Coastal Land Management Research Articles

Urbanization of a Subtropical Island (Okinawa, Japan) Alters Physicochemical Characteristics and Disrupts Microbial Community Dynamics in Nearshore Ecosystems

Subtropical and tropical islands are undergoing rapid urbanization as the human population expands globally. Urbanization disrupts coastal ecosystems through several pathways—including the replacement of natural habitats with concrete structures that increase runoff pollution—but it remains difficult to isolate and characterize specific impacts of urbanization on marine ecosystems. The historical gradient in urbanization on the subtropical island of Okinawa, Japan, sets up a natural laboratory to study urbanization effects on nearshore ecosystems. Physicochemical parameters and bacterial community composition were assessed every 2 weeks for 1 year at two nearshore sites adjacent to watersheds with > 70% urban land use and two nearshore sites adjacent to watersheds with > 70% rural land use. Urbanization increased freshwater input and nutrient loading—indicated by decreased salinity and elevated nitrate + nitrite, ammonium, and phosphate at urban sites—despite the urban sites being more open to flushing due to land reclamation projects filling in the coral lagoon. Urbanization significantly altered microbial community composition by increasing diversity through the addition of fecal indicator and pathogenic bacteria—eight orders of bacteria were only detected in urban samples, whereas only Verrucomicrobiales was unique to rural samples. The change in microbial community composition at urban sites persisted throughout the seasonal cycle, suggesting a regime change or sustained disturbance. The altered physicochemical conditions and microbial communities at urban sites could degrade nearby coral reefs and their ecosystem services, highlighting the importance of coastal land management in marine conservation efforts.

Community local awareness in respecting coastal land conservation in Cemara Labat Village of Central Kalimantan

Utilization of coastal land in the community of Cemara Labat Village has been passed down from generation to generation. The people of Cemara Labat Village still maintain the tradition of coastal land management, such as planting certain types of mangroves, prohibiting cutting down mangrove forests and hunting animals which are regulated in unwritten customary law or local wisdom. Utilization of coastal area resources by humans from time to time continues to increase. The intensity of exploiting the potential of coastal areas resources often does not pay attention to the carrying capacity and principles of optimal and sustainable use of natural resources. Therefore, the mangrove forest ecosystem in Cemara Labat Village needs to be preserved both ecologically and biologically with an awareness approach to local wisdom. The results showed that Avicennia marina species had a very high dominance (80%) in the mangrove forest area of Cemara Labat Village, for animal especially in the mangrove forest area, was bird dominant species (Aves), while the level of community participation in mangrove forest conservation was moderate (75%).

Spatiotemporal changes of coastal land use land cover and its drivers in Shanghai, China between 1989 and 2015

The coastal zone, an ecotone that provides vital diverse ecosystem services, is one of the most ecologically fragile and sensitive areas on the Earth. It has been strongly influenced by human activities and climate change. Thus, understanding the spatiotemporal changes of land use land cover in the coast is an essential prerequisite for the comprehensive evaluation of coastal ecosystems and the promotion of sustainable development. This study investigated the spatial and temporal changes of land use land cover in the coastal zone of mainland Shanghai by using high spatial resolution aerial images, and the associated driving factors obtained from statistical yearbooks between 1989 and 2015. Our results show that the total land area in the coastal zone exhibited an increasing trend at an annual rate of 7.6% on average. The coastal urban land use also experienced substantial increases, with the degree of urban expansion reaching 42.1% in 2015. The coastal urbanization was at the cost of natural and semi-natural lands. Nearly 64.4% of agricultural land, 24.4% of ocean area within the buffer, 84.9% of fresh water, and 92.8% of the tidal flat had been converted to urban land during 1989–2015. The gradient analysis of land use land cover change along the north-to-south coastal line revealed the spatiotemporal patterns of total land, urbanization degree, and natural and semi-natural lands. The majority of the socioeconomic factors influenced land use land cover change in the coastal zone, positively contributing to the increase of public facilities’ use of land, but negatively affecting the freshwater areas. These findings can provide insights for decision-making in the future for coastal land use land cover planning and management in Shanghai.

