Assessing The Impact of Wastewater Outfalls Pollution Points on The WQI of Qilyasan Stream in Sulaymaniyah, Kurdistan Region, Iraq, Using FL Modelling

The aim of this study is to propose an index of Fuzzy Water Quality Index (FWQI), to assess the water quality of Qilyasan Stream. The suggested fuzzy index incorporates the specified thresholds for quality indicators, which are primarily taken from Iraqi water laws. Eighteen parameters are combined in the suggested index including temperature, pH, alkalinity, total hardness, EC, TDS, TSS, turbidity, NO3, SO4, PO4, BOD, COD, DO, Pb, Cd, Zn, and Cu. MATLAB R2022b was used to develop the fuzzy model. Five stations in the stream were selected for sampling. These membership-grade classifications can be a useful tool for decision-making, helping to designate a progressive quality sub-objective to each stream segment. The obtained results from FWQI were compared with Weighted Arithmetic Water Quality Index (WAWQI). The results revealed that the FWQI at St 1, St 2, and St 5 is (9.78), and at St 3, and St 4 is (10.1), the quality ranking of all stations was very poor, and WAWQI shows that all stations were unsuitable reusing purposes. The proposed approach shows a convenient tool for monitoring of stream waters.