GIS-based Analysis and Modelling with Empirical and Remotely-Sensed Data on Coastline Advance and Retreat

With the understanding that far more research remains to be done on the development and use of innovative and functional geospatial techniques and procedures to investigate coastline changes this thesis focussed on the integration of remote sensing, geographical information systems (GIS) and modelling techniques to provide meaningful insights on the spatial and temporal dynamics of coastline changes. One of the unique strengths of this research was the parameterization of the GIS with long-term empirical and remote sensing data. Annual empirical data from 1941û2007 were analyzed by the GIS, and then modelled with statistical techniques. Data were also extracted from Landsat TM and ETM+ images. The band ratio method was used to extract the coastlines. Topographic maps were also used to extract digital map data. All data incorporated into ArcGIS 9.2 were analyzed with various modules, including Spatial Analyst, 3D Analyst, and Triangulated Irregular Networks. The Digital Shoreline Analysis System was used to analyze and predict rates of coastline change. GIS results showed the spatial locations along the coast that will either advance or retreat over time. The linear regression results highlighted temporal changes which are likely to occur along the coastline. Box-Jenkins modelling procedures were utilized to determine statistical models which best described the time series (1941û2007) of coastline change data. After several iterations and goodness-of-fit tests, second-order spatial cyclic autoregressive models, first-order autoregressive models and autoregressive moving average models were identified as being appropriate for describing the deterministic and random processes operating in GuyanaÆs coastal system. The models highlighted not only cyclical patterns in advance and retreat of the coastline, but also the existence of short and long-term memory processes. Long-term memory processes could be associated with mudshoal propagation and stabilization while short-term memory processes were indicative of transitory hydrodynamic and other processes. An innovative framework for a spatio-temporal information-based system (STIBS) was developed. STIBS incorporated diverse datasets within a GIS, dynamic computer-based simulation models, and a spatial information query and graphical subsystem. Tests of the STIBS proved that it could be used to simulate and visualize temporal variability in shifting morphological states of the coastline

Atlas of Global Surface Water Dynamics

It is impossible to overstate the importance of freshwater in our daily lives – for proof, try going without it for any length of time. Surface waterbodies (lakes, ponds, rivers, creeks, estuaries… it doesn't matter what name they go under) are particularly important because they come into direct contact with us and our biophysical environment. But our knowledge concerning where and when waterbodies might be found was, until recently, surprisingly sparse. The paucity of information was because trying to map a moving target is actually very difficult – and waterbodies undeniably move, in both geographical space and time. By 2013 the U.S. Geological Survey and NASA were making petabyte scale archives of satellite imagery freely available, archives that covered the entire planet's surface and stretched back decades. Other's such as the European Commission / European Space Agency Copernicus programme were also putting full free and open data access policies into place, and Google's Earth Engine had become a mature, powerful cloud-based platform for processing very large geospatial datasets. Back in 2013 a small team working at the European Commission's Joint Research Centre were looking at ways satellite imagery could be used to capture surface waterbody dynamics, and create new maps that accurately incorporated time dimensions. Concurrently the Google Earth Engine team were focussing their massive computational capabilities on major issues facing humanity, such as deforestation, food security, climate change - and water management. The two teams came together in a partnership based not on financial transactions but on a mutual exchange of complementary capabilities, and devoted thousands of person hours and thousands of CPU years into turning petabytes of Landsat satellite imagery into unique, validated surface water maps, first published in 2016, and made available to everyone through a dedicated web portal, the Global Surface Water Explorer. Since then satellites have continued to image the Earth, surface water has continued to change and the JRC Goole Earth Engine partnership has continued to work on improving our knowledge of surface water dynamics and making sure this knowledge benefits as many people as possible. This Atlas is part of the outreach; it is not a guide to the Global Surface Water Explorer, it is not a Google Earth Engine tutorial (though if it inspires you to visit either of these resources then it has achieved one of its objectives), but it is a stand-alone window into how people and nature affect, and are affected by the 4.46 million km2 of the Earth's landmass that have been under water at some time over the past 35 years.JRC.D.5-Food Securit

Spatial and temporal dynamics of suspended sediment concentrations in coastal waters of the South China Sea, off Sarawak, Borneo: ocean colour remote sensing observations and analysis

