Groundwater is the major source of water by inhabitants of Zanzibar communities. In this study, twenty-one water sources from three districts of Urban West Region of Unguja Island were studied in May to July 2019. Insitu measurements for temperature, pH, Dissolved Oxygen (DO) and Electrical Conductivity (EC) in groundwater sources were taken by Professional Digital Sampling System (ProDSS). Data analysis revealed that parameters undergo dynamics (spatial and temporal). During the wet period, the ranges of pH, DO and EC were: (4.98 – 7.50), (3.51 – 7.51 mg/L), and (156.2 – 2047.6 μS/cm) respectively. During dry period the ranges were: (5.14 – 7.41), (2.71 – 7.20 mg/L), and (223.1 – 1936.8 μS/cm) respectively. temperature and EC had positive relationship. Nevertheless, small change in groundwater temperature led a remarkable change in DO. Strong correlation existed between EC and salinity (R2 = 0.999). Also, a strong correlation existed between EC (dry period) and EC (wet period) with R2 = 0.896. During wet period, the mean values recorded for all studied parameters were: 27.87° C, 6.92, 782.85 μS/cm, and 5.44 mg/L for temperature, pH, EC, and DO, respectively. While, during dry period the values were: 27.83° C, 6.97, 743.80 μS/cm, and 5.12 mg/L for temperature, pH, EC, and DO, respectively. Remarkably, during wet period, pH was 4.98 (27.17° C - 28.88° C), while in dry period pH was 5.14 (26.74 - 28.83° C). The present study revealed that even slight change in temperature could cause a remarkable effect on other groundwater parameters specifically dissolved oxygen. If water DO is under pressure it might affect other water quality parameter significantly.

DO, Unguja, groundwater, temperature, pH.

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VOLUME 02 ISSUE 02 NOVEMBER 2019