**7. Results and discussions**

This sections details the results of the field data observations and the laboratory analysis on the water sampled collected. It was intended to give an overall picture of the water quality status against the available water resources, human activities and land use changes in the basin.

The results in **Table 6** and **Figure 4** clearly indicate a close link between river flow characteristics and rainfall patterns within the basin and the entire catchment area. The high flows were noted to occur in the months of April–May and replicated in the months of October to December corresponding quite well to the rainfall patterns in the basin.

From **Table 7**, it can be observed that downstream the river profiles, the amount of total sediment load increases. The exception only occurs at Njiru 2 sampling point, which is the outlet of all the three streams investigated where the value of TSS was calculated to the value of 5166.23 t year�<sup>1</sup> . This was attributed to widening of the river channel, sedimentation and dilution effects, which may have resulted to the deposition of the sediment loads and combined stream discharge increase from the three streams at this point.


#### **Table 6.**

*Measured mean monthly river discharge sub-basin*�*<sup>1</sup> .*

#### **Figure 4.**

*Mean monthly river discharge per sub-basin in the upper sub-basins (m3 /s). Source: filed data (1998–2017).*


#### **Table 7.**

*Mass loadings of total suspended sediments (TSS) in the Nairobi river sub-basins in tonnes per year.*
