RISK ASSESSMENT TO DETERMINE SOURCES OF … · Rhodes University. Introduction zThe marine...
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RISK ASSESSMENT TO DETERMINE SOURCES OF IMPACT ON COASTAL STORM WATER: THE CASE OF JEFFREYS BAY (SOUTH AFRICA) R. Seebach & KJ. Whittington-Jones Department of Environmental Science Rhodes University
Transcript of RISK ASSESSMENT TO DETERMINE SOURCES OF … · Rhodes University. Introduction zThe marine...
RISK ASSESSMENT TO DETERMINE SOURCES OF IMPACT ON COASTAL STORM WATER:
THE CASE OF JEFFREYS BAY (SOUTH AFRICA)
R. Seebach & KJ. Whittington-JonesDepartment of Environmental Science
Rhodes University
IntroductionIntroduction
The marine environment is of great natural and economic value.By 2025 three-quarters of the world’s population will live in the coastal zone.Storm water from developing communities has been identified as a major marine pollution source.Little is being done in developing countries to understand and reduce anthropogenic land-based marine pollution.
Study Area (Jeffreys Bay)Study Area (Jeffreys Bay)
HypothesisHypothesis
Waste management and sanitation in the storm water catchment at Jeffreys Bay,
South Africa are inadequate and therefore poses a pollution threat to storm water and
subsequently, the local marine environment.
Research questionsResearch questionsWhich aspects (activities and services) in the catchment pose the most significant risk to storm water quality, marine ecology, human health and the socio-economic status of the community? To what extent did rainfall influence the probability of aspects having a negative impact on receptors?What was the current quality of storm water within the catchment? Is there evidence that direct discharge of storm water has a negative impact on the water quality of the near shore marine environment at Jeffreys Bay?
Risk AssessmentRisk Assessment
Risk assessment was conducted to identify and prioritize pollution sources.Risk = (likelihood of occurrence + detection)
x consequenceSignificant aspects identified were; solid waste disposal, grey water disposal and informal ablution.
SnapSnap--shot Storm Water Analysesshot Storm Water AnalysesMonitoring Stations
Water Quality Constituent
Northernstorm water
outlet
YWAM Wetland Industrial C-Place SA Water QualityGuidelines
Suspended solids 120 116 100 96 84 <100(DWAF, 1996a)
COD 1160 765 <100 <100 <100 12.77Variance: 80%-120%
(DWAF, 1996a)
Phosphorous 0.3 6.3 0.23 0.09 0.12 <5(DWAF, 1996a).
Ammonium <0.05 <0.05 <0.05 <0.05 <0.05 0.007(DWAF, 1996a).
Nitrate 4.5 5.2 1.6 1.5 2.3 <0.5(DWAF, 1996a).
PH 7.85 7.86 7.71 8.46 8.44 6.5-8.5(DWAF, 1996b)
E. Coli 0 cfu/ml 18 000 cfu/ml
0 cfu/ml 0 cfu/ml 0 cfu/ml 0-130 cfu/ml(DWAF, 1996b)
Faecal Coliforms 0 cfu/ml 105 000 cfu/ml
0 cfu/ml 0 cfu/ml 0 cfu/ml 0-150 cfu/ml(DWAF, 1996b)
Marine Water Quality and Rainfall Marine Water Quality and Rainfall
0
20
40
60
80
100
120
11/03
/0212
/20/02
02/14
/0304
/28/03
06/08
/0308
/18/03
10/19
/0301
/13/04
03/07
/0404
/28/04
07/12
/0409
/06/04
10/31
/0412
/22/04
02/01
/0504
/10/05
06/20
/05
Date
Rai
nfal
l (m
m
0
500
1000
1500
2000
2500
3000
3500
E. c
oli/
100
ml
Rainfall (mm) E. coli/ 100ml
Sanitation Management StudySanitation Management Study
Solid Waste Management StudySolid Waste Management Study
ConclusionConclusion
Coastal water pollution from contaminated storm water is of growing concern. Source based solutions more effective long-term compared to end-of-pipe solutions.Recommended to integrate various technologies for example ecological sanitation and one-man contract solid waste removal.Strong emphasis need to be placed on community participation and education.
Sponsored by:Sponsored by:
Visit http://seawaste.uwc.ac.za for information on integrated pollution and waste
management for East and Southern African Coastal Areas
