scholarly journals Land Feature Extraction-Identification and Descrimincation using Geospatial Technique

10.29007/ckgd ◽  
2018 ◽  
Author(s):  
Dharmesh Modi ◽  
Subhash Bhandari ◽  
Laxmansinh B. Zala
Keyword(s):  
Remote Sensing ◽  
Time Scale ◽  
Regional Scale ◽  
High Tide ◽  
River Mouth ◽  
Tidal Currents ◽  
Tidal Range ◽  
Large Contribution ◽  
Geological Time Scale ◽  
Geomorphological Features

The Gulf of Cambay/Khambhat, (GoC), the study area is highly influenced by the tidal currents other than geological and structural set up of the region. In Gulf of Cambay, a large tidal range during high and low tides give rise to strong tidal currents and develops a mechanism of sediment transportation. Interestingly the inverted funnel shape of GoC has large contribution for the sediment deposition in this region. During high tide the tide currents move into the Gulf and encroaches the river mouth whereas during low tide, they move out. This regular phenomena since long period on geological time scale has modified the geomorphological features in this region.Along the major estuaries of Sabarmati, Mahi, Narmada and Tapi, the sediment budget is controlled by seasonal variation and also by tide and ebb phenomena.Using remote sensing images of different time scale and topographical map one can study the changes in geomorphological features. Satellite remote sensing technique has proven to be the paramount tool for studying surficial land features, especially for the inaccessible area or where time variable studies and regional scale studies are carried out. The well-developed natural or artificial features near to coastline viz salt pan, marshy land, mudflats, rocky cliffs, alluvial cliffs, wet land, mangroves, erosional and depositional features are well studied with the help of remote sensing techniques.

scholarly journals Studies of Internal Waves in the Strait of Georgia Based on Remote Sensing Images

2019 ◽  
Vol 11 (1) ◽  
pp. 96 ◽  
Author(s):  
Caixia Wang ◽  
Xin Wang ◽  
Jose C. B. Da Silva
Keyword(s):  
Remote Sensing ◽  
Internal Waves ◽  
River Mouth ◽  
Temporal Distribution ◽  
Tidal Currents ◽  
River Plume ◽  
Remote Sensing Images ◽  
Strait Of Georgia ◽  
Narrow Channels ◽  
Propagating Waves

This paper analyzes over 500 sets of internal waves in the Strait of Georgia (British Columbia, Canada) based on a large number of satellite remote sensing images. The spatial and temporal distribution of internal waves in the central region of the strait are discussed via statistical analysis. Possible generation origins of the observed internal waves are divided into three categories based on their different propagation directions and geographical locations: (1) the interaction between the narrow channels to the south of the Strait and the tidal currents, leading to the formation of mainly eastward and northward propagating waves; (2) the interaction between the tidal currents and the topography near Point Roberts, resulting in mainly westward propagating waves; (3) excitation by river plume, mainly near Fraser River mouth, leading to the formation of mainly westward waves along the direction of the river plume. The relation between the occurrence of internal waves in remote sensing images and wind or tide level is also discussed. It is found that most of the observed internal waves occur at low tides. However, due to the influence of the river, the eastward propagating internal waves near the river mouth seldom occur at the lowest tide. Also, internal waves are captured more easily by remote sensing images in summer due to the lower wind speed than winter and therefore the seasonal distribution of internal waves in remote sensing images may not be able to completely represent the real situation in the study area. Finally, combining the in situ measured data and model output data, the Benjamin-Ono equation is found to satisfyingly simulate the characteristic parameters of the studied internal waves.

scholarly journals Improving the Evapotranspiration Estimation under Cloudy Condition by Extending the Ts-VI Triangle Model

2021 ◽  
Vol 13 (8) ◽  
pp. 1516
Author(s):  
Boyang Li ◽  
Yaokui Cui ◽  
Xiaozhuang Geng ◽  
Huan Li
Keyword(s):  
Remote Sensing ◽  
Surface Temperature ◽  
Land Surface ◽  
Energy Exchange ◽  
Vegetation Index ◽  
Regional Scale ◽  
Reconstruction Algorithm ◽  
Heihe River ◽  
Main Process ◽  
In Situ Data

