[3] Kondolf, G.M. 1997. Hungry water: effects of dams and gravel mining on river channels.Environmental Management 21: 533–551.

[4] Kondolf,G.M, Williams, J.G, Horner, T.C. & Milan, D.2008. “Assessing physical quality of spawning habitat”. American fisheries society symposium 65:000-000

[5] Steiger.J, E. Tabacchi, S., Dufour, D. &Corenblit, J.L. P., 2005. “Hydrogeomorphic processes affecting riparian habitat within alluvial channel–floodplain river systems: a review for the temperate zone”. River Res. Applic. 21: 719–737

[6] Packer ,D.B., K. Griffin & K.E. Mc Glynn. 2005. “A review of the effects of in- and near-stream gravel extraction on anadromous fishes and their habitats, with recommendations for avoidance, minimization and mitigation,” NMFS-F/SPO-70

[7] Michael R. Meador & April 0.Layher, 1998.“Instream Sand and Gravel Mining: Environmental Issues and Regulatory Process in the United States“ Fisheriesvol 23.no 11

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