scholarly journals Integration of Satellite Image Derived Temperature and Water Depth for Assessing Fish Habitability in Dam Controlled Flood Plain Wetland

2021 ◽  
Author(s):  
Sonali Kundu ◽  
Swades Pal ◽  
Swapan Talukdar ◽  
Susanta Mahato ◽  
Pankaj Singha
Keyword(s):  
Water Depth ◽  
Thermal Environment ◽  
Satellite Image ◽  
Flood Plain ◽  
Habitable Zones ◽  
Optimum Depth ◽  
Field Information ◽  
Controlled Flood ◽  
Fish Survival ◽  
Future Work

Abstract The present study attempted to investigate the changes in temperature conducive to fish habitability during the summer months in a hydrologically modified wetland following damming over a river. Satellite image-driven temperature and depth data calibrated with field data were used to analyse fish habitability and the presence of thermally optimum habitable zones in some fishes such as Labeo Rohita, Cirrhinus mrigala, Tilapia fish, Small shrimp, and Cat fishes. The study was conducted both at the water's surface and at the optimum depth of survival. It is very obvious from the analysis that a larger part of wetland has become an area that destroyed aquatic habitat during the post-dam period and existing wetlands have suffered significant shallowing of water depth. This has resulted in a shrinking of the thermally optimum area of fish survival in relation to surface water temperature (from 100.09 km2 to 74.24 km2 before the dam to 93.97 km2 to 0 km2 after the dam) and an improvement in the optimum habitable condition in the comfortable depth niche of survival. In the post-dam period, it increased from 75.49 % to 99.765%. Since the damming effect causes a 30.53 to 100% depletion of the optimum depth niche, improving the thermal environment has no effect on fish habitability. More water must be released from dams for restoration. Image-driven depth and temperature data calibrated with field information has been successfully applied in data sparse conditions, and it is further recommended in future work.

scholarly journals Utilisation of satellite data in identification of geomorphic landform and its role in arsenic release in groundwater

2014 ◽  
Vol II-8 ◽  
pp. 29-35 ◽  
Author(s):  
R. P. Singh ◽  
N. Singh ◽  
S. Shashtri ◽  
S. Mukherjee
Keyword(s):  
Organic Matter ◽  
Iron Hydroxide ◽  
Satellite Image ◽  
Flood Plain ◽  
Spectral Signature ◽  
Brahmaputra River ◽  
Arsenic In Groundwater ◽  
Groundwater Samples ◽  
Geomorphic Features ◽  
Geomorphic Units

The present study was conducted to explore the influence of geomorphic features of the area on the mobilization of arsenic in groundwater. In this study, remote sensing and GIS techniques were used to prepare the geomorphic and slope map of the area. Different geomorphic features were identified on the basis of spectral signature on the LISS III and Landsat satellite image and field survey. Groundwater samples were collected from each representative geomorphic feature to inspect the arsenic contamination in the area. The study area is drained by the Brahmaputra river and its tributaries and contain mainly fluvial geomorphic units especially older flood plain, palaeochannels, oxbow lakes, channel islands; and hilly areas at some of the places. In this study it was observed that enrichment of arsenic in groundwater varies along the geomorphic units in following trends Paleochannel> Younger alluvial plain> Active flood plain> channel island > dissected hills. The above trend shows that a higher concentration of arsenic is found in the groundwater samples collected from the fluvial landforms as compared to those collected from structural landforms. Brahmaputra River and its tributaries carry the sediment load from the Himalayan foothills, which get deposited in these features during the lateral shift of the river’s courses. Arsenic bearing minerals may get transported through river and deposit in the geomorphological features along with organic matter. The flat terrain of the area as seen from the slope map provides more residence time to water to infiltrate into the aquifer. The microbial degradation of organic matter generates the reducing environment and facilitates the dissolution of iron hydroxide thus releasing the adsorbed arsenic into the groundwater.

AN EXPERIMENTAL STUDY OF SHIP MOTIONS DURING REPLENISHMENT AT SEA OPERATIONS BETWEEN A SUPPLY VESSEL AND A LANDING HELICOPTER DOCK

2021 ◽  
Vol 160 (A2) ◽  
Author(s):  
J Mathew ◽  
D Sgarioto ◽  
J Duffy ◽  
G Macfarlane ◽  
S Denehy ◽  
...  
Keyword(s):  
Experimental Study ◽  
Water Depth ◽  
Research Program ◽  
Hydrodynamic Interactions ◽  
Scale Model ◽  
Ship Motions ◽  
Intermediate Water ◽  
Large Ship ◽  
Future Work ◽  
Replenishment At Sea

