Presenter
Prof. Simon Mariwah, University of Cape Coast
Co-author(s)
Prof. Joseph T. Zume, Shippensburg University
Date: Sept. 12th Session No.: RS 13 Theme: 3-7 Submission No.: O-3-7-7
Sub-theme
3. Building Resilience for Disaster Prevention and Mitigation
Topic
3-7. Management of water risks induced by extreme weather and climate events
Abstract
Globally, millions of people in coastal areas rely on shallow groundwater systems, which are increasingly threatened by climate change, as rising sea levels cause saltwater intrusion into coastal aquifers. Additionally, many coastal locations are experiencing increased flooding owing to climate change. In Sub-Saharan Africa, where most urban areas are characterized by poor storm drainage systems amidst onsite sanitation infrastructure, coastal groundwater quality is vulnerable to both impacts of sea level rise and those owing to poorly drained flood waters. In this research, we collected and assessed groundwater samples t for evidence of salinization linked to saltwater intrusion, resulting from climate change. This research was conducted coastal communities in Cape Coast, one of the six metropolitan areas in Ghana. Data collection targeted five urban communities with varying demographic and physical characteristics, as well as varying densities and ages of the settlements. The following criteria were applied in selecting the study communities: (1) Proximity to the University of Cape Coast for ease of access, and the fact that off-campus student population increases the pressures on groundwater sources and sanitation facilities; (2) increasing distance from the coastline to test for impacts of saltwater intrusion; and (3) the density of settlements. A common denominator with all the communities is the prevalent use of shallow domestic wells alongside on-site sanitation facilities. A total of 52 wells were sampled and analyzed for salinity and the concentrations of sodium (Na), chloride (Cl), calcium (Ca), magnesium (Mg), bromide (Br), fluoride (F), bicarbonate (HCO3), and potassium (K). Several ionic ratios including Na/Cl, Cl/Br, Mg/Ca, and K/Ca, as well as the Base Exchange (BEX) index, were calculated and used alongside Stiff diagrams to assess saltwater intrusion at each sampled well. Field sample collection and handling strictly followed established quality assurance protocols for both the water chemistry and microbial testing. Lastly, temperature and precipitation data were analyzed to assess flood magnitudes and frequencies, and further gauge the vulnerability of groundwater quality to flooding. Results suggest evidence of saltwater intrusion into coastal groundwater and further indicate that flood frequencies and magnitudes are increasing. Both have implications for groundwater quality management in the study area, as well as broad policy implications for similar settings throughout Ghana and the entire Sub-Saharan Africa