scholarly journals Finite volume coastal ocean model for water-level fluctuation due to climate change in Aguelmam Sidi Ali Lake (Middle Atlas, Morocco)

2018 ◽  
Vol 54 ◽  
pp. 5 ◽  
Author(s):  
Soufiane Haddout ◽  
Abdelkrim Jamali ◽  
Mbarek Rhazi ◽  
Mohamed Aghfir
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Ocean Model ◽  
Water Level Fluctuations ◽  
Order Estimate ◽  
Natural Ecosystem ◽  
Dry Conditions ◽  
Water Level Variations ◽  
Coastal Ocean Model ◽  
Set Up

Climate changes are the main motivation for alteration of ecosystems; in fact the effects of these changes on biodiversity and ecosystems are considered as the most challenging cases in present century. Therefore, since the lakes are the most important services and functions of ecosystems, the effect of climate change on water level fluctuations of Aguelmam Sidi Ali Lake (Morocco) was analyzed as a natural ecosystem in this essay. The regular observations from the lake have found that a very sensitive withdrawal of their water level during the dry years. Therefore, a hydrodynamic model has been used to simulate the condition of Aguelmam Sidi Ali Lake, with observed field data (model has been set up to run annually for a total 35 year data, i.e., precipitation, evaporation, runoff discharges and water-level which are available for the last 35 years) being used for model calibration and validation. Additionally, the model validation process showed that the model results fit the observed data fairly well (R2 = 0.70−0.74, root mean square error [RMSE] = 1.63−1.71 m). On the other hand, different hydrological conditions regarding lake input and output data were tested and water depth was calculated using bathymetry to predict water-level fluctuations in the future. The results predict that the water-level will decrease continuously (In 2044, the water level will reach to 6.20 m). The water level decrease due to the climate change in both scenarios (dry and very dry) is dramatic and a profound adverse impact on the environmental balance is predicted in the region. Additionally, the lake will be dried up in about 20 years if very dry conditions continue in the region. This reveals the importance of this type of approach for obtaining a first-order estimate of water-level variations in Sidi Ali Lake, affected by climate change.

Lake water level response to drought in a lake-rich region explained by lake and landscape characteristics

2020 ◽  
Vol 77 (11) ◽  
pp. 1836-1845
Author(s):  
K. Martin Perales ◽  
Catherine L. Hein ◽  
Noah R. Lottig ◽  
M. Jake Vander Zanden
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Lake Water ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Lake Area ◽  
Lake Water Level ◽  
Landscape Characteristics ◽  
Lake Ecology ◽  
Coarse Woody Habitat

Climate change is altering hydrologic regimes, with implications for lake water levels. While lakes within lake districts experience the same climate, lakes may exhibit differential climate vulnerability regarding water level response to drought. We took advantage of a recent drought (∼2005–2010) and estimated changes in lake area, water level, and shoreline position on 47 lakes in northern Wisconsin using high-resolution orthoimagery and hypsographic curves. We developed a model predicting water level response to drought to identify characteristics of the most vulnerable lakes in the region, which indicated that low-conductivity seepage lakes found high in the landscape, with little surrounding wetland and highly permeable soils, showed the greatest water level declines. To explore potential changes in the littoral zone, we estimated coarse woody habitat (CWH) loss during the drought and found that drainage lakes lost 0.8% CWH while seepage lakes were disproportionately impacted, with a mean loss of 40% CWH. Characterizing how lakes and lake districts respond to drought will further our understanding of how climate change may alter lake ecology via water level fluctuations.

Effects of nutrients and water levels on emergent macrophyte biomass in a prairie marsh

1990 ◽  
Vol 68 (5) ◽  
pp. 1007-1014 ◽  
Author(s):  
Christopher Neill
Keyword(s):  
Water Level ◽  
Nutrient Limitation ◽  
Water Depth ◽  
Nitrogen Limitation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Depth Range ◽  
Dry Conditions ◽  
Second Year ◽  
Water Depths

