scholarly journals Selecting Suitable MODFLOW Packages to Model Pond–Groundwater Relations Using a Regional Model

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1111
Author(s):  
Carmen Serrano-Hidalgo ◽  
Carolina Guardiola-Albert ◽  
Javier Heredia ◽  
Francisco Javier Elorza Tenreiro ◽  
Nuria Naranjo-Fernández
Keyword(s):  
Boundary Condition ◽  
Large Scale ◽  
Groundwater Resources ◽  
Ecological Impacts ◽  
Small Scale ◽  
Groundwater Levels ◽  
Advantages And Disadvantages ◽  
Natural Park ◽  
Secondary Objective ◽  
Regional Aquifer

In large-scale regional models, used for the management of underground resources, it is quite common to find that relationships between the regional aquifer and small wetlands are not included. These models do not consider this connection because of the small amount of water involved, but they should consider the potential for significant ecological impacts if the groundwater resources in the ecosystems associated with these wetlands are mismanaged. The main objective of this work is to investigate the possibilities offered by MODFLOW LGR-V2 to represent (at small scale) the Santa Olalla pond, located in the Doñana Natural Park (South of Spain), and its relationship with the Almonte-Marismas regional aquifer. As a secondary objective, we propose to investigate the advantages and disadvantages that DRAIN, RIVER and LAKE MODFLOW packages offer within the MODFLOW LGR-V2 discretizations. The drain boundary condition with a coarse discretization implemented through ModelMuse allows the most adequate performance of the groundwater levels in the environment of the pond. However, when using lake boundary condition, the use of the MODFLOW LGR-V2 version is particularly useful. The present work also gives some guidelines to employ these packages with the MODFLOW graphical user’s interface, ModelMuse 4.2.

scholarly journals Causes and consequences of long-term groundwater overabstraction in Jordan

2021 ◽  
Author(s):  
Florian Brückner ◽  
Rebecca Bahls ◽  
Mohammad Alqadi ◽  
Falk Lindenmaier ◽  
Ibraheem Hamdan ◽  
...  
Keyword(s):  
Water Supply ◽  
Large Scale ◽  
Flow Direction ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Irrigated Agriculture ◽  
Groundwater Levels ◽  
Contour Lines ◽  
Hydraulic Conditions ◽  
Groundwater Basins

AbstractIn 2017, a comprehensive review of groundwater resources in Jordan was carried out for the first time since 1995. The change in groundwater levels between 1995 and 2017 was found to be dramatic: large declines have been recorded all over the country, reaching more than 100 m in some areas. The most affected areas are those with large-scale groundwater-irrigated agriculture, but areas that are only used for public water supply are also affected. The decrease of groundwater levels and saturated thickness poses a growing threat for drinking water supply and the demand has to be met from increasingly deeper and more remote sources, causing higher costs for drilling and extraction. Groundwater-level contour lines show that groundwater flow direction has completely reversed in some parts of the main aquifer. Consequently, previously established conceptual models, such as the concept of 12 “groundwater basins” often used in Jordan should be revised or replaced. Additionally, hydraulic conditions are changing from confined to unconfined; this is most likely a major driver for geogenic pollution with heavy metals through leakage from the overlying bituminous aquitard. Three exemplary case studies are presented to illustrate and discuss the main causes for the decline of the water tables (agriculture and population growth) and to show how the results of this assessment can be used on a regional scale.

scholarly journals The Triumph of Large-Scale Agriculture and Its Socioeconomic Impact

2018 ◽  
Vol 43 (2) ◽  
pp. 95-106
Author(s):  
András Schlett ◽  
Judit Beke
Keyword(s):  
Rural Areas ◽  
Large Scale ◽  
Socioeconomic Impact ◽  
Small Scale ◽  
Production Methods ◽  
Advantages And Disadvantages ◽  
Key Drivers

Large-scale farming that utilizes industrial methods to intensify production is becoming more significant worldwide. This study explores this phenomenon and sheds light on its consequences. Contingency factors serve as key drivers when determining the advantages and disadvantages of both large-scale and small-scale farming. Significant shifts in agro-production methods have fundamentally altered ownership and production structures in agriculture and had a disastrous impact on the livelihoods of people living in rural areas.

scholarly journals Shallow groundwater in sub-Saharan Africa: neglected opportunity for sustainable intensification of small-scale agriculture?

