 session, which will be given by R.E.A. Janoff. R.E.A. is a fellow at the U.S. House of Representatives Transportation and Infrastructure Subcommittee, and also the winner of this year's student modeler award. And R.E.A. will be talking about on from coastal retreat to seaward growth. The floor is yours. Thanks so much, Greg. Let's start the presentation. Okay. Good morning, everyone. My name is R.E.A. Janoff and I'm a Knaus Marine Policy Fellow in the U.S. House of Reps with the Committee on Transportation and Infrastructure Subcommittee on Coast Guard and Maritime Transportation. Thank you, systems for the Civitsky Student Modeler Award and for the opportunity to discuss my work with you all. I recently completed my Ph.D. at Montclair State University with Jorge Lorenzo Treba. And today I'll discuss a chapter in my dissertation on community-scale beach nourishment decisions along human-modified coasts, in which I explored the interplay between socioeconomics, coordination, and shoreline change. This work was done in collaboration with researchers at Hui. Thanks to NSF for funding this project under the Dynamics of Coupled Natural Human Systems program and for the computational resource support under the major research instrumentation program. Okay. Let's dive in first for some motivation. My overarching questions were, why are we intervening in the coastal zone? How do we make these decisions on how and when we intervene and how much? And what are the consequences of the decisions that we make? So what do I mean by interventions? Well, we dredge sediments from offshore or tidal inlet reservoirs to add to our beaches. We place hard structures in the surf zone to alter the beach's dynamics to our liking. We build hard revetments and, more recently, dunes to protect against damaging storm surges. And we modify the Siberial or above-water beach to enhance its tourism capacity in the summer months and to reduce the accumulation of windblown sand on roadways in the winter months. So why do we care about how human-developed coasts behave on multi-decadal time scales? Well, there's a lot of money at stake and not just in the form of large beachfront homes. There are municipal, county, and state roads, sewers, water mains, electricity lines, and telecommunication systems. And beaches provide other valuable services as well, such as boardwalk festivals and concessions, recreational facilities such as bachi courts, playgrounds, mini-golf, et cetera, outdoor venues for community building and private events, such as concerts, farm markets, and weddings, towel space to support sunbathing, swimming, surfing, fishing, sailing, and many other ocean-going activities, ecotourism centered on barrier islands, marsh dune, and intertidal habitats, and something spiritual by nature that grounds our soul into the sand and sea, solidifying our presence for generations to come. So what happens when our coastal life and infrastructure are threatened by chronic erosion, storms, or sea level rise? Well, we've abandoned our homes when the damage has been too great. We've raised our homes to avoid flood damage. We've hardened our coast to hold our position, and in recent years we've actually widened our beaches. And this anthropogenic signal is evident in shoreline morphologies. Previous research from Hapke et al. on the left found a switch from historically erosive beaches in bold to more recently progradational beaches in italics, as evidenced by the mean rate switch on the right bar graph from Armstrong et al. Armstrong et al. find that this switch correlates with a rapid uptick in beach nourishment starting in the 1960s. And zooming into Monmouth County, New Jersey, the geomorphic consequence of this signal is clear, spanning multiple communities along the coast. In this case, from 1920 to 2002, Avon by the Sea and Bradley Beach have experienced a seaward shift in their shorelines, highlighted by the red lines relative to their oceanfront infrastructure highlighted by the blue lines. So how do these intercommunity dynamics control systemic behavior? Well, Lazarus et al. and others observed that communities have failed to coordinate in the past. But Gopalakrishnan et al. indicate that coordinated beach nourishments result in higher nourishment rates and thus wider beaches by eliminating the free rider incentive, representing the economically optimal outcome. So can these behavioral feedbacks, based on management scheme, explain the beach widening that we see in New Jersey and along much of the U.S. east coast? This question is topical, given communities may maintain decentralized policies in the future, as suggested by Gopalakrishnan et al., which would serve to amplify wealth disparity due to sea level rise induced erosion. So I explored these questions using an idealized modeling framework. There are three alongshore cells in the model domain. Two neighboring communities, I equals one and I equals two, and one boundary cell, I equals three, the proxy's adjacent natural coast. In response to background erosion, the communities can nourish their beaches, forming an ephemeral seaward protrusion, and