Kearifan Lokal Masyarakat Menyikapi Konservasi Lahan Pesisir Di Desa Cemara Labat

Utilization of coastal land in the community of Cemara Labat Village has been passed down from generation to generation. The people of Cemara Labat Village still maintain the tradition of coastal land management, such as planting certain types of mangroves, prohibiting cutting down mangrove forests and hunting animals which are regulated in unwritten customary law or local wisdom. Utilization of coastal area resources by humans from time to time continues to increase. The intensity of exploiting the potential of coastal areas resources often does not pay attention to the carrying capacity and principles of optimal and sustainable use of natural resources. Therefore, the mangrove forest ecosystem in Cemara Labat Village needs to be preserved both ecologically and biologically with an awareness approach to local wisdom. The data collection which used in this research was interview method, observation method, and survey. The results showed that Avicennia marina species had a very high dominance (80%) in the mangrove forest area of Cemara Labat Village, especially in the mangrove forest area, was bird species (Aves), while the level of community participation in mangrove forest conservation was moderate (76%). The strategy of developing community local wisdom on coastal land conservation in Cemara Labat village is in the Strengths-Opportunities or SO strategy, which is quadrant I which means Growth (6.40) or experiencing growth. Some alternative SO (strength opportunities) strategies include :a) Formulate regional policies on mangrove forest management, b) Promote the potential value of mangroves and their development opportunities, c) Improve the role and performance of stakeholders in mangrove forest management, d) Improve people's economy and empower coastal communities.

Is Obliterated Land Still Land? Tenure Security and Climate Change in Indonesia

Both human activities and climate change have changed landscapes significantly, especially in coastal areas. Sea level rise and land subsidence foster tidal floods and permanent inundations, thus changing and limiting land use. Though many countries, including Indonesia, are aware of these phenomena, the legal status of this permanently inundated land remains unclear. Indonesia refers to this land legally as obliterated land. This qualification makes former landowners uncertain, as it does not recognize their previous land rights, and creates disputes during land acquisition. In view of policy pressures to develop large-scale projects, the government often fails to include obliterated land legally during land acquisition processes for these projects. This causes unfair and disputed compensation for those former landowners. Current scientific discourses do not yet address this legal quandary. This study therefore has the following three aims: (1) to describe the legal, institutional and procedural contradictions related to obliterated land; (2) to assess the validity of right of the owners whose land parcels are permanently inundated; and (3) to formulate a responsible and tenure responsive policy to deal with obliterated land. We investigate these questions for the construction of a toll road and sea embankment in Kecamatan Sayung, Kabupaten Demak involving obliterated land. We reviewed policies, regulations and documentations related to coastal land and disaster management, and the implementation of land acquisition. We used geospatial data to visualize the ways in which and locations where landscapes, land parcels and land right changed. We determined that legal uncertainty leads to policy inconsistencies in handling obliterated land, specifically during land acquisition. Additionally, former landowners suffer from the legal gaps to establish clarity of land tenure, which prevents them from receiving any compensation. We suggest a law revision that considers the social–historical aspects of land tenure when defining obliterated land. The law should also provide for a fairer and more just compensation for former landowners during land acquisition processes.

Coastalization patterns in the Mediterranean: a spatiotemporal analysis of coastal urban sprawl in tourism destination areas

Under the current climate change scenery, coastalization, i.e. a linear-type of urban sprawl along the coastal zone, has become a key planning and policy concern at a global scale. Such a coastal urban sprawl trend seems to be further intensifying by, among others, mass tourism development in coastal destinations. This is evident by the abundance of relevant examples, being detected, among others, in the Mediterranean region. Taking into consideration the extreme pressure of the coastalization trend on land/marine ecosystems and its impacts on sustainability and resilience objectives, the focus of this research is on the development of a spatiotemporal and data-driven methodological approach that is capable of quantifying the dynamics of coastal urban sprawl. The proposed approach is grounded on a set of spatial metrics and a combination of the multitemporal Global Human Settlement Layer and the Corine Land Cover data; and is tested in four Mediterranean highly-rated tourism destinations in Spain, France, Italy and Greece. The variation of spatial metrics along different time spots and distinct distance buffers from the coast, unveils diversifying coastalization typologies and urban sprawl patterns; and provides input for more informed and place-based policy decisions on sustainable coastal land management. The proposed approach is easily replicable to other coastal regions as well for capturing/quantifying aspects of urban sprawl and coastalization dynamics and supporting relevant evidence-based decision-making.

