scholarly journals Surrogate-based pumping optimization of coastal aquifers under limited computational budgets

2017 ◽  
Vol 20 (1) ◽  
pp. 164-176 ◽  
Author(s):  
Vasileios Christelis ◽  
Rommel G. Regis ◽  
Aristotelis Mantoglou
Keyword(s):  
Coastal Aquifers ◽  
Surrogate Model ◽  
Coastal Aquifer ◽  
Surrogate Models ◽  
Salt Transport ◽  
Direct Optimization ◽  
Aquifer Management ◽  
Pumping Optimization ◽  
Local Improvement ◽  
Coastal Aquifer Management

Abstract The computationally expensive variable density and salt transport numerical models hinder the implementation of simulation-optimization routines for coastal aquifer management. To reduce the computational cost, surrogate models have been utilized in pumping optimization of coastal aquifers. However, it has not been previously addressed whether surrogate modelling is effective given a limited number of numerical simulations with the seawater intrusion model. To that end, two surrogate-based optimization (SBO) frameworks are employed and compared against the direct optimization approach, under restricted computational budgets. The first, a surrogate-assisted algorithm, employs a strategy which aims at a fast local improvement of the surrogate model around optimal values. The other, balances global and local improvement of the surrogate model and is applied for the first time in coastal aquifer management. The performance of the algorithms is investigated for optimization problems of moderate and large dimensionalities. The statistical analysis indicates that for the specified computational budgets, the sample means of the SBO methods are statistically significantly better than those of the direct optimization. Additionally, the selection of cubic radial basis functions as surrogate models, enables the construction of very fast approximations for problems with up to 40 decision variables and 40 constraint functions.

Adaptive surrogate model based multiobjective optimization for coastal aquifer management

2018 ◽  
Vol 561 ◽  
pp. 98-111 ◽  
Author(s):  
Jian Song ◽  
Yun Yang ◽  
Jianfeng Wu ◽  
Jichun Wu ◽  
Xiaomin Sun ◽  
...  
Keyword(s):  
Multiobjective Optimization ◽  
Surrogate Model ◽  
Coastal Aquifer ◽  
Aquifer Management ◽  
Model Based ◽  
Coastal Aquifer Management

State of knowledge of coastal aquifer management in South America

2009 ◽  
Vol 18 (1) ◽  
pp. 261-267 ◽  
Author(s):  
Emilia Bocanegra ◽  
Gerson Cardoso Da Silva ◽  
Emilio Custodio ◽  
Marisol Manzano ◽  
Suzana Montenegro
Keyword(s):  
South America ◽  
Coastal Aquifer ◽  
Aquifer Management ◽  
Coastal Aquifer Management

Managing coastal aquifers in climate and socio-economic change: An indicator-based multi-criteria decision system approach

2021 ◽  
Author(s):  
Tobias Langmann ◽  
Hans Matthias Schöniger ◽  
Anke Schneider ◽  
Michael Sander
Keyword(s):  
Water Management ◽  
Groundwater Recharge ◽  
Coastal Aquifer ◽  
Methodological Approach ◽  
Chloride Concentration ◽  
Northwestern Part ◽  
Groundwater Abstraction ◽  
Coastal Regions ◽  
Aquifer Management ◽  
Coastal Aquifer Management