triggering a longshore sediment transport based on the coastline's gradient, denoted by the solid line connecting the white circles relative to the angle of wave approach. The sediment is taken from the upper shore face or a subarial beach in seward cells and deposited at the shoreline in landward cells, with a periodic condition at the system's boundary such that any sediments leaving one edge QL3 are received at the other. Now in cross shore, nourishments steepen the shore face slope beyond its equilibrium profile, denoted by the pink line, triggering transport from the upper shore face off shore to the lower shore face or shore face toe, thus relaxing the slope toward equilibrium. The system's morphodynamics can thus be described by two moving boundaries, that the shoreline XS and the shore face toe XT. The shoreline's location relative to the property setback forms the beach width, which is capitalized into the beachfront property value as an environmental amenity, adding both protective and recreational value. Combined with the corresponding project costs, I performed cost-benefit analyses for a range of return periods between nourishments or rotation lengths, and given a fixed project volume, I found the optimal strategy that yields a maximum net benefit. I then compared how communities optimize their rotation lengths based on their respective welfare analyses or the non-coordination scheme, or based on their joint net benefit, the coordination scheme. Next, I explored the role of long shore wealth disparities on strategy selections, and both the geomorphic and economic outcomes of these management decisions. And finally, I tested how this system might respond under higher erosion rates associated with sea level rise and higher sand costs associated with reduced resource availability in the future. In general, the model produces four behaviors on the left, seward growth due to a short rotation length in panel A, hold the line due to a moderate rotation length in panel B, slow retreat due to a long rotation length that results in beachfront property loss in panel C, and full retreat due to no nourishment also resulting in property loss in panel D. There's evidence of these mode behaviors in the field, based on nourishment records on the right, where communities such as Ocean City, New Jersey nourish a lot and widen their beaches in panel A, Brigantine, New Jersey nourishes just enough to protect their properties in panel B, and Dofan Island, Alabama, and Cedar Island, Virginia, panels CND respectively, nourish infrequently or not at all, resulting in property abandonment or relocation. From community scale nourishment and socioeconomic data in New Jersey, I found a community's rotation length decreases, or its nourishment frequency increases, as its beachfront wealth increases. Variability in this relationship, however, could be explained in part by the wealth and nourishment choices in neighboring communities as well. For instance, let's take a look at two pairs of neighboring communities in southern New Jersey. First, Avalon and Stone Harbor, and second, Strathamir and Cile City. So zooming in, we see that Avalon and Stone Harbor are spaced farther apart than Strathamir and Cile City, as evidenced by their scale bars on the bottom right corner in the imagery. This along shore effect manifests in their beach widths, where Avalon and Stone Harbor morphodynamics are more decoupled on the bottom left, and Strathamir and Cile City experience more interconnected beach morphodynamics on the bottom right. This highlights the importance of a longshore connectivity and nourishment policy development. Testing the effect of wealth distribution between neighbors with one community's property value on the y-axis and the others on the x-axis, I found a behavioral progression from full retreat to slow retreat to hold the line to sewer growth as wealth increases, with the thresholds between behaviors, depending on the combination of property values under coordination in the left panel, and on each community's individual property value under non-coordination in the right panel. But I was also interested in the economic implications of such management policies. Comparing the net benefit of coordination and non-coordination quantifies the marginal importance of working cooperatively, depending on a two-community couplets location within the regime's space. Aside from the scenario in which coordination avoids property abandonment highlighted by the arrows on the left, wealth disparate systems realize the greatest marginal increase in net benefit by coordinating, a pinpoint, a representative two-community couplet to show the key difference. In the uncoordinated scheme, wealthier communities tend to undernourish or nourish less frequently than they would have under coordination, because they ignore the external benefits associated with helping preserve their neighbor's features. Whereas, less wealthy communities tend to overnourish or nourish more frequently than they would have under coordination, because they do not account for the beneficial effects of their neighbor's