Hydrodynamic interactions during Replenishment at Sea (RAS) operations can lead to large ship motions and make it difficult for vessels to maintain station during the operation. A research program has been established which aims to validate numerical seakeeping tools to enable the development of enhanced operator guidance for RAS. This paper presents analysis of the first phase of scale model experiments and focuses on the influence that both the lateral and longitudinal separations between two vessels have on the interactions during RAS. The experiments are conducted in regular head seas on a Landing Helicopter Dock (LHD) and a Supply Vessel (SV) in intermediate water depth. The SV is shorter than the LHD by approximately 17%, but due to its larger block coefficient, it displaces almost 16% more than the LHD. Generally, the motions of the SV were larger than the LHD. It was found that hydrodynamic interactions can lead to large SV roll motions in head seas. Directions for future work are provided.

scholarly journals The Tolerance Characteristics of Resident Fish in the Upper Yangtze River under Varying Gas Supersaturation

2019 ◽  
Vol 16 (11) ◽  
pp. 2021 ◽  
Author(s):  
Qianfeng Ji ◽  
Shudan Xue ◽  
Quan Yuan ◽  
Yuan Yuan ◽  
Yuanming Wang ◽  
...  
Keyword(s):  
Laboratory Experiment ◽  
Water Depth ◽  
Yangtze River ◽  
Field Experiments ◽  
Resident Fish ◽  
Upper Yangtze River ◽  
Fluctuation Range ◽  
Fish Survival ◽  
The Upper Yangtze River ◽  
Natural Rivers

In circumstances where total dissolved gas (TDG) levels are variable, the peak TDG and duration are expected to be the dominant drivers of fish survival. Focusing on the peak TDG and duration in natural rivers, a laboratory experiment and field experiments in the upper Yangtze River were conducted with Prenant’s Schizothoracin (Schizothorax prenanti), a rare species inhabiting the upper Yangtze River, to examine the tolerance characteristics of fish under varying gas supersaturation levels. The results of the field experiments showed that TDG supersaturation in natural rivers changed greatly during the flood period due to reservoir regulation. The survival of fish was affected by TDG levels, water depth and TDG fluctuation range. A high TDG level, and shallow compensatory water depth caused fish mortality in the field experiment to be higher in September than in July. The results of the laboratory experiment showed that fish tolerance was lower under fluctuating TDG supersaturation than under constant TDG supersaturation. The tolerance of fish to TDG supersaturation varied depending on peak TDG and duration. Under the fluctuation range of 115–125%, fish survival in the 6 h–6 h cycle was significantly different from that in the 8 h–8 h cycle. The fluctuation cycle did not affect fish survival at the fluctuation range of 110–130%. Intermittent lower TDG supersaturation does not significantly increase the tolerance of fish. This study revealed the tolerance characteristics of resident fish in the upper Yangtze River to TDG supersaturation, which provides a reference to the ecological operation of reservoirs and may contribute to the protection of aquatic organisms.

scholarly journals Fate of terrigenous organic matter across the Laptev Sea from the mouth of the Lena River to the deep sea of the Arctic interior

2016 ◽  
Author(s):  
Lisa Bröder ◽  
Tommaso Tesi ◽  
Joan A. Salvadó ◽  
Igor P. Semiletov ◽  
Oleg V. Dudarev ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Water Depth ◽  
Deep Sea ◽  
River Mouth ◽  
The Arctic ◽  
Laptev Sea ◽  
Climate Feedbacks ◽  
Lena River ◽  
Lignin Phenols ◽  
Future Work

Abstract. Ongoing global warming in high latitudes may cause an increasing supply of permafrost-derived organic carbon through both river discharge and coastal erosion to the Arctic shelves. Here it can be either buried in sediments, transported to the deep sea or degraded to CO2 and outgassed, potentially constituting a positive feedback to climate change. This study aims to assess the fate of terrestrial organic carbon (TerrOC) in the Arctic marine environment by exploring how it changes in concentration, composition and degradation status across the wide Laptev Sea shelf. We analyzed a suite of terrestrial biomarkers as well as source-diagnostic bulk carbon isotopes (δ13C, Δ14C) in surface sediments from a Laptev Sea transect spanning more than 800 km from the Lena River mouth (~ 10 m water depth) across the shelf to the slope and rise (2000–3000 m water depth). These data provide a broad view on different TerrOC pools and their behavior during cross-shelf transport. The concentrations of lignin phenols, cutin acids and high-molecular weight (HMW) wax lipids (tracers of vascular plants) decrease by 89–99 % along the transect. Molecular-based degradation proxies for TerrOC (e.g., the carbon preference index of HMW lipids, the HMW acids/alkanes ratio and the acid/aldehyde ratio of lignin phenols) display a trend to more degraded TerrOC with increasing distance from the coast. We infer that the degree of degradation of permafrost-derived TerrOC is a function of the time spent under oxic conditions during protracted cross-shelf transport. Future work should therefore seek to constrain cross-shelf transport times in order to compute a TerrOC degradation rate and thereby help to quantify potential carbon-climate feedbacks.

