Date of Award

2021

Document Type

Open Access Master's Report

Degree Name

Master of Science in Civil Engineering (MS)

Administrative Home Department

Department of Civil and Environmental Engineering

Advisor 1

Brian Barkdoll

Committee Member 1

Kari Henquinet

Committee Member 2

David Watkins

Abstract

Water security has been declining rapidly in Lesotho, Africa in recent years. Lack of water has led to food insecurity, livestock deaths, and the spread of disease. Rural Basotho depend on rainfall to sustain their livelihoods; however, precipitation variability has recently increased due to climate change. For those who reside in the highlands of Lesotho, mountain springs can be a clean source of water. The tap system in the village of Ha Leronti relies on gravity to distribute water from two mountain springs to the ten village taps and nearby school campus. However, it is incapable of transporting the basic daily water amount that the Lesotho government says every citizen is entitled. The mountain springs alone cannot accommodate both the demands of the village and school campus, except during times with excessive precipitation. Furthermore, even if there was enough water to provide for the demand, the system would be unable to meet it. This report provides two scenarios in which modifications to the existing tap system are proposed. The scenarios were created with a 10-year design life taking in account the district’s population growth. To ensure the system could handle peak demands, it was assumed the school residences are at full capacity, both schools are in session, and a 24-hour event with an attendance of 600 people is occurring at the auditorium. Once the demands of the school campus and village were calculated, the tap system was modeled in EPANET, a water distribution network solver. New pipe diameters were calculated to accommodate both the peak demands of the school campus and the basic daily water amount of 30 liters per person for the village. Scenario 1 is the ideal solution with pipe diameters ranging from 16 mm to 90 mm. Scenario 2 is a more economical version of Scenario 1, with pipe diameters ranging from 25 mm to 90 mm. Since the existing system is constructed from 25 mm pipes, only the larger pipes would need replacing to modify the current system to fit Scenario 2. Although Scenario 1 is preferred when comparing water velocities and pressures during peak demand, Scenario 2 is feasible if washout valves are installed downstream of the pipes with low water velocities to prevent sediment accumulation. Additionally, valves should be installed upstream of junctions with high pressures to ensure they can be reduced to safe levels. In both scenarios, Pipe 16 should be monitored for damage due to its high water velocity during peak demand. If the pipe deteriorates, it could need replacing before the 10-year design life is complete. However, there is still the question of where to source the additional water to meet the demands for an updated system.

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