High-quality ocean colour observations are increasingly accessible to support various monitoring and research activities for water quality measurements. In this paper, we present a newly developed regional total suspended solids (TSSs) empirical model using MODIS Aqua's Rrs(530) and Rrs(666) reflectance bands to investigate the spatial and temporal variation in TSS dynamics along the southwest coast of Sarawak, Borneo, with the application of the Open Data Cube (ODC) platform. The performance of this TSS retrieval model was evaluated using error metrics (bias = 1.0, MAE = 1.47, and RMSE = 0.22, in milligrams per litre) with a log10 transformation prior to calculation as well as using a k-fold cross-validation technique. The temporally averaged map of the TSS distribution, using daily MODIS Aqua satellite datasets from 2003 until 2019, revealed that large TSS plumes were detected – particularly in the Lupar and Rajang coastal areas – on a yearly basis. The average TSS concentration in these coastal waters was in the range of 15–20 mg L−1. Moreover, the spatial map of the TSS coefficient of variation (CV) indicated strong TSS variability (approximately 90 %) in the Samunsam–Sematan coastal areas, which could potentially impact nearby coral reef habitats in this region. Study of the temporal TSS variation provides further evidence that monsoonal patterns drive the TSS release in these tropical water systems, with distinct and widespread TSS plume variations observed between the northeast and southwest monsoon periods. A map of relative TSS distribution anomalies revealed strong spatial TSS variations in the Samunsam–Sematan coastal areas, while 2010 recorded a major increase (approximately 100 %) and widespread TSS distribution with respect to the long-term mean. Furthermore, study of the contribution of river discharge to the TSS distribution showed a weak correlation across time at both the Lupar and Rajang river mouth points. The variability in the TSS distribution across coastal river points was studied by investigating the variation in the TSS pixels at three transect points, stretching from the river mouth into territorial and open-water zones, for eight main rivers. The results showed a progressively decreasing pattern of nearly 50 % in relation to the distance from shore, with exceptions in the northeast regions of the study area. Essentially, our findings demonstrate that the TSS levels on the southwest coast of Sarawak are within local water quality standards, promoting various marine and socio-economic activities. This study presents the first observation of TSS distributions in Sarawak coastal systems with the application of remote sensing technologies and aims at enhancing coastal sediment management strategies for the sustainable use of coastal waters and their resources.</p

Susceptibility to Changes in Coastal Land Dynamics in Bangladesh

Coastal areas of the world are physically dynamic in nature. The present study contributes new knowledge to studies on coastal land dynamics and land susceptibility to erosion. This study developed a raster GIS-based model namely, Land Susceptibility to Coastal Erosion (LSCE) to assess erosion susceptibility of coastal lands under hydro-climatic changes. The devised model was applied to the entire coastal area of Bangladesh. The model required the characterisation of the nature of land dynamics (i.e. erosion and accretion). The analysis showed a net gain of 237 km² of land over the past thirty years but, constant changes in land dynamics were observed in the area. The study then applied the LSCE model to measure the existing levels of land susceptibility of the coastal area to erosion. The validated model outputs were then used as a baseline for generating four possible scenarios of future land susceptibility to erosion in the coastal area. This allowed the model to ascertain the probable impacts of future hydro-climatic changes on land susceptibility to erosion in the area. Additionally, the study assessed seasonal variations of land susceptibility to erosion by using the same model. The model outputs showed that 276.33 km² of existing coastal lands classified as highly and very highly susceptible to erosion, would substantially increase in the future. Using a Fuzzy Cognitive Mapping (FCM) approach, the study elicited expert views to evaluate the model scenarios and to address uncertainties relevant to erosion susceptibility. This study could allow coastal managers and policymakers to develop effective measures in managing highly erosion susceptible coastal lands in the area

Relationship between Land Use and Water Quality and its Assessment Using Hyperspectral Remote Sensing in Mid- Atlantic Estuaries

Mid-Atlantic coastal waters are under increasing pressures from anthropogenic disturbances at various temporal and spatial scales exacerbated by the climate change. According to the National Oceanic Atmospheric Association (NOAA), 10 of the 22 estuaries in the Mid-Atlantic, including the Chesapeake Bay, exhibit high levels of eutrophic conditions while seven, including Delaware Bay, exhibit low conditions. Chesapeake Bay is the largest estuarine system in the United States and undergoes frequent eutrophication and low dissolved oxygen events. Although substantially lower in nutrients compared to other Mid-Atlantic Estuaries, the biological, chemical, and ecological status of the Delaware Bay has changed in the past few decades due to high coastal tourism, increased local resident populations, and agricultural activities which have increased nutrient inputs into this shallow coastal bay. As stated by the Academy of Natural Sciences, although the nutrient load has reduced since the Clean Water Act, years of nutrient accumulation, contaminations, and sedimentation have impacted estuarine systems substantially, long-term monitoring is lacking, and ecological responses are not well quantified. Eutrophication within the Bays has degraded water quality conditions advanced by sedimentation. Understanding the quality of the water in any aquatic ecosystem is a critical first step in order to identify characteristics of that ecosystem and draw conclusions about how well adapted the system is in terms of anthropogenic activity and climate change. Determining water quality in intertidal creeks along the Chesapeake and Delaware coastlines is important because land cover is constantly changing. Many of these tidal creeks are lined with forested riparian buffers that may be intercepting nutrients from running off into the waterways. Identifying water conditions, coupled with the marsh land cover, provides a strong foundation to see if the buffer systems are providing the ecosystem services they are designed to provide. Our primary goal in this chapter is to provide research findings on the application of the hyperspectral remote sensing to monitor specific land-use activities and water quality. Along with hyperspectral remote sensing, our monitoring was coupled with the integration of remotely sensed data, global positioning system (GPS), and geographic information system (GIS) technologies that provide a valuable tool for monitoring and assessing waterways in the Mid-Atlantic Estuaries

