Assessment of river health using physico-chemical parameters and macroinvertebrates: A case study of Mungonya River in Kigoma, Tanzania.

Abstract

Mungonya River is subjected to anthropogenic activities impacts from upstream to downstream, because of rapid population increases in the basin. The main pollution sources include irrigation, washing, bathing, brick making, sand mining and grazing. This study was conducted from December 2015 to March 2016 at six selected sampling points from the upper reaches of the river. The main aim was to assess water quality for river health using selected physico-chemical, biological parameters and macroinvertebrates using the TARISS scoring system in relation to land use and land cover changes. The National Sanitation Foundation Water Quality Index (NSFWQI) and TARISS scoring system methods were used to assess the water quality of the river. Eleven water quality parameters were analyzed and only two were tested in-situ, namely temperature and DO, and four were tested on-site namely, pH, EC, TDS and turbidity, while five were tested in the laboratory (BOD5, PO4-3, NO3-, TSS and FC). The physico-chemical and biological results were within acceptable standards, except for turbidity (202.5-413.2 NTU) and FC (270.0-616.5 cfu/100ml). It was concluded that the significant increases in irrigation and settlements Land Use Land Cover from 2013 to 2016 were correlated to changes in water quality parameters. The current water quality status of the river was within acceptable standards, except for turbidity and faecal coliforms, with the NSFWQI confirming that the water quality status was medium or average. The TARISS rapid bioassessment method also showed that the river health was fair and there was a weak significant correlation between NSFWQI and TARISS, suggesting complimentarity of the two indices. It was recommended that there should be means of control and mitigation of further pollution of the river and that further studies should be carried out along the river, covering different seasons, in order to establish the status of water quality of the entire river and to establish proper means of managing the river as proposed in the Integrated Water Resources Management and Development Plan (2015) for LTBWB. It is also recommended that the LTBWB should develop a water quality database in order to facilitate improved water quality monitoring.