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Brad A Murray - One of the best experts on this subject based on the ideXlab platform.
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recent shifts in coastline change and shoreline stabilization linked to storm climate change
Earth Surface Processes and Landforms, 2015Co-Authors: Jennifer M Johnson, Brad A Murray, Laura J Moore, K D Ells, Peter N Adams, Richard Mackenzie, John M JaegerAbstract:Since cuspate coastlines are especially sensitive to changes in wave climate, they serve as potential indicators of initial responses to changing wave conditions. Previous work demonstrates that Cape Hatteras and Cape Lookout, North Carolina, which are largely unaffected by shoreline stabilization efforts, have become increasingly asymmetric over the past 30 years, consistent with model predictions for coastline response to increases in Atlantic Ocean summer wave heights and resulting changes in the distribution of wave-approach angles. Historic and recent shoreline change observations for Cape Fear, North Carolina, and model simulations of coastline response to an increasingly asymmetric wave climate in the presence of Beach Nourishment, produce comparable differences in shoreline change rates in response to changes in wave climate. Results suggest that the effect of Beach Nourishment is to compensate for – and therefore to mask – natural responses to wave climate change that might otherwise be discernible in patterns of shoreline change alone. Therefore, this case study suggests that the effects of wave climate change on human-modified coastlines may be detectable in the spatial and temporal patterns of shoreline stabilization activities. Similar analyses of cuspate features in areas where the change in wave climate is less pronounced (i.e. Fishing Point, Maryland/Virginia) and where local geology appears to exert control on coastline shape (i.e. Cape Canaveral, Florida), suggest that changes in shoreline configuration that may be arising from shifting wave climate are currently limited to sandy wave-dominated coastlines where the change in wave climate has been most pronounced. However, if hurricane-generated wave heights continue to increase, large-scale shifts in patterns of erosion and accretion will likely extend beyond sensitive cuspate features as the larger-scale coastline shape comes into equilibrium with changing wave conditions. Copyright © 2014 John Wiley & Sons, Ltd.
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climate adaptation and policy induced inflation of coastal property value
PLOS ONE, 2015Co-Authors: Dylan E Mcnamara, Martin D Smith, Sathya Gopalakrishnan, Brad A MurrayAbstract:Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for Beach Nourishment. As climatic drivers and federal policies for Beach Nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including Beach Nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal Nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if Nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.
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the value of disappearing Beaches a hedonic pricing model with endogenous Beach width
Journal of Environmental Economics and Management, 2011Co-Authors: Sathya Gopalakrishnan, Jordan M Slott, Martin D Smith, Brad A MurrayAbstract:Beach Nourishment is a policy used to rebuild eroding Beaches with sand dredged from other locations. Previous studies indicate that Beach width positively affects coastal property values, but these studies ignore the dynamic features of Beaches and the feedback that Nourishment has on shoreline retreat. We correct for the resulting attenuation and endogeneity bias in a hedonic property value model by instrumenting for Beach width using spatially varying coastal geological features. We find that the Beach width coefficient is nearly five times larger than the OLS estimate, suggesting that Beach width is a much larger portion of property value than previously thought. We use the empirical results to parameterize a dynamic optimization model of Beach Nourishment decisions and show that the predicted interval between Nourishment projects is closer to what we observe in the data when we use the estimate from the instrumental variables model rather than OLS. As coastal communities adapt to climate change, we find that the long-term net value of coastal residential property can fall by as much as 52% when erosion rate triples and cost of Nourishment sand quadruples.
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large scale responses of complex shaped coastlines to local shoreline stabilization and climate change
Journal of Geophysical Research, 2010Co-Authors: Jordan M Slott, Brad A Murray, Andrew D AshtonAbstract:[1] When modeling the large-scale (> km) evolution of coastline morphology, the influence of natural forces is not the only consideration; ongoing direct human manipulations can substantially drive geomorphic change. In this paper, we couple a human component to a numerical model of large-scale coastline evolution, incorporating Beach “Nourishment” (periodically placing sand on the Beach, also called “Beach replenishment” or “Beach fill”). Beach Nourishment is the most prevalent means humans employ to alter the natural shoreline system in our case study, the Carolina coastline. Beach Nourishment can cause shorelines adjacent to those that are nourished to shift both seaward and landward. When we further consider how changes to storm behaviors could change wave climates, the magnitude of morphological change induced by Beach Nourishment can rival that expected from sea level rise and affect the coast as far as tens of kilometers away from the Nourishment site. In some instances, nonlocal processes governing large-scale cuspate-cape coastline evolution may transmit the human morphological “signal” over surprisingly large (hundreds of kilometer) distances.
