This study uses topographic profiles, washover fan volumes, and shoreline retreat rates to explore relationships between barrier types and Hurricane Harvey storm washover sedimentation. Pre- and post-Hurricane Harvey topographic profiles were created on 15 transects using Bare Earth LiDAR (2016) and surveyed elevations (2019). Depth and area of washover fan measurements were collected to estimate washover fan volumes. An inverse relationship was found between washover fan volume and pre- and post-storm barrier heights. Based on the topographic profiles, one section of shoreline had a scarp up to 3m high which blocked overwash, but appears to have increased shoreline erosion. In contrast, a low-lying section of shoreline generated relatively large washover fans, but experienced less shoreline retreat. Shoreline retreat was further quantified between 2014 and 2019 using Google Earth Imagery from 2014, 2016, 2017, and 2019 to track migration of the shoreline. The entire shoreline in the study area is undergoing relatively rapid retreat, but the results suggest that Hurricane Harvey increased erosional rates. The Colorado River Jetty borders the study area and may have acted as an anthropogenic barrier, likely reducing storm surge energy and contributing to marsh aggradation on transects in its close proximity. The study findings indicate that the identification and incorporation of other variables that influence washover magnitude would further the understanding of this complex natural system. The research results provide valuable information on the interaction of hurricane storm surge with natural and anthropogenic barriers, beach and dune erosion, and marsh aggradation along the coast of Texas.

Oyster reefs provide valuable ecosystemservices that contribute to coastal resilience. Unfortunately, many reefs have been degraded or removed completely, and there are increased efforts to restore oysters in many coastal areas. In particular, much attention has recently been given to the restoration of shellfish reefs along eroding shorelines to reduce erosion. Such fringing reef approaches, however, often lack empirical data to identify locations where reefs are most effective in reducing marsh erosion, or fully take into account habitat suitability. Using monitoring data from 5 separate fringing reef projects across coastal Louisiana, we quantify shoreline exposure (fetch + wind direction + wind speed) and reef impacts on shoreline retreat. Our results indicate that fringing oyster reefs have a higher impact on shoreline retreat at higher exposure shorelines. At higher exposures, fringing reefs reduced marsh edge erosion an average of 1.0 m y-1. Using these data, we identify ranges of shoreline exposure values where oyster reefs are most effective at reducing marsh edge erosion and apply this knowledge to a case study within one Louisiana estuary. In Breton Sound estuary, we calculate shoreline exposure at 500 random points and then overlay a habitat suitability index for oysters. This method and the resulting visualization show areas most likely to support sustainable oyster populations as well as significantly reduce shoreline erosion. Our results demonstrate how site selection criteria, which include shoreline exposure and habitat suitability, are critical to ensuring greater positive impacts and longevity of oyster reef restoration projects.

Population living along the coast are at risk of losing land, households, and economic resources due to the hazards of coastal erosion. Scientific research has indicated that 70% of the planet's sandy coastal environment is being impacted by coastal erosion. Due to the different characteristics of the lands in the coastal zone versus other areas, it is important to understand how the hazard of shoreline erosion contributes to subsequent land use change in affected coastal regions. This study analyzes how the level of erosion, land loss, and developed land loss performs when added with the default land use change parameters such as existing developed land proximity, proximity to forested areas, population, transportation, etc. Sample points of 1020 from 10 years and 15 years of shoreline erosion data for the lower Meghna River estuary of Southeast Bangladesh have been obtained and from there, different erosion statistics have been developed. Developed land use data has been collected from ESA's World Settlement Footprint dataset and other datasets are also collected from secondary data sources. Logistic regression modeling shows that there are verified contributions of proximity to erosion and amount of land loss with the probability of developed land use conversion in the study area. Adding the variables of environmental hazards increases the prediction accuracy by 2-3% and overall, the models are at least 85% accurate. / Master of Science / Population living along the coast are at risk of losing land, households, and economic resources due to the hazards of coastal erosion. The coast of the Lower Meghna estuary in Bangladesh is a region experiencing chronic and severe shoreline erosion that causes the land to be lost to estuarine waters. This research quantifies the amount of land lost to erosion with a special focus on the amount of developed land that is lost. Developed land in this study is defined as a built-up area typically composed of buildings and roads. The research also evaluates the effects of lost land on the subsequent conversion of interior land from a non-developed to developed status. The main contribution is to quantitatively identify the association between the erosion-induced land loss to future land use conversion. Using statistical modeling and digital mapping methods, results show that loss of land is associated with the subsequent conversion of non-developed land to developed land use. In particular, conversion has a higher probability at sites that are located more distant from the eroding shoreline that also are proximal to shoreline sites with higher rates of erosion-induced land loss. These results are suggestive of a relocation process where previously lost developed land is reestablished at interior sites within five kilometers of the eroding shoreline.

