scholarly journals Wave-attenuation characteristics of combined-vegetation wave break forests for big rivers with large flood water level changes

2021 ◽  
Vol 83 (4) ◽  
pp. 831-840
Author(s):  
Jie Ren ◽  
Zengchuan Dong ◽  
Dawei Jin ◽  
Yue Zhou ◽  
Wei Xu ◽  
...  
Keyword(s):  
Water Level ◽  
Water Depth ◽  
Water Surface ◽  
Wave Attenuation ◽  
Water Levels ◽  
Large Rivers ◽  
Attenuation Effect ◽  
Practical Applications ◽  
Different Types ◽  
Wave Break

Abstract For large rivers with a compound cross section, the downstream channel has a very wide water surface during the flood season. A wide water surface, high water level, and larger wind speed will cause higher waves, increasing the threat of flooding to the dike. The design of a combined-vegetation wave break forest was put forward to achieve better wave attenuation effect. The main idea of this concept is to plant different types of vegetation at different locations in front of the dike. Three single-vegetation and four combined-vegetation forest schemes were tested under seven different water depth conditions. Both physical experiments and wave numerical simulations were carried out for each scheme to study the wave attenuation effect. The results showed that the wave attenuation effect of the single-vegetation wave break forest was significantly different under different water depth conditions, and the overall effect of the combined-vegetation of wave forest was better. Combined-vegetation wave break forests combine the advantages of different types of vegetation in different water levels, which makes it more economical and reasonable to plant by rivers with large water level variation. The proposed design ideas and methods could provide theoretical support for ecological revetment engineering of large rivers and insights for practical applications.

Denoising of river surface photogrammetric DEMs using deep learning

2021 ◽  
Author(s):  
Radosław Szostak ◽  
Przemysław Wachniew ◽  
Mirosław Zimnoch ◽  
Paweł Ćwiąkała ◽  
Edyta Puniach ◽  
...  
Keyword(s):  
Higher Education ◽  
Deep Learning ◽  
Water Level ◽  
Water Surface ◽  
Research University ◽  
Static Characteristic ◽  
Water Levels ◽  
Training Dataset ◽  
Observation Data ◽  
Characteristic Points

<p>Unmanned Aerial Vehicles (UAVs) can be an excellent tool for environmental measurements due to their ability to reach inaccessible places and fast data acquisition over large areas. In particular drones may have a potential application in hydrology, as they can be used to create photogrammetric digital elevation models (DEM) of the terrain allowing to obtain high resolution spatial distribution of water level in the river to be fed into hydrological models. Nevertheless, photogrammetric algorithms generate distortions on the DEM at the water bodies. This is due to light penetration below the water surface and the lack of static characteristic points on water surface that can be distinguished by the photogrammetric algorithm. The correction of these disturbances could be achieved by applying deep learning methods. For this purpose, it is necessary to build a training dataset containing DEMs before and after water surfaces denoising. A method has been developed to prepare such a dataset. It is divided into several stages. In the first step a photogrammetric surveys and geodetic water level measurements are performed. The second one includes generation of DEMs and orthomosaics using photogrammetric software. Finally in the last one the interpolation of the measured water levels is done to obtain a plane of the water surface and apply it to the DEMs to correct the distortion. The resulting dataset was used to train deep learning model based on convolutional neural networks. The proposed method has been validated on observation data representing part of Kocinka river catchment located in the central Poland.</p><p>This research has been partly supported by the Ministry of Science and Higher Education Project “Initiative for Excellence – Research University” and Ministry of Science and Higher Education subsidy, project no. 16.16.220.842-B02 / 16.16.150.545.</p>

Seedling recruitment of 11 wetland plant species along a water level gradient: shared or distinct responses?