2016 ◽  
Author(s):  
John Gowing ◽  
Geoff Parkin ◽  
Nathan Forsythe ◽  
David Walker ◽  
Alemseged Tamiru Haile ◽  
...  
Keyword(s):  
Groundwater Resources ◽  
Climatic Variability ◽  
Shallow Groundwater ◽  
Sustainable Intensification ◽  
Sub Saharan Africa ◽  
Small Scale ◽  
Groundwater Levels ◽  
Sub Saharan ◽  
Small Scale Irrigation

Abstract. There is a need for an evidence-based approach to identify how best to support development of groundwater for small scale irrigation in sub-Saharan Africa (SSA). We argue that it is important to focus this effort on shallow groundwater resources which are most likely to be used by poor rural communities in SSA. However, it is important to consider constraints, since shallow groundwater resources are likely to be vulnerable to over-exploitation and climatic variability. We examine here the opportunities and constraints and draw upon evidence from Ethiopia. We present a methodology for assessing and interpreting available shallow groundwater resources and argue that participatory monitoring of local water resources is desirable and feasible. We consider possib le models for developing distributed small-scale irrigation and assess its technical feasibility. Because of power limits on water lifting and also because of available technology for well construction, groundwater at depths of 50 m or 60 m cannot be regarded as easily accessible for small-scale irrigation. We therefore adopt a working definition of shallow groundwater as < 20 m depth. This detailed case study in the Dangila woreda in Ethiopia explores the feasibility of exploiting shallow groundwater for small-scale irrigation over a range of rainfall conditions. Variability of rainfall over the study period (9 % to 96 % probability of non-exceedance) does not translate into equivalent variability in groundwater levels and river baseflow. Groundwater levels, monitored by local communities, persist into the dry season to at least the end of December in most shallow wells, indicating that groundwater is available for irrigation use after the cessation of the wet season. Arguments historically put forward against the promotion of groundwater use for agriculture in SSA on the basis that aquifers are unproductive and irrigation will have unacceptable impacts on wetlands and other groundwater-dependent ecosystems appear exaggerated. It would be unwise to generalise from this case study to the whole of SSA, but useful insights into the wider issues are revealed by the case study approach. We believe there is a case for arguing that shallow groundwater in sub-Saharan Africa represents a neglected opportunity for sustainable intensification of small-scale agriculture.

scholarly journals A Computational Workflow for Flow and Transport in Fractured Porous Media Based on a Hierarchical Nonlinear Discrete Fracture Modeling Approach

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6667
Author(s):  
Wenjuan Zhang ◽  
Waleed Diab ◽  
Hadi Hajibeygi ◽  
Mohammed Al Kobaisi
Keyword(s):  
Boundary Condition ◽  
Porous Media ◽  
Boundary Conditions ◽  
Large Scale ◽  
Fractured Porous Media ◽  
Small Scale ◽  
Flow And Transport ◽  
Fracture Length ◽  
Discrete Fracture ◽  
Computational Workflow