A Dispersion Index for the Analysis of the Distribution of Activities in the Tunisian Coastal City of Nabeul

This research investigates the duality of the spatial organization and urban activities generated by the coastalization processes of the city of Nabeul. The first part of the study analyzes the city’s fragmentations of the urban landscape using a novel generic index of directional dispersion and a set of space syntax metrics. These structural and functional properties are studied by the concentration and/or dispersion of urban functions of the evolution and development patterns. Among the emerging features, we observe a dispersion of urban activities beyond a central radius all along the western periphery of the city, confirming the phenomenon of urban sprawl that many Tunisian cities are experiencing. These spaces generate urban fragmentations of “new polarity zones” under the influence of the coastline attraction. Finally, this study introduces a novel approach for identifying urban structural polarity and activities, as well as new perspectives for coastal land management and planning.

粤港澳大湾区城镇化对海岸线与海岸带的影响

海岸带以丰富的自然资源与优越的地理位置成为城镇化的关键地带。基于Google Earth平台2001、2010、2018年高分影像识别分析了粤港澳大湾区快速城镇化过程中海岸线长度的变化，并分析了大湾区海岸带土地利用/土地覆被（land use/land cover，LULC）变化，以及定量解析了大湾区滨海城市城镇化与海岸带城镇用地的关联关系。结果表明：（1）2001-2018年，粤港澳大湾区海岸线总长度净增加32.24 km，但自然岸线人工化问题突出，自然岸线共减少187.67 km，人工岸线共增加219.91 km；（2）海岸带（海岸线向陆侧5 km缓冲区） LULC组成以耕地为主，但城镇用地对耕地的侵占问题突出，2001-2018年，耕地面积减少347.58 km²，城镇用地面积增加588.33 km²；（3）2001-2018年，滨海城市土地城镇化与海岸带城镇用地增长呈显著相关，并且滨海城市土地城镇化对海岸带城镇用地增加的影响在加强（2001-2010年和2010-2018年贡献率分别为43.7%和68.51%）。研究结果可对粤港澳大湾区海岸带保护、修复以及土地利用规划管理提供科学参考。;The coastal zone has become the key area of urbanization with its rich natural resources and advantageously geographical location. This paper identified and analyzed the coastline length change of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) under rapid urbanization based on high-resolution images of Google Earth platform in 2001, 2010 and 2018. We analyzed land use/land cover (LULC) change in the GBA coastal zone, and analyzed the correlation between the urbanization of coastal cities and LULC change of coastal zone. The results showed that (1) the coastline length of the GBA increased by 32.24 km from 2001 to 2018, indicating that the human activities had marked impacts on the coastline; the artificial coastline increased by 219.91 km, mainly at the cost of the decrease (187.67 km) of natural coastline. (2) and the urban land in the coastal zone (5 km buffer zone on the landward side of coastline) increased by 588.33 km² and mainly encroached agriculture (347.58 km²); (3) there were significant correlations between the urbanization level of coastal cities and the growth of urban land in coastal zones from 2001-2018, and the relation became stronger during 2010 to 2018 (R²=0.6851) than that during 2001 to 2010 (R²=0.437), suggesting that the effects of urbanization was deepened. Our findings have important practical implications for coastal zone protection, restoration and land use planning and management in GBA.

