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 Sensitivity Analysis of Anchored Slopes under Water Level Fluctuations: A Case Study of Cangjiang Bridge—Yingpan Slope in China

2021 ◽  
Vol 11 (15) ◽  
pp. 7137
Author(s):  
Jinxi Liang ◽  
Wanghua Sui
Keyword(s):  
Sensitivity Analysis ◽  
Slope Stability ◽  
Water Level ◽  
Controlling Factors ◽  
Slope Instability ◽  
Water Level Fluctuations ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Slope Inclination ◽  
Main Controlling Factors

This paper presents an improved slope stability sensitivity analysis (ISSSA) model that takes anchoring factors into consideration in umbrella-anchored sand and clay slopes under reservoir water level fluctuation. The results of the ISSSA model show that the slope inclination and the layout density of anchors are the main controlling factors for sand slope stability under fluctuation of the water level, while the slope inclination and water head height are the main controlling factors for slope stability in the Cangjiang bridge—Yingpan slope of Yunnan province in China. Moreover, there is an optimum anchorage angle, in the range of 25–45 degrees, which has the greatest influence on slope stability. The fluctuation of the reservoir water level is an important factor that triggers slope instability; in particular, a sudden drop in the surface water level can easily lead to landslides; therefore, corresponding measures should be implemented in a timely manner in order to mitigate landslide disasters.

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.

scholarly journals Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers

2021 ◽  
Vol 25 (12) ◽  
pp. 6591-6602
Author(s):  
Zhaoyang Luo ◽  
Jun Kong ◽  
Chengji Shen ◽  
Pei Xin ◽  
Chunhui Lu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Sensitivity Analysis ◽  
Steady State ◽  
Seawater Intrusion ◽  
Analytical Solutions ◽  
Boussinesq Equations ◽  
Flow Boundary ◽  
Circle Center ◽  
Aquifer Geometry ◽  
Opposite Tendency

Abstract. Seawater intrusion in island aquifers was considered analytically, specifically for annulus segment aquifers (ASAs), i.e., aquifers that (in plan) have the shape of an annulus segment. Based on the Ghijben–Herzberg and hillslope-storage Boussinesq equations, analytical solutions were derived for steady-state seawater intrusion in ASAs, with a focus on the freshwater–seawater interface and its corresponding watertable elevation. Predictions of the analytical solutions compared well with experimental data, and so they were employed to investigate the effects of aquifer geometry on seawater intrusion in island aquifers. Three different ASA geometries were compared: convergent (smaller side is facing the lagoon, larger side is the internal no-flow boundary and flow converges towards the lagoon), rectangular and divergent (smaller side is the internal no-flow boundary, larger side is facing the sea and flow diverges towards the sea). Depending on the aquifer geometry, seawater intrusion was found to vary greatly, such that the assumption of a rectangular aquifer to model an ASA can lead to poor estimates of seawater intrusion. Other factors being equal, compared with rectangular aquifers, seawater intrusion is more extensive, and watertable elevation is lower in divergent aquifers, with the opposite tendency in convergent aquifers. Sensitivity analysis further indicated that the effects of aquifer geometry on seawater intrusion and watertable elevation vary with aquifer width and distance from the circle center to the inner arc (the lagoon boundary for convergent aquifers or the internal no-flow boundary for divergent aquifers). A larger aquifer width and distance from the circle center to the inner arc weaken the effects of aquifer geometry, and hence differences in predictions for the three geometries become less pronounced.

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.

AUTOMATIC WATER LEVEL MONITORING WITH IOT AND LPWAN

2019 ◽  
pp. 95-103
Author(s):  
Krum Videnov ◽  
Vanya Stoykova
Keyword(s):  
Water Level ◽  
Real Time ◽  
Early Warning ◽  
Water Sources ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Level Monitoring ◽  
Water Level Monitoring

Monitoring water levels of lakes, streams, rivers and other water basins is of essential importance and is a popular measurement for a number of different industries and organisations. Remote water level monitoring helps to provide an early warning feature by sending advance alerts when the water level is increased (reaches a certain threshold). The purpose of this report is to present an affordable solution for measuring water levels in water sources using IoT and LPWAN. The assembled system enables recording of water level fluctuations in real time and storing the collected data on a remote database through LoRaWAN for further processing and analysis.

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