Timing, duration, and magnitude of peak annual water-levels during ice breakup in the Mackenzie Delta and the role of river discharge

Despite the increasing number of studies on the river-tide interactions in estuaries, less attention has been paid to the role of seasonal morphological changes on tidal regime. This study analyzes the seasonal interplay of river and tide in the Qiantang Estuary, China, particularly focusing on the influences of the active morphological evolution induced by the seasonal variation of river discharge. The study is based on the high and low water levels at three representative stations along the estuary and daily river discharge through 2015, an intermediate flow year in which a typical river flood occurred, as well as the bathymetric data measured in April, July and November, 2015. The results show strong seasonal variations of the water level in addition to the spring-neap variation. These variations are obviously due to the interaction between river discharge and tide but can only be fully explained by including the effect of morphological changes. Two types of the influences of the variation of the river discharge on the tidal dynamics in the estuary can be distinguished: one is immediately induced by the high flow and the other continues for a much longer period because of the bed erosion and the following bed recovery. Tidal range in the upper reach can be doubled after the flood because of bed erosion and then decrease under normal discharge periods due to sediment accumulation. Over a relatively short term such as a month or a spring-neap tidal cycle, there exist good relationships between the tidal range, tidal amplification in the upper reach and the tidal range at the mouth, and between the hydraulic head over the upper and lower reaches. Such relationships are unclear if all data over the whole year are considered together, mainly because of the active morphological evolution.

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The role of tides, river discharge and wind on the residual circulation of Maputo Bay

Regional Studies in Marine Science ◽

10.1016/j.rsma.2020.101604 ◽

2020 ◽

pp. 101604

Author(s):

Paulo J. Sigaúque ◽

Carlos A.F. Schettini ◽

Samuel S. Valentim ◽

Eduardo Siegle

Keyword(s):

River Discharge ◽

Residual Circulation

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The role of the reef–dune system in coastal protection in Puerto Morelos (Mexico)

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-1247-2018 ◽

2018 ◽

Vol 18 (4) ◽

pp. 1247-1260 ◽

Cited By ~ 4

Author(s):

Gemma L. Franklin ◽

Alec Torres-Freyermuth ◽

Gabriela Medellin ◽

María Eugenia Allende-Arandia ◽

Christian M. Appendini

Keyword(s):

Sand Dunes ◽

Coastal Flooding ◽

Water Levels ◽

Coastal Protection ◽

Dune System ◽

Fore Reef ◽

Extreme Water Levels ◽

Reef Environments ◽

Storm Impact

Abstract. Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef–dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef–dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

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A Study on Role of Fluctuation in River Discharge in Forming River Environment

ENVIRONMENTAL SYSTEMS RESEARCH ◽

10.2208/proer1988.26.77 ◽

1998 ◽

Vol 26 ◽

pp. 77-84

Author(s):

Minoru YASUDA ◽

Yasuo SHIMIZU ◽

Takayuki TAKEMOTO

Keyword(s):

River Discharge

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Ice jam mitigation

Canadian Journal of Civil Engineering ◽

10.1139/l90-081 ◽

1990 ◽

Vol 17 (5) ◽

pp. 675-685 ◽

Cited By ~ 12

Author(s):

Harold S. Belore ◽

Brian C. Burrell ◽

Spyros Beltaos

Keyword(s):

Key Words ◽

Carrying Capacity ◽

Flood Control ◽

Human Life ◽

Water Levels ◽

Economic Losses ◽

River Ice ◽

Ice Jams ◽

Ice Jam ◽

Ice Breakup

In Canada, flooding due to the rise in water levels upstream of an ice jam, or the temporary exceedance of the flow and ice-carrying capacity of a channel upon release of an ice jam, has resulted in the loss of human life and extensive economic losses. Ice jam mitigation is a component of river ice management which includes all activities carried out to prevent or remove ice jams, or to reduce the damages that may result from an ice jam event. This paper presents a brief overview of measures to mitigate the damaging effects of ice jams and contains a discussion on their application to Canadian rivers. Key words: controlled ice breakup, flood control, ice jams, ice management, river ice.

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Toward continental hydrologic–hydrodynamic modeling in South America

Hydrology and Earth System Sciences ◽

10.5194/hess-22-4815-2018 ◽

2018 ◽

Vol 22 (9) ◽

pp. 4815-4842 ◽

Cited By ~ 29

Author(s):

Vinícius A. Siqueira ◽

Rodrigo C. D. Paiva ◽

Ayan S. Fleischmann ◽

Fernando M. Fan ◽

Anderson L. Ruhoff ◽

...

