An Evaluation of Sand and Gravel Extraction in Nzhelele River Valley, Limpopo Province of South Africa
Humphrey Mathada and Edmore Kori
Department of Geography and Geo-Information Sciences, University of Venda, Private bag X5050 Thohoyandou, 0950, Limpopo Province, South Africa
Abstract. The demand for construction sand and gravel is increasing in many parts of the world due to rapid economic development and consequent growth of building activities. This has resulted in increasedextraction of sand and gravel from in-stream and floodplain areas leading to serious ramifications on river basin environments. The lack of adequate information on the environmental impacts of sand and gravel extraction is a major challenge to regulatory effort in many developing countries. This study highlights the environmental impacts of sand and gravel extraction from the in-stream and floodplain areas of Nzhelele River Valley, Limpopo Province of South Africa. Field surveys and interviews were conducted to collect data. Data collection focused on identification of environmental aspects and their magnitude.The impacts identified included collapsing riverbanks dust and noise resulting from the operations. Using an aspect significance-measuring matrix,dust and noise pollution were found to be the environmental aspects with the highest magnitude of impacts. Itis suggested that formalised and enforceable regulations be formulated and implemented for the overall improvement of mining of sand and gravel from the uplands, rivers and their floodplains.
Keywords: Evaluation, Gravel extraction, Environmental impacts, Environmental aspects.
1. Introduction Sand and gravel are very important raw materials in the construction industry. The demand for
these materials is increasing more rapidly because sand and gravel form part of every construction infrastructure (Martin-vide, Ferrer-Boix&Ollero, 2010). The extraction of sand and gravel is causing a variety of impacts on the biophysical environment. Disproportionate in-stream sand and gravel mining degrades rivers and lowers the stream bedsresulting in riverbank erosion (Kondolf,Smeltzer& Kimball, 2002). The mining of these aggregates (sand and gravel) on the flood plains, called dry-pit mining,causes a variety of impacts on vegetation and the soil structure. The excavated pits on the floodplains affect the water table (Kondolf, 1997) and are mostly a threat to the surrounding communities as the miners usually leave without rehabilitating them.
The objectives of this paperare to identify and evaluate the magnitude of the impacts of sand and gravel mining and to suggest measures of reducing their impacts on the environment. Following this introduction is an outline of the methods used in the study followed by results and discussion. The paper closes with some conclusions and recommendations.
2. Methods
2.1. Data Collection The study employed a quantitative method of measurement and evaluation.Primary data was
obtained through key informant interviews as well as field observations.The key informants were the sand and gravel miners. A camera was useful during field observation to capture pictures to supplement the interview data. Six operational sand and gravel mining sites and eight abandoned siteswere visited to document the various environmental impacts arising from the activities.
2012 3rd International Conference on Biology, Environment and Chemistry IPCBEE vol.46 (2012) © (2012) IACSIT Press, Singapore
DOI: 10.7763/IPCBEE. 2012. V46. 28
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The change in land use occurs at the project site and proves to be permanent and is irreversible as the miners do not rehabilitate the area after mining. The sites tend to be of no value after mining and this permanently changes the type of landuse. The change in landuse is cumulative in nature and affects both the environmental and socio-economic character of the area. After mining has ceased, the former mining sitesare mostly transformed to wetlands if the excavated pits capture water.In some instances theythe pits become death trapsto children and animals.
Habitat degradation occurs within the project site and is permanent and irreversible. The impact is cumulative as it affects the local food chain and local ecosystems. For an example, Species A which feeds on species B will be affected if the habitat of species A is disturbed and species A population disappears. This leaves species B with no source of food. The cumulative effects continue like that.
Erosion is the dominant impact in both the in-stream and floodplain mining sites. It affects the natural environment at a local scale and its effects are irreversible and permanent. The eroded area loses its natural character and takes a new form after erosion. The impacts are cumulative in nature and affects biological, chemical and physical structure of both the river and the floodplain.
The mining activities affect the stability of the land at a local scale. The collapsing of riverbanks affect the Nzhelele River at a local scale as the sedimentation and increased turbidity will affect the river downstream of the mining site. This instability is permanent and irreversible causing cumulative impacts in the aquatic and terrestrial ecosystem as the terrestrial species rely on the river for survival. The instability is also occurring even on the floodplain sites.
The activities have a negative impact on both surface and ground water. The ground water is affected as a result of polluted excavated pits on the floodplains. The surface water is affected due to soil erosion and pollutants from water sources. This is triggered by compaction of soil by trucks. Soil compaction reduces infiltration and increases surface runoff which then erodes surface pollutants into the surface water source as the vegetation to filter pollutants is cleared for mining purposes. This is occurs at a local scale and is mostly permanent and causes some cumulative impacts to the natural environment.
Sand and gravel mining is degrading the value of the land at a regional scale.After thecessation of mining the area is left to be waste land. The degradation is permanent and irreversible, even though some restoration measures can be applied. This degradation causes some cumulative impacts to the surrounding natural environment.
Overall, sand and gravel mining cause significant environmental sustainability challenges. This study has found that sand and gravel mining causes 84.1% environmental degradation. As such the following are the concluding remarks to this paper.
4. Concluding remarks Sand and gravel mining activities have been on the rise in the past decade due to increased
construction activities. The demand for the two aggregates has put enormous pressure on environmental resources where they occur. Important to note is that sand predominantly occurs in river systems. River systems are sensitive and would react to the slightest alteration of their cycles. As such sand and gravel mining activities taking place along Nzhelele valley have significantly negative impacts on the environment. Making the activities a serious environmental threat is the lack of institutional and legal monitoring and regulation framework for the activities. It is therefore recommended that proper guidelines be developed and implemented to reduce the environmental degeneration.
5. References [1] Environmental Conservation Department, Malaysia, 2000. Environmental Impact Assessment (EIA) Guidelines
for River Sand, gravel and Stone Mining
[2] Kondolf, G.M. 1997. Hungry water: effects of dams and gravel mining on river channels.Environmental 135
Management 21: 533–551.
[3] Kondolf, G.M., M. Smeltzer, and L. Kimball. 2002. “Freshwater gravel mining anddredging issues”. Washington Departments of Fish and Wildlife, Ecology, and Transportation
[4] Martín-Vide J.P.. Ferrer-BoixC,. OlleroA ,.2010. Incision due to gravel mining: Modeling a case study from the Gállego River, Spain
[5] Neuman, W.L., 2006. Social research method: qualitative and quantitative approaches.Sixth Edition. USA, Boston: Pearson
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