scholarly journals PROPERTIES OF LONGSHORE BARS IN THE GREAT LAKES

1970 ◽  
Vol 1 (12) ◽  
pp. 53 ◽  
Author(s):  
James H. Saylor ◽  
Edward B. Hands
Keyword(s):  
Great Lakes ◽  
Incident Wave ◽  
Lake Level ◽  
Lake Michigan ◽  
Water Levels ◽  
Eastern Coast ◽  
Sediment Properties ◽  
Abrupt Changes ◽  
The Stability

Longshore bars are permanent features of nearshore bathymetry along the windward coasts of the Great Lakes The stability and permanency of these features have been noted by numerous investigators, but movements of the bars and troughs vn relation to varying lake levels and incident wave energies are not fully understood Studies of nearshore bathymetry and sediment properties were conducted during 1967 and 1969 along a forty-five kilometer reach of the eastern coast of Lake Michigan Results show that the offshore bars migrate significantly due to changes in lake level, a rise of one-half meter in the surface of Lake Michigan between 1967 and 1969 was accompanied by a shoreward movement of bar crests and troughs over a distance averaging SO meters Elevations of the crests and troughs are also built upward toward new equiblibrium levels during rising water levels, but elevating of the crests lags the increase in stage Extensive shore erosion occurs because of the reduced effectiveness of longshore bars in dissipating incident wave energy The average crest depth was found to increase linearly in the offshore direction Average distances between crests increase exponentially These relationships are preserved during the bar growth and shifting that accompanies long term changes in lake level Bar troughs are characteristically crescent shaped, with no abrupt changes in slope Fathograms from several ranges show atypical trough configurations consisting of flat bottoms with discontinuities in slope on ascent to adoacent crests This unusual trough shape is indicative of an immobile stratum exposed along the bottom of the trough.

scholarly journals Glacial Isostatic Adjustment of the Laurentian Great Lakes Basin: Using the Empirical Record of Strandline Deformation for Reconstruction of Early Holocene Paleo-Lakes and Discovery of a Hydrologically Closed Phase*

2007 ◽  
Vol 59 (2-3) ◽  
pp. 187-210 ◽  
Author(s):  
C.F. Michael Lewis ◽  
Steve M. Blasco ◽  
Pierre L. Gareau
Keyword(s):  
Great Lakes ◽  
Response Surface ◽  
Lake Michigan ◽  
Vertical Motion ◽  
Water Levels ◽  
Early Holocene ◽  
Great Lakes Basin ◽  
Isostatic Adjustment ◽  
Digital Elevation ◽  
Elevation Model

Abstract In the Great Lakes region, the vertical motion of crustal rebound since the last glaciation has decelerated with time, and is described by exponential decay constrained by observed warping of strandlines of former lakes. A composite isostatic response surface relative to an area southwest of Lake Michigan beyond the limit of the last glacial maximum was prepared for the complete Great Lakes watershed at 10.6 ka BP (12.6 cal ka BP). Uplift of sites computed using values from the response surface facilitated the transformation of a digital elevation model of the present Great Lakes basins to represent the paleogeography of the watershed at selected times. Similarly, the original elevations of radiocarbon-dated geomorphic and stratigraphic indicators of former lake levels were reconstructed and plotted against age to define lake level history. A comparison with the independently computed basin outlet paleo-elevations reveals a phase of severely reduced water levels and hydrologically-closed lakes below overflow outlets between 7.9 and 7.0 ka BP (8.7 and 7.8 cal ka BP) in the Huron-Michigan basin. Severe evaporative draw-down is postulated to result from the early Holocene dry climate when inflows of meltwater from the upstream Agassiz basin began to bypass the upper Great Lakes basin.