Nitrogen and phosphorus fertilizers were added over two growing seasons to marshes dominated by whitetop grass (Scolochloa festucacea) or cattail (Typha glauca) in a prairie lacustrine marsh to assess nutrient limitation and the interaction of nutrient limitation with water depth. For each species, stands were selected at the deep and shallow extremes of its water depth range. Water levels were high during the first year of fertilization and low during the second year, exposing the fertilized stands to a variety of water depths. Nitrogen limited growth in whitetop and cattail marshes. Water level, by controlling whether the soil was flooded or the water table was below the soil surface, affected growth and the degree of nitrogen limitation. In whitetop marshes, nitrogen increased biomass more when the soil was flooded or when standing water was deeper and in cattail marshes, it increased biomass more under intermediate water depths (approximately 0–20 cm) than under more deeply flooded (20–40 cm) or dry conditions. Nitrogen reduced biomass in whitetop marshes the second year, apparently because growth was inhibited by fallen litter from the previous year. Nitrogen did not limit cattail marsh biomass in the driest locations during a year of low water levels. Phosphorus caused a small increase in growth of both species after 2 years. Changes of nitrogen limitation with flooding suggest that annual water level fluctuations, by creating alternating flooded and dry conditions, may influence the primary production of emergent macrophytes through effects on nitrogen cycling.

scholarly journals Towards a Correlation between Long-Term Seawater Intrusion Response and Water Level Fluctuations

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 719
Author(s):  
Antoifi Abdoulhalik ◽  
Ashraf A. Ahmed ◽  
Abdelrahman M. Abdelgawad ◽  
G. A. Hamill
Keyword(s):  
Sensitivity Analysis ◽  
Steady State ◽  
Linear Relationship ◽  
Water Level ◽  
Linear Function ◽  
Seawater Intrusion ◽  
Water Level Fluctuations ◽  
Management Perspective ◽  
Perform Sensitivity Analysis ◽  
Water Level Variations

Laboratory and numerical experiments were conducted to provide a quantitative steady-state analysis of the effect of incremental variations of water level on saltwater intrusion. The purpose was to seek mathematical correlations relating both the wedge toe length and the height along the coastline to the boundary head difference. The laboratory experiments were completed in a 2D sand tank where both freshwater and seawater levels were varied. The experiments were conducted for two bead sizes having different hydraulic conductivities. The numerical model SEAWAT was used to validate the results and then to perform sensitivity analysis. The experimental results show that at steady-state conditions, the logarithmic toe length could be expressed as a linear function of the boundary head difference. The linear relationship was recorded in both advancing and receding wedge phases. The linearity of the correlation was also well demonstrated with analytical solutions. Similar relationships were also derived in the scenarios where the sea level fluctuated while the freshwater boundary head was constant. The height of the saltwater wedge along the coastline was also found to be a linear function of the boundary head difference. The sensitivity analysis shows that the regression coefficients were sensitive to the hydraulic conductivity, the dispersivity, and the saltwater density, while the porosity and the rate of boundary head change induced negligible effects. The existence of a linear relationship between the logarithmic toe length and the boundary head difference was also well evidenced in a field-scale aquifer model for all the different hydrogeological aquifer conditions tested. This study is the first attempt in identifying the underlying correlation between the boundary water level variations and the main seawater intrusion (SWI) external metrics under controlled laboratory conditions, which is of great relevance from a water resources management perspective.

scholarly journals Detection and Attribution of Lake Victoria’s Water-Level Fluctuations in a Changing Climate

2021 ◽  
Author(s):  
Obed M. Ogega ◽  
James Mbugua ◽  
Herbert O. Misiani ◽  
Maurice Nyadawa ◽  
Enrico Scoccimarro ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Level ◽  
Lake Victoria ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Return Periods ◽  
Model Intercomparison ◽  
Changing Climate ◽  
Intercomparison Project