nourishment activities. In short, working together, wealthier communities should nourish more, and less wealthy communities should nourish less than if they form their policies alone. There is evidence of this dynamic in the field, with many instances of less wealthy communities nourishing more than their wealthier neighbors, as seen in the left panel, showing the nourishment flux difference relative to the less wealthy community as a function of the wealth disparity for each data point representing a two-community couplet. Where data below zero indicate the less wealthy community has a higher nourishment flux than the wealthier community. This results in wider beaches, regardless of the magnitude of wealth disparity, as seen in the right panel, showing the beach width difference relative to the less wealthy community as a function of the wealth difference. Where data below zero indicate the less wealthy community realizes wider beaches than the wealthier community. While this data provides evidence of overnourishment, there are some dynamics outside of the model scope. I explore other possible determinants of this nourishment activity in future work. But what happens in the future, as these systems face climate threats such as sea level rise? In addition, as communities deplete their near shore sand supplies and must search for beach quality sand for their offshore, the cost of sand is expected to increase. How will systems respond to these physical and economic changes? I explored community responses and geomorphic behaviors associated with increased erosion rates on the y-axis and increased sand costs on the x-axis for coordination and non-coordination schemes in panels A and B, respectively. If communities coordinate, they might be able to nourish more and preserve their properties longer under higher erosion rates and sand costs than if they manage their beaches alone. This is clearer in the cross-section through the regime's spaces on the right and panel C. This result provides evidence that continued decentralized management will be detrimental for property preservation and that the current misallocation of nourishment effort could be unsustainable. More broadly, the model presents a potential complement to property buyout programs whereby nourishment can reduce the rate of retreat but still lead to the managed removal of properties from vulnerable areas. Ultimately, regional coordination is required to ensure that management policies are both economically and socially just. So what questions emerged? First, why are less wealthy communities nourishing more than wealthier communities in the field, which actually goes beyond model scope, and results in an appreciable geomorphic difference between communities? Can this be explained by non-coordination alone or is there something else within the system controlling this outcome? In addition, how are hard structures such as groins and jetties affecting these nourishment decisions? Do we see dampened nourishment efforts up drift of these structures due to impoundment and amplified efforts down drift due to sediment starvation? So to touch on this future work briefly. As stated, many communities rely on summer tourism for sustaining their local economies evidenced here in Long Branch, New Jersey. And at the multi-community scale, we see a difference in beach recreation by community. Where fewer tourists visit wealthier communities such as Seaside Park and more tourists visit less wealthy communities such as Seaside Heights. Often, these less wealthy communities have boardwalk attractions that, when threatened, require rebuilding and protecting. And wealthier communities like Deal have sought to restrict beach access and have chosen to nourish less, resulting in narrower beaches seen at the bottom of this image. This is evidence of the NIMBY effect, where those with adequate financial and political capital value and thus seek a more private beach experience. And we see evidence of this categorical difference in recreational preference at various points along the coast. On the left, Deal, the wealthier, more residential community, nourishes less than Asbury Park, the less wealthy tourism-centric community. On the right, wealthier Lavalette nourishes less than the less wealthy tourism-centric Seaside Heights. In both cases, these nourishment decisions have resulted in wider beaches for less wealthy communities. This dynamic could help explain the behavioral and geomorphic trends observed in the field. So what's the key takeaway from this work and what does this mean for coastal policy? Communities might forgo significant benefits by failing to coordinate their management plans. Decentralized schemes might make beachfront property protection more difficult under rapid sea-level rise and increasing resource costs. Particularly vulnerable are less wealthy communities overnourishing and present, possibly representing an environmental injustice. And in follow-up work that extended this model framework, I found that property value is not the only driver of community-scale nourishment decisions, but that local beach tourism is also