1985 ◽  
Vol 63 (10) ◽  
pp. 1876-1879 ◽  
Author(s):  
Paul A. Keddy ◽  
Timothy H. Ellis
Keyword(s):  
Water Level ◽  
Plant Species ◽  
Water Depth ◽  
Seedling Recruitment ◽  
Substrate Surface ◽  
Lythrum Salicaria ◽  
Water Levels ◽  
Acorus Calamus ◽  
Spartina Pectinata ◽  
Sagittaria Latifolia

Where many different plant species occupy an environmental gradient, the responses of their offspring to that gradient could show one of two patterns. All species could have similar requirements for maximum recruitment, in which case all would show maximum germination and emergence in the same region of the gradient ("shared responses"). Alternatively, each species could have different requirements for recruitment and therefore would show maximum recruitment in different regions of the gradient ("distinct responses"). The objective of this study was to test between these two alternatives in plants occurring along a water level gradient. Seeds of 11 wetland species were allowed to germinate in sand along a gradient of water depth, ranging from 10 cm above to 5 cm below the substrate surface. Scirpus americanus, S. validus, Sagittaria latifolia, Typha angustifolia, and Lythrum salicaria showed no significant response to this gradient, while Spartina pectinata, Polygonum punctatum, Bidens cernua, Acorus calamus, Alisma plantago-aquatica, and Eupatorium perfoliatum did. However, the six species in the latter group did not exhibit shared preferences along the water depth gradient. These different recruitment patterns were consistent with adult distributions in the field. Most species showed some recruitment at all water levels examined, suggesting that they have broad tolerance limits for water level in the recruitment phase of their life history.

scholarly journals Can GNSS-R Detect Abrupt Water Level Changes?

2020 ◽  
Vol 12 (21) ◽  
pp. 3614
Author(s):  
Sajad Tabibi ◽  
Olivier Francis
Keyword(s):  
Water Level ◽  
Vertical Velocity ◽  
Energy Demand ◽  
Water Surface ◽  
Spatial Scales ◽  
Satellite System ◽  
Water Levels ◽  
Level Gauge ◽  
Surface Reflection ◽  
Microwave Radar

Global navigation satellite system reflectometry (GNSS-R) uses signals of opportunity in a bi-static configuration of L-band microwave radar to retrieve environmental variables such as water level. The line-of-sight signal and its coherent surface reflection signal are not separate observables in geodetic GNSS-R. The temporally constructive and destructive oscillations in the recorded signal-to-noise ratio (SNR) observations can be used to retrieve water-surface levels at intermediate spatial scales that are proportional to the height of the GNSS antenna above the water surface. In this contribution, SNR observations are used to retrieve water levels at the Vianden Pumped Storage Plant (VPSP) in Luxembourg, where the water-surface level abruptly changes up to 17 m every 4-8 h to generate a peak current when the energy demand increases. The GNSS-R water level retrievals are corrected for the vertical velocity and acceleration of the water surface. The vertical velocity and acceleration corrections are important corrections that mitigate systematic errors in the estimated water level, especially for VPSP with such large water-surface changes. The root mean square error (RMSE) between the 10-min multi-GNSS water level time series and water level gauge records is 7.0 cm for a one-year period, with a 0.999 correlation coefficient. Our results demonstrate that GNSS-R can be used as a new complementary approach to study hurricanes or storm surges that cause abnormal rises of water levels.

Effects of nutrients and water levels on emergent macrophyte biomass in a prairie marsh

1990 ◽  
Vol 68 (5) ◽  
pp. 1007-1014 ◽  
Author(s):  
Christopher Neill
Keyword(s):  
Water Level ◽  
Nutrient Limitation ◽  
Water Depth ◽  
Nitrogen Limitation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Depth Range ◽  
Dry Conditions ◽  
Second Year ◽  
Water Depths

