Geoscientists play increasingly important roles in international development amidst population growth and concomitant demands on water resources and exposures to natural hazards. This paper demonstrates the value of geoscientists for public good by detailing the range and depth of contributions within a single case study of Dakar, Senegal. This urban agglomeration is home to 3 million residents and represents a major hub of business and migration within West Africa. Its unique geology and locus within the drought-prone western Sahel contribute to specific challenges that have strongly shaped its present cultural and environmental landscape. Sustainable development in Dakar depends in particular on groundwater monitoring, mapping of cliff retreat and landslides, flood studies, coastal erosion studies, and prediction of the local effect of sea-level rise. These critical geoscientific investigations, including fruitful collaborations between Senegalese and foreign geoscientists, are helping to mitigate the environmental effects of previous unplanned growth and to inform policy going forward.

The results of seven case studies by the author, colleagues, and graduate students performed at contaminated sites indicate that monitoring wells and piezometers installed in karstic carbonate aquifers often yield unreliable data. These devices more often gave misleading than useful information concerning aquifer properties, groundwater flow, and contaminant movement. These findings are in accord with the highly anisotropic and heterogeneous nature of these aquifers. The following cautions are provided when monitoring wells are to be used in karstic carbonate regions. (1) Monitoring wells may be unreliable in detecting contaminant releases. (2) A monitoring well that detects a contaminant is unlikely to provide valid data regarding the quantity of the release or the velocity and direction of the contaminant movement. (3) Water levels measured in wells often give erroneous indications of groundwater flow direction. (4) Well water levels and chemical parameters taken at random or traditional quarterly calendar intervals give little insight into the fluctuations that may actually occur in the well. (5) Head fluctuations in wells in response to nearby pumping or injection do not necessarily indicate flow connections. (6) Traditional well tests in carbonate aquifers typically do not sense the most important elements of the permeability structure. (7) Virtually every well in a carbonate aquifer is influenced by a unique suite of permeability and recharge elements. In spite of their manifest shortcomings in carbonate aquifers, monitoring wells are specified by law in virtually every case where contaminants may be or have been released. Unfortunately, these wells are usually placed using criteria appropriate for granular aquifers. Alternative and more appropriate means of aquifer assessment and monitoring in these aquifers are available, including wells augmented with tracer investigations and the use of springs and other access points to the conduit elements of the porosity system.