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

132

Field sufloodplain operations done to finin extractobservationwas analys

2.2. ImTo eva

EnvironmeEnvironmeevaluationathe operatillustrates tLeft – Table 1: S

3. Resul

3.1. SanSand an

the methodthe active riverbank aof the activmanual andof extractio

Manuawhereas thmine the muse 10 m3 produce aninvolves 5 miners prooperator ansand and /o

Gravel floodplainsthe extractcourse rivestream minimpacts as

urveys wersand and including q

nd out the tytion has ansfocused osed as expla

pact evaluaaluate the ental Impacental Conseand assessmtion, the cthe assessmSand and gravel m

lts and Di

nd and Grand gravel md of extracti

part of thareas often vity. On thed mechanicon and prod

al miners ushe mechanicmaterial.The

tipper truckn agreed m to 6 men t

oduce 15 loand the tippeor gravel.

is mostly s. Sand is cion of fine ber sand. Thening is inSediscussed i

e carried ougravel mi

quantities ofype of equia direct reon both flooained below

ation methenvironmenct Assessmervation Dement for sanomplexity

ment based omining evaluation

iscussion

avel Miningmining in Nzion.Extracti

he river chaflooded by

e other handcal mining aduction as she picks andcal miners

erefore manks as they u

maximum ofto excavateads per dayer driver. Th

excavatedcommonly mbuilding ane major floendedza, Pfuin the follow

ut in the stuining.Field f sand and ipment and elationship odplain and

w.

odology ntal impact

ment (EIA) epartment ond mining aof mining

on site charan based on site ch

g Classificazhelele vallion could beannel), flooywater durind if the methare identifiehown in Tab

d shovels to use excava

nual miners use powerfuf 6 loads p, load and o. The mech

he two extra

din upland mined on thnd plasteringoodplain actfumbada andwing section

udy area masurveys algravel extrmethods uswith env

d in-stream

ts of sand Guidelines

of Malaysiactivities de

methods, acteristics.haracteristics. Rig

ation ey can be ceclassified aodplain minng high flowhods of extred. The locable 2. extract the

ators and otcommonly

ful equipmeper miner eoffload the

hanical methaction meth

areas wherhe floodplaing sand whiletivities are d Mandala. n.

ainly for malso enabledracted by eased to extra

vironmental sites. Data

and gravels for Sanda. The gui

epends on sand locali

ght – Table 2: San

categorised aas in-streamning (mininws) or uplaraction areaation of the

material frther earth muse 7 m3 tru

ent to load teach day. T

material. Ohod of extrahods are use

reas sand in and in-stre in-stream inDopeni aThese activ

apping locad collectionach miner pact the resou

impacts collected t

l mining, wd, Gravel aideline stateeveral factoity (site ch

nd and gravel min

according tom (mining ofng of sand and mining adopted as aaggregates

om any plamoving equucks while the material

The manual On the otheraction only ed regardles

is extractedream. Floodmining inv

and Tshivhilvities have

ations of in-n of data per day. Thurces. Equipand magnthrough the

we adoptedand Stone es that envors, namelyharacteristic

ning classification

o either the f sand and g

and gravebasing on t

a classificatinfluences

ace of their ouipment to the mechanl. The manmethod of

r hand the involves ths of the loc

d in the ridplain mininvolves the exlidulu whilvarious env

-stream andon mining

his was alsopment useditude. These methods

d the 2000Mining by

vironmentaly the size ofcs).Table 1

n

location orgravel fromel from thethe locationtion methodthe method

occurrence,expose and

nical minersnual minersf extractionmechanicale excavatoration of the

ver and inng involvesxtraction ofe major in-vironmental

d g o d e s

0 y l f

r m e n d d

, d s s n l r e

n s f -l

133

3.2. EvaWe ad

Conservatimining in extraction 1000 m3 peand mechalocated wit

EnvironEach envicumulativeoverall envaspects.

The duthe local cit. Plantingcumulativemining ope

Deforebut it is psemblance regenerate aquatic ecoexposed topollutants iTable 1: Imp

Channethe miningand this brreversible aof the river

aluation ofdoptedthe ion DepartmNzhelele vsites in theer month (Tanical meththin 500 menmental imironmental e impact (Tvironmental

ust resultingommunity ag vegetatione as it causerations hav

estation occupermanent a

of the orito a near-n

osystems. To danger of pis removed.

pact matrix for

el degradatig and transprings perma

and are cumr channel.

f the Enviro2000 Env

ment of Mavalley. The study area

Table 1). Thod of extraeters of the r

mpacts are evaspect is r

Table 1). Thl impact of

g from miniare temporan species wses respiratve ceased. urs during and can beiginal state normal con

The terrestriapollutants e. r sand and gra

ion includesportation ofanent chang

mulative in n

onmental Ivironmental alaysia for matrix is b are categor

he activities action are prriver and thvaluated usrated in tehis will givthe activitie

ing and tranary and can which trap tory disease

the develope reversible

of the vegdition. Thisal animals a

entering the

avel mining (A

s all the phyf the materige in the chnature as the

mpacts Impacts

evaluatingbased on sitrized underin all the si

racticed. Fihis is considing the env

erms of its ve the impaes is then gi

nsportation be reversib

dust can ales to the lo

pment of the. Afforestgetation bes impact is are deprivedwater syste

Adaptedfrom E2000)

ysical, bioloial. The degharacter of ey affect th

Assessmenenvironme

te characterr small scalites are cateive mining dered as senvironmental

magnitudeact value ofiven by the

affects theble if water lso reduce ocal people

he project aation after fore operatcumulative

d of habitat em as the ve

Environmenta

ogical and chgradation aff the channehe biologica

nt Matrix ental impacristics as she as the minegorized as sites and sisitive. impacts as

e, permanef each envir

average of

e local commis constantits impact.

e even after

and is confioperation

tion and it e as it affecand food. T

egetation wh

al Conservatio

hemical alteffects the chel. The resul, chemical

from Envts of sand hown in Taners producsimple as oix abandone

sessment mence, reversronmental af the total of

munity. Thtly sprayed . It also prr the sand

ned to the cannot britakes a lo

cts both terrThe aquatic hich acts as

on Department

erations reshannel at a ultant changand physic

vironmentaland gravel

able 1. Thece less thanonly manualed sites are

matrix table.sibility andaspect. Thef individual

e effects toto suppress

roves to beand gravel

project siteing back a

ong time torestrial andspecies are

s a buffer of

t of Malaysia,

sulting fromlocal scale

ges are notcal structure

l l e n l e

. d e l

o s e l

e a o d e f

,

m e t e

134

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

136