scholarly journals Shallow Water Bathymetry Mapping of Xinji Island Based on Multispectral Satellite Image using Deep Learning

2021 ◽  
Author(s):  
Jiaxin Wan ◽  
Yi Ma
Keyword(s):  
Deep Learning ◽  
Shallow Water ◽  
Water Depth ◽  
Satellite Image ◽  
Absolute Error ◽  
Coastal Zones ◽  
Multispectral Data ◽  
Novel Approach ◽  
Multispectral Satellite Image ◽  
Remote Sensing Techniques

AbstractNearshore bathymetry is a basic parameter of the ocean, which is crucial to the research and management of coastal zones. Previous studies have demonstrated that remote sensing techniques can be employed in estimating bathymetric information. In this paper, we propose a deep belief network with data perturbation (DBN-DP) algorithm for shallow water depth inversion from high resolution multispectral data, and applying it in Xinji Island of Malacca Strait and Yongxing Island in China. Results show that the DBN-DP method can produce more accurate water depth estimations than other traditional methods particularly for deeper water, which reaches 1.2 m of mean absolute error (MAE) and 12.8% of mean relative error (MRE) in Xinji Island. Most of the estimated bathymetry meet the category of zone of confidence C level defined by the International Hydrographic Organization. These findings are encouraging for employing deep learning in bathymetry, which may become a novel approach for bathymetric inversion in the future.

scholarly journals Wetlands of Dhaka City: Its Past and Present Scenario

2014 ◽  
Vol 7 ◽  
pp. 83-90 ◽  
Author(s):  
Md Shahidul Islam ◽  
AKM Shahabuddin ◽  
M Mostafa Kamal ◽  
Raquib Ahmed
Keyword(s):  
Resource Constraints ◽  
Satellite Image ◽  
Flood Plain ◽  
Water Bodies ◽  
Dhaka City ◽  
Topographic Map ◽  
Urbanization Process ◽  
Gis And Remote Sensing ◽  
Remote Sensing Technique ◽  
The City

Landscape of Dhaka city, one of the fastest growing mega cities in the world, is undergoing continuous changes and modifications due to unplanned hasty urbanization process. As the growth of urbanization taking place at an exceptionally rapid rate the city is unable to cope with changing situation due to internal resource constraints and management limitations. Dhaka city endowed with a large number of water-bodies both big and small, which includes river, khals, lakes, flood plain low-lying areas etc. However, pre and post-urban changes of water-bodies in the city were studied using topographic map of 1960 and a satellite image of 2008 (ALOS VNIR 2008) through GIS and remote sensing technique. It is found that in 1960 total areas of water-bodies and lowland were 2952.02 and 13527.58 hectares. But in 2008 total areas of water-bodies and lowland found 1990.71 and 6414.57 hectares. Categories (water-bodies and lowlands) of wetland areas were decreased harshly. Study shows that water-bodies and lowland areas were decreased 32.57% and 52.58% that means more than 49% of the wetland areas decreased over the period 1960 to 2008. The changes of low-lying areas in the south-western corner extending towards Mirpur, Muhammadpur and Pallabi-Cantonment areas and filled for the urban development. The part of Gulshan and Dhanmondi lakes has also been reduced; and some of the channels of Motijheel areas are not identifiable at present. The growth of urban infrastructures have been taking place in unplanned way; as a result it destroyed natural drainage systems, fill-up the water-bodies, causing water-loggings during rainy season in various part of the city. This study revealed that immediate necessary steps should take by concern authority to prevent from various disasters that might be occurred due to unwise and unplanned wetland changes.DOI: http://dx.doi.org/10.3329/jles.v7i0.20126 J. Life Earth Sci., Vol. 7: 83-90, 2012

scholarly journals Analysis of Very High Spatial Resolution Images for Automatic Shoreline Extraction and Satellite-Derived Bathymetry Mapping

