Land-water Boundaries Research Articles

Leveraging deep learning for coastal monitoring: A VGG16-based approach to spectral and textural classification of coastal areas with sentinel-2A data

Coastal ecosystems are vital for the planet's health, providing essential habitats for diverse species and supporting human communities. However, these complex environments face increasing threats from climate change and human activities. Effective monitoring of these areas requires large-scale, efficient, and accurate methods. This study explores the potential of deep learning for automated coastal land cover classification using Sentinel-2A satellite imagery on the Google Earth Engine (GEE) platform. We investigate the impact of transfer learning and spectral band combinations on classification accuracy for five coastal types: artificial, bedrock, sandy, muddy, and vegetation-covered. Our findings demonstrate that a pre-trained VGG16 Convolutional Neural Network (CNN) with transfer learning significantly improves classification accuracy (average 19.3% increase) compared to using default weights. Notably, including the near-infrared (NIR) band in training data leads to superior results, particularly for artificial and bedrock coastlines, where the NIR band's effectiveness in separating land-water boundaries enhances classification accuracy. These results highlight the potential of deep learning for large-scale, automated coastal monitoring, informing applications in sustainable fisheries management, coastal vulnerability assessment, and marine ecosystem conservation.

Manual-Based Improvement Method for the ASTER Global Water Body Data Base

A water body detection technique is an essential part of digital elevation model (DEM) generation to delineate land–water boundaries and to set flattened elevations. The initial tile-based water body data that are created during production of the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) GDEM, as a by-product, are incorporated into ASTER GDEM V3 to improve the quality. At the same time as ASTER GDEM V3, the Global Water Body Data Base (ASTWBD) Version 1 is also released to the public. The ASTWBD generation consists of two parts: separation from land area, and classification into three categories: sea, lake, and river. Sea water bodies have zero elevation. Lake water bodies have flattened elevations. River water bodies have a gradual step-down from upstream to downstream with a step of one meter. The separation process from land area is carried out automatically using an algorithm, except for sea-ice removal, to delineate the real seashore lines in the high latitude areas; almost all of the water bodies are created through this process. The classification process into three categories, i.e., sea, river, and lake, is carried out, and incorporated into ASTER GDEM V3. For inland water bodies, it is not possible to perfectly detect all water bodies using reflectance and spectral index, which are the only available parameters for optical sensors. The only way available to identify the undetected inland water bodies is to manually copy them with visual inspection from the earth’s surface images, like Landsat images. GeoCover2000 images are the main part of the object images. Color–Land ASTER MosaicS (CLAMS) images are used to cover the deficiency of the GeoCover2000 images. This kind of time-consuming, unsophisticated way is inevitable as it is a manual-based method to improve the quality of the ASTWBD. This paper describes the manual-based improvement method; specifically, how deficient water body images are efficiently copied as rasterized images from the earth’s surface images to obtain a more complete global water body data set.

Technical Methodology for ASTER Global Water Body Data Base

A waterbody detection technique is an essential part of a digital elevation model (DEM) generation to delineate land–water boundaries and set flattened elevations. This paper describes the technical methodology for improving the initial tile-based waterbody data that are created during production of the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) GDEM, because without improvement such tile-based waterbodies data are not suitable for incorporating into the new ASTER GDEM Version 3. Waterbodies are classified into three categories: sea, lake, and river. For sea-waterbodies, the effect of sea ice is removed to better delineate sea shorelines in high latitude areas: sea ice prevents accurate delineation of sea shorelines. For lake-waterbodies, the major part of the processing is to set the unique elevation value for each lake using a mosaic image that covers the entire lake area. Rivers present a unique challenge, because their elevations gradually step down from upstream to downstream. Initially, visual inspection is required to separate rivers from lakes. A stepwise elevation assignment, with a step of one meter, is carried out by manual or automated methods, depending on the situation. The ASTER global water database (GWBD) product consists of a global set of 1° latitude-by-1° longitude tiles containing water body attribute and elevation data files in geographic latitude and longitude coordinates and with one arc second posting. Each tile contains 3601-by-3601 data points. All improved waterbody elevation data are incorporated into the ASTER GDEM to reflect the improved results.