Modeling flow and transport in fractured porous media has been a topic of intensive research for a number of energy- and environment-related industries. The presence of multiscale fractures makes it an extremely challenging task to resolve accurately and efficiently the flow dynamics at both the local and global scales. To tackle this challenge, we developed a computational workflow that adopts a two-level hierarchical strategy based on fracture length partitioning. This was achieved by specifying a partition length to split the discrete fracture network (DFN) into small-scale fractures and large-scale fractures. Flow-based numerical upscaling was then employed to homogenize the small-scale fractures and the porous matrix into an equivalent/effective single medium, whereas the large-scale fractures were modeled explicitly. As the effective medium properties can be fully tensorial, the developed hierarchical framework constructed the discrete systems for the explicit fracture–matrix sub-domains using the nonlinear two-point flux approximation (NTPFA) scheme. This led to a significant reduction of grid orientation effects, thus developing a robust, applicable, and field-relevant framework. To assess the efficacy of the proposed hierarchical workflow, several numerical simulations were carried out to systematically analyze the effects of the homogenized explicit cutoff length scale, as well as the fracture length and orientation distributions. The effect of different boundary conditions, namely, the constant pressure drop boundary condition and the linear pressure boundary condition, for the numerical upscaling on the accuracy of the workflow was investigated. The results show that when the partition length is much larger than the characteristic length of the grid block, and when the DFN has a predominant orientation that is often the case in practical simulations, the workflow employing linear pressure boundary conditions for numerical upscaling give closer results to the full-model reference solutions. Our findings shed new light on the development of meaningful computational frameworks for highly fractured, heterogeneous geological media where fractures are present at multiple scales.

scholarly journals Large-scale Climate Variability Footprint in Water Levels of Alluvial Aquifers Across Iran

2021 ◽  
Author(s):  
Abolfazl Rezaei
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Groundwater Resources ◽  
Water Levels ◽  
Climate Indices ◽  
Frequency Bands ◽  
Groundwater Levels ◽  
Aquifer Storage ◽  
Atmospheric Circulations

Abstract The ability to predict future variability of groundwater resources in time and space is of critical
importance in society’s adaptation to climate variability and change. Periodic control of large scale ocean-atmospheric circulations on groundwater levels proposes a potentially effective source of longer term forecasting capability. In this study, as a first national-scale assessment, we use the continues wavelet transform, global power spectrum, and wavelet coherence analyses to quantify the controls of the Atlantic Multidecadal Oscillation (AMO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), and El Niño Southern Oscillation (ENSO) over the representative groundwater levels of the 24 principal aquifers, scattered across different 14 climate zones of Iran. The results demonstrate that aquifer storage variations are partially controlled by annual to interdecadal climate variability and are not solely a function of pumping variations. Moreover, teleconnections are observed to be both frequency and time specific. The significant coherence patterns between the climate indices and groundwater levels are observed at five frequency bands of the annual (~1-yr), interannual (2-4- and 4-6-yr), decadal (8-12-yr), and interdecadal (14-18yr), consistent with the dominant modes of climate indices. AMO’s strong footprint is observed at interdecadal and annual modes of groundwater levels while PDO’s highest imprint is seen in interannual, decadal, and interdecadal modes. The highest controlling influence of ENSO is observed across the decadal and interannual modes whereas the NAO’s footprint is marked at annual and interdecadal frequency bands. Further, it is observed that the groundwater variability being higher modulated by a combination of large-scale atmospheric circulations rather than each individual index. The decadal and interdecadal oscillation modes constitute the dominant modes in Iranian aquifers. Findings also mark the unsaturated zone contribution in damping and lagging of the climate variability modes, particularly for the higher frequency indices of ENSO and NAO where the groundwater variability is observed to be more correlated with lower frequent climate circulations such as PDO and AMO, rather than ENSO and NAO. Finally, it is found that the data length can significantly affect the teleconnections if the time series are not contemporaneous and only one value of coherence/correlation is computed for each particular series instead of separate computations for different frequency bands and different time spans.

scholarly journals Evaluasi Pengadaan Tanah Skala Kecil dengan dan tanpa Penetapan Lokasi di Kabupaten Sleman

2021 ◽  
Vol 1 (1) ◽  
pp. 61-75
Author(s):  
Wenny Yolanda Ratna Sari ◽  
Priyo Katon Prasetyo ◽  
Sudibyanung Sudibyanung
Keyword(s):  
Government Regulation ◽  
Large Scale ◽  
Implementation Process ◽  
Land Acquisition ◽  
Small Scale ◽  
Infrastructure Development ◽  
Advantages And Disadvantages ◽  
Land Availability ◽  
The Government

