**6. Sediment measurement**

Water samples for suspended sediment analysis were collected at the middle and both sides of the river banks using USDH48 sampler. At each point, a depth

*A Critical Analysis of the Water Quality Impacts on Water Resources in the Athi River… DOI: http://dx.doi.org/10.5772/intechopen.99667*

integrated (equal transit rate) water-sediment mixture samples were taken. The samples were stored in a 3 liters sample bottle and taken to the laboratory for suspended sediment concentration determination according to American Public Health Association [15–17] techniques and methods. Sediment discharge (mg l�<sup>1</sup> ) at the cross-section was computed by multiplying suspended sediment concentration (mg l�<sup>1</sup> ) with the river discharge m<sup>3</sup> s �1 ), and the correction factor of 0.0864 [18]. The total sediment yield in tonnes for the days (n) sampled was computed according to Jorgensen and Vollenweider, [19] and Sharma [18] as:

$$\mathbf{S} = \mathbf{0}.0864 \sum\_{i=1}^{n} \mathbf{C}\_{i} \,\mathrm{Q}\_{\mathrm{r}} \tag{1}$$

Where:

S is the sediment yield in t day�<sup>1</sup> , Ci is the measured suspended sediment concentration in mg l�<sup>1</sup> and Qr is the cross sectional river flow in m<sup>3</sup> s �1 . This procedure was used to calculate the sediment yields and mass loadings in the sub-basins investigated and as means for sediment loading downstream the river profile.