Risk Assessment of Coastal Flooding under Different Inundation Situations in Southwest of Taiwan (Tainan City)

The Pacific island countries are particularly vulnerable to the effects of global warming including more frequent and intense natural disasters. Seawater inundation, one of the most serious disasters, could damage human property and life. Regional sea level rise, highest astronomic tide, vertical land motions, and extreme sea level could result in episodic, recurrent, or permanent coastal inundation. Therefore, assessing potential flooding areas is a critical task for coastal management plans. In this study, a simulation of the static flooding situation in the southwest coast of Taiwan (Tainan city) at the end of this century was conducted by using a combination of the Taiwan Digital Elevation Model (DEM), regional sea level changes reconstructed by tide gauge and altimetry data, vertical land deformation derived from leveling and GPS data, and ocean tide models. In addition, the extreme sea level situation, which typically results from high water on a spring tide and a storm surge, was also evaluated by the joint probability method using tide gauge records. To analyze the possible static flood risk and avoid overestimation of inundation areas, a region-based image segmentation method was employed in the estimated future topographic data to generate the flood risk map. In addition, an extreme sea level situation, which typically results from high water on a spring tide and a storm surge, was also evaluated by the joint probability method using tide gauge records. Results showed that the range of inundation depth around the Tainan area is 0–8 m with a mean value of 4 m. In addition, most of the inundation areas are agricultural land use (60% of total inundation area of Tainan), and two important international wetlands, 88.5% of Zengwun Estuary Wetlands and 99.5% of Sihcao Wetlands (the important Black-faced Spoonbills Refuge) will disappear under the combined situation. The risk assessment of flooding areas is potentially useful for coastal ocean and land management to develop appropriate adaptation policies for preventing disasters resulting from global climate change.

Differences in the Morphology of Restored and Invaded Foredunes on the North Spit of Humboldt Bay, California, U.S.A.

McDonald, K.L., 2020. Differences in the morphology of restored and invaded foredunes on the North Spit of Humboldt Bay, California, U.S.A. Journal of Coastal Research, 36(5), 973–980. Coconut Creek (Florida), ISSN 0749-0208.Invasive plants have altered wide-ranging coastal dune vegetation communities worldwide, and the effects of nonnative vegetation and invasive plant management on dune geomorphology are of interest to many coastal land managers, researchers, and coastal communities. This study compared the slopes, elevations, and profiles of invaded and restored foredunes on the North Spit of Humboldt Bay, California, using data from a high-resolution 2010 digital elevation model. Restoration of foredunes by removing invasive European beachgrass (Ammophila arenaria [L.] Link) took place over the last three decades in approximately half of the study area, and the restored areas now primarily support American dunegrass (Elymus mollis Trin.) and other native dune species. Despite recently voiced public concerns that restoration might be permanently lowering the foredune, restored and invaded areas showed no significant difference in height. However, invaded foredunes were significantly steeper with a flatter, plateau-like top, while restored areas were more gently sloping with rounded peaks. Foredune heights increased from the southern end of the study area to the north, regardless of restoration status, suggesting that other factors control foredune height.

Salt Marsh Migration Potential at Cape Cod National Seashore (Massachusetts, U.S.A.) in Response to Sea-Level Rise

Smith, S.M., 2020. Salt marsh migration potential at Cape Cod National Seashore (Massachusetts, U.S.A.) in response to sea-level rise. Journal of Coastal Research, 36(4), 771–779. Coconut Creek (Florida), ISSN 0749-0208.Salt marshes can adjust to sea-level rise (SLR) through vertical elevation gain and horizontal expansion into terrestrial environments. The latter depends on the topography of adjacent uplands and the availability of suitable substrate for halophyte colonization. Within Cape Cod National Seashore (CCNS), calculations of marsh migration potential in response to 1-m of SLR were completed using ArcGIS (version 10.4) based on real-time kinematic GPS marsh elevations, local tide data, land-use, and upland topography derived from 2011 LIDAR scans of CCNS. These estimates were combined with marsh-loss predictions from a previous study within their present-day footprint under the same SLR scenario. The results suggest that individual marshes will respond quite disparately, as dictated by their position in the tidal frame, adjacent terrestrial slopes, land-use, and barrier-beach losses. Most sites are expected to gain or lose relatively small amounts of marsh area under few or no migration constraints. However, there could be a large increase (∼144–240 ha) at one site and an almost a complete loss at another (∼260–290 ha). Where migration was constrained to slopes ≤1%, opportunities for marsh expansion diminished the most—even more so when barrier-beach losses are simulated. Overall, losses at five marsh sites were offset by gains at Hatches Harbor and Pleasant Bay, Massachusetts, such that the total area of salt marsh actually increases with 1-m of SLR, except under the strictest slope constraints. Changes in the spatial distribution and total extent of salt marsh within the CCNS will influence both the quality and quantity of ecosystem services they provide. For coastal land managers, understanding the potential for overland marsh migration is critical for the kind of land-use planning that accommodates these transitioning salt marshes.