important, especially in New Jersey. And that population density has been a key driver of community responses to growing induced erosion. In future policymaking, we must include social equity as well. This means reframing how we define benefits, given that a wealth-centered analysis will invariably disadvantage low-wealth communities, making their project justifications more difficult if the benefit-cost ratio is too low. As a start, President Biden recently signed an executive order that included a Justice 40 initiative to deliver 40 percent of climate investment benefits to disadvantaged communities. Such directives are key, especially in concert with state-level policy changes. Concurrently, legislators could introduce language that adds priority within existing grant programs to fund projects with environmental justice considerations, to expand how agencies define project benefits, or to stand up new programs with similar goals. So to close, I'd like to extend my heartfelt thanks to the system's community. Since my first meeting, I have felt welcomed, supported, inspired, and a sense of belonging. It is an honor to have this platform to speak on such issues as science policy and environmental equity. Special thanks to my PhD advisor Jorge Lorenzo Treba and my undergraduate advisor Nicole Gasperini. I am proud to follow in your footsteps. And with that, I'll open the floor to questions and leave you with a photo of where we'd all rather be today in beautiful, bolder Colorado at the foot of the Flatirons. Thank you so much, Ariya. That was a terrific talk. Questions for Ariya, either in the chat or with Ray's hand. Well, while you guys are thinking about it, I have one question. I'm curious, Ariya, whether you've had the opportunity to present any of your findings to city councils, mayors, and so on of New Jersey coastal communities or any coastal communities, especially, you know, your finding about the value of coordination and what their reaction has been. Yeah, that's a great question since this work is very applied. So I'm actually the secretary of my towns, my small coastal communities, environmental commission. So I get the chance to work on the ground with some of these issues. And it deals less with coordination and more with just broader environmental issues. But I am engaged in the town council. And I've actually spoken in front of the mayor and council about sea level rise planning. But specifically on coordination, during my PhD defense, I was lucky enough to have the mayor and one of the councilmen join in and listen. And I had a follow up discussion about how we can better coordinate with the councilmen with our neighboring communities. It's a little bit difficult because beach nourishment policies are largely now hashed out at the Army Corps level, you know, the planning stage is at least. And then the opt-in stage and the local financing is done at the local level. But this could be extended beyond just beach nourishment. This could include coordination on living shorelines project for coastal lakes that span to communities. Or, you know, there are shared services between communities. The first one that comes to mind is trash and recycling pickup. I know that that's not exactly resource economics related. But it's similar in that the hardest part about coordination is getting folks to the table and actually being like not doing duplicate duplicative work and being able to work toward one common goal. So hopefully the mayor and council took some of the insights from my defense in our conversations and are trying to implement them at the local level. That's great. Thank you. I see a question from Brad. Go ahead, Brad. All right. Very, very cool talk. Fascinating stuff. I'm wondering, since the modeling is based on the economic benefits to the housing market, and you've shown pretty convincingly that at least in the communities you're looking at the tourism benefit is more dominant in some of those communities. Do you have plans to try to quantify the economic benefits of tourism to feed into this modeling framework to make the model more relevant to those communities that you're looking at? Yeah, that's a great question. And that was actually the focus of my second dissertation chapter. So that was more of an empirical analysis to try to understand how tourism plays a role in determining nourishment policies. And what I found was that the extent of commercial real estate in the community was actually a pretty significant predictor of nourishment policies. So if it's a predictor, that must mean that it's accumulating benefits in some way. So if we could extend the benefit function to not only include residential real estate, but also to include commercial real estate and how nourishment policies can then support a tourism economy, like, if you figure out what the towel space is to then determine how many people are going to be recreating at nearby sites, going to restaurants, what the revenue would be generated for the hotels, and then how that feeds back into the local policies, that could be an example of an extension of the benefit function. Yeah.