Keyword(s):

South America ◽

Land Surface ◽

River Discharge ◽

Hydrological Modeling ◽

Water Levels ◽

Scale Model ◽

Global Models ◽

Discharge Data ◽

Continental Scale ◽

Terrestrial Water

Abstract. Providing reliable estimates of streamflow and hydrological fluxes is a major challenge for water resources management over national and transnational basins in South America. Global hydrological models and land surface models are a possible solution to simulate the terrestrial water cycle at the continental scale, but issues about parameterization and limitations in representing lowland river systems can place constraints on these models to meet local needs. In an attempt to overcome such limitations, we extended a regional, fully coupled hydrologic–hydrodynamic model (MGB; Modelo hidrológico de Grandes Bacias) to the continental domain of South America and assessed its performance using daily river discharge, water levels from independent sources (in situ, satellite altimetry), estimates of terrestrial water storage (TWS) and evapotranspiration (ET) from remote sensing and other available global datasets. In addition, river discharge was compared with outputs from global models acquired through the eartH2Observe project (HTESSEL/CaMa-Flood, LISFLOOD and WaterGAP3), providing the first cross-scale assessment (regional/continental × global models) that makes use of spatially distributed, daily discharge data. A satisfactory representation of discharge and water levels was obtained (Nash–Sutcliffe efficiency, NSE > 0.6 in 55 % of the cases) and the continental model was able to capture patterns of seasonality and magnitude of TWS and ET, especially over the largest basins of South America. After the comparison with global models, we found that it is possible to obtain considerable improvement on daily river discharge, even by using current global forcing data, just by combining parameterization and better routing physics based on regional experience. Issues about the potential sources of errors related to both global- and continental-scale modeling are discussed, as well as future directions for improving large-scale model applications in this continent. We hope that our study provides important insights to reduce the gap between global and regional hydrological modeling communities.

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

10.5194/os-2021-58 ◽

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.

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PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-3-w8-261-2019 ◽

2019 ◽

Vol XLII-3/W8 ◽

pp. 261-266

Author(s):

A.-L. Montreuil ◽

M. Chen ◽

A. Esquerré ◽

R. Houthuys ◽

R. Moelans ◽

...

Keyword(s):

Management Practices ◽

Morphological Changes ◽

Storm Surges ◽

High Water ◽

Water Levels ◽

Airborne Lidar ◽

Coastline Change ◽

The Mean ◽

The Impact

Abstract. Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km2 were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.

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The effect of rainfall amount and timing on annual transpiration in a grazed savanna grassland

10.5194/hess-2021-292 ◽

2021 ◽

Author(s):

Matti Räsänen ◽

Mika Aurela ◽

Ville Vakkari ◽

Johan P. Beukes ◽

Juha-Pekka Tuovinen ◽

...

Keyword(s):

Leaf Area ◽

Gross Primary Production ◽

Co2 Exchange ◽

Wet Season ◽

Area Index ◽

C4 Grass ◽

Precipitation Timing ◽

Dry Spells ◽

Annual Water

Abstract. The role of precipitation (P) variability on evapotranspiration (ET) and its two components, transpiration (T) and evaporation (E) from savannas, continues to draw significant research interest given its relevance to a number of eco-hydrological applications. Our study reports on six years of measured ET and estimated T and E from a grazed savanna grassland in Welgegund, South Africa. Annual P varied significantly in amount (508 to 672 mm yr−1), with dry years characterized by infrequent early-season rainfall. T was determined using annual water-use efficiency and gross primary production estimates derived from eddy covariance measurements of latent heat flux and net ecosystem CO2 exchange rates. The computed annual T was nearly constant, 331 ± 11 mm yr−1 (T/ET = 0.52), for the four wet years with frequent early wet-season rainfall, whereas annual T was 268 and 175 mm yr−1 during the dry years. Annual T/ET was linearly related to the early wet-season storm frequency. The constancy of annual T during wet years is explained by the moderate water stress of C4 grass and constant annual tree transpiration covering 15 % of the landscape. However, grass transpiration declines during dry spells. Moreover, grasses respond to water availability with a dieback-regrowth pattern, reducing leaf area and transpiration during drought. These changes lead to an anomalous monthly T/ET relation to leaf-area index (LAI). The results highlight the role of the C4 grass layer in the hydrological balance and suggest that the grass response to dry spells and drought is reasonably described by precipitation timing.

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Role of intertidal wetlands for tidal and storm tide attenuation along a confined estuary: a model study

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-3-3181-2015 ◽

2015 ◽

Vol 3 (5) ◽

pp. 3181-3224 ◽

Cited By ~ 5

Author(s):

S. Smolders ◽

Y. Plancke ◽

S. Ides ◽

P. Meire ◽

S. Temmerman

Keyword(s):

Surface Area ◽

Wave Attenuation ◽

Spring Tide ◽

Storm Surges ◽

High Water ◽

Water Levels ◽

Storm Tide ◽

Flood Risks ◽

Model Study

Abstract. Coastal lowlands and estuaries are subjected to increasing flood risks during storm surges due to global and regional changes. Tidal wetlands are increasingly valued as effective natural buffers for storm surges by dissipating wave energy and providing flood water storage. While previous studies focused on flood wave attenuation within and behind wetlands, this study focuses on the effects of estuarine wetland properties on the attenuation of a storm tide that propagates along the length of an estuary. Wetland properties including elevation, surface area, and location within the estuary were investigated using a numerical model of the Scheldt estuary (Belgium, SW Netherlands). For a spring tide lower wetland elevations result in more attenuation of high water levels along the estuary, while for a higher storm tide higher elevations provide more attenuation compared to lower wetland elevations. For spring and storm tide a arger wetland surface area results in a better attenuation along the estuary up to a threshold wetland size for which larger wetlands do not further contribute to more attenuation. Finally a wetland of the same size and elevation, but located more upstream in the estuary, can store a larger proportion of the local flood volume and therefore has a larger attenuating effect on upstream high water levels. With this paper we aim to contribute towards a better understanding and wider implementation of ecosystem-based adaptation to increasing estuarine flood risks associated with storms.

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