Low-Cost Pressure Gauges for Measuring Water Waves

Temple, N.A.; Webb, B.M.; Sparks, E.L., and Linhoss, A.C., 2020. Low-cost pressure gauges for measuring water waves. Journal of Coastal Research, 36(3), 661–667. Coconut Creek (Florida), ISSN 0749-0208.Waves have profound effects on coastal geomorphology, but the understanding of wave climate effects on coastal ecology is limited due, in part, to the high cost of commercial wave gauges. High-cost gauges also limit the scope of coastal wave models and the ability of coastal land managers to design effective restoration, conservation and enhancement projects. To address these limitations, a low-cost do-it-yourself (DIY) wave gauge was constructed using commercial plumbing parts, a pressure sensor, an Arduino© microcontroller and adapted accessories. Details on gauge construction, coding and an instructional video tutorial are provided. Performance of the DIY gauge was determined by measuring the agreement of raw pressure data recorded by the DIY gauge to a comparable commercial gauge in both a laboratory wave channel study featuring a series of wave tests and in a complementary field test. Agreement of raw pressure data among gauges in the wave channel study was assessed using paired t-tests and by fitting linear models. Field test data agreement was assessed by comparing the total wave field energy recorded by each gauge and by fitting a linear model to recorded raw pressure data. Pressure data agreement between the gauges was excellent in all wave channel tests with mean differences between pressure readings consistently near zero and with 95% of all differences lying within ±63 Pascals (<1 cm static water depth), on average. The greatest variability between readings occurred within tests featuring high-frequency waves, mirroring results reported by others. Still, raw DIY wave gauge data explained, on average, 91% of the variance in raw commercial gauge data in wave channel tests. Field performance testing indicated similar gauge responses with 92% total wave energy agreement. Thus, the DIY wave gauge is a viable alternative to high-cost gauges that could improve the understanding and management of coastal environments.

Combined influence of weir construction and sea-level rise on freshwater resources of a coastal aquifer in northern Germany

A significant volume of an aquifer along the coastline in the German Bight is salinized by seawater intrusion. The mean sea-level rise (MSLR) is expected to continue in the future due to global climatic change, subsequently degrading the fresh groundwater resources. To impede further salinization in the future, a solution is proposed based on weir construction in an existing canal hydraulically connected to the aquifer. The effect is twofold: (1) the elevated groundwater level can upgrade present fresh groundwater resources by shifting the saltwater–freshwater interface position further seaward, or by inhibiting its landward movement, and (2) the inland water level can be elevated, expanding surface water ponds. A fully coupled three-dimensional numerical surface-subsurface model (a modified HydroGeoSphere code) was used to simulate the effects of variable weir construction heights under different MSLR rates, and to quantify the gain of aquifer freshwater volume and loss of usable land due to surface ponding. Construction of a higher weir increases the desalinized aquifer volume and decreases the newly salinized aquifer volume under future MSLR. A minimum height of a weir was determined under a certain MSLR rate to maintain the present freshwater resource. Both weir construction and MSLR can cause the loss of land usage. Computed loss-gain ratio curves can be utilized to determine the optimal weir height, meeting the economic requirements of coastal land management under future MSLR.

