WATER QUALITY PROFILE OF RUVU RIVER IN TANZANIA

Abstract

Increase in population and industrialization has strongly impacted the rivers and lakes all over the world. Meanwhile, Tanzania rivers water quality faces the same challenges. The Government of Tanzania is trying to overcome the problems by analysing water quality data from its rivers. However, a lot of data collected is required to be converted into a single number (index) understandable by decision and policy-makers. Therefore, the assessment by using different water quality indices like National Sanitation Foundation for Water Quality Index (NSFWQI), River Pollution Index (RPI) and Overall Index of Pollution (OIP) are very useful. The present thesis uses water quality indices and land use maps to assess and investigates the water quality profile of Ruvu river in Tanzania. Water quality samples collected from 14 sampling locations from year 2014-2017 were used to assess the quality of the river for Temperature, pH, Turbidity, Color, TDS, Total phosphates, Nitrates, Hardness, Cl2, DO, BOD5, TSS, NH3-N, SO4, Faecal coliform and Total Coliform. All these parameters were converted into a single index of water quality; NSFWQI, RPI and OIP. The three water quality indices used in evaluation categorized the water quality of Ruvu river as medium, polluted and moderately polluted as per NSFWQI, OIP and RPI respectively. The index values were; 53.2, 4.69 and 4.78 for NSFWQI, OIP and RPI respectively. The study revealed the poor water quality in Morogoro urban area. At this location the average score declined from 59.9 to 46.325, from 3.397 to 7.25 and from 3.682 to 5.957 for NSFWQI, RIP and OIP respectively. This decline has been contributed by the increase in land use intensity. These sources of pollutions include discharges from Morogoro town and Industrial wastewater. Industrial areas had a lowest index scores of 41.1 as per NSFWQI and 8.17 and 8.37 as per RPI and OIP respectively. These results indicate that river water quality at this location is not suitable for beneficial use like drinking and recreation The impact of land use on water quality done by using GIS and Remote Sensing (RS) techniques and ERDAS imagine. These assessment tools revealed that urban land use and agricultural land uses were highly contributing to pollution of this river. BOD, DO and FC was found to be the most stressing parameters. The maximum average results for BOD5 was 129.73mg/L at sampling location S6 and the minimum was 1.86mg/L at sampling location S3. Average Dissolved Oxygen (DO) levels assessed were between 1.49 mg/L iv to 8.1 mg/L at sampling locations S7 and S2 respectively. All the locations except S6 had high value of FC. The maximum value was 1143 CFU/100mL at sampling location S12. These high values were due to improper sanitation systems, discharge of untreated and partially treated wastewaters from industries and domestic areas into the river. Therefore, watershed management and pre-treatment of wastewaters from Industries and domestic areas were recommended. This thesis will be useful to policy-makers and managers for river protection and monitoring.