Nitrogen and phosphorus fertilizers were added over two growing seasons to marshes dominated by whitetop grass (Scolochloa festucacea) or cattail (Typha glauca) in a prairie lacustrine marsh to assess nutrient limitation and the interaction of nutrient limitation with water depth. For each species, stands were selected at the deep and shallow extremes of its water depth range. Water levels were high during the first year of fertilization and low during the second year, exposing the fertilized stands to a variety of water depths. Nitrogen limited growth in whitetop and cattail marshes. Water level, by controlling whether the soil was flooded or the water table was below the soil surface, affected growth and the degree of nitrogen limitation. In whitetop marshes, nitrogen increased biomass more when the soil was flooded or when standing water was deeper and in cattail marshes, it increased biomass more under intermediate water depths (approximately 0–20 cm) than under more deeply flooded (20–40 cm) or dry conditions. Nitrogen reduced biomass in whitetop marshes the second year, apparently because growth was inhibited by fallen litter from the previous year. Nitrogen did not limit cattail marsh biomass in the driest locations during a year of low water levels. Phosphorus caused a small increase in growth of both species after 2 years. Changes of nitrogen limitation with flooding suggest that annual water level fluctuations, by creating alternating flooded and dry conditions, may influence the primary production of emergent macrophytes through effects on nitrogen cycling.

scholarly journals Wave model verification based on measurements in the Wadden Sea

2016 ◽  
Author(s):  
Cordula Berkenbrink ◽  
Luise Hentze ◽  
Andreas Wurpts
Keyword(s):  
Water Level ◽  
Wadden Sea ◽  
Wave Attenuation ◽  
Calculated Data ◽  
Barrier Islands ◽  
Wave Model ◽  
Water Levels ◽  
Model Verification ◽  
Coastal Protection ◽  
Lower Saxony

Abstract. The design height of coastal protection structures in Lower Saxony / Germany is determined by the design water level and the corresponding wave run up. For the calculation of these parameters several mathematical models are used which need to be verified for the conditions at the East Frisian Wadden Sea area. For this issue a wave measuring programme is operationally run, which includes various measurement locations and devices around the islands Norderney and Juist. The measurements are continuously extended and adapted in order to improve models and measurements. This paper shows a comparison between measured and calculated data for the storm surge of the 10.–11.01.2015 incorporating to new wave and water level gauges operated within COSYNA as well as a second research project dealing with wave attenuation behind barrier islands. Water levels within the investigation area were calculated by hydrodynamic models driven with a wind field originating from weather forecast and compared to water level measurements. The corresponding wave energy field was calculated by means of a third generation wave model and results compared to measurements of several devices located around the barrier Islands. The aim of the study shown here is to give a brief overview of possible error sources for model-data as well as data-data comparisons.

scholarly journals Using White Star (Nymphoides humboldtiana) for lake landscaping

2019 ◽  
Vol 37 (2) ◽  
pp. 133-137
Author(s):  
Carla D Tedesco ◽  
Claudia Petry ◽  
Edson C Bortoluzzi ◽  
Alfredo Castamann
Keyword(s):  
Water Level ◽  
Leaf Area ◽  
Water Depth ◽  
Native Species ◽  
High Water ◽  
Water Levels ◽  
Vegetative Development ◽  
High Water Level ◽  
Number Of Leaves ◽  
White Star

ABSTRACT White Star (Nymphoides humboldtiana), an aquatic-environmental native species of Brazilian flora, was selected in order to be used as ornamental plant in lakes. White Star plants were submitted to two water levels (high water level, up to 30 cm water depth and, low water level until substrate saturation) and two light intensities (full sun and 50% shading) to evaluate vegetative and flowering development. The experimental design was completely randomized, in a subplot scheme, being the water level the main plot and luminosity the subplot. Seven replicates were performed, and the sample unit consisted of one plant. Data related to number of leaves and flowers, length and diameter of petioles and leaf area were submitted to analyze of variance and regression. We observed an increase in number of leaves and flowers in the treatment of high water level in full sun, and an increase of petiole length in high water level with shading. No difference between leaf area of plants grown under full sun and with shading (p<0.05) was observed. At low water level, plants presented lower vegetative development than those grown at high water level, besides the flowering inhibition in shaded condition. These results demonstrated that White Star can be used in ornamental lakes with a water depth of at least 20 cm above the rhizome and exposed to full sun.