Assessing coastal landscape vulnerability using geospatial techniques along Vizianagaram–Srikakulam coast of Andhra Pradesh, India

Vizianagaram–Srikakulam coastal shoreline consisting of beaches, mangrove swamps, tidal channel and mudflats is one of the vulnerable coasts in Andhra Pradesh, India. Five site-specific parameters, namely rate of geomorphology, coastal elevation, coastal slope, shoreline change and mean significant wave height, were chosen for constructing coastal vulnerability index and assessing coastal landscape vulnerability. The findings revealed a shift of 2.5 km in shoreline towards the land surface because of constant erosion and that of 1.82 km towards the sea due to accretion during 1997–2017. The rate of high erosion was found in zones IV and V, and high accretion was found in zones II and III. Coastal vulnerability index analysis revealed constant erosion along shoreline and sea level rise in the study area. Most of the coast in zone V has recorded very high vulnerability due to erosion, high slope, significant wave height and sea level rise. Erosion and accretion, significant wave height, sea level rise and slope are attributed to high vulnerability in zones III and IV. Zone II recorded moderate vulnerability. Relatively lower slope, mean sea wave height and sea level rise have made this zone moderately vulnerable. Very low vulnerability was found in zone I, and low vulnerability was recorded in zone II. Accretion, low slope and low sea level rise were found to be causative factors of lower vulnerability. Thus, zones III, IV and V should be accorded higher priorities for coastal management. The findings can be helpful in coastal land planning and management and preparing emergency plans of the coastal ecosystems.

Institutionalizing Coastal Restoration in Louisiana After Hurricanes Katrina and Rita: The Importance of Advocacy Coalitions and Claims-Making in Post-disaster Policy Innovation

Why do disasters sometimes lead to the creation of innovative, new policy frameworks? People often assume that this happens because disasters cause people to understand environmental problems in new ways. However, this case study of changes in Louisiana’s coastal land management policy after Hurricanes Katrina and Rita in 2005 tells a different story. After the hurricanes, state and federal legislators passed several laws that created a framework for comprehensive coastal restoration, replacing the haphazard and poorly funded approach that preceded the storms. This policy innovation occurred because the hurricanes created an opportunity to enact ideas developed by a coalition of coastal scientists, environmental attorneys, and local businesspeople during the previous three decades. Without the long-term work of this advocacy coalition, policy innovation would probably not have occurred. The case study presents the history of coastal restoration policy in Louisiana and explains how this history illustrates models of policy agenda setting from political science and environmental problems construction from sociology. In turn, these models provide a key to interpreting other examples of post-disaster policy change.

Managed Realignment (MR) along the Eastern German Baltic Sea: A Catalyst for Conflict or for a Coastal Zone Management Consensus

ABSTRACT de la Vega-Leinert, A.C.; Stoll-Kleemann, S., and Wegener, E., 2018. Managed realignment (MR) along the Eastern German Baltic Sea: A catalyst for conflict or for a coastal zone management consensus. Managed Realignment (MR), which involves the removal of coastal defences or their relocation further inland, is a desirable option for demographically and economically marginal rural areas, from scientific, political and managerial perspectives. In Europe, MR is reshaping coastal landscapes, and, though not directly endangering lives, is affecting people's sense of safety and control over their land and livelihoods. This can elicit conflict, but also foster consensus. In this study, participatory qualitative research methods were used to investigate stakeholders' perceptions and preferences with regard to coastal land management strategies on the eastern German Baltic coast in the state of Mecklenburg–Western Pomerania. MR reflects a change in the way in which coastal land is valued, with supporting a...

Land use change and farmer behavior in reclaimed land in the middle Jiangsu coast, China

In order to find space for urban expansion and food production, China is rapidly converting its coastal wetlands through large-scale land reclamation. These conversions are dramatically altering the coastal environment, affecting the associated ecosystem services and threatening the regional ecological security. Since this trend is expected to continue for maintaining the economic growth and food security considerations, understanding the extent of reclamation and its related land use changes is important for sustainable coastal land use planning and management. In this study, we analyze land use changes between 1977 and 2015 in middle Jiangsu coast, China, an area that is characterized by land reclamation from wetland conversion. In addition, we surveyed local farmers occupying the reclaimed land and compared their farm characteristics and attitudes against their inland counterparts to understand their role in these processes. We observed that 17% of the reclaimed land was converted to farmland and 43% to aquaculture ponds during the study period. At the same time, the natural wetlands, which originally dominated the area, were substantially reduced by 96%. Characteristics of farmers cultivating the reclaimed land were relatively similar to the inland farmer in many aspects. However, coastal farmers owned larger farms with less fragmented parcels, have a higher income from their farm and showed more enthusiasms for implementing agricultural land use changes comparing to their inland counterparts. The environmental value of the coastal wetlands and the limited opportunities for further land reclamation will pose significant challenges in the context of the region being a hotspot of urban expansion and an important contributor to food production.

