A review of the historical background, needs, design approaches and future challenges in groundwater level monitoring networks

Abstract

A Groundwater Level Monitoring Network (GWLMN) is the most direct and important source of data for monitoring hydrogeological variations in aquifers. Extensive research has been conducted on surface water and groundwater quality monitoring networks, but less consideration has been given to GWLMNs. Due to a lack of funding and negligence, GWLMNs are either limited or not enough for decision-making purposes. This review initially summarizes the historical developments of GWLMNs in different countries and then, the needs, design approaches, recent developments and future challenges are articulated comprehensively. The needs for GWLMNs generally include information on (1) spatiotemporal assessments (2) climate change (3) land subsidence and (4) Groundwater and Surface Water (GW-SW) interactions. This article reviews the evolution of various design approaches utilized in the past, with respect to their strengths and weaknesses such as geostatistical, entropy, Multi-Criteria Analysis (MCA), and others. The present and shifting trends in research on the design of groundwater monitoring networks are discussed. In addition, developments, challenges and opportunities in utilizing recent remote sensing products are briefly outlined. Future research scopes include the need to develop systematic and continuous GWLMNs in many developing countries, the conjunctive use of field and remotely sensed data, such as NASA's Gravity Recovery and Climate Change Experiment (GRACE) data to design GWLMNs, and the design of an integrated monitoring network to study the link between climate and groundwater level changes to better and more efficiently design GWLMNs.