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Beach Nourishment as a dynamic capital accumulation problem
Journal of Environmental Economics and Management, 2009Co-Authors: Martin D Smith, Jordan Slott, Dylan E Mcnamara, Brad A MurrayAbstract:Abstract Beach Nourishment is a common coastal management strategy used to combat erosion along sandy coastlines. It involves building out a Beach with sand dredged from another location. This paper develops a positive model of Beach Nourishment and generates testable hypotheses about how the frequency of Nourishment responds to property values, project costs, erosion rates, and discounting. By treating the decision to nourish as a dynamic capital accumulation problem, the model produces new insights about coupled economic geomorphological systems. In particular, determining whether the frequency of Nourishment increases in response to physical and economic forces depends on whether the decay rate of Nourishment sand exceeds the discount rate.
Sathya Gopalakrishnan - One of the best experts on this subject based on the ideXlab platform.
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shoreline defense against climate change and capitalized impact of Beach Nourishment
Journal of Environmental Economics and Management, 2018Co-Authors: Yun Qiu, Sathya GopalakrishnanAbstract:Beach communities respond to storm risks through shoreline stabilization policies and often rebuild eroding Beaches with sand dredged from offshore locations and inlets. Investments in natural capital through Beach Nourishment are, at least partly, capitalized in coastal property values. We combine data on housing sales between 2008 and 2014 in Dare County, North Carolina with geo-spatial information on the timing and location of the first Beach Nourishment in the town of Nags Head to estimate the perceived risk-reduction effect, using Hurricane Sandy as a natural experiment. We find that the effect is heterogeneous both within and across nourished and unnourished regions. Triple difference estimates reveal that investment in Nourishment results in a price premium of 11.7% to 16.5% for oceanfront homes located in a nourished Beach. Converting the average treatment effect of 13.4% from our preferred model to aggregate benefits capitalized by oceanfront homes in Nags Head suggests that the value of Beach Nourishment exceeds $16 million.
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Decentralized Management Hinders Coastal Climate Adaptation: The Spatial-dynamics of Beach Nourishment
Environmental and Resource Economics, 2017Co-Authors: Sathya Gopalakrishnan, Martin D Smith, Dylan Mcnamara, A. Brad MurrayAbstract:Climate change threatens to alter coastline erosion patterns in space and time and coastal communities adapt to these threats with decentralized shoreline stabilization measures. We model interactions between two neighboring towns, and explore welfare implications of spatial-dynamic feedbacks in the coastal zone. When communities are adjacent, the community with a wider Beach loses sand to the community with a narrower Beach through alongshore sediment transport. Spatial-dynamic feedbacks create incentives for both communities to nourish less, resulting in lower long-run Beach width and lower property values in both communities, a result that parallels the classic prisoner’s dilemma. Intensifying erosion—consistent with accelerating sea level rise—increases the losses from failure to coordinate. Higher erosion also increases inequality in the distribution of benefits across communities under spatially coordinated management. This disincentive to coordinate suggests the need for higher-level government intervention to address a traditionally local problem. We show that a spatially targeted subsidy can achieve the first best outcome, and explore conditions under which a second-best uniform subsidy leads to small or large losses.
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climate adaptation and policy induced inflation of coastal property value
PLOS ONE, 2015Co-Authors: Dylan E Mcnamara, Martin D Smith, Sathya Gopalakrishnan, Brad A MurrayAbstract:Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for Beach Nourishment. As climatic drivers and federal policies for Beach Nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including Beach Nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal Nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if Nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.
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emergent behavior in a coupled economic and coastline model for Beach Nourishment
Nonlinear Processes in Geophysics, 2011Co-Authors: Eli D Lazarus, Martin D Smith, Dylan E Mcnamara, Sathya Gopalakrishnan, A B MurrayAbstract:Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. "Beach Nourishment", a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered Beach, causing further changes to the shoreline that in turn affect subsequent Beach-Nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens when an optimization strategy that explicitly ignores spatial interactions is incorporated into a physical model that is spatially dynamic? The long-term attractor that develops for the coupled system (the state and behavior to which the system evolves over time) is unclear. We link an economic model, in which town-manager agents choose economically optimal Beach-Nourishment intervals according to past observations of their immediate shoreline, to a simplified coastal-dynamics model that includes alongshore sediment transport and background erosion (e.g. from sea-level rise). Simulations suggest that feedbacks between these human and natural coastal processes can generate emergent behaviors. When alongshore sediment transport and spatially myopic Nourishment decisions are coupled, increases in the rate of sea-level rise can destabilize economically optimal Nourishment practices into a regime characterized by the emergence of chaotic shoreline evolution.