<p>Worldwide, climate change as well as socio-economic changes are increasing pressure on water supply in coastal regions and lead to major changes in groundwater recharge as well as the regional water balance as parts of the hydrosystem. These changes are threatening water security and, thereby, impede the fulfillment of the SDG 6 targets, esp. SDG targets 6.2., 6.4. and 6.6 of the UN 2030 Agenda for Sustainable Development. Thus, a modern water management demands innovative and profound methods and tools that comprehensively cover these complex changes. To address this challenge,  in the BMBF project "go-CAM" (Implementing strategic development goals in Coastal Aquifer Management) we took the methodological approach of developing new groundwater status indicators (e.g. chloride concentration in groundwater, position of saltwater/freshwater interface, freshwater volume) and corresponding target functions implemented in a new online-based management and evaluation tool called "CAM" (Coastal Aquifer Management). Both the physically based indicators as well as the target functions tackle economic as well as ecological issues. The groundwater status indicators are directly derived from the results of high-resolution, process-based (hydrological and hydrogeological) modeling of coastal hydrosystems. Due to their physical nature, the indicators are only applicable with appropriately designed climate and socio-economic scenarios for coastal water management if they are generated with models that also capture the system-relevant processes: Groundwater recharge, groundwater abstraction, discharge dynamics through drainage systems, sea level rise and groundwater discharge to the sea and saltwater intrusion.</p><p>The CAM platform is a tool that provides a way to make the results of the complex and extensive numerical modeling usable for a wider community and thus allow for a more efficient result exploitation. Building on the indicators and the selection of target functions and weighting factors the CAM tool uses Multi-Criteria Decision Analysis techniques (MCDA) to strengthen transparency and objectivity in decision-making processes and encourage communication between decision-makers in the water sector of coastal regions. In this way, the application of the CAM tool contributes to the establishment of an integrated water resources management and to derive and discuss future water management strategies as well as concrete measures.</p><p>Our methodological approach as well as the results are presented applied to a regional coastal groundwater study area in the northwestern part of Germany, the Sandelermöns region, which covers an area of about 1,000 km².</p>

An over-used ocean island coastal aquifer, Tenerife (Spain) – tracing inputs for improved resource management

2021 ◽  
Author(s):  
Beverley Coldwell ◽  
María Cordero ◽  
Nemesio M. Pérez ◽  
Cecilia Amonte ◽  
María Asensio-Ramos ◽  
...  
Keyword(s):  
Coastal Aquifers ◽  
Coastal Aquifer ◽  
Isotopic Signature ◽  
Careful Consideration ◽  
Human Consumption ◽  
Aquifer Management ◽  
Volcanic Degassing ◽  
Ocean Island ◽  
Physical Fractionation ◽  
Intensive Exploitation

<p>The island of Tenerife (Canary Islands, Spain) relies on basalt-hosted aquifers to provide 90% of water for agriculture and human consumption. The island is characterised by a low-permeability core, overlain by permeable materials which are cut by impermeable dykes. The effect is a compartmentalised aquifer, which is exploited sequentially as each “pocket” of water is exhausted. The island is home to ~1 million people (with an additional 5 million visiting tourists per year), and although rain/snowfall can be heavy in winter storms, it is unpredictable from year to year, and rapid surface water run off occurs due to the steep geography. While net recharge into the upper zones of the Tenerife aquifer have been quantified (around 2 months between intense rainfall and water table fluctuations), water must then follow a tortuous path to recharge lower zones and aquifer “pockets”. Water recharge to the coastal aquifers is also interrupted and extracted during its journey. Human and agricultural pressure is highest near the coast, and has led to intensive exploitation of existing wells and horizontal galleries. In response to the intensification of water extraction and slow recharge rates, marine intrusions into the coastal aquifers of Tenerife have occurred, traditionally recorded by rising chloride levels and resulting in well/gallery closures as well as increased pressure on other extraction sites. However, in a volcanic ocean island setting, natural processes can mimic the appearance of salinisation in a coastal aquifer. Management of aquifer resources require careful consideration of seawater incursions vs. volcanic degassing contributions vs. ocean island rainfall. Full hydrochemical breakdown of 43 coastal aquifer extraction sites reveal seawater intrusion is affecting the western coastal aquifer, with the agreement of multiple parameters. The strontium isotopic signature of well samples was also measured, because it is not subject to the biological or physical fractionation processes of other isotopic systems, thereby forming distinct reservoirs for groundwater (<sup>87</sup>Sr/<sup>86</sup>Sr of host rock), and seawater. <sup>87</sup>Sr/<sup>86</sup>Sr signatures suggest the northern coastal aquifers are also subject to seawater incursions. This parameter may be a more sensitive indicator than chlorides and conductivity markers for salinisation, especially in an ocean island environment where coastal aquifers are subject to intensive land use practices, seawater spray, and affected by diffuse volcanic degassing.</p>

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