Sedimentary Cladocera as indicators of past water-level changes in shallow northern lakes

2011 ◽  
Vol 75 (3) ◽  
pp. 430-437 ◽  
Author(s):  
Liisa Nevalainen ◽  
Kaarina Sarmaja-Korjonen ◽  
Tomi P. Luoto
Keyword(s):  
Water Level ◽  
Lake Level ◽  
Water Levels ◽  
Sediment Record ◽  
Inference Model ◽  
Water Level Changes ◽  
Long Term Changes ◽  
Lower Water Level ◽  
The Relationship

AbstractThe usability of subfossil Cladocera assemblages in reconstructing long-term changes in lake level was examined by testing the relationship between Cladocera-based planktonic/littoral (P/L) ratio and water-level inference model in a surface-sediment dataset and in a 2000-yr sediment record in Finland. The relationships between measured and inferred water levels and P/L ratios were significant in the dataset, implying that littoral taxa are primarily deposited in shallow littoral areas, while planktonic cladocerans accumulate abundantly mainly in deepwater locations. The 2000-yr water-level reconstructions based on the water-level inference model and P/L ratio corresponded closely with each other and with a previously available midge-inferred water-level reconstruction from the same core, showing a period of lower water level around AD 300–1000 and suggesting that the methods are valid for paleolimnological and -climatological use.

scholarly journals What Caused Record Water Level Rise in the Great Lakes?

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Great Lakes ◽  
Water Level ◽  
Water Levels ◽  
Climate Trends ◽  
Modeling Framework ◽  
Water Level Rise ◽  
Short And Long Term ◽  
Insight Into

A new modeling framework offers insight into how specific lakes' water levels respond to short- and long-term climate trends.

scholarly journals HINDCAST WAVE STATISTICS FOR THE GREAT LAKES

2000 ◽  
Vol 1 (4) ◽  
pp. 1
Author(s):  
Thorndike Saville, Jr.
Keyword(s):  
Great Lakes ◽  
Lake Level ◽  
Lake Erie ◽  
Lake Michigan ◽  
Lake Ontario ◽  
Beach Erosion ◽  
Wave Statistics ◽  
Local Problems ◽  
Existing Data

The General Investigations program of the Beach Erosion Board comprises investigations, regional rather than local in scope, designed to improve, simplify, and expedite the solution of local problems, by giving a compilation of all existing data pertinent to shore processes in the particular region. As a first step in the compilation of these data, a study of wave and lake level conditions on the Great Lakes is being made. The results of such studies for Lake Michigan, Lake Erie, and Lake Ontario have recently been completed and published as Technical Memorandums of the Beach Erosion Board (Saville, 1953).

scholarly journals Wave Climate Associated With Changing Water Level and Ice Cover in Lake Michigan

2021 ◽  
Vol 8 ◽  
Author(s):  
Chenfu Huang ◽  
Longhuan Zhu ◽  
Gangfeng Ma ◽  
Guy A. Meadows ◽  
Pengfei Xue
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Lake Michigan ◽  
Linear Trend ◽  
Ice Cover ◽  
Wave Climate ◽  
Water Levels ◽  
Regional Warming ◽  
Model Simulations

Detailed knowledge of wave climate change is essential for understanding coastal geomorphological processes, ecosystem resilience, the design of offshore and coastal engineering structures and aquaculture systems. In Lake Michigan, the in-situ wave observations suitable for long-term analysis are limited to two offshore MetOcean buoys. Since this distribution is inadequate to fully represent spatial patterns of wave climate across the lake, a series of high-resolution SWAN model simulations were performed for the analysis of long-term wave climate change for the entirety of Lake Michigan from 1979 to 2020. Model results were validated against observations from two offshore buoys and 16 coastal buoys. Linear regression analysis of significant wave height (Hs) (mean, 90th percentile, and 99th percentile) across the entire lake using this 42-year simulation suggests that there is no simple linear trend of long-term changes of Hs for the majority (>90%) of the lake. To address the inadequacy of linear trend analysis used in previous studies, a 10-year trailing moving mean was applied to the Hs statistics to remove seasonal and annual variability, focusing on identifying long-term wave climate change. Model results reveal the regime shifts of Hs that correspond to long-term lake water level changes. Specifically, downward trends of Hs were found in the decade of 1990–2000; low Hs during 2000–2010 coincident with low lake levels; and upward trends of Hs were found during 2010–2020 along with rising water levels. The coherent pattern between the wave climate and the water level was hypothesized to result from changing storm frequency and intensity crossing the lake basin, which influences both waves (instantly through increased wind stress on the surface) and water levels (following, with a lag through precipitation and runoff). Hence, recent water level increases and wave growth were likely associated with increased storminess observed in the Great Lakes. With regional warming, the decrease in ice cover in Lake Michigan (particularly in the northernmost region of the lake) favored the wave growth in the winter due to increased surface wind stress, wind fetch, and wave transmission. Model simulations suggest that the basin-wide Hs can increase significantly during the winter season with projected regional warming and associated decreases in winter ice cover. The recent increases in wave height and water level, along with warming climate and ice reduction, may yield increasing coastal damages such as accelerating coastal erosion.