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the value of disappearing Beaches a hedonic pricing model with endogenous Beach width
Journal of Environmental Economics and Management, 2011Co-Authors: Sathya Gopalakrishnan, Jordan M Slott, Martin D Smith, Brad A MurrayAbstract:Beach Nourishment is a policy used to rebuild eroding Beaches with sand dredged from other locations. Previous studies indicate that Beach width positively affects coastal property values, but these studies ignore the dynamic features of Beaches and the feedback that Nourishment has on shoreline retreat. We correct for the resulting attenuation and endogeneity bias in a hedonic property value model by instrumenting for Beach width using spatially varying coastal geological features. We find that the Beach width coefficient is nearly five times larger than the OLS estimate, suggesting that Beach width is a much larger portion of property value than previously thought. We use the empirical results to parameterize a dynamic optimization model of Beach Nourishment decisions and show that the predicted interval between Nourishment projects is closer to what we observe in the data when we use the estimate from the instrumental variables model rather than OLS. As coastal communities adapt to climate change, we find that the long-term net value of coastal residential property can fall by as much as 52% when erosion rate triples and cost of Nourishment sand quadruples.
Martin D Smith - One of the best experts on this subject based on the ideXlab platform.
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Decentralized Management Hinders Coastal Climate Adaptation: The Spatial-dynamics of Beach Nourishment
Environmental and Resource Economics, 2017Co-Authors: Sathya Gopalakrishnan, Martin D Smith, Dylan Mcnamara, A. Brad MurrayAbstract:Climate change threatens to alter coastline erosion patterns in space and time and coastal communities adapt to these threats with decentralized shoreline stabilization measures. We model interactions between two neighboring towns, and explore welfare implications of spatial-dynamic feedbacks in the coastal zone. When communities are adjacent, the community with a wider Beach loses sand to the community with a narrower Beach through alongshore sediment transport. Spatial-dynamic feedbacks create incentives for both communities to nourish less, resulting in lower long-run Beach width and lower property values in both communities, a result that parallels the classic prisoner’s dilemma. Intensifying erosion—consistent with accelerating sea level rise—increases the losses from failure to coordinate. Higher erosion also increases inequality in the distribution of benefits across communities under spatially coordinated management. This disincentive to coordinate suggests the need for higher-level government intervention to address a traditionally local problem. We show that a spatially targeted subsidy can achieve the first best outcome, and explore conditions under which a second-best uniform subsidy leads to small or large losses.
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climate adaptation and policy induced inflation of coastal property value
PLOS ONE, 2015Co-Authors: Dylan E Mcnamara, Martin D Smith, Sathya Gopalakrishnan, Brad A MurrayAbstract:Human population density in the coastal zone and potential impacts of climate change underscore a growing conflict between coastal development and an encroaching shoreline. Rising sea-levels and increased storminess threaten to accelerate coastal erosion, while growing demand for coastal real estate encourages more spending to hold back the sea in spite of the shrinking federal budget for Beach Nourishment. As climatic drivers and federal policies for Beach Nourishment change, the evolution of coastline mitigation and property values is uncertain. We develop an empirically grounded, stochastic dynamic model coupling coastal property markets and shoreline evolution, including Beach Nourishment, and show that a large share of coastal property value reflects capitalized erosion control. The model is parameterized for coastal properties and physical forcing in North Carolina, U.S.A. and we conduct sensitivity analyses using property values spanning a wide range of sandy coastlines along the U.S. East Coast. The model shows that a sudden removal of federal Nourishment subsidies, as has been proposed, could trigger a dramatic downward adjustment in coastal real estate, analogous to the bursting of a bubble. We find that the policy-induced inflation of property value grows with increased erosion from sea level rise or increased storminess, but the effect of background erosion is larger due to human behavioral feedbacks. Our results suggest that if Nourishment is not a long-run strategy to manage eroding coastlines, a gradual removal is more likely to smooth the transition to more climate-resilient coastal communities.
