Adaptation Planning to Minimize Damage to Road Infrastructure from Rising Groundwater Associated with Climate Change and Sea Level Rise in Coastal New Hampshire

Abstract:

Coastal communities with high population density and infrastructure close to the shoreline are vulnerable to the effects of climate change and sea level rise (SLR). In the northeast, annual precipitation has increased by more than 10-percent in the last 100 years and is projected to increase further in the future. In addition, sea level in coastal New Hampshire is projected to rise 1.2 to 2.0 meters by the year 2100 (New Hampshire Coastal Risks and Hazards Commission). Climate change vulnerability and adaptation studies have primarily focused on surface water flooding from SLR; however, little attention has been given to rising waters from beneath the ground surface. Groundwater in many coastal communities will rise with rising sea level which will likely have important consequences for water quality, the structural integrity of foundations and infrastructure, and the health of natural ecosystems in the coastal zone.

In this study, we have constructed a regional groundwater flow model of coastal New Hampshire to investigate the effect of various climate change and SLR scenarios on groundwater levels, focusing on impacts to road infrastructure. Using LiDAR datasets and downscaled global climate predictions, we determined that the interaction of several hydrogeological factors resulted in distinct spatial patterns of groundwater rise that were not evident from simple models linking SLR and terrain. Furthermore, by loosely coupling the groundwater model to a hydraulic model for pavement systems, we were able to identify sections of roadways that will have compromised pavement performance due to rising groundwater intersecting the sublayers of these roadways. Our findings broadly suggest that adaptation strategies designed to counter the effects of climate change and SLR in coastal communities must consider potential damage from rising groundwater in addition to surface water impacts not only immediately along the coast but also at significant distances inland.