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 172
Author(s):  
Giovanni Randazzo ◽  
Giovanni Barreca ◽  
Maria Cascio ◽  
Antonio Crupi ◽  
Marco Fontana ◽  
...  
Keyword(s):  
Shallow Water ◽  
Spatial Resolution ◽  
Water Depth ◽  
High Spatial Resolution ◽  
Satellite Image ◽  
Atmospheric Correction ◽  
Coastal Areas ◽  
Ratio Method ◽  
Very High Spatial Resolution ◽  
Very High

The amount of Earth observation images available to the public has been the main source of information, helping governments and decision-makers tackling the current world’s most pressing global challenge. However, a number of highly skilled and qualified personnel are still needed to fill the gap and help turn these data into intelligence. In addition, the accuracy of this intelligence relies on the quality of these images in times of temporal, spatial, and spectral resolution. For the purpose of contributing to the global effort aiming at monitoring natural and anthropic processes affecting coastal areas, we proposed a framework for image processing to extract the shoreline and the shallow water depth on GeoEye-1 satellite image and orthomosaic image acquired by an unmanned aerial vehicle (UAV) on the coast of San Vito Lo Capo, with image preprocessing steps involving orthorectification, atmospheric correction, pan sharpening, and binary imaging for water and non-water pixels analysis. Binary imaging analysis step was followed by automatic instantaneous shoreline extraction on a digital image and satellite-derived bathymetry (SDB) mapping on GeoEye-1 water pixels. The extraction of instantaneous shoreline was conducted automatically in ENVI software using a raster to vector (R2V) algorithm, whereas the SDB was computed in ArcGIS software using a log-band ratio method applied on the satellite image and available field data for calibration and vertical referencing. The results obtained from these very high spatial resolution images demonstrated the ability of remote sensing techniques in providing information where techniques using traditional methods present some limitations, especially due to their inability to map hard-to-reach areas and very dynamic near shoreline waters. We noticed that for the period of 5 years, the shoreline of San Vito Lo Capo sand beach migrated about 15 m inland, indicating the high dynamism of this coastal area. The bathymetric information obtained on the GeoEye-1 satellite image provided water depth until 10 m deep with R2 = 0.753. In this paper, we presented cost-effective and practical methods for automatic shoreline extraction and bathymetric mapping of shallow water, which can be adopted for the management and the monitoring of coastal areas.

scholarly journals Applying Artificial Intelligence (AI) Techniques to Implement a Practical Smart Cage Aquaculture Management System

2021 ◽  
Author(s):  
Chung-Cheng Chang ◽  
Jung-Hua Wang ◽  
Jenq-Lang Wu ◽  
Yi-Zeng Hsieh ◽  
Tzong-Dar Wu ◽  
...  
Keyword(s):  
Survival Rate ◽  
Management System ◽  
Cage Culture ◽  
Feed Conversion ◽  
Data Platform ◽  
Aquaculture Management ◽  
Field Information ◽  
Cage Aquaculture ◽  
Fish Survival ◽  
Feed Conversion Rate

Abstract Purpose This paper presents our team’s results to establish an AIoT smart cage culture management system. Methods According to the built system, the farmed field information is transmitted to the data platform of Ocean Cloud, and all collected data and analysis results can be applied to the cage culture field after the bigdata analysis. Results This management system successfully integrates AI and IoT technologies and is applied in cage culture. Using underwater biological analysis images and AI feeding as examples, this paper explains how the system integrates AI and IoT into a feasible framework that can constantly acquire information about the health status of fish, survival rate of fish, as well as the feed residuals. Conclusion The results of our research enable the aquaculture operators or owners to efficiently reduce the feed residual, monitor the growth of fish, and increase fish survival rate, thereby increasing the feed conversion rate.

scholarly journals THE EFFECT OF WAVE REFRACTION OVER DREDGED HOLES

1974 ◽  
Vol 1 (14) ◽  
pp. 35 ◽  
Author(s):  
J.M. Motyka ◽  
D.H. Willis
Keyword(s):  
Water Depth ◽  
Beach Erosion ◽  
English Channel ◽  
Extreme Waves ◽  
Sand Beach ◽  
Hole Depth ◽  
Wave Refraction ◽  
Side Slope ◽  
Future Work ◽  
Original Water

Preliminary results are presented of a study of the beach erosion caused by wave refraction over offshore dredged holes. A mathematical model is used of an idealised sand beach, typical of those on the English Channel and North Sea coasts of Great Britain. Depth and side slopes of dredged area and original water depth before dredging were varied. Beach erosion increased with increasing hole depth and with decreasing original water depth. The effects of side slope and hole depth will be separated in future work, as will the effects of hole shape. Beach erosion due to holes in water depths greater than half the length of "normal" waves, or a fifth of the length of extreme waves, was negligible.

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