Evaluating the Impact of Submarine Groundwater Discharge on Nutrients and Trace Elements in Coastal Systems: The Examples of the Tuckean Swamp (Australia) and the Mississippi Sound (USA)

Submarine groundwater discharge (SGD) is the advective flow of both fresh terrestrial groundwater and recirculating seawater through aquifer sediments, which is released into the coastal ocean. In this dissertation, I evaluated the impact of SGD on the distributions and input of trace metals and nutrients. In the Tuckean Swamp, an estuary in Australia dominated by coastal acid sulfate soils, I determined the impact of groundwater on Ba and U during the flood season, when the local aquifer is flushed out after a rapid increase in water table elevation. For Ba and U, groundwater contributed up to 18 and 66 % to the total surface water flux out of the Tuckean Swamp, respectively. This can have implications for the use of these elements as proxies of river influences, upwelling, and sea surface temperature on a regional scale. In the Mississippi Sound, an estuary in the northern Gulf of Mexico, the main sources of nutrients and trace metals to the estuary are thought to be from inputs of local rivers, and the occasional input of the Mississippi River from the opening of the Bonnet Carré Spillway. Using radium and radon, I evaluated the magnitude and distribution of SGD in the Mississippi Sound. I found that submarine groundwater discharge can dominate nutrient fluxes when the river discharge is low, suggesting that during the drier months of the year, SGD was main source of dissolved nutrients to the Sound. This has implications for biological parameters, as the dissolved materials from SGD are often reducing with a high oxygen demand (i.e., ammonium and methane), and the groundwater in itself is often lacking oxygen. This has potential to cause bottom up hypoxia along the coastline and in the western Sound, where the majority of the SGD is infiltrating into the Sound. Trace element inputs to the Mississippi Sound were dominated by river inputs and were affected by the opening of the Bonnet Carré Spillway. This work explores the importance of SGD versus river and surface runoff, and how all of these parameters combined can affect the water quality of coastal systems

The Parnaiba River Delta - from modern hydro and morphodynamics to sea level change

This study presents the first findings regarding the hydrography, morphodynamics, hydrodynamics and sea-level change on Parnaíba River (PR) and its delta. The PR is 1,400 km long and located in NE Brazil. It forms an asymmetric wave dominated delta, the Parnaíba River Delta (PRD). The delta region is approximately 100 km wide and has tidal channels forming an estuarine-lagoonal system, west of PR. The delta is located in a transition zone in terms of climatic and oceanographic conditions. Despite the existence of a river dam on its mid-course, the river has a moderate (approximately 91 mg/l, in average) suspended sediment load which is mainly attributed to the geology and the climatic conditions of its drainage basin. Rainfall data from 1965 to 2009 revealed seasonal variations on rainfall and suspended sediment concentration (SSC). Moreover, harmonic analysis of time series revealed a correlation of both, rainfall and SSC, with El Niño-Southern Oscillation (ENSO). The suspended sediment concentration was calculated from a set of 12 multispectral satellite images (CBERS 2-B and LANDSAT TM 5), which were calibrated using in situ measurements. Using averaged river discharge and remote sensed suspended sediment concentration it was possible to estimate the amount of sediment that is transported through the PR to the continental shelf. The PR is the primary sediment source to the adjacent coast and this is evidenced by the shoreline stability and progradation noticed at the vicinities of the river mouth (observed on decadal time scale using satellite images). The river runoff interferes on the direction of the offshore bottom currents on the continental shelf up to 4 km in front of the river mouth. It acts as a hydrodynamic groin preventing sediment bypass. Offshore bathymetry and seismic profiles depicted evidences of past sea level on the continental shelf offshore PRD in the form of incised valley and paleo-channels. Interpretations of architectural elements, seismic facies and seismic boundaries were related to extreme events of sea level such as sea level low- and highstand providing relative age control for the formation and complete burial of the paleo-channels. Relating worldwide reconstructions of sea level curves to the interpretations it is suggested that the valley incision occurred during the Late Pleistocene sea-level drop and lowstand (70,000 – 20,000 years BP). Moreover, the valley infill indicates the flooding of the shelf during deglacial sea-level rise that reached the mid-Holocene highstand around 5,500 years BP

