scholarly journals What's streamflow got to do with it? A probabilistic simulation of the competing oceanographic and fluvial processes driving extreme along-river water levels

Author(s):  
Katherine A. Serafin ◽  
Peter Ruggiero ◽  
Kai A. Parker ◽  
David F. Hill

Abstract. Extreme water levels driving flooding in estuarine and coastal environments are often compound events, generated by many individual processes like waves, storm surge, streamflow, and tides. Despite this, extreme water levels are typically modeled in isolated open coast or estuarine environments, potentially mischaracterizing the true risk to flooding facing coastal communities. We explore the variability of extreme water levels near the tribal community of La Push, within the Quileute Indian Reservation on the Washington state coast where a river signal is apparent in tide gauge measurements during high discharge events. To estimate the influence of multivariate forcing on high water levels, we first develop a methodology for statistically simulating discharge and river-influenced water levels in the tide gauge. Next, we merge probabilistic simulations of joint still water level and discharge occurrences with a hydraulic model that simulates along-river water levels. This methodology produces water levels from thousands of combinations of events not necessarily captured in the observational record. We show that the 100-yr ocean or 100-yr streamflow event does not always produce the 100-yr along-river water level. Along specific sections of river, both still water level and streamflow are necessary for producing the 100-yr water level. Understanding the relative forcing of extreme water levels along an ocean-to-river gradient will better prepare communities within inlets and estuaries for the compounding impacts of various environmental forcing, especially when a combination of extreme or non-extreme forcing can result in an extreme event with significant impacts.

2019 ◽  
Vol 19 (7) ◽  
pp. 1415-1431 ◽  
Author(s):  
Katherine A. Serafin ◽  
Peter Ruggiero ◽  
Kai Parker ◽  
David F. Hill

Abstract. Extreme water levels generating flooding in estuarine and coastal environments are often driven by compound events, where many individual processes such as waves, storm surge, streamflow, and tides coincide. Despite this, extreme water levels are typically modeled in isolated open-coast or estuarine environments, potentially mischaracterizing the true risk of flooding facing coastal communities. This paper explores the variability of extreme water levels near the tribal community of La Push, within the Quileute Indian Reservation on the Washington state coast, where a river signal is apparent in tide gauge measurements during high-discharge events. To estimate the influence of multiple forcings on high water levels a hybrid modeling framework is developed, where probabilistic simulations of joint still water level and river discharge occurrences are merged with a hydraulic model that simulates along-river water levels. This methodology produces along-river water levels from thousands of combinations of events not necessarily captured in the observational records. We show that the 100-year still water level event and the 100-year discharge event do not always produce the 100-year along-river water level. Furthermore, along specific sections of river, both still water level and discharge are necessary for producing the 100-year along-river water level. Understanding the relative forcing driving extreme water levels along an ocean-to-river gradient will help communities within inlets better understand their risk to the compounding impacts of various environmental forcing, which is important for increasing their resilience to future flooding events.


Author(s):  
J Wolf ◽  
R.A Flather

Waves and sea levels have been modelled for the storm of 31 January–1 February 1953. Problems in modelling this event are associated with the difficulty of reconstructing wind fields and validating the model results with the limited data available from 50 years ago. The reconstruction of appropriate wind fields for surge and wave models is examined. The surges and waves are reproduced reasonably well on the basis of tide-gauge observations and the sparse observational information on wave heights. The maximum surge coincided closely in time with tidal high water, producing very high water levels along the coasts of the southern North Sea. The statistics of the 1953 event and the likelihood of recurrence are also discussed. Both surge and wave components were estimated to be approximately 1 in 50 year events. The maximum water level also occurred when the offshore waves were close to their maximum. The estimation of return period for the total water level is more problematic and is dependent on location. A scenario with the 1953 storm occurring in 2075, accounting for the effects of sea level rise and land movements, is also constructed, suggesting that sea level relative to the land could be 0.4–0.5 m higher than in 1953 in the southern North Sea, assuming a rise in mean sea level of 0.4 m.