Evapotranspiration (ET) of soil-vegetation system is the main process of the water and energy exchange between the atmosphere and the land surface. Spatio-temporal continuous ET is vitally important to agriculture and ecological applications. Surface temperature and vegetation index (Ts-VI) triangle ET model based on remote sensing land surface temperature (LST) is widely used to monitor the land surface ET. However, a large number of missing data caused by the presence of clouds always reduces the availability of the main parameter LST, thus making the remote sensing-based ET estimation unavailable. In this paper, a method to improve the availability of ET estimates from Ts-VI model is proposed. Firstly, continuous LST product of the time series is obtained using a reconstruction algorithm, and then, the reconstructed LST is applied to the estimate ET using the Ts-VI model. The validation in the Heihe River Basin from 2009 to 2011 showed that the availability of ET estimates is improved from 25 days per year (d/yr) to 141 d/yr. Compared with the in situ data, a very good performance of the estimated ET is found with RMSE 1.23 mm/day and R2 0.6257 at point scale and RMSE 0.32 mm/day and R2 0.8556 at regional scale. This will improve the understanding of the water and energy exchange between the atmosphere and the land surface, especially under cloudy conditions.

scholarly journals Regional-scale phenology modeling based on meteorological records and remote sensing observations

2012 ◽  
Vol 117 (G3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Xi Yang ◽  
John F. Mustard ◽  
Jianwu Tang ◽  
Hong Xu
Keyword(s):  
Remote Sensing ◽  
Regional Scale

Regional characterisation of soil properties by combining soil science and hyperspectral and thermal remote sensing: A technical overview of lab and field remote sensing methods

2021 ◽  
Author(s):  
Richard Mommertz ◽  
Lars Konen ◽  
Martin Schodlok
Keyword(s):  
Remote Sensing ◽  
Soil Properties ◽  
Regional Scale ◽  
Arable Land ◽  
Soil Mapping ◽  
Soil Science ◽  
Near Surface ◽  
Soil Parameter ◽  
The Impact ◽  
Parameter Retrieval

<p>Soil is one of the world’s most important natural resources for human livelihood as it provides food and clean water. Therefore, its preservation is of huge importance. For this purpose, a proficient regional database on soil properties is needed. The project “ReCharBo” (Regional Characterisation of Soil Properties) has the objective to combine remote sensing, geophysical and pedological methods to determine soil characteristics on a regional scale. Its aim is to characterise soils non-invasive, time and cost efficient and with a minimal number of soil samples to calibrate the measurements. Konen et al. (2021) give detailed information on the research concept and first field results in a presentation in the session “SSS10.3 Digital Soil Mapping and Assessment”. Hyperspectral remote sensing is a powerful and well known technique to characterise near surface soil properties. Depending on the sensor technology and the data quality, a wide variety of soil properties can be derived with remotely sensed data (Chabrillat et al. 2019, Stenberg et al. 2010). The project aims to investigate the effects of up and downscaling, namely which detail of information is preserved on a regional scale and how a change in scales affects the analysis algorithms and the possibility to retrieve valid soil parameter information. Thus, e.g. laboratory and field spectroscopy are applied to gain information of samples and fieldspots, respectively. Various UAV-based sensors, e.g. thermal & hyperspectral sensors, are applied to study soil properties of arable land in different study areas at field scale. Finally, airborne (helicopter) hyperspectral data will cover the regional scale. Additionally forthcoming spaceborne hyperspectral satellite data (e.g. Prisma, EnMAP, Sentinel-CHIME) are a promising outlook to gain detailed regional soil information. In this context it will be discussed how the multisensor data acquisition is best managed to optimise soil parameter retrieval. Sensor specific properties regarding time and date of acquisition as well as weather/atmospheric conditions are outlined. The presentation addresses and discusses the impact of a multisensor and multiscale remote sensing data collection regarding the results on soil parameter retrieval.</p><p> </p><p>References</p><p>Chabrillat, S., Ben-Dor, E. Cierniewski, J., Gomez, C., Schmid, T. & van Wesemael, B. (2019): Imaging Spectroscopy for Soil Mapping and Monitoring. Surveys in Geophysics 40:361–399. https://doi.org/10.1007/s10712-019-09524-0</p><p>Stenberg, B., Viscarra Rossel, R. A., Mounem Mouazen, A. & Wetterlind, J. (2010): Visible and Near Infrared Spectroscopy in Soil Science. In: Donald L. Sparks (editor): Advances in Agronomy. Vol. 107. Academic Press:163-215. http://dx.doi.org/10.1016/S0065-2113(10)07005-7</p>

