dam rehabilitation and maintenance : the role of sa municipalities

7/28/2019 Dam rehabilitation and maintenance : The role of SA municipalities

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OVERVIEW

BRIEF DESCRIPTION OF THE MTHATHA DAM ANDTHE MTHATHA RIVER

ROLE IDENTIFICATION

DAM REHABILITATION & MANAGEMENT PROCESS

CONCLUSIONS



MTHATHA DAMOwnership: Owned, operated and maintained by DWA according to the National Water Act. 36 of 1998

Opening date ; 1977

Type : It is an earth embankment dam

Purpose : Multipurpose-

Potable water Supply -It serves as the main source of raw water supply ( 65.9 ML /day) for the Thornhil WTW which treats andsupplies water to the city of Mthatha and its environs with a total population of about 750,000.

Hydropower generation- Supplies water for hydropower power generation by Eskom at 2 No. 6 MW hydropower station slocated downstream of the Mthatha river ( First/Second Falls hydro scheme ) - 338 ML/day is utilized, but since the water isreturned to the river, this use is non-consumptive

Recreation/Fisheries- Fishing competitions held bi-annually by the Dept.of Agriculture. However these activities are currentlydefunct.

Location ; The Mthatha Dam impounds the Mthatha river at a location about eight kilometers upstream of the city of Mthatha inthe OR Tambo District Municipality of the Eastern Cape

Accessibility : located off the R61 by a 2km partially tarred access road currently undergoing rehabilitation.

Coordinates ; 31 °32′56″S , 28°44′0″E / 31.54889 °S, 28.733333 °E

Height ; 12- 38 meters

Crest Length ;680 metersStorage Capacity ; 253,674,000 cubic meters

Surface area ; 2,542 hectares (6,280 acres)

Raw Water Quality : The upper reaches of the river/Headwaters where the dam is located are almost pristine so negativeimpacts on water quality are relatively low. However forestry activities upstream may be releasing herbicides and pesticides andpoor quality effluent in this section but their impact is currently not detectable in the available water quality data.



MTHATHA DAM-AERIAL VIEW

MTHATHA DAM



MTHATHA DAM-DAM WALL, SPILLWAY/OUTLET WORKS



MTHATHA DAM-DOWNSTREAM SLOPES



MTHATHA DAM-UPSTREAM SLOPES



MTHATHA DAM- ACCESS BRIDGE /CONTROL TOWER /SPILLWAY



MTHATHA DAM-SPILLWAY /OUTLET



MTHATHA RIVER-CATCHMENT CHARACTERISTICS

Source : The Mthatha river drains from the Baziya mountain range at Langeni Forests -1500m above sea level.

Mouth : Indian Ocean at an estuary at Coffee Bay,Catchment Size : 2600km 2

Major Tributaries ; Ngqungqu and Cicira

River Flow : From the North West to the South East

Length : 250 km

Climate : The area experiences a temperate to subtropical climate, with rainfall occurring predominantly insummer. Average rainfall is relatively high along the coast (1 000 to 1 300 mm per annum), decreasing towardsthe interior (700 mm per annum) and finally increasing in the upper catchment areas of the escarpment (up to 1500 mm per annum).

Geology : Dominated by mudstone, shale and considerable amount of dolerite

Vegetation : vegetation cover consists of temperate and transitional forests. The headwaters are under pineplantations.

Land use:

Grazing for livestock occupies 70%, Settlements and subsistence agriculture takes up 15%., Approximately 4%is under commercial afforestation, e.g. Langeni plantations and Only 0.05% is under irrigation.

Water Use:

Commercial Forestry-related industries,( e.g. the sawmills at Langeni and KwaBhaca ),Urban settlements andsmall scale industrial water users, rural water users, small scale Irrigation for subsistence agriculture. Etc.



MTHATHA RIVER-ECOLOGICAL HEALTH

Upper ReachesThe upper reaches of the river is almost pristine so negative impacts on water quality are relativelylow. However forestry activities upstream may be releasing herbicides and pesticides and poor quality effluent in this section but their impact is currently not detectable in the available water qualitydata.Middle ReachesDense peri-urban and rural settlements has impacted negatively on this section of the river.Some disturbed areas due to human activities have been invaded by alien vegetation, resulting inundercutting and slumping of the riverbanks, siltation and reduced run-off .Overloaded sewage treatment works( operating capacity=18 ML/day, design capacity=12 ML/day),poor management of the sewage systems result in the discharge of untreated sewage effluent into theriver,(Green drop status-22%)Lower ReachesDense peri-urban and rural settlements has impacted negatively on this section of the river as well.High pollution levels further downstream of the dam due to the disposal of raw or poorly treateddomestic and industrial waste(liquid/solid) into the river and secondly high erosion in certain areas of the catchment caused by poor land use practices.High nutrient loads causing eutrophication and proliferation of potential toxic algal blooms

Increased sediment load due to erosion from overgrazing, poor agricultural practices and vegetationclearing within the catchment.

