"ESTUARY BUILDER": A DIAGNOSTIC TOOL FOR COASTAL VULNERABILITY RELATED TO LAND-SEA CONNECTIONS

Assessment of the vulnerability of estuaries to impairments requires knowledge of how drivers of vulnerability governed by land-sea connections vary across different characteristic estuary settings. Methods for making these assessments in a systematic way become particularly important as the geographic scope of the problem increases. In Maine, where bacteria pollution from contaminated runoff and other sources threatens valuable estuarine shellfisheries with implications to both health and coastal businesses, managers are faced with the task of sustainably managing estuaries along a ~5,600 km long, geographically varied coastline without the resources to monitor conditions at all sites.

This talk describes an interactive setting identification tool for coastal Maine, dubbed the “Estuary Builder,” that combines geographic information systems (GIS) and machine learning to classify estuarine areas into several archetypical setting types, or “coastal pollution response units” (CPRUs), that share physiographic and land cover characteristics. The tool uses flow paths derived from LiDAR elevation data to route landscape precipitation runoff to user-defined embayment outlets, aggregates proxy metric data related to bacteria sources, delivery, and residence time (SDR) for the contributing land-sea connection domain, and identifies which CPRU the delineated estuary unit belongs to based on SDR metrics. This allows it to be used as a research aid and decision support tool to identify setting type and vulnerability drivers for a site and transfer knowledge of management strategies from other estuaries within the same CPRU.

Land-sea connection interfaces, including estuaries and the “margin” watershed areas along their boundaries, are vulnerable to climate change dynamics that will affect transport of contaminants and sediment in freshwater flows, vegetation patterns, and sea levels. While the current version of the Estuary Builder is focused on bacteria pollution, its design provides a flexible framework that can be adapted to accommodate diagnosis of multiple axes of vulnerability related to land-sea connections and coastal morphometry in diverse coastal settings.