2021 ◽  
Author(s):  
Haiyan Wang ◽  
Jun Yang ◽  
Tao Li ◽  
Jianqiang Zhu ◽  
Zhangyong Liu

Abstract Changhu Lake, a large shallow eutrophic lake in central China, experienced an extreme low water level event from November 2015 to January 2016 followed by an extreme high water level event in July 2016. In this study, we examined the effects of two extreme water levels on the nutrient status of Changhu Lake over five years. The nutrient concentrations in Changhu Lake showed significant interannual variations and the water quality of sites in the western part of Changhu Lake was better compared to sites at the outlet of the lake. In late 2015, the effect of low water levels led to a significant increase in nutrient concentrations. After July 2016, however, the high water level occurred leading to a marked decrease in nutrient concentrations. These changes in nutrient parameters were strongly related to the water level fluctuations. The dilution effect was the key process that determined the variations of nutrient parameters in Changhu Lake. As extreme water levels are likely to become more frequent during the twenty-first century, this work may provide some insights into the conservation and management of lake ecosystems in the face of climate change and human activity.


The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.


Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Phil J. Watson

This paper provides an Extreme Value Analysis (EVA) of the hourly water level record at Fort Denison dating back to 1915 to understand the statistical likelihood of the combination of high predicted tides and the more dynamic influences that can drive ocean water levels higher at the coast. The analysis is based on the Peaks-Over-Threshold (POT) method using a fitted Generalised Pareto Distribution (GPD) function to estimate extreme hourly heights above mean sea level. The analysis highlights the impact of the 1974 East Coast Low event and rarity of the associated measured water level above mean sea level at Sydney, with an estimated return period exceeding 1000 years. Extreme hourly predictions are integrated with future projections of sea level rise to provide estimates of relevant still water levels at 2050, 2070 and 2100 for a range of return periods (1 to 1000 years) for use in coastal zone management, design, and sea level rise adaptation planning along the NSW coastline. The analytical procedures described provide a step-by-step guide for practitioners on how to develop similar baseline information from any long tide gauge record and the associated limitations and key sensitivities that must be understood and appreciated in applying EVA.


1958 ◽  
Vol 50 (3) ◽  
pp. 243-252 ◽  
Author(s):  
H. H. Nicholson ◽  
D. H. Firth

An account is given of a field experiment in the control of ground water-level in a Fen peat soil, together with its results on the yields of crops in a six-course rotation.The seasonal variations in rainfall are presented in terms of potential evaporation and soil moisture deficit. The effect of the water-level on the moistness of the soil above it is indicated. Even in a wet summer, drying was perceptible within 18–20 in. of the ground water-level between successive falls of rain.The fluctuations of the ground water-levels are discussed. Those of the high water-levels were chiefly due to individual incidences of rain causing rises short in duration, but sufficient in the case of water-levels within 20 in. of the surface to cause total waterlogging and surface ponding. Those of the deep water-levels were most influenced by evaporation, with steady and persistent falls during any rain-free period.The deterioration of the physical condition of the soil over high water-levels is shown in the result of sieving tests. In 6 years the loss of tilth over waterlevels within 20 in. of the surface was very marked and was discernible over those as low as 30 in.The possibilities of effectively using high ground water-levels occasionally in soils in good condition are shown by the results with celery and potatoes.


2020 ◽  
Author(s):  
John Maskell

<p>Two case studies are considered in the UK, where uncertainty and drivers of coastal flood risk are explored through modelling and visualisations. Visualising the impact of uncertainty is a useful way of explaining the potential range of predicted or simulated flood risk to both expert and non-expert stakeholders.</p><p>Significant flooding occurred in December 2013 and January 2017 at Hornsea on the UK East Coast, where storm surge levels and waves overtopped the town’s coastal defences. Uncertainty in the potential coastal flooding is visualised at Hornsea due to the range of uncertainty in the 100-year return period water level and in the calculated overtopping due to 3 m waves at the defences. The range of uncertainty in the simulated flooding is visualised through flood maps, where various combinations of the uncertainties decrease or increase the simulated inundated area by 58% and 82% respectively.</p><p>Located at the mouth of the Mersey Estuary and facing the Irish Sea, New Brighton is affected by a large tidal range with potential storm surge and large waves. Uncertainty in the coastal flooding at the 100-year return period due to the combination of water levels and waves is explored through Monte-Carlo analysis and hydrodynamic modelling. Visualisation through flood maps shows that the inundation extent at New Brighton varies significantly for combined wave and surge events with a joint probability of 100 years, where the total flooded area ranges from 0 m<sup>2</sup> to 10,300 m<sup>2</sup>. Waves are an important flood mechanism at New Brighton but are dependent on high water levels to impact the coastal defences and reduce the effective freeboard. The combination of waves and high-water levels at this return level not only determine the magnitude of the flood extent but also the spatial characteristics of the risk, whereby flooding of residential properties is dominated by overflow from high water levels, and commercial and leisure properties are affected by large waves that occur when the water level is relatively high at the defences.</p>


