Date of Award

Spring 2008

Project Type

Dissertation

Program or Major

Natural Resources and Environmental Studies

Degree Name

Doctor of Philosophy

Abstract

Given the growing national water crisis, this research quantified and refined the states of stratified-drift aquifers with potential to yield 75+ gpm (OSDA75) and 150+ gpm (OSDA150) in New Hampshire for 2000 and 2025. Surface waters, cultural features and groundwater hazards from 13 federal/state datasets were buffered according to desired well yields, and then overlain within a geographic information system onto stratified-drift aquifer (OSDA) layer. Non-buffered, highly-transmissive polygons defined the aquifer areas remaining available with potential to meet 75+gpm or 150+ gpm well yields (RSDA75 or RSDA150). Aquifer losses for 2025 were modeled by principal-components regression as function of aquifer area and projected on-aquifer populations. Finally, the source OSDA area and RSDA estimates were reassessed using 1300 verification wells.

Results. OSDA encompasses 13.4% of New Hampshire, 41 % of its population and 58.3% of its groundwater hazards. The greatest population and groundwater-hazard densities exist on the most vulnerable aquifer areas, OSDA75 and OSDA150. After overlay analysis, RSDA75 and RSDA150 were estimated as 118.4 mi2 (9.5%) and 47.6 mi2 (3.8%), respectively. Most towns have less than 0.5 mi2 of RSDA75/150, while the majority of RSDA75/150 exists in relatively few towns. Regionally, the highly populated coast has minimal high-yield OSDA, while the more urban South and North each have about 5% and 2% of the state's RSDA75 and RSDA150, respectively. 1990-2000 population growth for Uplands and OSDA was 14% and 7% respectively. Projected OSDA75/150 losses for 2025 were unexpectedly low since historical OSDA population growth was lower than average; losses early in development are high, and the largest aquifers, (those forecast for the greatest population growth), accommodate additional people with lower per capita losses, since buffer overlap increases.

Verification wells suggest that 26% of all OSDA is either till, clay or unsaturated. Based on the Mazzafero equation, about 50% of the above RSDA75 and RSDA150 areas lack sufficient saturated thickness to sustain high yields. Existing water-quality issues will likely further reduce these estimates .

In summary, high-yield stratified-drift aquifers are far less available, and far more threatened than commonly thought. Given the national situation, these water resources need to be conserved to the greatest degree possible in the present.

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