The impact of hydrodynamics and texture on the infiltration of rain and marine waters into sand bank island sediments — Aspects of infiltration and groundwater dynamics

2008 ◽  
Vol 38 (2) ◽  
pp. 163-171 ◽  
Author(s):  
K. Klaassen ◽  
H. Bormann ◽  
T. Klenke ◽  
G. Liebezeit
Keyword(s):  
Marine Waters ◽  
Groundwater Dynamics ◽  
Sand Bank ◽  
The Impact

Quantification of the impact of lunar semidiurnal tides on groundwater dynamics in estuarine aquifers

2020 ◽  
Author(s):  
Xiaoying Zhang ◽  
Zhenxue Dai ◽  
Bill Hu ◽  
Heng Dai ◽  
Ziqi Ma ◽  
...  
Keyword(s):  
River Estuary ◽  
Pearl River Estuary ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Groundwater Dynamics ◽  
Groundwater Aquifers ◽  
Tidal Constituents ◽  
The Pearl River ◽  
Heterogeneous Sediments ◽  
The Impact

<p>The influences of lunar semidiurnal tides on coastal groundwater aquifers have been conceptualized for decades. However, in estuarine aquifers, comprehensive work is needed to quantify the impact of the tides on groundwater dynamics due to the widely distributed waterways and heterogeneous sediments. Taking the Pearl River estuary in southeast China as a study site, the tidal impacts on the groundwater dynamics have been investigated through wavelet and time series analysis. The groundwater level and electrical conductivity (EC) in four monitoring wells, along with waterway water level (tidal level) at three tidal stations, were monitored every 30 minutes over a 2-month period to determine how nearshore groundwater responds to tidal forcing. The results show that the estuarine groundwater fluctuations have two significant short periodicities (0.51 and 1 day), which correspond to the major tidal constituents in the tides: M<sub>2</sub><sub> </sub>(semidiurnal), K<sub>1</sub><sub> </sub>and O<sub>1</sub> (diurnal) signals. The significant impacts decrease with increasing distance inland of the locations of the wells. Additionally, the coherence analysis displays a higher correlation between tides and groundwater levels for the spring tide than for the neap tide. The tidal influences on groundwater EC are weaker. In addition, when the tide level increases, the EC decreases in the wells located in the estuarine entrance. This phenomenon is related to the high salinity of retained paleo-seawater in the strata lens. A conceptual model is proposed to illustrate the complex groundwater flow dynamics, which provides useful insights into understanding groundwater systems in other geographically similar coastal estuarine regions.</p>

scholarly journals The impact of increasing land productivity on groundwater dynamics: a case study of an oasis located at the edge of the Gobi Desert

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Wu Lei ◽  
Li Changbin ◽  
Xie Xuhong ◽  
He Zhibin ◽  
Wang Wanrui ◽  
...  
Keyword(s):  
Gobi Desert ◽  
Land Productivity ◽  
Groundwater Dynamics ◽  
The Impact

scholarly journals The impact of hillslope groundwater dynamics and landscape functioning in event-flow generation: a field study in the Rietholzbach catchment, Switzerland

2015 ◽  
Vol 23 (5) ◽  
pp. 935-948 ◽  
Author(s):  
Jana von Freyberg ◽  
P. Suresh C. Rao ◽  
Dirk Radny ◽  
Mario Schirmer
Keyword(s):  
Field Study ◽  
Groundwater Dynamics ◽  
Flow Generation ◽  
Event Flow ◽  
The Impact

scholarly journals Conceptual Model of Drainage-Sub Irrigation System Functioning-First Results from a Case Study of a Lowland Valley Area in Central Poland

2020 ◽  
Vol 13 (1) ◽  
pp. 107
Author(s):  
Andrzej Brandyk ◽  
Edmund Kaca ◽  
Ryszard Oleszczuk ◽  
Janusz Urbański ◽  
Jan Jadczyszyn
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Conceptual Model ◽  
Soil Profile ◽  
Management Practices ◽  
Soil Moisture Content ◽  
Irrigation System ◽  
Irrigation Systems ◽  
Groundwater Dynamics ◽  
The Impact

The search for simple models of drainage–irrigation systems functioning and management has still been an important research objective. Therefore, we presented a conceptual model based on groundwater dynamics equation along with proper assumptions on water equivalent of transient porosity-i.e., storage in the soil profile based on the long-term experience of the research on drainage-sub-irrigation systems. Several parameters have been incorporated in the model to effectively and comprehensively describe drainage/irrigation time, leakage from the soil profile, the soil moisture content in the root zone, and the shape of the groundwater table on the drainage–sub-irrigation plot. The model was successfully validated on groundwater level data in ditch midspacing on an experimental site located within a valley sub-irrigation system with the advantage of a relatively simple representation of flows through the soil profile. The robust character of the conceptual equation of groundwater dynamics, as well as the approach to its’ parameters, were proved through a close match between the model and observations. This promotes the capacities of the proposed modeling procedure to conceptualize drainage-irrigation development with the impact of external and internal sources of water. The potential was offered for the evaluation of water management practices in a valley system influenced by horizontal inflows from surrounding areas as indicated by calibration results. Future challenges were revealed in terms of water exchange between the plots and validation of soil moisture content modeling.

scholarly journals Impacts of Fracture Roughness and Near-wellbore Tortuous on Proppant Transport Within Hydraulic Fractures

2021 ◽  
Author(s):  
Di Wang ◽  
Bingyang Bai ◽  
Bin Wang ◽  
Dongya Wei ◽  
Tianbo Liang
Keyword(s):  
Hydraulic Fracturing ◽  
Analytical Model ◽  
Volume Fraction ◽  
Transport Model ◽  
Sand Transport ◽  
Hydraulic Fractures ◽  
Fracture Roughness ◽  
Transport Velocity ◽  
Sand Bank ◽  
The Impact

Abstract For unconventional reservoirs hydraulic fracturing design, a greater fracture length is a prime factor to optimize. However, core observation results from Hydraulic Fracturing Test Site (HFTS) show the propped fractures are far less or shorter than expected which suggests the roughness and tortuous of hydraulic fractures are crucial to sand transport. In this study a transport model of sands is first built based on experimental measurements on the height and transport velocity of sand bank in fractures with predetermined width and roughness. The fracture roughness is quantified by using surface height integral. Then, three-dimensional simulations are conducted with this modified model to further investigate the impact of fractures tortuous on sand transport, from which an analytical model is established to estimate the propped length of hydraulic fractures at a certain pumping condition. Experiments results show that height of sand bank in roughness fracture is 20-50% higher than that in smooth. The height of sand bank decreases with the reduction of slurry velocity and increases with the sand diameters increasing. Sand sizes do little effect on the transport velocity of sand bank but the increase in slurry velocity and sand volume fraction can dramatically enhance the migration velocity of sand bank. The appearance of tortuous decreases the horizontal velocity of suspended particles and results in a higher sand bank compared with that in straight fractures. When the sand bank gets equilibrium at the tortuous position, it is easy to produce vortices. So, there is a significant height of sand bank change at the tortuous position. Moreover, sand plugging can occur at the entrance of the fractures, making it difficult for the sand to transport deep in fractures. This study explains why the propped length of fractures in HFTS is short and provides an analytical model that can be easily embedded in the fracturing simulation to fast calculate dimensions of the propped fractures network to predict length and height of propped fractures during fracturing.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

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