scholarly journals RESPONSES OF WETLAND VEGETATION TO WATER LEVEL VARIATIONS IN LAKE ONTARIO

1984 ◽  
Vol 1 (1) ◽  
pp. 519-524 ◽  
Author(s):  
Wolf-Dieter N. Busch ◽  
Lynn M. Lewis
Keyword(s):  
Water Level ◽  
Lake Ontario ◽  
Wetland Vegetation ◽  
Water Level Variations

Presentation and assessment of tides and water level records for geophysical investigations

1970 ◽  
Vol 7 (2) ◽  
pp. 607-625 ◽  
Author(s):  
G. C. Dohler ◽  
L. F. Ku
Keyword(s):  
Water Level ◽  
Power Spectra ◽  
Rate Of Change ◽  
Regression Technique ◽  
Level Data ◽  
Water Level Data ◽  
Geophysical Investigations ◽  
Water Level Variations ◽  
Mean Water Level ◽  
Change In Mean

The methods and problems involved in collecting water level data are explained, and the processing and formats of the data are illustrated. The trend of the change in mean water level is plotted and the corresponding rate of change is estimated by the regression technique. The power spectra of the water level variations are plotted to illustrate these variations in terms of frequencies.

scholarly journals Dynamics of fortnightly water level variations along a tide-dominated estuary with negligible river discharge

2021 ◽  
Author(s):  
Erwan Garel ◽  
Ping Zhang ◽  
Huayang Cai
Keyword(s):  
Water Level ◽  
Phase Difference ◽  
River Discharge ◽  
Water Levels ◽  
Level Increase ◽  
Upstream Direction ◽  
Water Level Variations ◽  
Mean Water Level ◽  
The Mean ◽  
Guadiana Estuary

Abstract. Observations indicate that the fortnightly fluctuations in mean water level increase in amplitude along the lower half of a tide-dominated estuary (The Guadiana estuary) with negligible river discharge but remain constant upstream. Analytical solutions reproducing the semi-diurnal wave propagation shows that this pattern results from reflection effects at the estuary head. The phase difference between velocity and elevation increases from the mouth to the head (where the wave has a standing nature) as the high and low water levels get progressively closer to slack water. Thus, the tidal (flood-ebb) asymmetry in discharge is reduced in the upstream direction. It becomes negligible along the upper estuary half, as the mean sea level remains constant despite increased friction due to wave shoaling. Observations of a flat mean water level along a significant portion of an upper estuary, easier to obtain than the phase difference, can therefore indicate significant reflection of the propagating semi-diurnal wave at the head. Details of the analytical model shows that changes in the mean depth or length of semi-arid estuaries, in particular for macrotidal locations, affect the fortnightly tide amplitude, and thus the upstream mass transport and inundation regime. This has significant potential impacts on the estuarine environment.

Water Level Variations along California Coast

1980 ◽  
Vol 106 (3) ◽  
pp. 335-348
Author(s):  
Raymond A. Smith ◽  
Robert J. Leffler
Keyword(s):  
Water Level ◽  
California Coast ◽  
Water Level Variations

scholarly journals Feedback Mechanism in Bifurcating River Systems: the Effect on Water-Level Sensitivity

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1915
Author(s):  
Matthijs R.A. Gensen ◽  
Jord J. Warmink ◽  
Fredrik Huthoff ◽  
Suzanne J.M.H. Hulscher
Keyword(s):  
Water Level ◽  
Flood Risk ◽  
River System ◽  
Feedback Mechanism ◽  
Water Levels ◽  
River Systems ◽  
Water Level Variations ◽  
System Water ◽  
Discharge Distribution ◽  
Single Branch

Accurate and reliable estimates of water levels are essential to assess flood risk in river systems. In current practice, uncertainties involved and the sensitivity of water levels to these uncertainties are studied in single-branch rivers, while many rivers in deltas consist of multiple distributaries. In a bifurcating river, a feedback mechanism exists between the downstream water levels and the discharge distribution at the bifurcation. This paper aims to quantify the sensitivity of water levels to main channel roughness in a bifurcating river system. Water levels are modelled for various roughness scenarios under a wide range of discharge conditions using a one-dimensional hydraulic model. The results show that the feedback mechanism reduces the sensitivity of water levels to local changes of roughness in comparison to the single-branch river. However, in the smaller branches of the system, water-level variations induced by the changes in discharge distribution can exceed the water-level variations of the single-branch river. Therefore, water levels throughout the entire system are dominated by the conditions in the largest branch. As the feedback mechanism is important, the river system should be considered as one interconnected system in river maintenance of rivers, flood-risk analyses, and future planning of river engineering works.

scholarly journals Modeling the Spatial Distribution of Three Typical Dominant Wetland Vegetation Species’ Response to the Hydrological Gradient in a Ramsar Wetland, Honghe National Nature Reserve, Northeast China

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2041
Author(s):  
Dandan Yan ◽  
Zhaoqing Luan ◽  
Dandan Xu ◽  
Yuanyuan Xue ◽  
Dan Shi
Keyword(s):  
Spatial Distribution ◽  
Water Level ◽  
Northeast China ◽  
Nature Reserve ◽  
Wetland Vegetation ◽  
Vegetation Communities ◽  
National Nature Reserve ◽  
Carex Lasiocarpa ◽  
Vegetation Species ◽  
Calamagrostis Angustifolia

Water level fluctuations resulting from natural and anthropogenic factors have been projected to affect the functions and structures of wetland vegetation communities. Therefore, it is important to assess the impact of the hydrological gradient on wetland vegetation. This paper presents a case study on the Honghe National Nature Reserve (HNNR) in the Sanjiang Plain, located in Northeast China. In this study, 210 plots from 18 sampling line transects were sampled in 2011, 2012, and 2014 along the hydrological gradient. Using a Gaussian logistic regression model, we determined a relationship between three wetland plant species and a hydrologic indicator—a combination of the water level and soil moisture—and then applied that relationship to simulate the distribution of plants across a larger landscape by the geographic information system (GIS). The results show that the optimum ecological amplitude of Calamagrostis angustifolia to the hydrological gradient based on the probability of occurrence model was [0.09, 0.41], that of Carex lasiocarpa was [0.35, 0.57], and that of Carex pseudocuraica was [0.49, 0.77]. The optimum of Calamagrostis angustifolia was 0.25, Carex lasiocarpa was 0.46, and Carex pseudocuraica was 0.63. Spatial distribution probability maps were generated, as were maps detailing the distribution of the most suitable habitats for wetland vegetation species. Finally, the model simulation results were verified, showing that this approach can be employed to provide an accurate simulation of the spatial distribution pattern of wetland vegetation communities. Importantly, this study suggests that it may be possible to predict the spatial distribution of different species from the hydrological gradient.

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