Assessment of groundwater quality in a semiarid region of Northwestern Algeria using water quality index (WQI)

Abstract The present paper aims at determining the status and trends of groundwater quality of 12 aquifers situated in Northwestern Algeria, especially under conditions of last drought that has affected the region using water quality index (WQI) over a period of 4 years. Multivariate statistical methods have been used jointly with conventional graphical methods, to classify the samples according to plausible levels of groundwater evolution. The computed WQI values range from 67 to 588 and therefore can be categorized into four categories: “good water” to “water unsuitable for drinking.” Overall, 36% of groundwater sites sampled in the study area had good water quality, while 53% were poor. Unfortunately, 6% of the samples indicate “very poor water quality” and 5% represent water “unsuitable for drinking purposes.” Results show that the majority of groundwater of Tafna basin fell under good water quality. Groundwater of poor and medium quality characterizes the majority of the studied aquifers of Macta basin. The result showed that the water quality at monitoring station “Ain Skhouna” fell under good water quality (Chott Chergui aquifer). Results also show that groundwater of Coastal Oranais basin showed poor water quality, very poor at some monitoring stations of Mléta Plain aquifer. It has been demonstrated that the water of some aquifers has degraded under water scarcity conditions and will continue to degrade given the ongoing and projected development in the study area. The analysis reveals that the water of some aquifers needs treatment before it is used for human consumption. The influence of salt water on the some freshwater aquifers in the study area needs special attention in terms of monitoring and for sustainable management

Status and trends of water quality in the Tafna catchment: a comparative study using water quality indices

Water quality indices (WQIs) are necessary for resolving lengthy, multi-parameter, water analysis reports into single digit scores; different WQIs have been developed worldwide which are greatly differing in terms of mathematical structures, the numbers and types of variables included, etc. The aim of this paper is to evaluate trends of water quality in Tafna basin with a comparison of 10 WQIs perceived as the most important indices for water quality assessment. The results show that there is an appreciable difference between indices values for the same water sample. The results also show that water quality categorization for sampling stations in the Canadian Council of Ministers of the Environment WQI (CCMEWQI) and British Columbia WQI (BCWQI) was found to be ‘marginal’ for all sampling stations, except Hammam Boughrara reservoir and Mouillah wadi where it was found to be ‘poor’. For the Aquatic Toxicity Index, it was found to be ‘totally unsuitable for normal fish life’ for all stations and ‘suitable only for hardy fish species' for Mouillah wadi and Boughrara reservoir. The results show that this transboundary catchment always needs strategies for more effective pollution control management. Future use of WQIs in this way should prove a valuable tool for environmental planning decision-makers in tracking water quality change