Lagrangian Analyses of Rainfall Structure and Evolution for Organized Thunderstorm Systems in the Urban Corridor of the Northeastern United States

AbstractIn this study, a climatology of the structure and evolution of rainfall for organized thunderstorm systems in the urban corridor of the northeastern United States is developed. These storm systems are major agents of flash flooding for urban regions of the northeastern United States and, more generally, for the United States east of the Rocky Mountains. The analyses are motivated by problems that center on characterizing flash flood hazards. The authors focus on spatial heterogeneities of rainfall associated with urbanization in a region of complex landscape including mountainous terrain and land–water boundaries along the geometrically complex coastline of the New York City–New Jersey metropolitan region. The sample of storms selected for investigation consists of the 50 days from April to September 2001–09 with the largest cloud-to-ground lightning flash density derived from National Lightning Detection Network (NLDN) observations over the study region. Storm-tracking analyses of 3D radar reflectivity fields are performed for the 50 storm days and used to develop a Lagrangian climatology of storm structure and evolution for the study region. Rainfall analyses for the 50 storm days are based on high-resolution (1 km, 15 min) bias-corrected radar rainfall fields developed from the Hydro-NEXRAD system. The analyses suggest that complex terrain and land–water boundaries have large impacts on Lagrangian storm properties. Areas of increased heavy rainfall and lightning flash density over New York City were identified. The authors found evidence for changing storm structure as thunderstorms pass over New York City, but little evidence that thunderstorms split as they approach New York City.

Determination of water flushing characteristics and their influencing factors on the Dahuofang Reservoir in China using an improved ECOMSED model

A three-dimensional hydrodynamic model with the capability to deal with changing land water boundaries was developed based on ECOMSED in this study. The model was configured to numerically study the water flushing characteristics of Dahuofang Reservoir in China through the determination of spatially distributed residence times. The model successfully reproduced the intra-annual water level variations, as well as the temporal evolution and spatial distribution of water temperature. Through a series of numerical experiments, it can be concluded that (1) the water flushing of the reservoir is both temporally and spatially variable; and (2) inflows and withdrawals are the decisive factors influencing the water flushing characteristics. Heat fluxes are the controlling factors of the water flushing of a strong stratified reservoir. Wind has the weakest effect, but it still should be considered in determination of reservoir water flushing characteristics.

Future ecological studies of Brazilian headwater streams under global-changes

This paper results from discussions triggered during the "Stream Ecology Symposium" that took place at the XIII Congress of the Brazilian Society of Limnology in September of 2011 in Natal, Brazil. Based on our experiences, we have raised several questions regarding ecological studies of headwater streams facing threats under global-changes and proposed numerous subjects to be addressed in future studies in Brazil. These studies deal with the necessity of knowing species biology and the elaboration of models to assess changes (which implies the availability of time-series or large-scale data sets); the ecology of riparian zones and the interchange of materials and energy across the land-water boundaries; forest conversions and standardized sampling strategies and data treatment to assess global change.

Impact of Antenna Pattern on Measurement of the Third Stokes Parameter From Space at L-Band

The third Stokes parameter will be observed from space for the first time at L-band by the Soil Moisture and Ocean Salinity and Aquarius/SAC-D satellites. The correlation between polarizations, which is the source of the third Stokes parameter, is of interest at L-band to measure Faraday rotation and also to indicate novel features of the surface. However, spurious signals (false indication of correlation) can occur in the third Stokes parameter. For example, this happens when the radiometer crosses boundaries associated with a large change in brightness temperature, such as land-water boundaries. In this paper, calculations with the Aquarius radiometer antennas will be used to show that these spurious signals are due to the cross-polarization coupling and large beamwidth associated with realistic L-band antennas in space.