This study investigated the influence of land-use and precipitation change and variability on Lake Victoria’s water-level fluctuations. Extreme precipitation events, corresponding to extreme water-levels, over the lake and its catchment area were identified and their return periods estimated by fitting them into a generalized extreme value (GEV) distribution. Using general circulation models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6)’s Detection & Attribution Model Intercomparison Project (DAMIP), an assessment of the potential contribution of human-induced climate change on the observed precipitation patterns over the study area was done. The greatest precipitation anomalies for the period 1900-2020 were recorded in 1961’s October-December (OND) season and 2019’s June-August (JJA) and OND seasons, corresponding to the period when the highest water-levels were recorded in Lake Victoria. While land-use change in the study domain was observed, extended and unusually heavy June to December 2019 precipitation bore the greatest responsibility for the 2019/2020 high water-levels in Lake Victoria. The OND precipitation event of 2019 was a 1-in-52-year event compared to the 1961’s 1-in-693 years. Differences in return periods at various parts of the lake imply a high spatial climate variability within the lake itself. An analysis of the fraction of attributable risk (FAR) showed natural variability to have a greater influence on the JJA and OND precipitation patterns over Lake Victoria than human-induced climate change. However, variability over the land area of the study domain was mainly driven by human-induced climate change rather than natural variability, implying a unique climate system over Lake Victoria. Findings from the current study enhance the understanding of Lake Victoria’s water budget and motivate for further research to inform effective strategies on the planning and use of Lake Victoria’s water resources in a changing climate.

A delay nonautonomous model for the effects of fear and refuge on predator–prey interactions with water-level fluctuations

2022 ◽  
Author(s):  
Abhijit Sarkar ◽  
Pankaj Kumar Tiwari ◽  
Samares Pal
Keyword(s):  
Periodic Solution ◽  
Time Delay ◽  
Water Level ◽  
Positive Periodic Solution ◽  
Time Dependent ◽  
Water Level Fluctuations ◽  
Prey Refuge ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Water Level Variations

The interaction of prey (small fish) and predator (large fish) in lakes/ponds at temperate and tropical regions varies when water level fluctuates naturally during seasonal time. We relate the perceptible effect of fear and anti-predator behavior of prey with the water-level fluctuations and describe how these are influenced by the seasonal changing of water level. So, we consider these as time-dependent functions to make the system more realistic. Also, we incorporate the time-dependent delay in the negative growth rate of prey in predator–prey model with Crowley–Martin-type functional response. We clearly provide the basic dynamics of the system such as positiveness, permanence and nonpersistence. The existence of positive periodic solution is studied using Continuation theorem, and suffiecient conditions for globally attractivity of positive periodic solution are also derived. To make the system more comprehensive, we establish numerical simulations, and compare the dynamics of autonomous and nonautonomous systems in the absence as well as the presence of time delay. Our results show that seasonality and time delay create the occurrence of complex behavior such as prevalence of chaotic disorder which can be potentially suppressed by the cost of fear and prey refuge. Also, if time delay increases, then system leads a boundary periodic solution. Our findings assert that the predation, fear of predator and prey refuge are correlated with water-level variations, and give some reasonable biological interpretations for persistence as well as extinction of species due to water-level variations.

scholarly journals Analysis of Long-Term Water Level Variations in Qinghai Lake in China

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2136 ◽  
Author(s):  
Fang ◽  
Li ◽  
Rubinato ◽  
Ma ◽  
Zhou ◽  
...  
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Water Level ◽  
Water Levels ◽  
Qinghai Lake ◽  
The Tibetan Plateau ◽  
Climate Change Effects ◽  
Water Level Variations ◽  
Respective Contribution

Qinghai Lake is the largest inland saline lake on the Tibetan Plateau. Climate change and catchment modifications induced by human activities are the main drivers playing a significant role in the dramatic variation of water levels in the lake (Δh); hence, it is crucial to provide a better understanding of the impacts caused by these phenomena. However, their respective contribution to and influence on water level variations in Qinghai Lake are still unclear and without characterizing them, targeted measures for a more efficient conservation and management of the lake cannot be implemented. In this paper, data monitored during the period 1960–2016 (e.g., meteorological and land use data) have been analyzed by applying multiple techniques to fill this gap and estimate the contribution of each parameter recorded to water level variations (Δh). Results obtained have demonstrated that the water level of Qinghai Lake declined between 1960 and 2004, and since then has risen continuously and gradually, due to the changes in evaporation rates, precipitation and consequently surface runoff associated with climate change effects and catchment modifications. The authors have also pinpointed that climate change is the main leading cause impacting the water level in Qinghai Lake because results demonstrated that 93.13% of water level variations can be attributable to it, while the catchment modifications are responsible for 6.87%. This is a very important outcome in the view of the fact that global warming clearly had a profound impact in this sensitive and responsive region, affecting hydrological processes in the largest inland lake of the Tibetan Plateau.

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