Bathymetric mapping is an important tool for reservoir management, typically completed before reservoir construction. Historically, bathymetric maps were produced by interpolating between points measured at a relatively large spacing throughout a reservoir, typically on the order of a few, up to 10, meters or more depending on the size of the reservoir. These measurements were made using traditional survey methods before the reservoir was filled, or using sonar surveys after filling. Post-construction issues such as sedimentation and erosion can change a reservoir, but generating updated bathymetric maps is difficult as the areas of interest are typically in the sediment deltas and other difficult-to-access areas that are often above water or exposed for part of the year. We present a method to create complete reservoir bathymetric maps, including areas above the water line, using small unmanned aerial vehicle (sUAV) photogrammetry combined with multi-beam sonar data--both established methods for producing topographic models. This thesis presents methods to create accurate above-water shoreline models using images from sUAVs, processed using a commercial software package and a method to accurately knit sonar and Structure from Motion (SfM) data sets by matching slopes. The models generated by both approaches are point clouds, which consist of points representing the ground surface in three-dimensional space. Generating models from sUAV-captured images requires ground control points (GCPs), i.e., points with a known location, to anchor model creation. We explored issues with ground control spacing, masking water regions (or omitting water regions) in the images, using no GCPs, and incorrectly tagging a GCP. To quantify the effect these issues had on model accuracy, we computed the difference between generated clouds and a reference point cloud to determine the point cloud error. We found that the time required to place GCPs was significantly more than the time required to capture images, so optimizing GCP density is important. We found that we needed to mask water and areas related to distant regions and sky in images used for model creation. This is because water, objects in the far oblique distance, and sky confuse the algorithms that match points among images. Our sonar point clouds, while self-consistent, were not accurately georeferenced. We demonstrate a method using cross-sections of the transition between the above-water clouds and sonar clouds to geo-locate the sonar data and accurately knit the two data sets. Shore line topography models and integration of sonar and drone data is a niche area that leverages current advances in data collection and processing. Our work was applied at three different reservoirs to show that accurate post-construction reservoir bathometry maps can assist with reservoir management. A report is included that compares historical bathymetric maps with the current bathymetric maps at each of the three different reservoirs. A guide to perform the drone surveys is included in the report's appendix.

Efforts to mitigate shoreline erosion through living shoreline methods along the USA Atlantic seaboard have often incorporated the cultivation and transplantation of smooth cordgrass, Spartina alterniflora. Assessments of these transplants at several sites in the Indian River Lagoon have shown that survival is variable after a year (survival: 10-93%). Lower survival has been attributed to environmental variables such as dislodgement by wave energy, and transplant shock due to salinity changes from cultivation to estuarine conditions. To improve living shoreline projects, we examined the effects of cultivation salinity (0 ppt, 15ppt) on transplantation success, and the success of anchoring plants to biodegradable mats (Jute mesh, 5 individuals per 50 cm2) and utilizing oyster bags as breakwaters in facilitating reestablishment of new transplants. Spartina alterniflora individuals were grown under salinity treatments for 20 weeks; plants grown in 15 ppt produced new shoots with significantly greater heights than those grown in freshwater. The plants were then transplanted to two sites in the IRL, and monitored after four weeks. After four weeks there was a greater net increase in stem density and larger decrease in plant height for plants grown in 15 ppt. Jute-mesh mats and oyster bags did not impact growth or survival of transplants. Low-saline (15 ppt) conditions increased shoot growth of the project by 50% in four weeks at a cost of 30 cents per additional shoot produced by an individual. Longer-term monitoring will determine if benefits persist or decrease over time, and if the cost is justified by the benefits.