Land availability is the great significant part in infrastructure development. To support the land availability, the government pursues a program called land acquisition. Land acquisition is regulated in Law Number 2 of 2012 and Government Regulation Number 71 of 2012. Based on Government Regulation Number 40 of 2014, land acquisition is divided into two, including large scale with an area of more than 5 hectares and small scale based with an area of less than 5 hectares. Small-scale land acquisition is further regulated in Presidential Regulation Number 148 of 2015 Article 121 paragraph (3) which does not require a determination of location. The purpose of this study was to determine the implementation process as well as the advantages and disadvantages of small-scale land acquisition with and without location determination in Sleman Regency. This research used a qualitative method with a descriptive approach. The results of this research showed that the implementation of land acquisition with determination of location has advantages (4) and weaknesses (6) while land acquisition without determination of location has advantages (6) and disadvantages (4).

scholarly journals Tree diversity regulates forest pest invasion

2019 ◽  
Vol 116 (15) ◽  
pp. 7382-7386 ◽  
Author(s):  
Qinfeng Guo ◽  
Songlin Fei ◽  
Kevin M. Potter ◽  
Andrew M. Liebhold ◽  
Jun Wen
Keyword(s):  
Species Diversity ◽  
Native Species ◽  
Large Scale ◽  
Tree Diversity ◽  
Ecological Impacts ◽  
Invasion Success ◽  
Small Scale ◽  
Forest Pest ◽  
Natural Ecosystems

Nonnative pests often cause cascading ecological impacts, leading to detrimental socioeconomic consequences; however, how plant diversity may influence insect and disease invasions remains unclear. High species diversity in host communities may promote pest invasions by providing more niches (i.e., facilitation), but it can also diminish invasion success because low host dominance may make it more difficult for pests to establish (i.e., dilution). Most studies to date have focused on small-scale, experimental, or individual pest/disease species, while large-scale empirical studies, especially in natural ecosystems, are extremely rare. Using subcontinental-level data, we examined the role of tree diversity on pest invasion across the conterminous United States and found that the tree-pest diversity relationships are hump-shaped. Pest diversity increases with tree diversity at low tree diversity (because of facilitation or amplification) and is reduced at higher tree diversity (as a result of dilution). Thus, tree diversity likely regulates forest pest invasion through both facilitation and dilution that operate simultaneously, but their relative strengths vary with overall diversity. Our findings suggest the role of native species diversity in regulating nonnative pest invasions.

scholarly journals Additive Manufacture of Small-Scale Metamaterial Structures for Acoustic and Ultrasonic Applications

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 634
Author(s):  
Alicia Gardiner ◽  
Paul Daly ◽  
Roger Domingo-Roca ◽  
James F. C. Windmill ◽  
Andrew Feeney ◽  
...  
Keyword(s):  
Large Scale ◽  
Acoustic Properties ◽  
Small Scale ◽  
Additive Manufacture ◽  
Acoustic Metamaterials ◽  
Acoustic Metamaterial ◽  
Multi Scale ◽  
Advantages And Disadvantages ◽  
Scale Structures ◽  
Small Scale Structures

Acoustic metamaterials are large-scale materials with small-scale structures. These structures allow for unusual interaction with propagating sound and endow the large-scale material with exceptional acoustic properties not found in normal materials. However, their multi-scale nature means that the manufacture of these materials is not trivial, often requiring micron-scale resolution over centimetre length scales. In this review, we bring together a variety of acoustic metamaterial designs and separately discuss ways to create them using the latest trends in additive manufacturing. We highlight the advantages and disadvantages of different techniques that act as barriers towards the development of realisable acoustic metamaterials for practical audio and ultrasonic applications and speculate on potential future developments.

scholarly journals Photovoltaic and Wind Turbine: A Comparison as Building Integrated Renewable Energy in Indonesia

