Model estimated baseflow for streams with endangered Atlantic Salmon in Maine,USA

Abstract

We present a regression model for estimating mean August baseflow per square kilometer of drainage area to help resource managers assess relative amounts of baseflow in Maine streams with Atlantic Salmon habitat. The model was derived from mean August baseflows computed at 31 USGS streamflow gages in Maine. We use an ordinary least squares regression model to estimate mean August baseflow per unit drainage area from two explanatory variables: percentage of the basin underlain by sand and gravel aquifers and mean July precipitation in the basin. This model provides the ability to estimate mean August baseflow in cubic meters per second per square kilometer of basin area on user-selected, ungaged sites throughout Maine south of 46 21 0 55 00 N latitude. The model has an adjusted R 2 of 0.78 and a mean 95% prediction interval of plus or minus 0.002 cubic meters per second per square kilometer. A map of the Narraguagus watershed in eastern coastal Maine shows reaches color coded by relative amounts of baseflow predicted by the model as an example of how this method could be applied throughout Maine. The map can be used to identify reaches with relatively higher amounts of baseflow during summer low flows for habitat conservation and restoration work. These areas have the potential to be high-quality habitat for Atlantic salmon and other cold-water fish because baseflows are known to moderate stream temperatures in summer low-flow periods.

Modeling Landscape Influence on Stream Baseflows for Watershed Conservation

“…Spatial analysis using Geographic Information Systems (GIS) is used to quantify levels of model variables [17]. A multiple regression model [13,34] is specified to quantify the Land 2024, 13, 324 4 of 14 direction and magnitude of impacts using a sample of various watersheds. A nonlinear baseflow function of watershed attributes (linear and interaction terms) is specified as (1).…”

“…Reducing baseflows can degrade water quality through increased concentrations of particulates, nutrients, chemical contaminants, and microorganisms, affect riparian habitats, and interfere with navigable waterways [12]. Low summer baseflows can cause fish mortalities through flow velocity, cross-sectional area, and water depth [13,14]. Baseflows also influence summer water temperatures that, in turn, impact the health and mortality of fish and aquatic ecosystems [15].…”

Daily stream temperature predictions for free-flowing streams in the Pacific Northwest, USA

“…Although we represented potential surface-subsurface interactions with an index of base flow (BFI), it is difficult to empirically assess groundwater inputs and losses at a large spatial scale. However, a recently developed base flow model produced by [65] seems a promising way to improve representation of the interaction of subsurface and surface water on stream temperature. In addition, planform and longitudinal channel morphology influences rates of surface and hyporheic aquifer exchange, and thus stream temperature, in a complex and not well characterized manner [66], that is strongly influenced by the degree of riverscape impairment, particularly floodplain disconnection [67].…”

NOAA fisheries research geared towards climate-ready living marine resource management in the northeast United States

“…River reaches with high baseflow tend to be cooler in the summer and warmer in the winter providing for longer growth periods and shorter duration of thermal stress for Atlantic salmon. Lombard et al (2021) developed a model to predict and map relative baseflow quantities across Maine at a high spatial resolution (~2.5 km 2 ), providing valuable information to managers making decisions about where to conserve or restore habitat [104]. Through the Collaborative Management Strategy for the Gulf of Maine Atlantic Salmon Recovery Program, work has been initiated with tribal partners, the state of Maine, and non-governmental organizations to identify and protect climate-resilient habitats important to Atlantic salmon.…”

“…Progress has been made to advance regional watershed science through continued coordination across the region. Projects arising through these efforts include two noted in Section 6.2 associated with Atlantic salmon: a range-wide analysis of existing and projected habitat conditions for Atlantic salmon and baseflow mapping across Maine watersheds [104]. Synthesis work on diadromous fish communities and ecosystem interactions of these twelve species was also completed [120].…”