Water Clarity And Suspended Particle Dynamics In The Chesapeake Bay: Local Effects Of Oyster Aquaculture, Regional Effects Of Reduced Shoreline Erosion, And Long-Term Trends In Remotely Sensed Reflectance

Water clarity is a key indicator of the ecosystem health in the Chesapeake Bay. Estuarine water clarity fluctuates due to external inputs from the watershed as well as processes occurring within the estuary itself, such as sediment resuspension and organic matter production. Therefore, water clarity requires study at multiple spatial and temporal scales and with multiple metrics. One local-scale process potentially influencing water clarity is shellfish aquaculture. One part of this dissertation examined how water quality and hydrodynamics varied among oyster farms as well as inside versus outside the extent of caged areas located in southern Chesapeake Bay. Current speed and water quality were measured within and adjacent to four oyster farms during two seasons. Results revealed minor effects of oyster farms on water quality, likely due to high background variability, relatively high flushing rates, relatively low oyster density, and small farm footprints. Minimal impacts overall suggest that low-density oyster farms located in adequately flushed areas are unlikely to negatively impact local water quality. At a larger spatial scale, another potential influence on water clarity is shoreline erosion. The second part of this dissertation examined the impact of shoreline erosion on water clarity via a numerical modeling study. Experiments were conducted to simulate realistic shoreline conditions representative of the early 2000s, increased shoreline erosion, and highly armored shorelines. Together, reduced shoreline erosion and the corresponding low seabed resuspension resulted in decreased concentrations of inorganic particles in surface waters, improving water clarity overall. However, clearer waters relaxed light limitation on phytoplankton, which often increased organic matter production, sometimes yielding opposite effects on water clarity according to different metrics. Clarity improved in mid-Bay central channel waters in terms of light attenuation depth, but simultaneously degraded in terms of Secchi depth because the resulting increase in organic matter decreased the water’s transparency. A final water clarity process considered was the long-term trend in water clarity from satellite remote sensing. The third part of this dissertation examined how remote sensing reflectance changed over time in Chesapeake Bay from 2002 to 2020 using the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on satellite Aqua. MODIS-Aqua remote sensing reflectance trends were evaluated from 2002 to 2020 at multiple wavelengths and spatial resolutions for surface waters of the Chesapeake Bay. Trends showed long-term decreasing reflectancein the upper estuary yet increasing reflectance in the lower estuary in the green wavelengths. Band ratios involving red-to-green and red-to-blue have decreased, suggesting improved water clarity, while green-to-blue ratios have increased over time, suggesting increasing contribution of phytoplankton to water cloudiness. Reflectance change over time relates well to observed decreases in total suspended solids and light attenuation, yet inconclusive trends in chlorophyll-a, suggesting a long-term change in particle properties such as size and composition that affect light scattering behavior

Assessing Hazard Vulnerability, Habitat Conservation, and Restoration for the Enhancement ofmainland China’s Coastal Resilience

Worldwide, humans are facing high risks from natural hazards, especially in coastal regions with high population densities. Rising sea levels due to global warming are making coastal communities’ infrastructure vulnerable to natural disasters. The present study aims to provide a coupling approach of vulnerability and resilience through restoration and conservation of lost or degraded coastal natural habitats to reclamation under different climate change scenarios. The integrated valuation of ecosystems and tradeoffs model is used to assess the current and future vulnerability of coastal communities. The model employed is based on seven different biogeophysical variables to calculate a natural hazard index and to highlight the criticality of the restoration of natural habitats. The results show that roughly 25% of the coastline and more than 5 million residents are in highly vulnerable coastal areas of mainland China, and these numbers are expected to double by 2100. Our study suggests that restoration and conservation in recently reclaimed areas have the potential to reduce this vulnerability by 45%. Hence, natural habitats have proved to be a great defense against coastal hazards and should be prioritized in coastal planning and development. The findings confirm that natural habitats are critical for coastal resilience and can act as a recovery force of coastal functionality loss. Therefore, we recommend that the Chinese government prioritizes restoration (where possible) and conservation of the remaining habitats for the sake of coastal resilience to prevent natural hazards from escalating into disasters. Plain Language Summary: Coastal populations are especially at risk from sea-level rise (SLR), induced storm surges, and other natural hazards. Therefore, it becomes essential to analyze the current and future vulnerabilities of coastal regions to natural hazards. Furthermore, it is desirable for the policy and the decision making to propose the suitable approaches for the resilience enhancement. This paper analyzes the current and future vulnerability of mainland China’s coast to the SLR-induced natural hazards using a natural hazard index incorporating a coupled approach to vulnerability and resilience. The results show that the restoration of lost mangroves (where possible) and conservation of remaining coastal natural habitats can reduce the future coastal vulnerability by 45%. This study confirms that natural habitats are significant for coastal resilience and the governments should prioritize them for the sake of coastal resilience to mitigate the impacts of natural hazards. Includes supplemental material