Phreatic Water Surface Profiles along Ice Jams – An Experimental Study

1996 ◽  
Vol 27 (3) ◽  
pp. 185-201 ◽  
Author(s):  
Raafat G. Saadé ◽  
Semaan Sarraf
Keyword(s):  
Water Level ◽  
Water Surface ◽  
Surface Profile ◽  
Water Levels ◽  
Ice Jams ◽  
Ice Jam ◽  
Phreatic Water ◽  
Northern Regions ◽  
Water Surface Profile ◽  
Ice Floes

In Northern Regions, the formation of ice jams along many rivers is a common phenomena. These ice jams may occur during the freeze-up and more importantly during the spring break-up period. Ice jams in general have considerable effects on the water levels because they alter the water surface profile for stretches of tens of kilometers along the rivers. As a consequence, water levels increase significantly upstream of the ice jam and result in the flooding of towns situated along the river banks. Knowledge of the water levels within an ice jam can be used to estimate many parameters that are difficult to measure and observe. Examples of such parameters are the local and global ice jam resistance to the flow, and forces acting within an ice jam. While ice jams are notorious causes of serious problems in hydraulic engineering, very little engineering methodology exists to deal with such problems. In this paper, the results of a laboratory study aimed at investigating the development of the water surface profile along an ice jam that is lodged in place, are analyzed and presented. A rectangular flume with a horizontal bed was used for the experiments. Twelve experiments carried out under different geometrical, hydrodynamic and ice conditions, were analysed. A simulated floating ice cover was used to arrest the downstream transport of the ice floes, forming the ice jams. The experiments indicate two types of ice jams, those that are floating and others that are lodged at one or more locations along their length. The phreatic water level along a floating ice jam is up to 0.92 the ice jam thickness. This is not true when an ice jam is lodged in place. Different experiments have shown that the water surface profile along a lodged ice jam follows similar tendencies regardless of the geometry, ice floe size distribution and hydrodynamic conditions. It was found that the phreatic water level varies linearly from the trailing edge of the ice jam up to approximately 90% of its length downstream. Towards the remaining part of the jam's length the water level follows a cubic polynomial line.

scholarly journals Accuracy Enhancement for Forecasting Water Levels of Reservoirs and River Streams Using a Multiple-Input-Pattern Fuzzification Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Nariman Valizadeh ◽  
Ahmed El-Shafie ◽  
Majid Mirzaei ◽  
Hadi Galavi ◽  
Muhammad Mukhlisin ◽  
...  
Keyword(s):  
Water Level ◽  
Case Studies ◽  
Water Resource Management ◽  
Water Levels ◽  
Anfis Model ◽  
New Approach ◽  
Multiple Input ◽  
Different Types ◽  
Output Pattern ◽  
And Performance

Water level forecasting is an essential topic in water management affecting reservoir operations and decision making. Recently, modern methods utilizing artificial intelligence, fuzzy logic, and combinations of these techniques have been used in hydrological applications because of their considerable ability to map an input-output pattern without requiring prior knowledge of the criteria influencing the forecasting procedure. The artificial neurofuzzy interface system (ANFIS) is one of the most accurate models used in water resource management. Because the membership functions (MFs) possess the characteristics of smoothness and mathematical components, each set of input data is able to yield the best result using a certain type of MF in the ANFIS models. The objective of this study is to define the different ANFIS model by applying different types of MFs for each type of input to forecast the water level in two case studies, the Klang Gates Dam and Rantau Panjang station on the Johor river in Malaysia, to compare the traditional ANFIS model with the new introduced one in two different situations, reservoir and stream, showing the new approach outweigh rather than the traditional one in both case studies. This objective is accomplished by evaluating the model fitness and performance in daily forecasting.

scholarly journals AN ORIGINAL PROCESSING METHOD OF SATELLITE ALTIMETRY FOR ESTIMATING WATER LEVELS AND VOLUME FLUCTUATIONS IN A SERIES OF SMALL LAKES OF THE PANTANAL WETLAND COMPLEX IN BRAZIL

