scholarly journals Fluctuating water levels influence access to critical habitats for threatened Cowichan Lake lamprey

FACETS ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 488-502
Author(s):  
Chiranjib Chaudhuri ◽  
Joy Wade ◽  
Colin Robertson
Keyword(s):  
Water Level ◽  
Water Levels ◽  
Spawning Period ◽  
Habitat Area ◽  
Management Actions ◽  
Bear Lake ◽  
Aerial Vehicle ◽  
Key Drivers ◽  
Term Data

Cowichan Lake lamprey ( Entosphenus macrostomus) is a threatened species resident to Mesachie Lake, Cowichan Lake, and adjoining Bear Lake and their major tributaries in British Columbia. Decreases in trapping success have created concerns that the population is declining. Some potential threats include water use, climate change, and management actions. Owing to the absence of long-term data on population trends, little information is available to estimate habitat quality and factors that influence it. We sought to fill this gap by examining associations between habitat area and variables representing suspected key drivers of habitat availability. Critical habitat areas were imaged using an unmanned aerial vehicle over a period of three years at three sites at Cowichan Lake and a subsequent habitat area was classified. Meteorological and anthropogenic controls on habitat area were investigated through automatic relevance detection regression models. The major driver of habitat area during the critical spawning period was water level during the storage season, which also depends on the meteorological variables and anthropogenic control. It is recommended that regulation of the weir should aim to ensure that the water level remains above the 1 m mark, which roughly equates to the 67% coverage of water on the habitat area used for spawning.

Development of an Atlantic Canadian Coastal Water Level Neural Network Model

2008 ◽  
Vol 25 (11) ◽  
pp. 2117-2132 ◽  
Author(s):  
Guoqi Han ◽  
Yu Shi
Keyword(s):  
Neural Network ◽  
Water Level ◽  
Sea Level ◽  
Coastal Water ◽  
Water Levels ◽  
Atlantic Canada ◽  
Level Data ◽  
Coastal Water Level ◽  
Term Data

Abstract Coastal water-level information is essential for coastal zone management, navigation, and oceanographic research. However, long-term water-level observations are usually only available at a limited number of locations. This study discusses a complementary and simple neural network (NN) approach, to predict water levels at a specified coastal site from the data gathered at other nearby or remote permanent stations. A simple three-layer, feed-forward, back-propagation network and a neural network ensemble, named Atlantic Canadian Coastal Water Level Neural Network (ACCSLENNT) models, was developed to correlate the nonlinear relationship of sea level data among stations by learning from their historical characteristics. Instantaneous hourly observations of water level from five stations along the coast of Atlantic Canada—Argentia, Belledune, Halifax, North Sydney, and St. John’s—are used to formulate and validate the ACCSLENNT models. Qualitative and quantitative comparisons of the network output with target observations showed that despite significant changes in sea level amplitudes and phases in the study area, appropriately trained NN models could provide accurate and robust long-term predictions of both tidal and nontidal (tide subtracted) water levels when only short-term data are available. The robust results indicate that the NN models in conjunction with limited permanent stations are able to supplement long-term historical water-level data along the Atlantic Canadian coast. Because field data collection is usually expensive, the ACCSLENNT models provide a cost-effective alternative to obtain long-term data along Atlantic Canada.

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.

Long-Term Tidal Water Level Measurements in Abu Dhabi Emirate

2008 ◽  
Author(s):  
Khaled A. Mohamed
Keyword(s):  
Water Level ◽  
Water Levels ◽  
Abu Dhabi ◽  
Tidal Analysis ◽  
Tidal Motion ◽  
Tidal Water ◽  
Abu Dhabi Emirate ◽  
Tidal Constituents ◽  
Water Level Measurements

Abu Dhabi Emirate, United Arab Emirates has a unique tidal system. Understanding the tidal hydrodynamics in Abu Dhabi waters is very important for the design of the hydraulic structures and in the marine environmental studies. The objective of this study is to investigate the tidal water levels and tidal motion in Abu Dhabi, making use of the long-term water levels available. To achieve the aim of the study, the National Energy and Water Research Center (NEWRC) of Abu Dhabi Water and Electricity Authority installed tidal gauges at different locations in Abu Dhabi waters to obtain long-term water level measurements. At present, long-term water level measurements for at least 3 years period are available at different locations in Abu Dhabi waters. Tidal analysis was carried out on the available data to determine the characteristics of the tidal wave in Abu Dhabi Emirate and to get the main tidal constituents affecting the tidal motion. The obtained tidal constituents are used in updating and improving the boundary conditions of the numerical hydrodynamic models simulating the flow pattern in Abu Dhabi waters. The set up of the water level measurement program in Abu Dhabi waters and the results of the tidal analysis are presented and discussed in the paper.

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 Daily water-level variations of supraglacial lakes in the southern Inylchek Glacier, Central Asia

2020 ◽  
Author(s):  
Naoki Sakurai ◽  
Chiyuki Narama ◽  
Mirlan Daiyrov ◽  
Muhammed Esenamanov ◽  
Zarylbek Usekov ◽  
...  
Keyword(s):  
Water Level ◽  
Drainage Water ◽  
Water Levels ◽  
Supraglacial Lakes ◽  
Surface Models ◽  
Increase Rate ◽  
Aerial Vehicle ◽  
Water Level Variations ◽  
Daily Water ◽  
Lake Drainage

Abstract. To better understand the storage in and drainage through supraglacial lakes and englacial conduits, we investigated the daily water-level variations of supraglacial lakes on the southern Inylchek Glacier in Kyrgyzstan. To examine these variations, we used daily aerial digital images over three years (22 July–15 August 2017, 8–29 July 2018, and 12–19 July 2019) from an unmanned aerial vehicle (UAV) that were converted to digital surface models (DSMs) and ortho-images. Our main results are as follows. 1) When one lake drained, the water levels of other lakes might simultaneously increase, indicating that drainage water is shared with several lakes through a main englacial conduit. In one drainage event, a branch englacial conduit clearly connected to a main englacial conduit. 2) Sometimes, several lakes discharged simultaneously, indicating that several lakes had connected to a main englacial conduit that had opened. Such a case can cause larger-scale drainage than that from the opening of a branch englacial conduit. 3) Several lakes discharged twice in the same year, each time through a different conduit, indicating that the main englacial conduit can be abandoned and reused. 4) In some lakes, the water level gradually increased with nearly the same increase rate just before drainage. Such an increase may be an indicator of imminent lake drainage.