scholarly journals Extent of Sedge/Grass Meadow in a Lake Michigan Drowned-River-Mouth Wetland Dictated by Topography/Bathymetry and Lake Level

2021 ◽  
Author(s):  
Douglas A. Wilcox ◽  
John Bateman ◽  
Kurt Kowalski ◽  
James Meeker ◽  
Nicole Dunn
Keyword(s):  
Great Lakes ◽  
Plant Communities ◽  
Lake Level ◽  
Lake Michigan ◽  
River Mouth ◽  
Water Level Fluctuations ◽  
Lake Levels ◽  
High Lake Level ◽  
Grass Meadow ◽  
High Lake Levels

Abstract Water-level fluctuations are critical in maintaining the diversity of plant communities in Great Lakes wetlands. Sedge/grass meadows are especially sensitive to such fluctuations. We conducted vegetation sampling in a sedge/grass-dominated Lake Michigan drowned-river-mouth wetland in 1995, 2002, and 2010 that followed high lake levels in 1986 and 1997. We also conducted photointerpretation studies in 16 years dating back to 1965 to include responses to high lake level in 1952 and 1974. Topographic/bathymetric data were collected to assess their influence on areal extent of sedge/grass meadow. Dominant species in short emergent and submersed/floating plant communities changed with water availability from 1995 to extreme low lake levels in 2002 and 2010. Sedge/grass meadow was dominated by Calamagrostis canadensis and Carex stricta in all years sampled, but Importance Values differed among years partly due to sampling in newly exposed areas. Photointerpretation studies showed a significant relation between percent of wetland in sedge/grass meadow and summer lake level, as well as the number of years since an extreme high lake level. From the topographic/bathymetric map created, we calculated the cumulative area above each 0.2-m contour to determine the percent of wetland dewatered in select years following extreme high lake levels. When compared with percent sedge/grass meadow in those years, relative changes in both predicted land surface and sedge/grass meadow demonstrated that accuracy of lake level as a predictor of area of sedge/grass meadow is dependent on topography/bathymetry. Our results regarding relations of plant-community response to hydrology are applicable to other Great Lakes wetlands.

scholarly journals Preliminary Analysis of Middle Holocene Lake-Level Change of Ancestral Lake Michigan, Wentworth Woods, Cook County, Illinois

2019 ◽  
Vol 1 ◽  
Author(s):  
Todd Alan Thompson ◽  
Erin Argyilan ◽  
Henry Loope ◽  
John Johnston ◽  
Kenneth Lepper
Keyword(s):  
Great Lakes ◽  
Lake Level ◽  
Lake Michigan ◽  
Cook County ◽  
Upper Great Lakes ◽  
Lake Level Change ◽  
Level Change ◽  
Level Elevation ◽  
Forest Preserve ◽  
Nipissing Phase

Study of past lake-level change and isostasy in the upper Great Lakes has demonstrated the need to reconstruct relative lake-level history at each outlet during the Nipissing phase of ancestral Lakes Huron, Michigan, and Superior. Although elevation and age data exist for the Port Huron/Sarnia and Sault outlets of Lake Huron and Lake Superior, respectively, no paleohydrograph has been created for southern Lake Michigan near the Chicago outlet. The Wentworth Woods area of the Cook County Forest Preserve, Illinois, contains more than 30 beach ridges that formed during the rise and fall from the peak elevation of the Nipissing phase. These relict shorelines were vibracored to recover basal foreshore sediments that can be used as a proxy for lake-level elevation at the time of individual shoreline formation. In addition, sand samples from soil pits and vibracores were collected for optically stimulated luminescence age determinations. This report addresses the sedimentological data used to determine the elevation of the conjoined upper Great Lakes (Lake Nipissing) when each beach ridge formed. The age data will be presented in future reports.