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Det är tack vare strandskydd som möjligheten att promenera längs stränder, bada, fiska, åka skridskor och även gå i land från en båt finns. Skyddet bistår även med skydd för både djur och växter som lever på och i närheten av stränderna, samt i vattnet.  Inom ett strandskyddat område finns det en del förbud och regler gällande vad man får och inte får göra. Önskar man ändå bygga, ändra eller åtgärda något inom ett strandskyddat område kan man ansöka om dispens från strandskyddet hos sin kommun. För att få igenom dispens krävs att man har särskilda skäl. Länsstyrelsen ska granska alla beslut om dispens som kommunen tagit, och de har rätt att både överpröva samt upphäva en dispens i syfte att tillvarata det allmänna intresset som strandskyddet utgör.  Årligen ser man artiklar gällande beslut om dispens från strandskydd, som blir både omdebatterade och ifrågasatta. Debatten handlar bland annat om att reglerna kring strandskydd inte tillämpas lika, och att länsstyrelsen inte fattar konsekventa beslut. Kan det vara så att bestämmelserna i lagstiftningen innehåller vaga definitioner och svårtolkade rekvisit, som i sin tur leder till en olikartad tillämpning?  Syftet med analysen är att undersöka länsstyrelsens hantering av beslut avseende dispens från strandskydd, för att ta reda på om den nämnda myndigheten är konsekvent i sitt sätt att hantera ärenden där kommunen givit dispens. En avgränsning kommer dock att göras till enbart ärenden på Gotland, under en begränsad tidsperiod. Utredningen bygger på en kvalitativ studie där resultatet arbetas fram genom att en komparativ fallstudie utförs. Studien bygger främst på material från olika offentliga handlingar och juridiska ärenden/rättsfall, som analyseras i syfte att se ett samband, eller inte, mellan hanteringen av olika ärenden avseende en och samma juridiska fråga, strandskyddsdispens.  Resultatet visar på att vaga definitioner och otydliga kriterier i lagen, kombinerat med bristande dokumentation och underlag i bedömningar och beslut, ger upphov till en olikartad tillämpning i ärenden om strandskyddsdispens. Bilden av en olikartad tillämpning är inte nödvändigtvis något som skett aktivt och genomtänkt, utan det mest sannolika är att det lämnas för mycket utrymme för tolkning och egen bedömning åt de beslutande myndigheterna. Det som saknas är tydliga riktlinjer, definitioner och kriterier för att kunna få ett mer konsekvent beslutsfattande. Framförallt krävs tydligare och mer omfattande dokumentation i länsstyrelsens bedömningar och beslut, detta för att skapa en naturlig mall för framtida bedömningar. / Thanks to the shoreline protection we have the possibility to walk along the beach, swim, go fishing, ice-skate and even go ashore from a boat. It also assists protection for both animals and plants who live close to or on beaches, as well as in the water.  Within the shoreline protection there are some prohibitions and rules. If you want to build or change anything within the area you have to get an exemption from your municipality. To get an exemption you need to have special reasons for it. The county administration needs to review all the decisions from the municipality, and also have the right to reexamine and even repeal the decision.  Yearly, we see articles about the given exemptions from the shoreline protection that get debated and questioned. The debates are often about how the rules are not applied consistently. Can it be that the laws are too vague or difficult to interpret? And that is why it is applied inconsistently? The purpose with this analysis is to examine the county administration's way of dealing with shoreline protection exemptions, to see if they’re consistent or not in the decision making. I’ve delimited this study to cases only on Gotland, all decided on during a specific period of time. This analysis will be a qualitative investigation where the results will come from a comparative case study. The study is built on material from public and legal documents, which will be analyzed with the purpose to find connections between similar cases about exemption from the shoreline protection. The result shows that vague definitions and unclear criterias in the law, combined with insufficient documentation in assessments and decisions, is what have resulted in an inconsistency in the matter. The picture of an inconsistent decision making is not necessarily an active choice, more likely are the authorities left with too much possibility to interpret the matter. What is needed is clear guidelines, definitions and criterias to be able to make consistent decisions.  Most of all there needs to be a lot more comprehensive documentation from the authorities, in both their assessments and final decisions. This, to get a template for future assessments.

Salt marsh creation provides functions and values that are essential to maintain the welfare of people and the integrity of coastal area ecosystems. The literature review provides greater understanding of salt marsh functions and values technical information regarding wetland creation in coastal regions. Interviews and case study analyses identify issues and opportunities regarding salt marsh creation. Products of this study include a model approach, criteria for project evaluation, and principles and guidelines for salt marsh creation and coastal residential development. Model approach applies the technical information and processes of salt marsh creation provided by scientists and engineers to the landscape architecture design process. The model approach encourages involvement of the client and other professionals throughout the planning and design process. The proposed criteria provide a framework for landscape architects to evaluate the structure and function of created ecosystems and developments. Four salt marsh creation projects around the Chesapeake Bay were selected for review and evaluated according to these criteria. Each project provides evidence that salt marsh creation can benefit residential developments by providing long-term shoreline protection, water purification, wildlife habitat, and amenity of a naturalistic landscape. Design principles and guidelines will help ensure that the model approach is used by developers to attain salt marsh creation that fits the patterns and functions of surrounding ecological systems and increases residents' awareness of both functions and values of salt marsh and the larger. / Master of Landscape Architecture