China
Africa
Explore chapters and articles related to this topic
Review of Conceptual Models of Estimating the Spatio-Temporal Variations of Water Depth Using Remote Sensing and GIS for the Management of Dams and Reservoirs
Published in Shruti Kanga, Suraj Kumar Singh, Gowhar Meraj, Majid Farooq, Geospatial Modeling for Environmental Management, 2022
Water depth measurement (Bathymetry) is required whenever a detailed survey of waterbed level is to be carried out; it is a method of quantifying depths to study the topography of water bodies, including oceans, seas, rivers, streams, and lakes (Jawak et al., 2015). It is also very important for the studies of the riverbed and seabed morphology, environmental research, and resource management of dams and reservoirs as well as coastal zones.
The Geoid and Oceanic Lithosphere
Published in Petr Vaníček, Nikolaos T. Christou, GEOID and Its GEOPHYSICAL INTERPRETATIONS, 2020
However, several important questions concerning the oceanic lithosphere and mantle remain to be solved. For example, what is the exact nature of the interaction of mantle plumes with oceanic plates? Does small-scale asthenospheric convection develop below the lithosphere? What is the fine thermal structure of oceanic plates? What are the details of the crustal accretion process along mid-ocean ridges? While continuing theoretical efforts are still essential, new geoid and topography data of higher resolution than presently available are needed. These would greatly help to understand the above problems in offering important new constraints. One of the main contributions in solid Earth physics from space missions in the coming years will be to obtain a very dense geoid coverage of oceanic areas (≈15 km resolution). The ERS 1 altimeter satellite may fulfill this objective when placed on a long term (≈180-d) repeat orbit. However, without topography data, geoid data are of poor help. Accurate and uniform topography data over the entire ocean domain are also strongly needed Hence continuing efforts to collect detailed bathymetry measurements from ships is of primary importance.
Remote Sensing
Published in Julio Sanchez, Maria P. Canton, William Perrizo, Space Image Processing, 2018
Julio Sanchez, Maria P. Canton
The science of bathymetry is concerned with the depth of bodies of water. This determination can be of critical importance in harbors and coastlines where sudden changes in the water depth can create hazards to navigation. For years, water depth has been measured by instruments carried on board vessels. Acoustic instruments, such as sonar, allow measuring the water depth below the vessel. This information can later be compiled into bathymetric maps. Aerial photography has also been used to determine water depths, especially in areas of clear waters. In the case of photography, filters are used to isolate radiation in the spectral band where solar energy is more easily transmitted by clear water (0.44 μm to 0.54 μm). Although there are significant technical difficulties in photogrametric methods of water depth determination, they have been successfully used for mapping shallow water areas.
Mobile-bed similitude evaluation of hydraulic sediment response models
Published in Journal of Applied Water Engineering and Research, 2019
Muhammed T. Mustafa, Amanda L. Cox, Robert D. Davinroy, Bradley J. Krischel, Ivan H. Nguyen
Uncertainty in computed parameters due to instrumentation accuracy in both the HSR and HEC-RAS models was evaluated using the first-order variance estimation method by Coleman and Steele (1999) (Equation (19)) where xi is the variables; Ur/r is the relative uncertainty in the result; and is the relative uncertainties of each variable. The following instruments were used to collect data in the HSR models: a 3-D laser scanner with accuracy of 24 µm, an automatic engineering level with accuracy of 1 mm at 30 m distance, a level rod with accuracy of ±0.5 mm, and an electromagnetic flowmeter with an accuracy of ±0.4% of measured value +1 mm s−1. For the prototype data collection, the error margin in the bathymetric and water-surface profile measurements was ±6 and ±3 cm, respectively. Using Equation (19) and the reported instrument accuracies, uncertainty of 17%, 13%, and 19% was computed for the Shields parameters calculations for both HSR models, the UBB HEC-RAS model, and the WP HEC-RAS model, respectively. Uncertainty in the computed values of the particle size dimensionless numbers was determined to be 14%, 13%, and 17% for both HSR models, the UBB HEC-RAS model, and the WP HEC-RAS model, respectively.
Monitoring volumetric fluctuations in tropical lakes and reservoirs using satellite remote sensing
Published in Lake and Reservoir Management, 2018
Tyler A. Keys, Durelle T. Scott
Sustainable management of lakes and reservoirs is becoming increasingly more important as global population and water demand increases. There are currently 117 million lakes and reservoirs greater than 0.002 km2 (2,000 m2) in the world, making up 3.7% of the Earth's land surface area (Verpoorter et al. 2014). Societal well-being depends on these surface water bodies and yet very few lakes or reservoirs are actually monitored (Alsdorf et al. 2007). Generally, hydrographic surveying of water body bathymetry is conducted via Sound Echoing and Ranging (SONAR; Yesuf et al. 2013) or bathymetric Light Detection and Ranging (LiDAR; Hilldale and Raff 2008, Skinner 2011). Unfortunately, these methods require a great deal of money, time, and labor (Peng et al. 2006). Furthermore, in situ monitoring of lakes and reservoirs is often problematic in developing nations due to the hydro-political dangers of monitoring in international basins (Hossain et al. 2007).
The influence of submarine currents associated with the Subtropical Front upon seafloor depression morphologies on the eastern passive margin of South Island, New Zealand
Published in New Zealand Journal of Geology and Geophysics, 2018
Jess I. T. Hillman, Ingo Klaucke, Ingo A. Pecher, Andrew R. Gorman, Jens Schneider von Deimling, Joerg Bialas
Here, we present multibeam bathymetry, sub-bottom profiler and boomer seismic data acquired during the 2012 TAN1209 cruise on the R/V Tangaroa, the 2013 SO226 cruise on the R/V Sonne and the 2013 13PL235 cruise on the R/V Polaris II (Mitchell and Neil 2012; Bialas et al. 2013). A hull-mounted Kongsberg EM120 multibeam echosounder (MBES) was used to acquire multibeam bathymetry data during cruise SO226, generating 191 beams with operational frequencies ranging from 11.25 to 12.60 kHz (Bialas et al. 2013). During cruise TAN1209, a hull-mounted Kongsberg Simrad EM302 was used, with an operational frequency of 30 kHz and a swath width of 130°. Multibeam bathymetry data were first calibrated for roll-offset, and then processed using MBSystem® software to remove spikes and other anomalous soundings. Grids of bathymetric data across the survey area were created with a resolution of 25 × 25 m. Using these grids, seafloor depressions were mapped in ArcGIS® to calculate the apparent aspect ratio (ARA) of the depressions.