OBSERVATIONS OF SEASONAL CHANGES AND STORM EFFECTS ON A BEDROCK-INFLUENCED, PARAGLACIAL COASTAL SYSTEM: NEW HAMPSHIRE

Coastal systems are undergoing increasing pressure due to growing anthropogenic influences, accelerated eustatic sea-level rise, and more intense storms due to climate change. Consequently, a thorough understanding of coastal processes and sediment dynamics is necessary to create and maintain a sustainable balance between human influences and coastal environments. Like many other areas in the northeastern United States, the New Hampshire coastal region is heavily developed and features almost continuous engineering structures along the entire coast. Despite the extensive development, the New Hampshire coast has not been systematically studied to evaluate changes in beach morphology and sedimentology on seasonal bases nor in response to storms. To address these needs, monitoring stations have been established along the New Hampshire coast to study beach morphology, volumetric changes, sediments, and morphodynamics. Beach profiles are being measured primarily utilizing a GPS rover system. Each beach has been profiled at approximately bimonthly intervals, with additional surveys before and after high energy events. In addition, an uncertainty analysis was conducted. Initial profiling results indicate significant changes in beach elevation in response to relatively weak events. For example, the berm crest at the northernmost Hampton Beach station shifted 8.5m landward and lost 31 cm of elevation between June 2015 and July 2015, with no major storms as influences. In contrast, the berm crest at the northernmost Seabrook Beach station retreated 19.5m between July and October 2015 (likely in response to a minor storm), then steadily prograded 18.5m between October and December 2015. The beaches will continue to be monitored through spring 2016 to assess the impacts of winter storms.