Modification of the Canadian Water Quality Index : Case Study Assessment of Groundwater Quality in Mekong Delta, Vietnam

Abstract

In water resources management, there exists a significant disconnect between interests and goal stettings of stakeholders, policy-makers, and decision-makers. Researches have shown that water quality indices have become useful tools for water quality assessment and management. This study aims to determine the groundwater quality status of the Vietnamese Mekong Delta with a suitable water quality index regarding the European Water Framework Directive and the Vietnamese National Regulation. Building on existing works, the needed Water Quality Index must have the following fundamental properties: independence of the particular set of quality parameters and sensitivity to individual bad parameters. Based on a review of the literature on water management and theories of water quality indices, the Canadian Water Quality Index (CCME WQI) is chosen as the basis of argumentation, because it has the first of the above properties. Analysis of the implicit statistical data, especially the inclusion of the number of quality parameters with one failed test (Scope) as well as the number of failed tests (Frequency) in the definition of CCME WQI, demonstrated that CCME WQI is also a quality index for the quality of water control: a high number of failed tests or a high number of quality parameters with failed tests indicate that water control is not sufficient. Nevertheless, there are situations where water must be regarded as good, while CCME WQI qualifies it as bad by its statistical factors. Therefore, this research presents a modification of CCME WQI, called Modified Canadian Water Quality Index (MCWQI), which widely has the same behavior as CCME WQI but is better in situations where the statistical factors furnish the wrong picture of the situation. The useability of MCWQI is verified by an application to the case study “Groundwater Quality in Mekong Delta”. The results concerning the Vietnamese groundwater regulation and the European drinking water regulation are compared. MCWQI is defined as a new tool to help not only water stakeholders and policy-makers but also communities to target scant resources more effectively and sustainably.