Design of Water Supply Systems

Forecast water demand with linear and exponential models using Qi and Qi+n at a 2.5% growth rate, illustrated by 200,000 residents at 150 litres per capita per day including leakage.

Use linear and exponential population growth models to forecast future water demand from the 2018 census to 2042, applying current population, annual growth rate, and per capita daily consumption.

Explore how the Bernoulli equation explains hydraulic losses and energy heads, including piezometric head, elevation head, pressure head, and velocity head, in water supply networks.

Explore major and minor hydraulic losses, and derive hf from the Darcy–Weisbach equation using lamda, length, diameter, and flow.

Derive and compare friction losses using Hazen–Williams, Manning, and Darcy equations to calculate hf from flow, length, and diameter, with lambda, Chw, and N as roughness factors.

Learn to calculate friction factors for water systems by lambda from Bar equation, Colebrook-White, or Moody diagram, using k, D, and Re; apply Hazen-Williams Chw and Manning N as needed.

Explore friction losses in a 400 m pvc pipe at 300 mm diameter and 130 l/s flow using Darcy–Weisbach, Hazen-Williams, and Manning equations at 10 C.

Compare friction losses using Hazen–Williams with a corrected Chw for a 300 mm PVC pipe and Manning’s equation, noting hf values of about 3.15, 3.46, and 3.4 m.

Learn about minor losses in hydraulic systems, caused by bends, elbows, valves, enlargers, and reducers. Use the head loss equation h_m = k v^2/(2g) and Q/A based form to compute.

Analyze minor losses with k values for enlargers, reducers, tank inlets and outlets, and branches with different directions, using hm = v^2/(2g) to evaluate a1, a2, and k.

Compute total hydraulic losses by friction losses from the Darcy equation using velocity, diameter, and temperature-based viscosity, then add minor losses from tank entrances and elbows to reach 9.4 m.

Compute downstream and upstream piezometric heads in a 0.4 m pipe, applying Darcy equation losses and Bernoulli energy balance to determine the required upstream pressure head.

Applying the energy balance for upflow, this example shows a 68 meter water column pump head to achieve 30 meter pressure at the city entrance using Bernoulli.

Learn to compute maximum pipe capacity for a known diameter using an iterative method with Reynolds number, lamda factor, and Darcy-Weisbach, illustrated by a 500 mm pipe reaching 0.48 m3/s.

Compute the optimal pipe diameter for a given flow by iterating velocity using the diameter–flow relation, Reynolds number, and lamda; Moody diagram offers an alternative. The example yields 500 mm.

design branched water supply networks by estimating nodal demands from population and per person consumption, compute pipe flows and nodal pressures via mass conservation, and select pipe diameters.

Calculate nodal pressures in a branched water supply network by computing hydraulic losses with Darcy's equation (or Hazen-Williams/Manning), selecting diameters, and determining velocity and Reynolds number in an Excel sheet.

Explain how pressure head equals piezometric head minus elevation head, and how nodal pressures from 2 through 9 vary with diameter changes to reduce friction loss.

Explore looped network design using hardy cross methods, balancing heads or balancing flows with Q and H corrections, to determine pipe flows and nodal pressures in a reservoir-fed system.

Apply the balancing heads method to correct Qs in a looped water supply network, iterating with hf, Reynolds number, and Delta Q using Excel calculations.

Design looped water supply networks using an Excel-based method, assigning pipe diameters and loop directions, computing Q values, and applying hf corrections to update flows.

Iterate Q and delta Q corrections in a looped network design using Excel sheets to update loop flows and shared pipe adjustments.

Use excel sheet-4 to iteratively refine the first flow assumption in a looped network, stopping when delta q is small and final pressure remains stable.