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 Worldwide lake level trends and responses to background climate variation

2020 ◽  
Vol 24 (5) ◽  
pp. 2593-2608 ◽  
Author(s):  
Benjamin M. Kraemer ◽  
Anton Seimon ◽  
Rita Adrian ◽  
Peter B. McIntyre
Keyword(s):  
Water Level ◽  
Lake Water ◽  
Environmental Changes ◽  
Southern Oscillation ◽  
Climate Variation ◽  
Water Levels ◽  
P Value ◽  
Long Term Trends ◽  
Background Climate

Abstract. Lakes provide many important benefits to society, including drinking water, flood attenuation, nutrition, and recreation. Anthropogenic environmental changes may affect these benefits by altering lake water levels. However, background climate oscillations such as the El Niño–Southern Oscillation and the North Atlantic Oscillation can obscure long-term trends in water levels, creating uncertainty over the strength and ubiquity of anthropogenic effects on lakes. Here we account for the effects of background climate variation and test for long-term (1992–2019) trends in water levels in 200 globally distributed large lakes using satellite altimetry data. The median percentage of water level variation associated with background climate variation was 58 %, with an additional 10 % explained by seasonal variation and 25 % by the long-term trend. The relative influence of specific axes of background climate variation on water levels varied substantially across and within regions. After removing the effects of background climate variation on water levels, long-term water level trend estimates were lower (median: +0.8 cm yr−1) than calculated from raw water level data (median: +1.2 cm yr−1). However, the trends became more statistically significant in 86 % of lakes after removing the effects of background climate variation (the median p value of trends changed from 0.16 to 0.02). Thus, robust tests for long-term trends in lake water levels which may or may not be anthropogenic will require prior isolation and removal of the effects of background climate variation. Our findings suggest that background climate variation often masks long-term trends in environmental variables but can be accounted for through more comprehensive statistical analyses.

scholarly journals Simultaneous drainage events from supraglacial lakes on the southern Inylchek Glacier, Central Asia

2021 ◽  
pp. 1-12
Author(s):  
Naoki Sakurai ◽  
Chiyuki Narama ◽  
Mirlan Daiyrov ◽  
Muhammed Esenamanov ◽  
Zarylbek Usekov ◽  
...  
Keyword(s):  
Water Level ◽  
Drainage Water ◽  
Water Levels ◽  
Aerial Images ◽  
Supraglacial Lakes ◽  
Surface Models ◽  
Increase Rate ◽  
Aerial Vehicle ◽  
Water Level Variations ◽  
Gradient Line

Abstract To understand the mechanism of simultaneous drainage event related to supraglacial lakes on a debris-covered glacier, we investigated water-level variations of supraglacial lakes on the southern Inylchek Glacier in Kyrgyzstan. To examine these variations, we used daily aerial images for 2017–2019 from an uncrewed aerial vehicle that were converted to 15 cm-digital surface models and ortho-images. Our main results are as follows: (1) When one lake drained, the water levels of other lakes simultaneously increased, indicating that drainage water is shared with several lakes through a main englacial conduit. In one drainage event, a branched off englacial conduit clearly connected to a main englacial conduit. (2) Sometimes several lakes discharged simultaneously, indicating that several lakes had connected to a main englacial conduit that had opened. Such cases can cause larger-scale drainage than that from the opening of a branched off englacial conduit. (3) Simultaneous drainage occurred twice in the same year, each time through a different conduit, indicating that the main englacial conduit can be abandoned and reused. (4) In some lakes, the water level on the hydraulic gradient line increased gradually with nearly the same increase rate just before drainage. Such an increase may be an indicator of a possible simultaneous drainage event.

scholarly journals Natural and anthropogenic conditions of water level fluctuations in lakes – Lake Powidzkie case study (Central-Western Poland)

2019 ◽  
Vol 40 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Bogumił M. Nowak ◽  
Mariusz Ptak
Keyword(s):  
Water Level ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Anthropogenic Factors ◽  
Water Shortages ◽  
Natural Factors ◽  
Precipitation Increase ◽  
Water Outflow

Abstract The article presents the analysis of water level fluctuations in Lake Powidzkie in the years 1961–2015. The study shows a considerable decrease in mean water levels in the aforementioned multiannual period, averaging 9 cmꞏdecade−1. Such a situation is caused by natural as well as anthropogenic factors, co-determining water relations in the study area. The natural factors include the amount and distribution of precipitation, increase in air temperature and evaporation size, unfavourable relations between the lake and catchment or hydrogeological conditions. Anthropogenic factors particularly include long-term transformations of the natural environment in the region, currently associated with meliorations accompanying the nearby opencast brown coal mines and exploitation of groundwaters for municipal purposes. Water shortages occurring during dry periods were shown not to be compensated in the study area in humid years. This is particularly related to the regional lowering of the aquifer remaining in close relations with Lake Powidzkie. Counteracting the unfavourable hydrological situation is done through hydrotechnical infrastructure which partially limits water outflow from the lake through damming.

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