scholarly journals Periodic structures of Great Lakes levels using wavelet analysis

2011 ◽  
Vol 59 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Taner Cengiz
Keyword(s):  
Wavelet Transform ◽  
Great Lakes ◽  
Lake Level ◽  
Lake Erie ◽  
Lake Michigan ◽  
Periodic Structures ◽  
Lake Superior ◽  
Great Lakes Region ◽  
Continuous Wavelet ◽  
Lake Levels

Periodic structures of Great Lakes levels using wavelet analysisThe recently advanced approach of wavelet transforms is applied to the analysis of lake levels. The aim of this study is to investigate the variability of lake levels in four lakes in the Great Lakes region where the method of continuous wavelet transform and global spectra are used. The analysis of lake-level variations in the time-scale domain incorporates the method of continuous wavelet transform and the global spectrum. Four lake levels, Lake Erie, Lake Michigan, Lake Ontario, and Lake Superior in the Great Lakes region were selected for the analysis. Monthly lake level records at selected locations were analyzed by wavelet transform for the period 1919 to 2004. The periodic structures of the Great Lakes levels revealed a spectrum between the 1-year and 43- year scale level. It is found that major lake levels periodicities are generally the annual cycle. Lake Michigan levels show different periodicities from Lake Erie and Lake Superior and Lake Ontario levels. Lake Michigan showed generally long-term (more than 10 years) periodicities. It was shown that the Michigan Lake shows much stronger influences of inter-annual atmospheric variability than the other three lakes. The other result was that some interesting correlations between global spectrums of the lake levels from the same climatic region were found.

scholarly journals Monitoring Long-Term Lake Level Variations in Middle and Lower Yangtze Basin over 2002–2017 through Integration of Multiple Satellite Altimetry Datasets

2020 ◽  
Vol 12 (9) ◽  
pp. 1448 ◽  
Author(s):  
Peng Li ◽  
Hui Li ◽  
Fang Chen ◽  
Xiaobin Cai
Keyword(s):  
Water Level ◽  
Satellite Altimetry ◽  
Lake Level ◽  
Yangtze River Basin ◽  
Water Levels ◽  
Lake Level Changes ◽  
Lower Yangtze ◽  
Increasing Trends ◽  
The Impact

Satellite altimetry has been effectively used for monitoring lake level changes in recent years. This work focused on the integration of multiple satellite altimetry datasets from ICESat-1, Envisat and Cryosat-2 for the long-term (2002–2017) observation of lake level changes in the middle and lower Yangtze River Basin (MLYB). Inter-altimeter biases were estimated by using the gauged daily water level data. It showed that the average biases of ICESat-1 and Cryosat-2 with respect to Envisat were 6.7 cm and 3.1 cm, respectively. The satellite-derived water levels were evaluated against the gauged data. It indicated significantly high correlations between the two datasets, and the combination of three altimetry data produced precise water level time series with high temporal and spatial resolutions. A liner regression model was used to estimate the rates of lake level changes over the study period after the inter-altimeter bias adjustment was performed. The results indicated that ~79% of observed lakes (41/52) showed increasing trends in water levels with rates up to 0.203 m/y during 2002–2017. The temporal analysis of lake level variations suggested that ~60% of measured lakes (32/53) showed decreasing trends during 2002–2009 while ~66% of measured lakes (79/119) exhibited increasing trends during 2010–2017. Most of measured reservoirs displayed rapidly rising trends during the study period. The driving force analysis indicated that the temporal heterogeneity of precipitation can be mainly used to explain the observed pattern of lake level changes. The operation of reservoirs and human water consumption were also responsible for the lake level variations. This work demonstrated the potential of integrating multiple satellite altimeters for the long-term monitoring of lake levels, which can help to evaluate the impact of climate change and anthropogenic activities on regional water resources.

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