Water quality assessment stands essential for managing water resources sustainably when rivers act as fundamental water supply networks for drinking purposes and watershed systems and irrigation networks. A Water Quality Index (WQI) analysis has been conducted to determine the water quality condition of the Al Zab River flowing inside Al-Dibbis District. The analysis included measurements of pH with four other parameters which included dissolved oxygen (DO), biochemical oxygen demand (BOD) and total dissolved solids (TDS) and electrical conductivity (EC) and heavy metal assessments. GIS based Weighted Arithmetic (WA) method was used to evaluate the WQI. The weights of parameters extracted using Analytical Hierarchy Process (AHP). Interpolation method allowed researchers to visualize water quality changes in spatial format thus revealing areas with serious pollution issues. The study revealed water quality variations that steered from seasonal climate changes besides human-made pollution and farm runoffs. Results of Water quality in the river varies seasonally, based on spring and autumn 2022 Water Quality Index map comparisons. During the spring, the Water Quality Index ranged from 35.3579 to 48.375, resulting in the majority of places being labeled as having acceptable water quality since green and yellow hues predominated on the maps. The Autumn WQI map shows water quality zones labeled as good or bad, with values ranging from 32.559 to 59.394. The water quality in October is poorer than in spring, but both seasons are generally good. The shift in WQI values reflects seasonal water quality fluctuations, necessitating continual evaluation and particular pollution source reduction actions to maintain overall water health.