Water Supply Management Quiz

Bong County Technical College Information

• Location: Gbarnga City, Bong County
• Department: Engineering
• Course Title: Water supply and environmental Engineering
• Lecturer: Eng. Cooper B. Saysay
• Qualifications: BSc, MSc in Civil Engineering
• Email: [email protected]
• Phone numbers: +231-770-299-886/+231-880-538-294

Hydrology - Sources of Water

• Rain water
• Surface water
• Ground water
• Water from reclamation

Water Supply Systems

• Primary objective: To take water from the best available source and subject it to processing to ensure good physical quality; free from unpleasant taste, odour and containing nothing detrimental to health. This involves additions to, subtractions from, or chemical changes to raw water.
• Units: Collection works, Transmission works, Purification works, and Distribution works (diagrammatic representation in Fig. 1.4)

The Water Cycle

• Hydrology: Science dealing with the occurrence, distribution and movement of water on Earth (atmosphere and below the surface)
• Water exists: as vapour in the atmosphere, water on the surface, snow or ice on the surface, and ground water filling the voids within a geologic stratum.
• Water cycle processes: Evaporation, Transpiration, Precipitation, Run-off

Computation of Average Rainfall

• Methods for calculating average precipitation from multiple rain gauge stations in a basin: Arithmetic average, Thiessen polygon, and Isohyetal methods
• Arithmetic average method: Simplest method of calculating average rainfall; calculate by summing all recorded rainfall values at various stations and dividing by the total number of recording stations
• Thiessen polygon method: More common method of weighting rain gauge observations which is more accurate than the arithmetic average method. Steps:
• Connect adjacent rain gauge stations with straight lines.
• Construct bisectors of these lines
• The polygon formed by these perpendicular bisectors will be closer to the station than to any other
• Multiply each area by the rain gauge value
• Find the total area
• Compute the average precipitation following formula
• Isohyetal method: More accurate. Contour lines representing equal amounts of rainfall within an area are drawn through relevant records. Then calculate the area encompassed by each contour line to estimate average rainfall.

Infiltration

• Definition: Movement of water through the soil surface to into the soil.
• Infiltration capacity: Maximum rate of water entry into the soil.
• Infiltration rate: Rate at which water enters the soil.
• Infiltration indices: Two types: Average infiltration rate (W-index) & index (k) calculated by using W = (P-R)/t
• Calculation for an index of average infiltration rate, W: where P = total rainfall in cm, R = total run-off in cm, and t = duration of run-off in hours.

Chapter 1 - Introduction

• Purpose and scope: Introduction to selecting water sources and determining water requirements.
• Applicability: Guidelines applicable to the selection of water sources and planning and designing water supply systems.
• References: Many professional references available.
• Definitions:
• Water works: All construction related to the collection, transportation, pumping, treatment, storage, and distribution of water
• Supply works: Dams, impounding reservoirs, intake structures, pumping stations, wells.
• Supply line: Pipeline extending from the supply source to the treatment works or distribution system.
• Treatment works: All basins, filters, buildings and equipment
• Distribution system: A network of pipes used to distribute water for domestic, industrial and fire fighting purposes
• Feeder mains: The main distribution pipes
• Distribution mains: Pipelines which form part of the distribution system
• Service line: Pipeline extending to the building served by the distribution system.
• Effective population: Number of residents + an allowance for nonresident personnel
• Capacity factor: Multiplier applied to effective population to account for population increase, variation in water demand and uncertainties about actual water requirements
• Required daily demand: Total daily water requirement, calculated by multiplying design population by appropriate per capita values
• Peak domestic demand: The major factor considered for system design; maximum day demand (2.5 the daily required demand) or fire flow plus 50% of daily demand
• Fire flow: The required amount of water per minute at a given pressure to battle fire at a specific point.
• Fire demand: Required flow rate to fight fires
• Rated Capacity: Maximum amount of water that can be passed through the system under given conditions.

Chapter 2 - Water Requirements

• Domestic requirements: Illustrative per-capita water allowances provided in Table 2-1.
• Fire Flow requirements: The system must be capable of fulfilling the specified fire flow and any other demands that cannot be reduced during a fire period at the required residual pressure and for the required duration.
• Irrigation: Allowances include water for limited watering or planted/grassed areas but not major lawn or other irrigation uses.

Chapter 3 - Capacity of Water Supply System

• Capacity factors: Table 3-1 presents capacity factors based on different population ranges.
• Use of Capacity Factor: Capacity factors are applied in water supply projects.
• System design capacity: Design elements of the water supply system will be based on the population's design population

Chapter 4 - Water Supply Sources

• General: Water supplies may be obtained from different sources, by expansion of existing systems or by purchase
• Use of existing Systems: Determine the existing capacity and reliability to use the system's possible arrangements with or without enlargement.
• Other water systems: Investigating water supply systems nearby if the proposed development is near it

Chapter 5 - Ground Water Supplies

• General: Ground water: Subsurface water that fills the saturated zone.
• Economy: Ground water supplies are often more economical than surface water if the aquifer yield is adequate.
• Water Quality Evaluation: Steps involved in determining the quality of available water
• Well Hydraulics:
• Definitions: Static water level, pumping level, drawdown, cone of depression, radius of influence
• Permeability, hydraulic conductivity
• Discharge formulas (equations): For water table and artesian wells.
• Determination of water values.
• Aquifer testing: Methods for determining aquifer characteristics, such as pumping tests.

Chapter 6 - Surface Water Supplies

• Surface water sources: Streams, lakes, and impounding reservoirs, generally found in eastern half of the US.

Chapter 7 - Intakes

• General: Intake is the structure used for taking water from natural bodies of water.
• Capacity and reliability: Intake must have sufficient water and be reliable in all conditions over the expected life.
• Ice problems: Ice may clog or damage intake structures.
• Intake location: Various considerations, like streams, meandering streams, bends, depth and water quality factors.

Chapter 8 - Raw Water Pumping Facilities

• Pumping station arrangements: Arrangement of raw water pumping stations based on local needs and requirements for water.
• Pumping protection: Safety considerations regarding the pumping equipment or facilities in flood or debris-prone locations
• Structural and ventilation considerations: Pump station building design and ventilation system requirements
• Pumping Equipment: Providing of adequate pumping equipment based on water treatment plant and the rated capacity
• Ground water sources: Methods considered based on need/application

Chapter 9 - Water System Design Procedure

• General: Coordination of water supply system planning, and design in a large project.
• Selection of materials and equipment: Appropriate materials and equipment used in the system; prohibition of certain materials.
• Restrictions: Lead, copper, and asbestos. Prohibitions on materials.
• Energy conservation: Considering energy requirements when deciding on water sources or system design

Appendix (e.g., B) - Sample well design

• Site situation/selection
• Size the well
• Location
• Water quality
• Pump selection
• Construction/additional details

Test your knowledge on the critical factors involved in selecting and evaluating water sources for development. This quiz covers essential considerations such as feasibility studies, supply line definitions, and treatment suitability. Enhance your understanding of water supply management best practices.