URBAN GROUNDWATER URBAN GROUNDWATER
POLLUTION MONITORING:
POLLUTION MONITORING:
CASE OF WATER SUPPLY CASE OF WATER SUPPLY
AQUIFER OF ABIDJAN AQUIFER OF ABIDJAN
Dr. J. Patrice JOURDA
UNIVERSITY OF COCODY- ABIDJAN
Groundwater Governance and Management In Arid & Semi-Arid Climates 3 to 8 April 2005, Cairo, Egypt
PLAN
1-BACKGROUND SETTING
2-MONITORING AND ASSESSMENT OF POLLUTION STATUS 3-PROCESS TO RESOLVE OR PRACTICES TO CHANGE
4-FORWARD LOOKING PRACTICES 5-REMAINING GAPS
6-LESSONS LEARNED
7-CONCLUSIONS AND RECOMMENDATION
1-BACKGROUND SETTING
Abidjan is economic capital and
located at the South of and of the Côte.d'ivoire
•Geology :belong to the coastal sedimentary basin of Cretaceous age to Quaternary.
Groundwater resources : three aquifers of unequal importance
Reservoirs are sandstone with clay
ABIDJAN HAVE ONLY ONE SOURCE OF WATER SUPPLY: AQUIFER OF CONTINENTAL TERMINAL CALLED COMMONLY “AQUIFER OF ABIDJAN”
ALL FIELD OF BOREHOLES IS SITUATED IN THE URBAN ZONE
PREOGRESSION OF POLLUTION
WHAT ARE THE ORIGINS OF WATER SUPPLY AQUIFER PROBLEMS ?
RAPID EXPANSION OF URBANIZATION
RAPID GROWTH OF POPULATION
EMBRYONIC SANITATION
NETWORK
IN CONTEXT OF ECONOMIC RECESSION AND NOW THE WAR, THE INRASTRUCTURES HAVE NOT FOLLOW UP THE DEVELOPPEMENT OF ABIDJAN :WATER SUPPLY AQUIFER START TO BE CONFRONT TO THE POLLUTION
137000 ha 137000 ha 20000000
20000000 2050*
2050*
60000 ha 60000 ha 3600000
3600000 20002000
12000 ha 12000 ha 550000
550000 19701970
600 ha 600 ha 65000
65000 19501950
URBANIZATION URBANIZATION POPULATION
POPULATION YEARS
YEARS
Sewage :29.11 %
On-site sanitation :66.07 %
Other : 4.82 %
* Estimation
NOW : around 4 million inhab.
2-MONITORING AND ASSESSMENT OF POLLUTION STATUS
In response to the serious sudden attacks by the water supply aquifer of Abidjan, laboratory STEE in the framework of
UNESCO/UNEP jointly Project, carried out 2 actions:
a survey to identify the threats which bear on the aquifer of Abidjan;
the water quality monitoring and assessment of pollution.
MAJORS THREATS (1)
Non-respect of the public property utility (All boreholes protection zoning are invaded by the habitats and became intra- urban and dedicated to the abandon).
Sewages emerge in the valleys constituting a serious threat for the water supply aquifer
Unplanned expansion of the cities
MAJORS THREATS (2)
All bottomlands,where aquifer is vulnerable, are occuped by informal
settlements with on-site sanitation.
The hollows and the basins of storms are used as septic tank and of outfalls of
wastewater and solid waste
Hole dug in the ground in which one pours muds of draining
of the septic tanks hole filled and
closed after filling
WATER QUALITY MONITORING AND ASSESSMENT OF POLLUTION
Curves of variation of conductivity indicates 3 groups:
First group characterizes not polluted water and the second group
characterizing water not polluted;
Second group correspond at level 1 of pollution
(New axe of pollution toward Est.);
Third group correspond at level 2 and 3 of pollution (polluted water, axe
South-North).