2011 ◽  
Vol 2 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Dale M. Robertson ◽  
William J. Rose

To determine how climate-induced changes in hydrology and water level may affect the trophic state (productivity) of stratified lakes, two relatively pristine dimictic temperate lakes in Wisconsin, USA, were examined. Both are closed-basin lakes that experience changes in water level and degradation in water quality during periods of high water. One, a seepage lake with no inlets or outlets, has a small drainage basin and hydrology dominated by precipitation and groundwater exchange causing small changes in water and phosphorus (P) loading, which resulted in small changes in water level, P concentrations, and productivity. The other, a terminal lake with inlets but no outlets, has a large drainage basin and hydrology dominated by runoff causing large changes in water and P loading, which resulted in large changes in water level, P concentrations, and productivity. Eutrophication models accurately predicted the effects of changes in hydrology, P loading, and water level on their trophic state. If climate changes, larger changes in hydrology and water levels than previously observed could occur. If this causes increased water and P loading, stratified (dimictic and monomictic) lakes are expected to experience higher water levels and become more eutrophic, especially those with large developed drainage basins.


1974 ◽  
Vol 4 (1) ◽  
pp. 76-81 ◽  
Author(s):  
T. S. Dai ◽  
V. F. Haavisto ◽  
J. H. Sparling

Depths to water level and changes due to local climate were dissimilar in five peatland conditions in northeastern Ontario. The deepest water level and the greatest fluctuations occurred in an ombrotrophic black spruce bog site. The sedge-dominated poor fen site was submerged following every heavy rain. Waterlogged conditions remained within 6 cm of the surface at all times because of the influence by the water level of Dai Lake. The water level of Dai Lake varied within a narrow range because the loss of water was primarily dependent on slow seepage and evaporation. The lagg site was affected by continuous inflow, high water levels, and fast run-off, therefore, a larger fluctuation of water level prevailed at this site.


2014 ◽  
Vol 1010-1012 ◽  
pp. 821-825
Author(s):  
Song Mei Wang ◽  
Chun Du Wu ◽  
Jin Yu Chu ◽  
Qing Jie Xie

We perform a study of the waste water from overflow in the Zhenjiang Neijiang . Determine content of COD、NH3-N、TP which changing along the distance at different water levels . Based on the SPSS14.0 correlation analysis , single factor pollution index and the comprehensive pollution index we study water movement rule and quality assessment. The results showed that : At low water level COD、NH3-N、TP decrease alleviation, the whole datum are high; at high water level COD、NH3-N、TP decrease greatly between 0~7m,but decrease alleviation between 7~200m. (2) Only the content of NH3-N (0~7m ) has significant differences (p<0.05),the other content all has not significant differences (p>0.05), the waste water from overflow was seriously polluted so that the wetland can not purify it adequately. (3)Based on the Vwater quality grade standard, at low water level the content of COD、NH3-N、TP(0~200m ) are all beyond standard; at high water level the content of COD、NH3-N、TP(80~200m ) are all beyond standard; the order of the potential ecological rick is: NH3-N>TP>COD. The study on the datum could offer a favorable plan for purifying the waste water from overflow in the Zhenjiang Neijiang. Keyword: overflow; water movement rule; correlation analysis; water quality assessment


Sign in / Sign up

Export Citation Format

Share Document