Chapter 5 · MCQ Read Mode

Water Supply Engineering

In selecting a source for a water supply scheme, the yield must be assessed on the basis of

The maximum daily demand for a water supply system is commonly taken as

The distribution system of a town is normally designed for

The geometric increase method of population forecasting is most appropriate for

Components of a water supply system that are difficult to extend later, such as transmission mains, should be given

Escherichia coli is used as an indicator organism in water quality testing because it

The drinking water standard for Escherichia coli is

Trachoma and scabies are classified as

The national drinking water standard for arsenic in Nepal is

The distinction between a water quality guideline and a water quality standard is that a standard

In a Nepali hill gravity water supply scheme, the characteristic structure that distinguishes it from a pumped urban system is the

The principal reason many rural water supply schemes fail a few years after construction is that

An increasing block tariff is generally preferred for domestic water supply because it

The solubility of dissolved oxygen in water

In a thermally stratified reservoir during summer, the hypolimnion typically becomes

The autumn overturn of a reservoir is significant for a water treatment plant because it quality

The critical point on an oxygen sag curve is the location at which

Self-purification of a stream proceeds fastest in a stream that is

The BOD test is conventionally carried out over five days at 20 °C, and the result represents approximately

The chemical oxygen demand of a wastewater is always greater than its biochemical oxygen demand because COD agents

COD is preferred to BOD for day-to-day process control because it

Which parameter must be determined on a grab sample rather than a composite sample?

Biological monitoring using benthic macro-invertebrates has the advantage over spot chemical sampling that the organisms

An ambient or stream standard differs from an effluent standard in that the stream standard

In the hierarchy of water pollution control strategies, the most preferred option is

Under Nepal's Water Resources Act, 2049, the first priority among competing uses of water is given to

An intake on a river serving a town should be located

The entry velocity at the screen of an intake is normally kept low, around 0.1 to 0.3 m/s, in order to

Ports at more than one level are provided in a reservoir intake tower so that

The standard pipe material for buried transmission and distribution mains in Nepali rural water supply schemes is

A sluice (gate) valve should be operated

Air valves and washout valves in a pipeline are located respectively at

Thrust blocks are provided at bends, tees and dead ends in a pressure main in order to

The principal purpose of a break pressure tank in a gravity water supply scheme is to

A service reservoir allows the source, treatment plant and pumping works to be designed for

The total capacity of a service reservoir is made up of

Balancing storage for a service reservoir is determined from

The principal disadvantage of a branched (dead-end) distribution system is that

Where a water main and a sewer must be laid in the same street, the water main should be

Filtration must precede disinfection in a water treatment plant because

In ideal settling theory, the removal efficiency of discrete particles in a sedimentation tank depends on

The essential difference between coagulation and flocculation is that coagulation grows the flocs

When alum is used as a coagulant and the raw water has insufficient natural alkalinity

The optimum coagulant dose for a particular raw water is determined by

The effective size of filter sand is defined as the sieve size through which

Compared with a rapid gravity filter, a slow sand filter operates at a filtration rate that is approximately

The schmutzdecke in a slow sand filter is

A slow sand filter is cleaned by

Air scouring during the backwashing of a rapid gravity filter is provided in order to required

A roughing filter is provided upstream of a slow sand filter in order to

Chlorination is more effective at low pH because

Ozone and ultraviolet radiation share the limitation, compared with chlorine, that they

The principal water quality danger of an intermittent water supply is that

An intermittent supply is also inequitable because

The principal advantage of a combined pumping and storage system over direct pumping is that

The balancing storage required in a service reservoir is determined from a mass curve as

In hilly terrain such as Nepal's, elevated service reservoirs are rarely built because

The inlet and outlet of a service reservoir should be located at opposite ends in order to

Reducing excess pressure in a distribution system is an effective means of controlling losses because

In the analysis of a looped water distribution network, the two conditions that must be satisfied are

In the Hardy Cross method using the Hazen-Williams formula, the exponent n used in the correction formula is

Non-revenue water is defined as

Which of the following is an apparent (commercial) loss rather than a real loss?

Minimum night flow analysis is used in a district metered area to

Active leakage control is necessary because

The total dynamic head that a pump must generate is

A positive displacement pump must never have its delivery valve closed against it without a relief valve because it

The operating point of a pumping installation is found at

Partially closing a valve on the delivery side of a centrifugal pump will move the operating point to

Selecting a pump considerably larger than the duty requires is undesirable because the pump will

Two identical centrifugal pumps operating in parallel will deliver

According to the affinity laws, reducing the speed of a centrifugal pump to 80 per cent changes the power required to approximately

Cavitation in a pump is avoided by ensuring that

At a high-altitude site in the Nepali hills, the available NPSH for a given installation is

The most severe pressure transient in a pumping main usually arises from

A flywheel is sometimes fitted to a pump set in order to

The volume of a pump sump is determined principally by the requirement to

In a solar photovoltaic pumping system, water is stored in a tank rather than energy in batteries because