URBAN GROUNDWATER POLLUTION MONITORING: CASE OF WATER SUPPLY AQUIFER OF ABIDJAN

Transcription

1 Groundwater Governance and Management In Arid & Semi-Arid Climates 3 to 8 April 2005, Cairo, Egypt URBAN GROUNDWATER POLLUTION MONITORING: CASE OF WATER SUPPLY AQUIFER OF ABIDJAN Dr. J. Patrice JOURDA UNIVERSITY OF COCODY- ABIDJAN

2 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

3 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 PREOGRESSION OF POLLUTION 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

4 WHAT ARE THE ORIGINS OF WATER SUPPLY AQUIFER PROBLEMS? RAPID GROWTH OF POPULATION NOW : around 4 million inhab. RAPID EXPANSION OF URBANIZATION YEARS POPULATION URBANIZATION 600 ha ha EMBRYONIC SANITATION NETWORK ha Sewage :29.11 % On-site sanitation :66.07 % 2050* ha Other : 4.82 % * Estimation 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

5 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.

6 MAJORS THREATS (1) Non-respect of the public property utility (All boreholes protection zoning are invaded by the habitats and became intraurban and dedicated to the abandon). Unplanned expansion of the cities Sewages emerge in the valleys constituting a serious threat for the water supply aquifer

7 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

8 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.); TWO AXES OF POLLUTION HAVE BEEN DETECTED : SOUTH TO NORTH; Third group correspond at level 2 and 3 of pollution (polluted water, axe South-North). TOWARD EST ( NEW AXE)

9 VARIATION OF NO3 RATE IN SOME DEEP BOREHOLES BOREHOLES CLOSED FROM 1994 TO 2004 BOREHOLE STOPPED 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; 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.

10 3-PROCESS TO RESOLVE OR PRACTICES TO CHANGE LACK OF INSTITUTIONAL FRAMEWORK 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

11 4-FORWARD LOOKING PRACTICES STAKEHOLDER CONSULTATION AND COORDINATION 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

12 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

13 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

14 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.

15 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;

16 THANK YOU FOR YOR ATTENTION Acknowledgements to: UNEP/DEWA (NAIROBI OFFICE) UNESCO/PHI (NAIROBI OFFICE)