Groundwater resources in Haiti are considered abundant, with greater than 2 billion cubic meters per year (2 × 10 9 m 3 /yr) of renewable resources and 56 billion cubic meters of reserves. However, groundwater is not available everywhere and many aquifers are often low yielding, discontinuous, or are at risk from saltwater intrusion, overexploitation, reduced recharge, and contamination. Economic development, population growth, and climate change are factors that will increase stress on groundwater resources. Sector leadership, capacity building mechanisms, integrated water policy, and a clear regulatory framework are urgently needed to manage, regulate, and protect Haiti’s groundwater resources to achieve long-term security. Accomplishing this requires technical support and practical references that summarize the groundwater resources and their vulnerabilities, complexities, and opportunities. This chapter includes a summary of knowledge, information, and experience to aid the development and management of Haiti’s groundwater resources, as well as provides an overview of its complex hydrogeology. Five broad hydrogeological environments are differentiated: (1) Unconsolidated alluvium accounts for 26% of Haiti’s land area—it includes a large portion of the country’s groundwater reserves and is the most exploited for irrigation, industry, and potable water; (2) interior sedimentary units account for 32% of Haiti’s land area and include up to 25% of the country’s groundwater reserves—springs from carbonate aquifers are significant sources of water supply throughout the country; (3) reef carbonate accounts for 6% of Haiti’s land area, with locally available coastal karst aquifer systems serving some of the most rural, driest, and impoverished areas of Haiti; (4) semiconsolidated units account for 21% of Haiti’s land area—their low groundwater potential limits rural and urban water use throughout the country; and (5) igneous bedrock accounts for 15% of Haiti’s land area—its discontinuous groundwater reserves are an important source of water in rural and mountainous areas.

Groundwater is the source of drinking water for ~1.4 million people in the Coastal Plain Province of Maryland (USA). In addition, groundwater is essential for commercial, industrial, and agricultural uses. Approximately 0.757 × 10 9 L d ‒1 (200 million gallons/d) were withdrawn in 2010. As a result of decades of withdrawals from the coastal plain confined aquifers, groundwater levels have declined by as much as 70 m (230 ft) from estimated prepumping levels. Other issues posing challenges to long-term groundwater sustainability include degraded water quality from both man-made and natural sources, reduced stream base flow, land subsidence, and changing recharge patterns (drought) caused by climate change. In Maryland, groundwater supply is managed primarily by the Maryland Department of the Environment, which seeks to balance reasonable use of the resource with long-term sustainability. The chief goal of groundwater management in Maryland is to ensure safe and adequate supplies for all current and future users through the implementation of appropriate usage, planning, and conservation policies. To assist in that effort, the geographic information system (GIS)–based Maryland Coastal Plain Aquifer Information System was developed as a tool to help water managers access and visualize groundwater data for use in the evaluation of groundwater allocation and use permits. The system, contained within an ESRI ArcMap desktop environment, includes both interpreted and basic data for 16 aquifers and 14 confining units. Data map layers include aquifer and confining unit layer surfaces, aquifer extents, borehole information, hydraulic properties, time-series groundwater-level data, well records, and geophysical and lithologic logs. The aquifer and confining unit layer surfaces were generated specifically for the GIS system. The system also contains select groundwater-quality data and map layers that quantify groundwater and surface-water withdrawals. The aquifer information system can serve as a pre- and postprocessing environment for groundwater-flow models for use in water-supply planning, development, and management. The system also can be expanded to include features that evaluate constraints to groundwater development, such as insufficient available drawdown, degraded groundwater quality, insufficient aquifer yields, and well-field interference. Ultimately, the aquifer information system is intended to function as an interactive Web-based utility that provides a broad array of information related to groundwater resources in Maryland’s coastal plain to a wide-ranging audience, including well drillers, consultants, academia, and the general public.

