Challenge
EGGI, a division of GZA, was selected by a $6 billion international consortium – with extensive private and public interests throughout the Dominican Republic – to design and complete a first-of-its-kind countrywide advanced groundwater resources assessment.
Portions of the Dominican Republic are arid and the Country’s water supply situation has become increasingly dire. New supplies of affordable and sustainable fresh water are needed. Groundwater resources have been overlooked and under-investigated; in many regions far more renewable groundwater than previously realized can be utilized to meet current and future demands. These critical resources must be better understood to enable their sustainable utilization, and to help ensure their protection for future generations.
The Client was seeking an accurate, forward-looking assessment of the country’s groundwater supplies in light of existing water supply challenges, anticipated increased shortages, and the time delays and costs associated with developing new surface water supplies. The client’s specific motivations for commissioning the study included desires to:
- Identify and develop groundwater resources that could be used for agriculture, mining and real estate concerns;
- Discover new opportunities for groundwater development in areas throughout the Country previously deemed to lack sufficient renewable water supplies; and
- Facilitate national sustainable groundwater management efforts, to help preserve the Dominican Republic’s increasingly precious groundwater supplies for future generations.
Solution
EGGI evaluated the potential to sustainably develop new groundwater resources – for both potable and non-potable use – across the entire Country; a Study Area of roughly 48,000 km2. This groundwater assessment of the Dominican Republic required the evaluation of many varying hydrogeologic settings. This included: mapping of unconsolidated deposits; bedrock geologic mapping; delineation of karst terrain features; a remote sensing/lineament analyses; a groundwater recharge assessment; bedrock fracture fabric analyses; and a comprehensive review of groundwater quality. A numerical model was constructed that incorporated all of the hydrogeologic data which led to the ability to highlight those areas within the country that are considered to be “potentially” favorable for developing groundwater resources.
Benefit
The results generated from the numerical model (at 100m2 grid resolution) were used to create a “Groundwater Development Potential Model”. Groundwater development opportunities were grouped into four categories of relative favorability for groundwater development: Less Favorable, Average Favorability, More Favorable, and Most Favorable. These categories were further refined by defining “Exclusion Areas” where groundwater development is not recommended due to several factors, including those areas having: the presence of existing or potential contaminant threats to groundwater quality, a very dense population, the potential for marine intrusion, regions with steep topographic slopes, and areas of protected wetlands and mangroves. The model formed the basis for the creation of national and province-based Regional Groundwater Favorability Contour Maps, enabling the assessment of the relative groundwater resource development potential at any given location, anywhere in the country.