2016 ◽  
Vol XLI-B8 ◽  
pp. 327-334 ◽  
Author(s):  
Paulo Henrique Costa ◽  
Eric Oliveira Pereira ◽  
Philippe Maillard
Keyword(s):  
Water Level ◽  
Water Surface ◽  
Satellite Altimetry ◽  
Water Levels ◽  
Small Lakes ◽  
Water Surface Area ◽  
Volume Fluctuations ◽  
Calm Water ◽  
Gauging Station

Satellite altimetry is becoming a major tool for measuring water levels in rivers and lakes offering accuracies compatible with many hydrological applications, especially in uninhabited regions of difficult access. The Pantanal is considered the largest tropical wetland in the world and the sparsity of &lt;i&gt;in situ&lt;/i&gt; gauging station make remote methods of water level measurements an attractive alternative. This article describes how satellites altimetry data from Envisat and Saral was used to determine water level in two small lakes in the Pantanal. By combining the water level with the water surface area extracted from satellite imagery, water volume fluctuations were also estimated for a few periods. The available algorithms (retrackers) that compute a range solution from the raw waveforms do not always produce reliable measurements in small lakes. This is because the return signal gets often “contaminated” by the surrounding land. To try to solve this, we created a “lake” retracker that rejects waveforms that cannot be attributed to “calm water” and convert them to altitude. Elevation data are stored in a database along with the water surface area to compute the volume fluctuations. Satellite water level time series were also produced and compared with the only nearby &lt;i&gt;in situ&lt;/i&gt; gauging station. Although the “lake” retracker worked well with calm water, the presence of waves and other factors was such that the standard “ice1” retracker performed better on the overall. We estimate our water level accuracy to be around 75 cm. Although the return time of both satellites is only 35 days, the next few years promise to bring new altimetry satellite missions that will significantly increase this frequency.

scholarly journals Run-up parameterization and beach vulnerability assessment on a barrier island: a downscaling approach

2016 ◽  
Vol 16 (1) ◽  
pp. 167-180 ◽  
Author(s):  
G. Medellín ◽  
J. A. Brinkkemper ◽  
A. Torres-Freyermuth ◽  
C. M. Appendini ◽  
E. T. Mendoza ◽  
...  
Keyword(s):  
Water Level ◽  
Water Depth ◽  
Shallow Water Equation ◽  
Barrier Island ◽  
Water Levels ◽  
Tidal Level ◽  
Extreme Water Level ◽  
Extreme Water Levels ◽  
Run Up ◽  
Wave Induced

Abstract. We present a downscaling approach for the study of wave-induced extreme water levels at a location on a barrier island in Yucatán (Mexico). Wave information from a 30-year wave hindcast is validated with in situ measurements at 8 m water depth. The maximum dissimilarity algorithm is employed for the selection of 600 representative cases, encompassing different combinations of wave characteristics and tidal level. The selected cases are propagated from 8 m water depth to the shore using the coupling of a third-generation wave model and a phase-resolving non-hydrostatic nonlinear shallow-water equation model. Extreme wave run-up, R2%, is estimated for the simulated cases and can be further employed to reconstruct the 30-year time series using an interpolation algorithm. Downscaling results show run-up saturation during more energetic wave conditions and modulation owing to tides. The latter suggests that the R2% can be parameterized using a hyperbolic-like formulation with dependency on both wave height and tidal level. The new parametric formulation is in agreement with the downscaling results (r2  =  0.78), allowing a fast calculation of wave-induced extreme water levels at this location. Finally, an assessment of beach vulnerability to wave-induced extreme water levels is conducted at the study area by employing the two approaches (reconstruction/parameterization) and a storm impact scale. The 30-year extreme water level hindcast allows the calculation of beach vulnerability as a function of return periods. It is shown that the downscaling-derived parameterization provides reasonable results as compared with the numerical approach. This methodology can be extended to other locations and can be further improved by incorporating the storm surge contributions to the extreme water level.

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