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emergent behavior in a coupled economic and coastline model for Beach Nourishment
Nonlinear Processes in Geophysics, 2011Co-Authors: Eli D Lazarus, Martin D Smith, Dylan E Mcnamara, Sathya Gopalakrishnan, A B MurrayAbstract:Developed coastal areas often exhibit a strong systemic coupling between shoreline dynamics and economic dynamics. "Beach Nourishment", a common erosion-control practice, involves mechanically depositing sediment from outside the local littoral system onto an actively eroding shoreline to alter shoreline morphology. Natural sediment-transport processes quickly rework the newly engineered Beach, causing further changes to the shoreline that in turn affect subsequent Beach-Nourishment decisions. To the limited extent that this landscape/economic coupling has been considered, evidence suggests that towns tend to employ spatially myopic economic strategies under which individual towns make isolated decisions that do not account for their neighbors. What happens when an optimization strategy that explicitly ignores spatial interactions is incorporated into a physical model that is spatially dynamic? The long-term attractor that develops for the coupled system (the state and behavior to which the system evolves over time) is unclear. We link an economic model, in which town-manager agents choose economically optimal Beach-Nourishment intervals according to past observations of their immediate shoreline, to a simplified coastal-dynamics model that includes alongshore sediment transport and background erosion (e.g. from sea-level rise). Simulations suggest that feedbacks between these human and natural coastal processes can generate emergent behaviors. When alongshore sediment transport and spatially myopic Nourishment decisions are coupled, increases in the rate of sea-level rise can destabilize economically optimal Nourishment practices into a regime characterized by the emergence of chaotic shoreline evolution.
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the value of disappearing Beaches a hedonic pricing model with endogenous Beach width
Journal of Environmental Economics and Management, 2011Co-Authors: Sathya Gopalakrishnan, Jordan M Slott, Martin D Smith, Brad A MurrayAbstract:Beach Nourishment is a policy used to rebuild eroding Beaches with sand dredged from other locations. Previous studies indicate that Beach width positively affects coastal property values, but these studies ignore the dynamic features of Beaches and the feedback that Nourishment has on shoreline retreat. We correct for the resulting attenuation and endogeneity bias in a hedonic property value model by instrumenting for Beach width using spatially varying coastal geological features. We find that the Beach width coefficient is nearly five times larger than the OLS estimate, suggesting that Beach width is a much larger portion of property value than previously thought. We use the empirical results to parameterize a dynamic optimization model of Beach Nourishment decisions and show that the predicted interval between Nourishment projects is closer to what we observe in the data when we use the estimate from the instrumental variables model rather than OLS. As coastal communities adapt to climate change, we find that the long-term net value of coastal residential property can fall by as much as 52% when erosion rate triples and cost of Nourishment sand quadruples.
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Beach Nourishment as a dynamic capital accumulation problem
Journal of Environmental Economics and Management, 2009Co-Authors: Martin D Smith, Jordan Slott, Dylan E Mcnamara, Brad A MurrayAbstract:Abstract Beach Nourishment is a common coastal management strategy used to combat erosion along sandy coastlines. It involves building out a Beach with sand dredged from another location. This paper develops a positive model of Beach Nourishment and generates testable hypotheses about how the frequency of Nourishment responds to property values, project costs, erosion rates, and discounting. By treating the decision to nourish as a dynamic capital accumulation problem, the model produces new insights about coupled economic geomorphological systems. In particular, determining whether the frequency of Nourishment increases in response to physical and economic forces depends on whether the decay rate of Nourishment sand exceeds the discount rate.
Fedor Baart - One of the best experts on this subject based on the ideXlab platform.