Needs Assessment of Coastal Land Managers for Drought Onset Indicators in the Southeastern United States

ABSTRACT Nolan, C.B.; Tufford, D.L., and Chalcraft, D.R., 2016. Needs assessment of coastal land managers for drought onset indicators in the southeastern United States. The ability to detect the onset of drought is important to coastal resource managers because the knowledge enhances preparedness and mitigation. Existing drought indicators, however, were generally designed with agricultural, hydrological, meteorological, socio-economic, or wildfire management in mind and generally quantify deficits in freshwater availability. It is unclear whether coastal resource managers find existing indicators adequate for managing coastal resources and, if not, what information would be most useful to manage resources under threat of drought. A needs assessment was conducted with 30 land managers and natural resource specialists of the coastal Carolinas region to enhance the understanding of drought indicators and to comprehend the indicators' utility for managing coastal natural resources. Eighty-three percent of p...

Impact of topography on groundwater salinization due to ocean surge inundation

AbstractSea‐level rise and increases in the frequency and intensity of ocean surges caused by climate change are likely to exacerbate adverse effects on low‐lying coastal areas. The landward flow of water during ocean surges introduces salt to surficial coastal aquifers and threatens groundwater resources. Coastal topographic features (e.g., ponds, dunes, barrier islands, and channels) likely have a strong impact on overwash and salinization processes, but are generally highly simplified in modeling studies. To understand topographic impacts on groundwater salinization, we modeled a theoretical overwash event and variable‐density groundwater flow and salt transport in 3‐D using the fully coupled surface and subsurface numerical simulator, HydroGeoSphere. The model simulates the coastal aquifer as an integrated system considering overland flow, coupled surface and subsurface exchange, variably saturated flow, and variable‐density groundwater flow. To represent various coastal landscape types, we simulated both synthetic fields and real‐world coastal topography from Delaware, USA. The groundwater salinization assessment suggested that the topographic connectivity promoting overland flow controls the volume of aquifer that is salinized. In contrast, the amount of water that can be stored in surface depressions determines the amount of seawater that infiltrates the subsurface and the time for seawater to flush from the aquifer. Our study suggests that topography has a significant impact on groundwater salinization due to ocean surge overwash, with important implications for coastal land management and groundwater vulnerability assessment.

Using Future Benefits to Set Conservation Priorities for Wetlands

In an era of rising sea levels, costal land managers including land trust representatives, municipal planners, and others contributing to decisions about whether to develop or protect coastal parcels do not have viable means of evaluating future values on wetlands that will be created when sea levels rise. This project develops and tests a software modeling approach to help address this issue, in combination with a novel, expert-opinion driven benefit-cost framework. The beta test used three parcels in Scarborough, Maine: Hampton Circle, Maine Audubon, and Pine Point. It used a group of experts to 1) allocate initial values to these parcels for a range of ecosystem services, using Wetland Benefit Units, and 2) create depth-benefit curves that estimate how those values would change with increasing water depth at each site. Experts estimated that the Hampton Circle site had the highest initial values across all services. But once sea level rise and topographic diversity was accounted for via use of the software (Marsh Adaptation Strategy Tool), what initially appeared to be the most valuable site became the least valuable. The analysis demonstrates the importance of being able to examine interactions among a diversity of ecosystem service values, local topography, and possible sea level rise, and demonstrates the utility of a new software tool and benefit-cost framework to support coastal land management decisions before and during upland conversion to wetland.