Application of Monitoring Network Design and Feedback Information for Adaptive Management of Coastal Groundwater Resources

Abstract

Optimal strategies for the management of coastal groundwater resources can be derived using coupled simulation-optimization based management models. However, the management strategy actually implemented on the field sometimes deviates from the recommended optimal strategy, resulting in field-level deviations. Monitoring these field-level deviations during actual implementation of the recommended optimal management strategy and sequentially updating the management model using the feedback information is an important step towards efficient adaptive management of coastal groundwater resources. In this study, a three-phase adaptive management framework for a coastal aquifer subjected to saltwater intrusion is applied and evaluated for a regional-scale coastal aquifer study area. The methodology adopted includes three sequential components. First, an optimal management strategy (consisting of groundwater extraction from production and barrier wells) is derived and implemented for optimal management of the aquifer. The implemented management strategy is obtained by solving a homogenous ensemble-based coupled simulation-optimization model. Second, a regional-scale optimal monitoring network is designed for the aquifer system considering possible user noncompliance of a recommended management strategy, and uncertainties in estimating aquifer parameters. A new monitoring network design objective function is formulated to ensure that candidate monitoring wells are placed in high risk (highly contaminated) locations. In addition, a new methodology is utilized to select candidate monitoring wells in areas representative of the entire model domain. Finally, feedback information in the form of measured concentrations obtained from the designed optimal monitoring wells is used to sequentially modify pumping strategies for future time periods in the management horizon. The developed adaptive management framework is evaluated by applying it to the Bonriki aquifer system located in Kiribati, which is a small developing island country in the South Pacific region. Overall, the results from this study suggest that the implemented adaptive management strategy has the potential to address important practical implementation issues arising due to noncompliance of an optimal management strategy and uncertain aquifer parameters.

Groundwater Level Monitoring Networks Design with Machine Learning Methods

“…Even if there are no budgetary limits for monitoring projects, OBWs should be installed at the scattered points determined by the hydrogeological properties of the region to avoid redundancy in collected data. A key feature of optimal GLMN design is to locate a permissible number of OBWs at locations suitable for collecting useful, non-redundant, and reliable groundwater head data 14,27 .…”

Application of the Kilimanjaro Concept in Reversing Seawater Intrusion and Securing Water Supply in Zanzibar, Tanzania

“…This may include raising public awareness and the use of legal, economic, and financial instruments, such as incentives/disincentives, to promote RWH systems. (5) A need to draw lessons from other similar islands elsewhere (e.g., [15]), to identify relevant concepts that can complement KC. Such lessons may include: (i) the determination of optimal groundwater abstraction to prevent seawater intrusion, and (ii) the use of GIS spatial tools for identifying the optimal location of runoff infiltration points and RWH systems.…”

“…A number of scientific publications, dissertations, and technical documents have emerged to critically evaluate the sustainability of water management on small islands [1][2][3]5,8,[13][14][15][16][17]. However, the application of existing and well-established sustainability assessment largely requires a complex set of tools.…”

A review of groundwater sustainability crisis in the Pacific Island countries: Challenges and solutions

“…From all the models given, SEAWAT can test all four problems (namely; Elder, Henry/Hilleke, HYDROCOIN salt dome and rotating fluids problem), as it uses combined MODFLOW and MT3D models. Few PICs used FEMWATER for modeling and groundwater monitoring (Lal and Datta, 2019a;2019c), however, there is a vast opportunity to explore and use other 3D models in PICs for managing SWI in coastal aquifers. A sample 3D model developed from FEMWATER is shown in Fig.…”

“…Coupling the numerical simulation model with optimization models requires large amount of computational time, hence, it is computationally demanding (Lal and Datta, 2019a). Therefore, to minimize this time-related issue, S-O is coupled with data-driven mathematical models, known as surrogate models.…”