Analyses of the warm season rainfall climatology of the northeastern US using regional climate model simulations and radar rainfall fields

We examine the warm season (April–September) rainfall climatology of the northeastern US through analyses of high-resolution radar rainfall fields from the Hydro-NEXRAD system and regional climate model simulations using the weather research and forecasting (WRF) model. Analyses center on the 5-year period from 2003 to 2007 and the study area includes the New York–New Jersey metropolitan region covered by radar rainfall fields from the Fort Dix, NJ WSR-88D. The objective of this study is to develop and test tools for examining rainfall climatology, with a special focus on heavy rainfall. An additional emphasis is on rainfall climatology in regions of complex terrain, like the northeastern US, which is characterized by land–water boundaries, large heterogeneity in land use and cover, and mountainous terrain in the western portion of the region. We develop a 5-year record of warm season radar rainfall fields for the study region using the Hydro-NEXRAD system. We perform regional downscaling simulations for the 5-year study period using the WRF model. Radar rainfall fields are used to characterize the interannual, seasonal and diurnal variation of rainfall over the study region and to examine spatial heterogeneity of rainfall. Regional climate model simulations are characterized by a wet bias in the rainfall fields, with the largest bias in the high-elevation regions of the model domain. We show that model simulations capture broad features of the interannual, seasonal, and diurnal variation of rainfall. Model simulations do not capture spatial gradients in radar rainfall fields around the New York metropolitan region and land–water boundaries to the east. The model climatology of convective available potential energy (CAPE) is used to interpret the regional distribution of warm season rainfall and the seasonal and diurnal variability of rainfall. We use hydrologic and meteorological observations from July 2007 to examine the interactions of land surface processes and rainfall from a regional perspective.

A review on substances and processes relevant for optical remote sensing of extremely turbid marine areas, with a focus on the Wadden Sea

The interpretation of optical remote sensing data of estuaries and tidal flat areas is hampered by optical complexity and often extreme turbidity. Extremely high concentrations of suspended matter, chlorophyll and dissolved organic matter, local differences, seasonal and tidal variations and resuspension are important factors influencing the optical properties in such areas. This review gives an overview of the processes in estuaries and tidal flat areas and the implications of these for remote sensing in such areas, using the Wadden Sea as a case study area. Results show that remote sensing research in extremely turbid estuaries and tidal areas is possible. However, this requires sensors with a large ground resolution, algorithms tuned for high concentrations of various substances and the local specific optical properties of these substances, a simultaneous detection of water colour and land–water boundaries, a very short time lag between acquisition of remote sensing and in situ data used for validation and sufficient geophysical and ecological knowledge of the area.

Low frequency sound propagation across a land–water boundary

Army noise assessment capability has recently been improved to account for the effects of land–water transitions on a received sound level. Sound waves propagating beyond a shoreline experience changes in surface impedance, surface roughness, and refraction profile. Measurements of the temperature and wind with tethersonde balloons indicate significantly weaker sound speed gradients over water than over land. When a temperature inversion was observed over land, the inversion was always smaller over the water. When the solar heating produced strong upward refraction near the land surface, the temperature profile over water was neutral (lapse). Simulations were run with a parabolic equation model incorporating range-dependent boundary refraction profiles and range-dependent boundary conditions. The signal levels exhibit changes with distance due to strong refraction over land, but the changes nearly cease in places where the propagation extends over water. Measured spectrum levels from explosion sound propagating across land–water boundaries agree well with the simulations. [Work supported by the USACERL, USACHPPM, and NAVFAC.]

The Image Navigation Cloud Mask for the Multiangle Imaging Spectroradiometer (MISR)

Abstract The authors have developed a cloud mask technique that may be applied to the efficient selection of “clear enough” scenes for image navigation. While the mask can be applied generally, the motivation for its development comes from its intended use on Multiangle Imaging Spectroradiometer (MISR) imagery. The difficulties in detecting clouds in the presence of land–water boundaries when using prenavigated imagery is overcome by using a simple two-step direct threshold technique. The two steps involve the thresholding of two observables derived for each pixel. The first is a 0.86-μm reflectance. The second is a new observable, D = | NDVI |bR1−2, where NDVI = (R2 − R1)(R2 + R1)−1, R2 is the 0.86-μm reflectance, R1 is the 0.67-μm reflectance, and b is chosen so as to maximize the separation between clear and cloudy pixels. The success of the cloud mask is shown by applying it to degraded AVIRIS data. The authors make comparisons with a more popular NDVI technique to show the advantage of our method.