Maritime built heritage and marine wildlife: Remote sensing as a tool to identify and prioritise integrated conservation in coastal environments

2021 ◽  
Author(s):  
Tim Baxter ◽  
Martin Coombes ◽  
Heather Viles
Keyword(s):  
Remote Sensing ◽  
Structural Information ◽  
Regional Scale ◽  
Initial Assessment ◽  
Marine Biodiversity ◽  
Engineering Structures ◽  
Built Heritage ◽  
Ecological Importance ◽  
Integrated Conservation ◽  
Marine Wildlife

<p>Maritime built heritage is threatened by natural hazards and human activities around the world. Likewise, marine wildlife is increasingly threatened by the effects of climate change and human development. Due to their age and traditional construction, maritime built heritage (e.g. historic harbours) may provide unique habitats for diverse assemblages of marine wildlife. Yet, as aspects of built heritage are often missing in assessments of marine infrastructure, identifying which heritage assets have the potential to provide the greatest ecological benefits remains a challenge. An improved understanding of the ecological importance of maritime built heritage can enhance arguments for its continued protection, maintenance and repair. At the same time, this may present new opportunities to conserve important and largely unidentified hotspots of marine biodiversity.</p><p>Using preliminary results from the Isles of Scilly, UK, this study presents a novel method for quantifying the full extent of marine engineering structures (including heritage assets) at a regional scale, and for identifying priority structures for joint biodiversity and heritage conservation.</p><p>Remote sensing data were considered alongside historic environment data and records of modern coastal defences in a rapid desk-based assessment to create a complete inventory of marine structures along the entire coastline of the Isles of Scilly. In total, 68 structures were recorded (6,180 m in length), with over half registered as heritage assets. LiDAR and aerial photography were used to determine the site characteristics of each structure (e.g. shore position). This allowed for an initial assessment of the potential ecological importance of these structures when considered alongside structural information, including building age and material. By evaluating the ecological potential and heritage value of each structure using a novel scoring system, priorities for conservation and other managed interventions are identified. This includes listed buildings and scheduled monuments that due to their construction features and shore position are most likely to support diverse marine assemblages.</p><p>Combined ecological-heritage evaluations incorporating remote sensing datasets allow for the identification of those structures with the greatest potential for the integrated conservation of built heritage and marine wildlife. Research is now needed to develop this method further, ground-truth its outputs, and test its application in other geographical locations and at varying scales.</p>

From inflow to interflow, through plunging and lofting: uncovering the dominant flow processes of a sediment-rich negatively buoyant river inflow into a stratified lake

2021 ◽  
Author(s):  
Stan Thorez ◽  
Koen Blanckaert ◽  
Ulrich Lemmin ◽  
David Andrew Barry
Keyword(s):  
Remote Sensing ◽  
River Mouth ◽  
Ambient Water ◽  
Remote Sensing Images ◽  
Reservoir Water ◽  
Neutral Buoyancy ◽  
Wide Range ◽  
Adcp Measurements ◽  
Vorticity Production ◽  
Negatively Buoyant

