The present study proposes a new approach for indexing heavy metals ions to examine groundwater quality in North Kurdufan Province, Sudan. The new approach is developed based on the most frequently used methods for indexing heavy metals pollution in water. It is created in order to avoid the weaknesses of the current indexing systems. As per the new indexing approach, heavy metal contamination in water samples is evaluated by two types of indices: the negative evaluation index (NEI) and positive evaluation index (PEI). The water worthiness is assessed based on a pair of indices, NEI and PEI. Water quality increases with the decrease of PEI and NEI values. NEI indicates the contribution of heavy metals with a concentration not exceeding the highest desirable limit ( I i ) in the water sample, while vice versa regarding the PEI. If all heavy metals concentrations in the water sample do not exceed I i , the sum of NEI should be less than zero, but not less than −100, implying that the sum of PEI will be zero. When all heavy metals concentration exceeds I i , the sum of NEI should be equal to zero, and PEI will be greater than zero. The results of the newly proposed approach have been discussed and compared with the existing indexing methods as regards to the best and worst samples. The spatial distribution of NEI and PEI are in complete agreement with the metals spatial distribution. The comparison result showed that the new index is robust, with fair calculations, and gives the best classification of groundwater quality.

Deterioration of groundwater quality due to drastic human interventions is rising at an alarming rate particularly in lower- and middle-income countries. Yet, limited research effort has been devoted to monitoring and ascertaining groundwater quality. The present study develops a comprehensive irrigation water quality index (IWQI) for rating water quality of shallow and deep aquifers in North Kurdufan province, Sudan. The new approach is developed to overcome the deficiencies of the existing irrigation indices and coming up with a unified decision for classifying water quality for irrigation purposes. Because of these indices like permeability index (PI), sodium absorption ratio (SAR), etc., depending on specific elements, entirely subjective, as well as the great variations in their results, particularly when classifying water quality. Thus, IWQI is created based on eight indices that are generally used to evaluate irrigation water quality, plus three physicochemical parameters have been proven an impact on water quality. The analytic hierarchy process (AHP) is applied to minimize the subjectivity at assign parameter weights under multiple criteria decision analysis tools (MCDA). The spatial distribution of IWQI agrees with the spatial distribution of the most parameters. The results of our approach reveal that the majority of samples are suitable for irrigation uses for both aquifers except few wells in the confined aquifer. Also, noted that there are very variations in the irrigation indices results for classifying water quality. The comparison result showed that the new index robust, fair calculations and has best classifying of water quality.

Groundwater is a significant and crucial component for all development activities of any life support system. In this study, the hydrochemical analysis and water quality index method (WQI) were used to assess groundwater quality for drinking purposes. Twelve groundwater samples were collected and analyzed into fourteen parameters which were considered as important indicators for assessing groundwater quality. A comparative study of these parameters with that of the Chinese Groundwater Standard (GB/T14848-2017) was conducted. It can be depicted from the results that groundwater quality is categorized as very hard, fresh water and slightly alkaline in nature. The major sequence of dominant cations and anions in groundwater are Ca2+ > Mg2+ > Na+ > K+ and HCO-3 > SO2-4 > Cl- respectively. From the total 12 samples analyzed, the parameters of TH, NH+4, Fe and Mn of samples exceeded the limits set by (GB/T14848-2017) standard. Piper diagram illustrated that groundwater samples of the studied area are mostly of Ca-Mg-HCO3-SO4 type. WQI showed all samples fall between excellent to good category of water and suitable for drinking purposes. The quality of groundwater is mainly affected from anthropogenic activities and natural influence. The proposed method is reliable and effcient for groundwater pollution assessment and can be used in decision-making.