Fish and Fisheries Ecology.

My paper on fish and fisheries ecology is offered to demonstrate a rich blending of applied and fundamental ecology, achieved by the intersections among fishery science, ichthyology, and ecology. The example, while specific, parallels practices and opportunities available in other areas of applied ecology. The emergence of fish and fisheries ecology as a discipline is evidence by such recent textbooks as Fisheries ecology by Pitcher and Hart (1982) and Ecology of teleost fishes by Wootton (1990). The ecology relevant to fish and fisheries includes not only marine and freshwater ecology, oceanography, and limnology, but also terrestrial study. Early work in fish and fisheries ecology came from Stephen A. Forbes > 100 yr ago in his books On some interactions of organisms (Forbes 1880) and The lake as a microcosm (Forbes 1887). These constitute one of the earliest conceptualizations of an ecosystem. By 1932 E. S. Russell concluded that fishery research was a study in marine ecology. I give examples of applications from six different categories of ecology. (1) Physiological ecology: The F. E. J. Fry school of fish physiology developed the concepts of temperature as a lethal, controlling and directive factor. More than 40 yr later, this knowledge is being combined with G. E. Hutchinson's concept of an n-dimensional niche to analyze potential influences of global climate warming on fishes. (2) Behavioral ecology: A. D. Hasler and students formulated and tested the hypothesis of olfactory imprinting as the mechanism by which Pacific salmon "home" to their natal spawning streams. Applications to reestablish salmon runs are as important to Hasler as the original scientific discovery; this is evident in his proposed "Salmon for Peace" for the river bounding USSR and China. (3) Population ecology: The realization that reproductive success of fishes depends more on larval mortality than on egg production emerged from the ideas of J. Hjort (1914). To this day inconsistencies between recruitment and reproductive stock size impart uncertainty into fishery management, while the search for explanatory mechanisms attracts the curious mind. (4) Community ecology: Species interactions are the grist of community ecology; predation and fishing are a natural for comparative study and application. Also, consumption by fish can control the dynamics of planktonic and benthic animal/plant communities; thus, apparent water quality of lakes depends on the consumer community as well as on nutrient inputs. (5) Ecosystem ecology: D. S. Rawson grouped external, abiotic influences on lakes into climatic, edaphic, and morphometric factors. The morphoedaphic index (Ryder 1965) predicts fish yields from this base, providing fish managers with a useful approximation and ecologists with a conceptual base for synthesis of production processes. (6) Landscape ecology: Regional ecology often incorporates land-water boundaries into the way ecological systems work. Application of island biogeography to lakes, as islands, has allowed predictions of fish assemblages for use by managers. Also, the extent and connectedness of lake and ocean "landscapes" offer insight into contrasts between marine and freshwater fishery research and management. In conclusion, the ecotone between academic and applied ecology seems an ideal place from which to advance both applied ecology and ecology in general.

Coastal definition using Landsat data†

Abstract An automated technique is described, for extracting land-water boundaries from Landsat MSS images by means of ‘density contour-threading’ of the band 7 data. The resulting coastlines, etc. can then be transformed to fit any map projection—in particular the British National Grid—with the aid of selected ground control points.

Projection Routines for Displaying Geophysical Data

Summary Algorithms were described for plotting data in any of five basic map projections, with or without basemaps derived from a tape of land-water boundaries. A contour routine has been adapted for use with the projection routines to allow contours of data to be similarly displayed. Using this routine with a tape of elevations allowed elevation contour maps of the world to be produced. Examples of plots were given. The routines are fast but lack ellipticity corrections and are intended primarily for routine data display. Program listings of the entire package are available from the author or from Teledyne Geotech, P.O. Box 334, Alexandria, Virginia.