<p>Lake and reservoir water quality is impacted greatly by the input of momentum, heat, oxygen, sediment, nutrients and contaminants delivered to them by riverine inflows. When such an inflow is negatively buoyant, it will plunge upon contact with the receiving ambient water and form a gravity-driven current near the bed (density current). If such a current is sediment-laden, its bulk density can be higher than that of the surrounding ambient water, even if its carrying fluid has a density lower than that of the surrounding ambient water. After sufficient sediment particles have settled however, the buoyancy of the current can reverse and lead to the plume rising up from the bed, a process referred to as lofting. In a stratified environment, the river plume may then find its way into a layer of neutral buoyancy to form an intermediate current (interflow). A deeper understanding of the wide range of hydrodynamic processes related to the transitions from open-channel inflow to underflow (plunging) and from underflow to interflow (lofting) is crucial in predicting the fate of all components introduced into the lake or reservoir by the inflow.</p><p>Field measurements of the plunging inflow of the negatively buoyant Rhône River into Lake Geneva (Switzerland/France) are presented. A combination of a vessel-mounted ADCP and remote sensing cameras was used to capture the three-dimensional flow field of the plunging and lofting transition zones over a wide range of spatial and temporal scales.</p><p>In the plunge zone, the ADCP measurements show that the inflowing river water undergoes a lateral (perpendicular to its downstream direction) slumping movement, caused by its density surplus compared to the ambient lake water and the resulting baroclinic vorticity production. This effect is also visible in the remote sensing images in the form of a distinct plume of sediment-rich water with a triangular shape leading away from the river mouth in the downstream direction towards a sharp tip. A wide range of vortical structures, which most likely impact the amount of mixing taking place, is also visible at the surface in the plunging zone.</p><p>In the lofting zone, the ADCP measurements show that the underflow undergoes a lofting movement at its edges. This is most likely caused by a higher sedimentation rate due to the lower velocities at the underflow edges and leads to a part of the underflow peeling off and forming an interflow, while the higher velocity core of the underflow continues following the bed. Here, the baroclinic vorticity production works in the opposite direction as that in the plunge zone. Further downstream, as more particles have settled and the surrounding ambient water has become denser, the remaining underflow also undergoes a lofting motion. The remnants of these lofting processes show in the remote sensing images as intermittent ‘boils’ of sediment rich water reaching the surface and traces of surface layer leakage.</p>

scholarly journals Assessment of model estimates of land-atmosphere CO<sub>2</sub> exchange across Northern Eurasia

2015 ◽  
Vol 12 (14) ◽  
pp. 4385-4405 ◽  
Author(s):  
M. A. Rawlins ◽  
A. D. McGuire ◽  
J. S. Kimball ◽  
P. Dass ◽  
D. Lawrence ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Soil Carbon ◽  
Residence Time ◽  
Primary Productivity ◽  
Ecosystem Respiration ◽  
Regional Scale ◽  
Northern Eurasia ◽  
Sink Strength ◽  
Vegetation Productivity ◽  
Co2 Sink

Abstract. A warming climate is altering land-atmosphere exchanges of carbon, with a potential for increased vegetation productivity as well as the mobilization of permafrost soil carbon stores. Here we investigate land-atmosphere carbon dioxide (CO2) cycling through analysis of net ecosystem productivity (NEP) and its component fluxes of gross primary productivity (GPP) and ecosystem respiration (ER) and soil carbon residence time, simulated by a set of land surface models (LSMs) over a region spanning the drainage basin of Northern Eurasia. The retrospective simulations cover the period 1960–2009 at 0.5° resolution, which is a scale common among many global carbon and climate model simulations. Model performance benchmarks were drawn from comparisons against both observed CO2 fluxes derived from site-based eddy covariance measurements as well as regional-scale GPP estimates based on satellite remote-sensing data. The site-based comparisons depict a tendency for overestimates in GPP and ER for several of the models, particularly at the two sites to the south. For several models the spatial pattern in GPP explains less than half the variance in the MODIS MOD17 GPP product. Across the models NEP increases by as little as 0.01 to as much as 0.79 g C m−2 yr−2, equivalent to 3 to 340 % of the respective model means, over the analysis period. For the multimodel average the increase is 135 % of the mean from the first to last 10 years of record (1960–1969 vs. 2000–2009), with a weakening CO2 sink over the latter decades. Vegetation net primary productivity increased by 8 to 30 % from the first to last 10 years, contributing to soil carbon storage gains. The range in regional mean NEP among the group is twice the multimodel mean, indicative of the uncertainty in CO2 sink strength. The models simulate that inputs to the soil carbon pool exceeded losses, resulting in a net soil carbon gain amid a decrease in residence time. Our analysis points to improvements in model elements controlling vegetation productivity and soil respiration as being needed for reducing uncertainty in land-atmosphere CO2 exchange. These advances will require collection of new field data on vegetation and soil dynamics, the development of benchmarking data sets from measurements and remote-sensing observations, and investments in future model development and intercomparison studies.

Neogene and Quaternary coexisting in the geological time scale: The inclusive compromise

2009 ◽  
Vol 96 (4) ◽  
pp. 249-262 ◽  
Author(s):  
Brian McGowran ◽  
Bill Berggren ◽  
Frits Hilgen ◽  
Fritz Steininger ◽  
Marie-Pierre Aubry ◽  
...  
Keyword(s):  
Time Scale ◽  
Geological Time ◽  
Geological Time Scale
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