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a cnn lstm method for the morphology evolution prediction of Beach mega Nourishment
IEEE Access, 2020Co-Authors: Peter Van Oosterom, Xiaoxiang Zhang, Fedor BaartAbstract:Sand Nourishment is widely adopted as an effective soft approach to provide long-term coastal safety, protect the ecology environment, and promote tourism and recreation. With the increase in frequency and expenses in Beach Nourishment worldwide, an adequate prediction of morphology evolution is greatly desired for coastline management. Based on detailed monitoring data of the mega-Nourishment Sand Engine, this article integrates a convolutional neural network (CNN) and long short-term memory (LSTM) to predict the Nourishment morphology evolution. The historical surveyed data are transformed into sequence grids, which are input into the CNN to obtain the spatial features of Beach Nourishment. The CNN is constructed by performing the convolutional and pooling operation on the historical data, which can extract actual spatial features and reduce network complexity. The output of the CNN is input to LSTM to learn the temporal relationship to predict future Nourishment terrain using past time-series features. Finally, the LSTM output is decoded by the fully connected layer to obtain the prediction result. The complex spatiotemporal correlations among the input data are identified through effective training of the proposed model. The major contribution of this article is to propose a data-driven model that combines CNN and LSTM for the morphology evolution prediction of Beach Nourishment, and validate the effectiveness of the proposed model by comparing with the performances of other popular methods in predicting the Nourishment changes.
Jordan M Slott - One of the best experts on this subject based on the ideXlab platform.
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the value of disappearing Beaches a hedonic pricing model with endogenous Beach width
Journal of Environmental Economics and Management, 2011Co-Authors: Sathya Gopalakrishnan, Jordan M Slott, Martin D Smith, Brad A MurrayAbstract:Beach Nourishment is a policy used to rebuild eroding Beaches with sand dredged from other locations. Previous studies indicate that Beach width positively affects coastal property values, but these studies ignore the dynamic features of Beaches and the feedback that Nourishment has on shoreline retreat. We correct for the resulting attenuation and endogeneity bias in a hedonic property value model by instrumenting for Beach width using spatially varying coastal geological features. We find that the Beach width coefficient is nearly five times larger than the OLS estimate, suggesting that Beach width is a much larger portion of property value than previously thought. We use the empirical results to parameterize a dynamic optimization model of Beach Nourishment decisions and show that the predicted interval between Nourishment projects is closer to what we observe in the data when we use the estimate from the instrumental variables model rather than OLS. As coastal communities adapt to climate change, we find that the long-term net value of coastal residential property can fall by as much as 52% when erosion rate triples and cost of Nourishment sand quadruples.
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large scale responses of complex shaped coastlines to local shoreline stabilization and climate change
Journal of Geophysical Research, 2010Co-Authors: Jordan M Slott, Brad A Murray, Andrew D AshtonAbstract:[1] When modeling the large-scale (> km) evolution of coastline morphology, the influence of natural forces is not the only consideration; ongoing direct human manipulations can substantially drive geomorphic change. In this paper, we couple a human component to a numerical model of large-scale coastline evolution, incorporating Beach “Nourishment” (periodically placing sand on the Beach, also called “Beach replenishment” or “Beach fill”). Beach Nourishment is the most prevalent means humans employ to alter the natural shoreline system in our case study, the Carolina coastline. Beach Nourishment can cause shorelines adjacent to those that are nourished to shift both seaward and landward. When we further consider how changes to storm behaviors could change wave climates, the magnitude of morphological change induced by Beach Nourishment can rival that expected from sea level rise and affect the coast as far as tens of kilometers away from the Nourishment site. In some instances, nonlocal processes governing large-scale cuspate-cape coastline evolution may transmit the human morphological “signal” over surprisingly large (hundreds of kilometer) distances.
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the value of disappearing Beaches a hedonic pricing model with endogenous Beach width
2009 Annual Meeting July 26-28 2009 Milwaukee Wisconsin, 2009Co-Authors: Sathya Gopalakrishnan, Jordan M Slott, Martin D Smith, Brad A MurrayAbstract:Beach Nourishment is a policy used to rebuild eroding Beaches with sand dredged from other locations. Previous studies indicate that Beach width positively affects coastal property values, but these studies ignore the dynamic features of Beaches and the feedback that Nourishment has on shoreline retreat. We correct for the resulting attenuation and endogeneity bias in a hedonic property value model by instrumenting for Beach width using spatially varying coastal geological features. We find that the Beach width coefficient is nearly five times larger than the OLS estimate, suggesting that Beach width is a much larger portion of property value than previously thought. We use the empirical results to parameterize a dynamic optimization model of Beach Nourishment decisions and show that the predicted interval between Nourishment projects is closer to what we observe in the data when we use the estimate from the instrumental variables model rather than OLS. As coastal communities adapt to climate change, we find that the long-term net value of coastal residential property can fall by as much as 52% when erosion rate triples and cost of Nourishment sand quadruples. (This abstract was borrowed from another version of this item.)