Coast KZN

Estuaries

Sand Mining in KZN Estuaries

Sand is a key habitat in rivers and estuaries, for KZN’s beaches and even the nearshore marine environment. The practice of river and estuary sand mining results in habitat loss and impacts negatively on the delivery of ecosystem goods and services further afield, such as the tourism value of KZN’s beaches.

Sand Mining Introduction


Economically, sand is a valuable commodity, particularly in the construction sector, where it is essential to concrete and other industrial applications. By volume, sand mining is the second largest extraction industry in the world, second only to water. Like water, sand is ecologically active as a key habitat-maker in rivers, estuaries, on beaches and in the sea. In estuaries sand and mud habitats support everything from rooted aquatic plants, to invertebrates that live in/on the estuary bed, to bottom-feeding fish, to the intertidal wading birds that depend on shallow sand- and mudbanks.


The vast amounts of sand washed downstream by rivers accumulates in estuaries and is periodically washed out of the estuary during high river flows or flooding events, not only creating dynamic estuarine habitat, but delivering important sediments and detritus accumulated over months or years into the sea.The sand is then cycled through inshore marine processes to be deposited back onto the shore in the form of beaches and dunes. Extracting sand from rivers and estuaries therefore has profound and far reaching consequences in both space and time.

Understanding historical and current scales of mining is critical to planning and management of activities that impact estuaries. A study is underway (Oceanographic Research Institute) using existing and freely available satellite imagery from GoogleTM Earth to provide basic information about the location and extent of sand mining affecting estuaries between Richards Bay in the north and Port Edward in the south (uMhlathuze Estuary to uMthavuna Estuary).


Using information from past activities and current operations, there is high mining pressure (in terms of the number, frequency and size of mining operations) in the rivers and estuaries of the uMngeni, iLovu and uMzumbe, the uThukela, uThongathi, uMkhomazi, aMahlongwa, uMthwalume, and uMzumbe and uMzimkhulu estuaries and the uMvoti, uMhlali, uMdloti, iZimbokodo, uMphambanyoni, uMuziwezinto, uMzumbe, and iMbizana rivers. These systems should be prioritised for future research and monitoring of the impacts and sustainability of local sand mining.


 

Sand Mining Impacts


In estuaries, the primary impacts of sand mining are:



  • Loss of habitat in the channel and on the banks and floodplain

  • Loss of plants and animals in the mined sand

  • Changes to the shape and size of the estuary

  • Uncontrolled erosion

  • Reduced water clarity

  • Smothering of habitats

  • Lowering of the local water table

  • Undermining and failure of public and private infrastructure

  • Reduced sediment and nutrients to the marine environment

  • Accelerated beach erosion

  • Steep-sided pits and dangerous deep-water areas that are hazards to humans and livestock


These impacts cannot be completely controlled or avoided and can result in significant ecological degradation, even where stringent management measures are applied.


Sand Mining Impacts on Estuaries

Management and Control


Sand mining authorisations are managed by the Department of Mineral Resources and Energy (DMRE) in terms of the Minerals and Petroleum Resourced Development Act No. 28 of 2002, although environmental regulation is managed by the DMRE according to the provisions for environmental impact assessment under the National Environmental Management Act No. 107 of 1998. In addition to mining authorisation, a water use licence from the Department of Water and Sanitation in terms of the National Water Act No. 36 of 1998 is required, and activities may be restricted by municipal land-use zoning. However, sand mining activities often take place unlawfully, and in remote areas that are difficult to monitor, and where there is little to no reporting on operations. As a result, sand mining in South Africa is almost completely unquantified.


A study in 2006/7[1] identified over 60 mining operations affecting 18 of KZN’s estuaries between the uThukela in the north and the uMthavuna in the south. A new study by the Oceanographic Research Institute has surveyed satellite data between 2001 and 2018 to estimate the extent of sand mining.


 



ORI Sand Mining Survey


The 2019 survey shows that sand mining in estuaries is extensive, more than previously estimated. Seventy-two mining sites were located within or partly-within the province’s estuaries between 2001 and 2018.


2019 Survey Results

Mining activities ranged from small borrow pits < 1 000 m2 (0.1 ha) to extensive commercial mining operations > 90 000 m2 (9 ha). At most sites, there has been loss of riparian and floodplain habitats, substantial change to the estuary bed, banks and floodplain, and altered water flow to the sea where natural channels have been in-filled to create access roads or widened as banks are mined away.

The survey was extended to the lower reaches of the inflowing rivers (for approximately 10 km), because mining there would have likely impacts on the state of the downstream estuaries. A further 239 river mining sites were identified within 10 km of the coast. Overall, between 2001 and 2018, 37 different watercourses were mined for sand. Almost half of KZN’s 76 coastal rivers and estuaries are affected by sand mining.

Estuaries and Coastal Rivers Mined Between 2001 and 2018

Larger rivers with predominantly open estuaries tended to support permanent or semi-permanent larger mines over the surveyed period. Although, at least 30 of the smaller rivers/estuaries have been subject to some mining, particularly in and adjacent to the eThekwini Municipal Area.


Low, Medium and High Mining Pressure in Estuaries (left) and Coastal Rivers (right)

In these smaller rivers with intermittently closed estuaries, mining may have a disproportionately large impact on estuary habitat, and there is a high risk of cumulative effects when estuary mouths are closed off from the sea. The number of active sand mines in estuaries in 2018 suggest that mining pressure on these smaller systems may be increasing relative to previous years.


Sand Mining in Different Estuary Types 2001-2018 (left) and 2018 (right)









References







1 . Demetriades, N. 2007. An Inventory of Sandmining Operations in KwaZulu-Natal Estuaries. Investigational Report prepared by Marine and Estuarine Research for Coastwatch, WESSA KZN in collaboration with Ezemvelo KZN Wildlife and the Environmental Management Department of the eThekwini Municipality, dated September 2007.

















Contributors







ORI

















Research Funders







EDTEA • ORI

















Acknowledgements







Fiona MacKay • Bianca Mckelvey • Bronwyn Goble • Tshegofatso Ramohlale