Abstract Over the past four decades, ongoing deformation of an 18-m-thick peat deposit within the flat-lying Mercer Slough has resulted in damaging deflections, and near-collapse in three cases, of pile-supported Interstate 90 bridges and a major water line on the east side of the slough. The peat is partially underlain by a dense sand unit, which includes a highly pressurized aquifer that produces artesian flow 1–2.5 m above the ground surface. Inclinometers on the east side of the slough show the peat flowing toward the structures and then apparently directed west along the interstate centerline. Large displacements recorded in several inclinometers near the center of the slough suggest a length of deforming peat that approaches 600 m, which is likely initiating retrogressively. Potential causal mechanisms include poor engineering characteristics of the peat, presence of high hydrostatic pressure transmitted within and beneath the peat, seasonal water-level variations of Lake Washington and induced hydraulic gradients within the peat, dredging of the Mercer Slough channel, puncturing of the underlying aquifer by numerous pile foundations, and fill placement along the eastern margin of the slough. The peat is flowing around the pile/shaft foundations; however, excessive lateral loads are still being applied to the foundations in a poorly understood and unpredictable manner. The most severe deflections have occurred in the outermost structures where the peat is primarily flowing transverse to the structures.

The regional Floridan aquifer system has been dewatered and otherwise altered extensively throughout much of Florida and coastal Georgia by groundwater pumpage (mining). An increasing threat to this karst aquifer system is structural mining of aquifer formations, primarily to produce fertilizers, titanium products, construction materials, and pet food supplements. These excavations often include mechanical dewatering to facilitate shallow and deep extraction of the aquifer formations. All include reduced aquifer levels, dewatering of the aquifer system, and altered hydroperiods at and surrounding the excavated pits, due to increased void space and evapotranspirative losses (nonmechanical dewatering). Only mechanical dewatering is considered by regulatory agencies during evaluations of applications for structural mining of the aquifer system. Despite refuting data, open pits resulting from these excavations increasingly are portrayed as subsurface “reservoirs” that create new or enhanced sources of water in areas where natural groundwater supplies have been depleted. Four permits and sites were evaluated for excavated and proposed pits in SE, NW, SW, and east-central Florida's natural areas used for groundwater supply. The combined surface area for pits under those four permits will result in ∼237,000 m 3 /d (∼62.7 million gallons per day [Mgd]) of induced discharge from the regional Floridan aquifer system due to nonmechanical dewatering. This volume is more than twice the reported pumpage from the combined three municipal supply wells at the Miami-Dade West Well Field. The ∼123 ha (∼308 ac) SW Florida mine, most recently excavated in an area designated as critical habitat for the federally listed Florida panther, will result in induced aquifer discharge of ∼1505 m 3 /d (0.4 Mgd) due to nonmechanical dewatering. This loss is equivalent to ∼5% of all water used by domestic supply wells in that county in 1990. That recently initiated excavation in SW Florida revealed environmental damage extending beyond the mine boundaries, to surrounding private property, and is the first documented case of such damage solely from aquifer formation mining and nonmechanical dewatering of the aquifer system. A federal court ruled on 22 March 2006 that the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service had failed to carry out their duty to protect the federal wetlands and protected species by issuing permits for mining in the SE case-study area.

Abstract Urbanization is increasing worldwide, and it has drastic effects on groundwater systems with ramifications for water management. Effects can include overexploitation, subsidence, water quality deterioration, destruction of environmental resources, increased runoff, alteration of the permeability and porosity fields, and changes in recharge. Commonly, it is assumed that recharge decreases, but data indicate the opposite: Groundwater recharge increases because of leaky utility (water and sewage) systems and urban irrigation. Urban areas are hydrologically similar to karst settings because they possess internal drainage (storm sewers), surface streams (paved drainage ways) that flow after heavy rains, and a shallow permeability structure dominated by fractures, conduits, and caves (buried utility trenches, abandoned pipes, etc.) that evolves very quickly. Secondary porosity from underground construction is similar in magnitude to karst secondary porosity. These structures and utility trenches increase permeability and make prediction of groundwater flow and transport difficult. Recharge is grouped into the following categories: direct (from precipitation), indirect (from surface water bodies and leaky utility systems), localized (through preferential pathways such as sinkholes), and artificial. Indirect recharge is commonly ignored in urban water budgets, but water main losses range from 5% to over 60%. Additional recharge comes from leaky sewers, leakage from beneath homes and industries, and irrigation return flow (e.g., lawn overwatering). A case study of Austin, Texas, demonstrates significant indirect recharge and the difficulties in its estimation. Nearly 8% of Austin water main flow is lost to become recharge. However, lawn irrigation may be a larger source.