Water Infrastructure and Resources
Management
Assessment 1 Answers
Year 2025
0027 63 985 5033
,
,
, PREVIEW
QUESTION 1
1.1 The role of hydraulic radius in open channel flow
a. It serves as a measure of the effective channel size that carries flow with minimum
friction.
b. It is a key variable in empirical equations (like Manning’s and Chezy’s) that are used
to predict flow velocity and discharge.
1.2 The Hazen–Williams equation provides a straightforward method to estimate friction
losses in water distribution piping systems by relating the head loss to flow rate Q, pipe
length L, internal diameter d, and a roughness coefficient.
The key parameters that Influence the calculation are as follows;
a. Flow Rate (Q): Higher flow rates increase the head loss due to greater turbulence and
friction within the pipe.
b. Pipe Diameter (D): Larger diameters reduce friction losses significantly, as resistance
to flow is lower in wider pipes.
c. Roughness Coefficient (C): Depends on the pipe material. Smoother materials like
PVC have higher C-values (e.g., 140), resulting in lower head losses. Older or rougher
pipes (e.g., cast iron) have lower C-values.
Management
Assessment 1 Answers
Year 2025
0027 63 985 5033
,
,
, PREVIEW
QUESTION 1
1.1 The role of hydraulic radius in open channel flow
a. It serves as a measure of the effective channel size that carries flow with minimum
friction.
b. It is a key variable in empirical equations (like Manning’s and Chezy’s) that are used
to predict flow velocity and discharge.
1.2 The Hazen–Williams equation provides a straightforward method to estimate friction
losses in water distribution piping systems by relating the head loss to flow rate Q, pipe
length L, internal diameter d, and a roughness coefficient.
The key parameters that Influence the calculation are as follows;
a. Flow Rate (Q): Higher flow rates increase the head loss due to greater turbulence and
friction within the pipe.
b. Pipe Diameter (D): Larger diameters reduce friction losses significantly, as resistance
to flow is lower in wider pipes.
c. Roughness Coefficient (C): Depends on the pipe material. Smoother materials like
PVC have higher C-values (e.g., 140), resulting in lower head losses. Older or rougher
pipes (e.g., cast iron) have lower C-values.