(Source: EC River Health Program; Technical Report: Mthatha River Monitoring 2004-2006)



MTHATHA RIVER - UPPER CATCHMENT - FORESTRY AND TIMBER RELATED ACTIVITIES -LANGENI

SAWMILLS



MTHATHA RIVER – UPPER CATCHMENT-UPSTREAM OF THE LANGENI SAWMILLS:



MTHATHA RIVER MIDDLE CATCHMENT - R EFUSE DUMPED ON THE BANKS OF THE MTHATHA RIVER AND

INFESTATION OF THE ALIEN INVASIVE : B UGWEED

M



MTHATHA RIVER

MIDDLE CATCHMENT -SAND MINING ON THE RIVER BANK TO MAKE BRICKS . T HE BRICK MAKING ALSO MAKES USE OF THE RIVER WATER , WHICH EXPOSES THE

BRICK -MAKERS TO HARMFUL SUBSTANCES AND DISEASE .



MTHATHA R IVER -LOWER CATCHMENT - ALIEN VEGETATION AND HIGH SEDIMENT LOAD



DAM REHABILITATION & MANAGEMENTROLE IDENTIFICATION

PRIMARY ROLEThe National Water Act ( Act No.36 of 1998) assigns the responsibility for the rehabilitation and management of most major dams in the district to the Department of Water Affairs(DWA). However there are other smaller dams and dug outs which are owned, operated and maintained directly by localmunicipalities, local farmers and game parks within the district.SECONDARY ROLEThe National Water Act(Act No.36 of 1998 ) assigns the role of a Water Service Authority/Provider to theOR TAMBO District Municipality and is responsible for the treatment, storage and supply of potable drinking water tothe city of Mthatha, the district administrative capital and surrounding towns.This therefore implies that OR Tambo DM is highly dependent on regular raw water supplies from the Mthatha dam inorder to carry out this legislative function of a water service authority/provider.OTHER ROLE PLAYERS /STAKEHOLDERSDEAT- Dept of Environment afffairs and TourismBeneficiary Communities(Traditional Councils)Department of rural development and Land reforms-custodians of rural or communal landsDepartment of Agriculture, forestry and fisheries

ESKOMWater User AssociationsWater BoardsDepartment Of Human SettlementsSurrounding Local Municipalities- Nyandeni, Mthlotlo and KSD Local Municipalities



DAM ASSET MANAGEMENT PROCESSDam Asset Management Planning

Dam Operation Dam Maintenance and Rehabilitation

Dam Safety

Water Resource ManagementRaw water Quality managementRaw water utilization managementRaw Water Conservation and demand managementEnvironmental ConservationCatchment land use management



DAM ASSET MANAGEMENT PLANNING

Dam asset strategicplanning process

•IDP: conceptual district wide water master plans/WSDP. Ward basedplanning & Information System

(Municipal Systems Act 32 of 2000)

•Dam Asset Mgt Policy•Dam O & M Plan•Dam Emergency

preparedness plan

•WCDM master plans•Disaster & Risk Management

plan(Disaster Mgt Act 2002) wddd

•Development plans• Conversion of borehole fed standalone schemes into Mthatha river fed Regional Water Supply Schemes•Upgrading of existing town sanitation systems into full water borne sewerage system.•Housing Developments(Emergency housing,eradication of informal settlements, urban renewal programs)



DAM OPERATION

DamOperations

Plant operators: WTW

•Example: In times of extreme staff shortage at the Mthatha dam site themunicipality sometimes deploys on a part-time basis some of its plantoperators from the water treatment works to assist in the normal operations of the dam(outlet works) and also for skills transfer.



DAM MAINTENANCE & REHABILITATION

DamMaintenance &

Rehabilitationprograms

•Labor Intensive constructiontechnology, Local SMEs, WardCommittees, Community Dev’t

Workers(CDW) etc•Public Participation policy &

strategy(Municipal Systems Act 32 of

2000)



•The use of Labor Intensive methods are applied in the rehabilitation of theaccess road to enhance the contribution of local labor and help to reducethe unemployment rate which currently stands at 68.1% within the district.

