Search results for "WATER DEPTH"
showing 9 items of 9 documents
Accuracy of IKONOS for mapping benthic coral-reef habitats: a case study from the Puerto Morelos Reef National Park, Mexico
2012
International audience; Reefs are being threatened by global warming, natural disasters, and the increased pressure of the global population. These habitats are in urgent need of mapping at high resolution so that these threats can be quantified. Remote sensing can potentially provide such quantitative data. In this article, we attempt to map benthic coral-reef habitats at the Puerto Morelos Reef National Park in Yucatan Peninsula (Mexico) and to assess the accuracy of the technique in providing a baseline data for future monitoring of changes and evolution of the reef system. An IKONOS image was used in combination with checkpoint ground sampling and classified using a supervised maximum l…
RESPONSE OF POSIDONIA OCEANICA TO WAVE MOTION IN SHALLOW-WATERS - PRELIMINARY EXPERIMENTAL RESULTS
2011
Aim of the present work is to contribute to the knowledge about the interaction between the flow induced by wave and the aquatic vegetation. More in details the results of preliminary tests of an experimental laboratory investigation about the response of a Posidonia Oceanica meadow to wave motion in shallow waters is reported. A wide attention was posed to the behavior of a synthetic plants with plastic material. To this aim an image acquisition technique was used to analyze and compare the movement of both the artificial plant and the real one. The experiments carried out about the interaction between the artificial meadow and the waves showed a significant wave dumping, in particular in …
Explicit equations for uniform flow depth
2017
Conventional approach in uniform open channel flow is to express the resistance coefficient in the Manning, Darcy-Weisbach or Chezy form. However, for practical cross-sections, including rectangular and trapezoidal ones, the governing equation is implicit in the uniform water depth. For these sections the water depth, corresponding to known values of the flow discharge, slope channel and resistance coefficient, is presently obtained by trial and error procedure. In this paper exact analytical solutions of uniform flow depth for rectangular and trapezoidal section have been obtained in the form of fast converging power series.
Testing the stage-discharge relationship of a sharp crested sluice gate deduced by the momentum equation for a free-flow condition
2018
Abstract In this paper the stage-discharge relationship of a sharp crested sluice gate is deduced by applying the momentum equation for a free flow condition. The theoretically deduced stage-discharge formula was then calibrated using experimental flume data obtained in previous investigations carried out for a free-flow condition. The deduced stage–discharge relationship is characterized by a momentum coefficient which is empirically estimated by the ratio between the height of the orifice and the water depth in the section upstream the gate. The relative errors are always less than or equal to - 10% to +10% and 71.4% of the errors are less than or equal to ± 2%.
New stage-discharge relationship for cylindrical and semi-cylindrical edged sluice gates
2019
Abstract Gates are simple hydraulic structures which have been widely used for flow control and measurement in irrigation networks. In this paper new sluice gates with cylindrical and semi-cylindrical edges were introduced and the flow movement below these types of gates was experimentally investigated for both free- and submerged-flow conditions. The Buckingham theorem of dimensional analysis and the self-similarity theory were applied for developing the stage-discharge relationships for the two investigated flow conditions. For these cylindrical and semi-cylindrical edged gates and a free-flow condition, the proposed stage-discharge relationship was characterized by an estimate error less…
New technique for measuring water depth in rill channels
2019
Abstract Water erosion is one of the most important soil degradation processes and rill erosion contribution to total soil loss is usually dominant as compared to interrill erosion. Rill erosion modelling requires that rill flow has to be adequately modelled. Flow depths in rills are typically of the order of millimeters to several centimeters and bed topography, characterized by steep slope values, significantly affects flow hydraulics. In this paper, a new technique for measuring the water depth inside a rill channel is proposed and the effects on flow resistance estimate are examined. This technique couples an accurate ground survey of the rill channel, obtained by close-range photogramm…
Quantitative Transfer Function Approaches in Palaeoclimatic Reconstruction Using Quaternary Ostracods
2012
Abstract Quantifying (palaeo-)environmental changes is a key challenge for aquatic biological proxies, but the number of published transfer functions is increasing rapidly for the main palaeoecologically relevant groups such as diatoms and chironomids, and several transfer functions have also been developed during the past decades based on ostracod findings. The main environmental variables influencing the species assemblage composition in ostracod training sets are specific ion concentrations or ratios, salinity, water temperature and/or water depth. The available transfer functions and training sets are globally scattered, but often regionally restricted in their application. The most com…
Persentase Tutupan Terumbu Karang di Perairan Pasir Putih Kabupaten Manokwari
2017
Penelitian ini dilakukan pada bulan Oktober sampai November 2014 di perairan Pasir Putih Kabupaten Manokwari, berlokasi di Pantai Air Salobar. Tujuan penelitian adalah untuk mengetahui persentase tutupan terumbu karang, kualitas fisik-kimia air dan korelasi kualitas fisik-kimia air terhadap persentase tutupan terumbu karang di bagian barat daya perairan Pasir Putih, Manokwari. Metode yang digunakan untuk memperoleh data persentase tutupan karang adalah Point Intercept Transect (PIT) pada kedalaman 3 m (Transek I), 7 m (Transek II) dan 10 m (Transek III). Hasil pengamatan diperoleh persentase tutupan karang pada Transek I adalah 91%, Transek II adalah 78% dan Transek III adalah 54%. Kondisi …
Simple flume with a central baffle
2016
Abstract In this paper the stage-discharge relationship of a flume with a central baffle is theoretically deduced using the Buckingham-Theorem of the dimensional analysis and the self-similarity theory. The new stage-discharge equation is calibrated by the measurements carried out by Peruginelli and Bonacci using a baffle having a given throat length and five different values of the contraction ratio. Finally, for a given throat length, a relationship linking the discharge with the upstream water depth, the contraction ratio and the contracted width is deduced.