TWO AXES OF POLLUTION HAVE BEEN DETECTED :
SOUTH TO NORTH;
TOWARD EST ( NEW AXE)
Nitrates, since October 1995, exceeded in a durable way the standard of potability in certain boreholes. This pollution progresses towards north in direction of the " clean
" zone of recharge;
Since July 1997 another pole of progressive pollution (ZO 6) of the deep aquifer according to second radial East-West appear;
VARIATION OF NO3 RATE IN SOME DEEP BOREHOLES FROM 1994 TO 2004
BOREHOLES CLOSED
BOREHOLE STOPPED
WESTERN ZONE 6 BOREHOLE (ZO 6) POLLUTED BY ON-SITE SANITATION DUE TO HABITATIONS
the western zone 6 borehole (ZO 6) contained strong rate of Escheriechia coli (909 u/100ml) in June 2004 .
3-PROCESS TO RESOLVE OR PRACTICES TO CHANGE
INFORMAL SETTLEMENTS IN THE BOTTOMLANDS
NON-RESPECT OF THE PUBLIC PROPERTIES UTILITY FOR BETTER PROTECT BOREHOLES
NOT MORE USE THE BASINS Of STORM AND THE VALLEYS LIKE STRUCTURES Of WASTEWATER EVACUATION AND SOLID WASTE
NOT MORE USE THE HOLES DIG IN THE GROUND TO EVACUATE MUDS OF DRAINING OF THE SEPTIC TANKS
LACK OF ORGANISED DOMESTIC WASTE DISPOSAL
LACK OF BASIC SANITATION BY DEVELOPING SEWAGE NETWORK
LACK OF INSTITUTIONAL FRAMEWORK
4-FORWARD LOOKING PRACTICES
PROMOTE PUBLIC AWARENESS IN COLLABORATION WITH NGO IN FIELD OF WATER:
Workshop;
Reporting (edit and diffuse the aquifer water quality bulletin;
Media publicity;
To carry out a documentary film which will pass to television
STAKEHOLDER CONSULTATION AND COORDINATION
5- REMAINING GAPS
HYDROGEOLOGICAL MODELING OF GROUNDWATER VULNERABILITY IN URBAN AREAS
POLICY OPTIONS FOR BETTER SAFEGUARDING SURFICIAL AND GROUNDWATER AQUIFERS IN URBAN AREAS,INCLUDING POLLUTION AND HEALTH PROBLEM MITIGATION
MONITORING WATER TABLE LEVEL
6-LESSONS LEARNED
THE GOOD INSTITUTIONAL FRAMEWORK CAN IMPROVE A MANAGEMENT OF THE ABIDJAN AQUIFER
THE IMPORTANT PLACE OF THE NGO IN THE PUBLIC AWARENESS PROMOTION
THE IMPORTANCE OF PUBLIC AWARENNESS IN THE AQUIFER PROTECTION
THE DEVELOPMENT OF CAPACITY BUILDING OF WATER
RESOURCE MANAGER IN POLLUTION ISSUES CAN LEAD THEM TO BE MORE SENSITIVE ABOUT POLLUTION OF AQUIFER
CONCLUSIONS AND RECOMMANDATIONS
Water supply aquifer of Abidjan is threatened :
On the qualitative level, insufficiency of sanitation implies bad
practices which pollute water supply aquifer ( Boreholes of southern Abidjan were abandoned because of pollution by nitrates).
On the quantitative level (the fall of precipitation and the proofing of the aquifer outcrop involve the fall of the
recharge, growth of water demand and overexploitation);
If nothing is done from here 2025 to protect urban
aquifer , the Abidjan population risk to be confronted with water problems.
we recommend for a better governance and management of the water supply aquifer of Abidjan the following
elements:
the creation of an institutional framework for a integrated water resources management in order to establish lawful measurements in the various fields of application of water:
an authority of water;
the development of a real policy of sanitation with the creation of sewage and station of treatment of wastewater in the goal of Re-use;
the creation of a synergy enters the scientific community, the NGO, the various users of water and the authorities in load of the management of the aquifer for the collection, the
diffusion of information and consultation;
THANK YOU FOR YOR ATTENTION
Acknowledgements
to:UNEP/DEWA (NAIROBI OFFICE)
UNESCO/PHI (NAIROBI OFFICE)