•Local SMEs and unskilled local labor are attached to the appointedservice provider for skills transfer/mentorship purposes.

DAM MAINTENANCE & REHABILITATIONExample -Dam access road rehabilitation(2km)



DAM SAFETY

Dam Safety Inspections/Audit are conductedperiodically by the DWA dam safety office.Plans are underway for the implementation of thefollowing dam safety programs:Dam reservoir augmentation –raising of the dam wall to meet the growing water demand requirementsRehabilitation of the outlet works to increase capacity and method of delivery. etc



WATER RESOURCE MANAGEMENT -RAW WATER QUALITY MANAGEMENT

Raw water quality results obtained from the Mthathadam had been fairly stable throughout the years.

Raw Water Quality

Management

Raw Water QualityTrends/Raw water user quality

requirements: WardCommittees, Water User

Associations, Village water committees



WATER RESOURCE MANAGEMENT -RAW WATER UTILISATION MANAGEMENT

Raw Water Utilization policy

dev’t &implementation



W R M



WATER RESOURCE MANAGEMENT -ENVIRONMENTAL CONSERVATION

EcologicalRestorationprograms:

Working for Water programs

Implementingagents;CDWs

Water PollutionControl

•Public Participationpolicy & strategy

(Municipal SystemsAct 32 of 2000)

•Participate in publicawareness, comm. &education programs;

Water week

River EcologicalStudies/Surveys

WardCommittees,Community

Dev’t Workers

WATER RESOURCE MANAGEMENT



WATER RESOURCE MANAGEMENT -EXAMPLE -WORKING FOR WATER PROGRAM - MTHATHA RIVER CLEANING

Clearing of invading alien plants and removal of solid waste in andaround the river using labor intensive/manual methods so as toconserve the ecological functioning and biological diversity of theMthatha river.OR Tambo DM entered in to a memorandum of agreement(MOA) withDWA for the planning, procurement of service providers/suppliers andimplementation of the exercise.Duration= Aug.2010 to 25 th March 2012Excellent low cost activityProject Budget-R9.8 millionBudget Source-DWAJob opportunities created -217Direct Involvement of the local communities which has led to the socio-economic upliftment of the communities through job creation.

WATER RESOURCE MANAGEMENT ACTIVITIES



WATER RESOURCE MANAGEMENT ACTIVITIES ENVIRONMENTAL CONSERVATION

EXAMPLE -WORKING FOR WATER PROGRAM - MTHATHA RIVERCLEANING



WATER RESOURCE MANAGEMENT ENVIRONMENTAL CONSERVATION

EnvironmentalConservation

•District spatialplanning &

environmental

mgt technicalforum,•Public

Participationpolicy & strategy

•(Municipal

Systems Act 32of 2000)

•EMP,•Environmental

policy statement,• IWMP (NEMA Act1998,NEMWA 2008)



WATER RESOURCE MANAGEMENT -CATCHMENT LAND USE MANAGEMENT

The Spatial Development framework provides guidance to the spatialdistribution of current & future desirable land uses/activities within thedistrict municipality in order to give physical effect to the vision, goalsand objectives of the IDP.

Catchment LandUse Mgt

Environmental &spatial planning

forum

Spatial Dev’t framework/Land Use

Mgt Guidelines.

Ward Based planning& Information System



CONCLUSION

The National Water Act No.36 of 1998 assigns the primaryrole of the rehabilitation and management of the Mthathadam to the DWA. However as a major stakeholder/roleplayer our role is therefore to offer the much needed

collaboration, assistance, support, facilitation and adviseto the work of DWA in the rehabilitation and managementof the Mthatha dam. This is to ensure the sustainability of the raw water supply for continuous economic productivity,promotion of human health ,survival of our naturalecosystems and the support of the tourism/recreationalindustries.



REFERENCES

OR TAMBO DM IDP -2012/13

OR TAMBO DM-WATER MASTER PLANS-2011/12

NATIONAL WATER ACT,1998

NATIONAL WATER POLICY,1997

DWA WEBSITE( www.dwa.gov.za )

THE WATER SERVICES INFRASTRUCTURE ASSET MANAGEMENTSTRATEGY_2010

NATIONAL WATER RESOURCE STRATEGY(NWRS,2004 )

EC RIVER HEALTH PROGRAM; TECHNICAL REPORT: MTHATHA RIVERMONITORING 2004-2006

http://www.dwa.gov.za/

http://www.dwa.gov.za/



THANK YOU

dam rehabilitation and maintenance : the role of sa municipalities

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