Modified Index-Overlay Method to Assess Spatial–Temporal Variations of Groundwater Vulnerability and Groundwater Contamination Risk in Areas with Variable Activities of Agriculture Developments

Abstract

The groundwater vulnerability (GV) assessment for contamination is an effective technique for the planning, policy, and decision-making, as well as for sustainable groundwater resource protection and management. The GV depends strongly on local hydrogeological settings and land-use conditions that may vary in response to the activities of agricultural development. In this study, a modified DRASTIC model, which employs an additional factor of land use coupled with the analytic hierarchy process (AHP) theory, was used to quantify the spatial and temporal variation of GV and groundwater contamination risk in the Pingtung groundwater basin. The results show that the GV slightly decreased due to the decrease in agricultural areas under the change of land use over two decades (1995–2017). The yearly changes or a shorter period of observations incorporated with the accurate land-use map in DRASTIC parameters could improve GV maps to obtain a better representation of site-specific conditions. Meanwhile, the maps of yearly contamination risk indicated that the counties of Jiuru and Ligang are at high risk of nitrate pollution since 2016. In other agriculture-dominated regions such as Yanpu, Changzhi, and Gaoshu in the Pingtung groundwater basin, the climate conditions influence less the temporal variations of groundwater contamination risk. The results of this study are expected to support policy-makers to adopt the strategies of sustainable development for groundwater resources in local areas.

Numerical Modeling of Surface Water and Groundwater Interactions Induced by Complex Fluvial Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan

“…In the downstream fan area, the flow directions of the Kaoping, Tungkang, and Linpien Rivers are generally in a north-south direction to the Taiwan Strait. The downstream fan area is also the region that had faced severe problems in groundwater over-pumping and groundwater contamination [20].…”

“…The flow directions of the Kaoping, Tungkang, and Linpien Rivers are generally in a north-south direction to the Taiwan Strait in the downstream fan area. With the intensive developments of aquaculture and agriculture industries, the downstream fan area had faced severe problems of groundwater over-pumping and groundwater contamination [20]. An artificial recharge project was proposed recently to mitigate the impact of over-pumping near the coastal area.…”

Emergy evaluation of human health losses for water environmental pollution

“…Custodio et al (2020), Genthe et al (2018), andNeogi et al (2018) evaluated the potential hazard risk of metals to human health in untreated coalfield mines and polluted river catchment water. Some scholars combined water environmental health risk assessment with mathematical analysis methods to make the results more authentic (Yang et al, 2011;Wongsasuluk et al, 2014;Sener et al, 2017;Ogbiye et al, 2018;Xu et al, 2018;Zhang et al, 2018;Vu et al, 2019). Although the mathematical methods were different, they all reflected the impact of different pollutants on human health and can judge what should be prioritized according to the risk, which plays a decisive role in the order of pollutant treatment.…”

Mapping Interflow Potential and the Validation of Index-Overlay Weightings by Using Coupled Surface Water and Groundwater Flow Model

“…The concept of index-overlay models to create different types of potential or vulnerability maps has been widely used for many implementations. Such potential or vulnerability maps are critical references to decision-making for land-use planning, groundwater management, monitoring, and remediation [8][9][10][11]. Previous investigations have shown that the advantages of the index-overlay models are their ease of use, minimal data demand, and precise definition of parameters for site-specific problems.…”

“…The study aims to develop a workflow that uses the physical-based numerical model to validate the indexoverlay model and quantify the interflow in the downstream area along the Kaoping River. The study uses the analytic hierarchy process (AHP) to modify the weightings and ratings in the index-overlay model [10,11]. The quantification of the interflow potential relies on the integrated GSFLOW model to account for groundwater and surface water interactions.…”