Humaniora ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Susan Susan ◽  
Dyah Kusuma Wardhani
Keyword(s):  
Energy Source ◽  
Renewable Energy ◽  
Wind Turbine ◽  
Rural Areas ◽  
Urban Areas ◽  
Large Scale ◽  
High Elevation ◽  
Building Envelope ◽  
Small Scale ◽  
Advantages And Disadvantages

The research aimed to comprehensively review the systems related to Building Integrated Photovoltaic (BIPV) and Building Integrated Wind Turbine (BIWT). The review purposed to observe the advantages and disadvantages of the application. Designers could use that comparison for consideration of choosing the most suitable Building Integrated Renewable Energy (BIRE) concept for projects. The research presented a literature review of BIRE systems, particularly on BIPV and BIWT systems. The critical analysis focused on some parameters related to their main energy source, type, influencing factor, efficiency, and boundary. The observation about BIPV would be divided into subgroups according to photovoltaic (PV) materials, modules, efficiency, performance’s boundaries, and the general rule of thumb of its installation. The research finds that the BIPV application has advantages in terms of the building’s application scale. It can be applied from small-scale to large-scale. Furthermore, the BIPV application does not need extra space and could directly replace the conventional building envelope materials. The issues of non-uniformity and heat transfer in BIPV can be solved by installing PV in folding-concept and placed an air gap with fins inside. On the other hand, BIWT also has an abundant energy source, but the application limits to windy areas (rural areas or urban areas in high elevation). Aside from those limitations, the BIWT application also has issues of structure, noise, and aesthetical value.

scholarly journals Mixed layer mesoscales: a parameterization for OGCMs

2010 ◽  
Vol 7 (2) ◽  
pp. 873-917 ◽  
Author(s):  
V. M. Canuto ◽  
M. S. Dubovikov ◽  
M. Luneva ◽  
C. A. Clayson ◽  
A. Leboissetier
Keyword(s):  
Boundary Condition ◽  
Mixed Layer ◽  
Large Scale ◽  
Mesoscale Model ◽  
Deep Ocean ◽  
Vertical Flux ◽  
Small Scale ◽  
Strong Wind ◽  
Global Circulation Models ◽  
Order Of Magnitude

Abstract. We derive and assess a parameterization of the mixed layer vertical and horizontal mesoscale fluxes of an arbitrary tracer. The results, which are obtained by solving the mesoscale dynamic equations and contain no adjustable parameters, are expressed in terms of the large scale fields resolved by coarse resolution OGCMs (ocean global circulation models). The new model can be put in the right perspective by considering the following. Thus far, the lack of a mixed layer mesoscale model that naturally satisfies the required boundary condition (the vertical flux must vanish at the surface), was remedied by extending the stream function modeled for the adiabatic deep ocean into the mixed layer using an arbitrary tapering function chosen to enforce the required boundary condition. The present model renders the tapering schemes unnecessary for the vertical flux automatically vanishes at the ocean surface. The expressions we derive for the vertical and horizontal mesoscale fluxes are algebraic and should be used in conjunction with any of the available mesoscale models valid in the adiabatic deep ocean. We also discuss a new feature representing the effect of sub-mesoscales on mesoscales. It is shown that in the case of strong wind, one must add to the mean Eulerian velocity that enters the parameterization of the mesoscale fluxes a new term due to sub-mesoscales whose explicit form we work out. The assessment of the model results is as follows. First, previous eddy resolving results indicated a robust re-stratification effect by mesoscales; we show that the model result for the mesoscale vertical flux leads to re-stratification (its second z-derivative is negative) and that it is of the same order of magnitude but opposite sign of the vertical flux by small scale turbulence, leading to a large cancellation. Second, since mesoscales act as a source of the eddy kinetic energy, we compare the predicted surface values vs. the Topex-Poseidon. Third, we carry out an eddy resolving simulation and assess both z-profile and magnitude of the model vertical flux against the simulation data. The tests yield positive results. A more stratified mixed layer has implication for the oceanic absorption of heat and CO2, a feature whose implications on climate predictions we hope to explore in the future.

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