Water Supply Engineering Short Question

1. What are the various types of water demand in the cities?

Ans- The water demands are as follows,

• Domestic water demand
• Institutional water demand
• Commercial water demand
• Industrial water demand
• Fire water demand.

2. What percentage of total water demand allotted for domestic water demand?

Ans- 50 % to 60%

1. Define per capita demand of water.

Ans- The annual average daily consumption of each person is known as the per capita demand of water.

1. Define design period.

Ans- The future period for which a provision is made in the water supply scheme of a city, is known as the design period.

1. What is the expected percentage of wastes and theft of water a best managed water works?

Ans- About 15% of the total consumption.

1. How will you estimate the total domestic water demand for a city?

Ans- The total domestic water demand is equal to the total design population of the city multiplied by per capita domestic consumption.

1. What is the industrial water demand for a town having small scattered industries?

Ans- 50 lit/person/day.

1. What is industrial water demand for industrial cities?

Ans- 450 lts/persons/per day.

1. What should be minimum water pressure at fire hydrants?

Ans- The water pressure should be 100 to 150 KN/m2(10 to 50 of water head).

1. What are the factor that affect per capita demand of the water?

Ans- The following factor affect per capita demand of water,

• The size of the city
• Climatic condition of the region
• The type of the population
• Industrial and commercial activities

11. What is Hydrological cycle?

Ans- Water loses its existence to the atmosphere as vapors from the earth surface and the same is precipitated back in the form of rain, hail etc.The process of precipitation and evaporation maintaining a balance between two kind of action is known as hydro logical cycle.

1. What is precipitation?

Ans- The evaporated water which returns back to the surface of the earth in its various forms as rain, snow, hail, etc. is known as precipitation.

1. What is cyclone?

Ans-The large whirling mass of air, moves from one place to another place and at the center of which the barometric pressure is low, is known as a cyclone.

1. What is the mechanism of precipitation during a cyclone?

Ans- The cyclone is a very large mass of air ranging from 800 to 1600 Km in diameter and moving with a velocity of about 50 Km/hr. The central portion of cyclone where pressure is low, acts as a chimney through the air gets lifted, expands, cools finally gets condensed as precipitation.

1. What is meant by occluded front?

Ans- An occluded front takes place when a cold front overtakes a warm front.

1. How connective precipitation occurred?

Ans- The connective precipitation may be caused due to the upward movement of air warmer than its surrounding. The vertical air currents develop tremendous velocities and precipitates in the form of showers of high intensity but of short duration.

1. What is orthographic precipitation?

Ans- The orthographic precipitation is caused by air masses which strike some natural topographic barriers such as mountains. Due to presence of the elevated-topographical features, the air mass is forced to rise up and thus causes condensation and precipitation.

1. What is ground rainfall?

Ans- The difference between total rainfall and rainfall interception, is known as the ground rainfall.

1. How rainfall is measured?

Ans- The rainfall is measured with the help of rain gauge with a circular aperture of known area and collecting and measuring the water at regular interval.

1. What is index of wetness?

Ans- The ratio of the actual rainfall in a given particular year at a given place to the normal rainfall of that place , is known as the index of wetness.

1. Differentiate between pond and Lake?

Ans-  If the size of the depression over the earth surface is comparatively small , it is termed as pond whereas a larger size depression is termed as Lake.

1. What are perennial rivers?

Ans- The rivers in which water is available throughout the year, are called the perennial rivers.

1. What are the various types of old dams?

Ans- a. Earth dam

• Rockfill dam
• Solid masonary gravity dams.

23A. Define the dead storage of a dam?

Ans-  The volume of water stored in the reservoir of a dam below the minimum pool level and the normal pool level is known as dead storage.

1.  What is surcharge storage of dam?

Ans- The surcharge storage of a dam maybe define as the volume of water stored between the normal pool level and the maximum pool level of the dam reservoir.

1. Differentiate between firm yield and secondary yield.

Ans-  The yield of the reservoir which corresponds to the worst or the most critical year on record is known as then firm yield or safe yield whereas the volume of water available in excess of the firm yield during the years of higher inflows , is known as secondary yield.

1. What is trap efficiency?

Ans- Trap efficiency may be defined as the percentage of the sediments deposited in the reservoir even in spite of taking necessary precautions and measures to control its deposition.

1. Define the capacity in flow ratio.

Ans-  The ratio of the reservoir capacity to the total inflow of water in it, is known as capacity in flow of ratio.

1.  What are the check dam?

Ans- To reduce the sediment inflow in the dam reservoir , dams of lesser height are constructed across the river /streams to trap the large amounts of coarser sediments .Such a dam is called check dam.

1. What is the important factor to minimize the cost of a dam?

Ans- The reservoir basin should have a deep and narrow opening in the valley so that the overall length of the dam is minimum.

1. What is economical height of a dam?

Ans- The economical height of a dam is defined as the  height of the dam , corresponding to which, the cost of the dam per unit of storage, is minimum.

31.Define the porosity of the soil<

Ans- The percentage of the voids present in a given volume of soil aggregate , is known as the porosity of soil.

32. Difference between zone of saturation and zone of aeration?

Ans- In the zone of saturation, water exists within the interstices under hydrostatic pressure and is usually known as ground water whereas the the space above the table and below the ground surface is known as the zone of aeration. The water in the zone of aeration is not at hydrostatic pressure.

33. What is coefficient of permeability?

Ans- The coefficient of permeability may be defined, based on the Darcys law, as the rate of flow of water through a unit cross-sectional area of water bearing strata under a unit hydraulic gradient and at a temperature of 20o C.

34. Define the coefficient of the transmissibility?

Ans- The coefficient of the transmissibility may be defined as the rate of flow of water through a vertical strip of the  water bearing material of unit width and full depth under a unit hydraulic gradient and at a temperature.

35. What is pellicular water?

Ans- The volume water being retained by the interstices of the material due to their attraction, is known as pellicular water.

36. Differentiate between aquifer and aquiclude.

Ans- The aquifer is a permeable stratum capable of yielding appreciable quantities of ground water under gravity whereas an aquifer overlain by a confined bed of the impervious material is called an aquiclude.

37. What is an artesian aquifer?

Ans- Aquiclude which is broadly inclined so as to expose the aquifer somewhere to the catchment area at a higher level for creation of sufficient hydraulic head, is called confined aquifer or an artesian aquifer.

38. What are flowing wells?

Ans- The wells dug into artesian aquifer through which water gushes out automatically, are called the flowing wells.

39. What is aquifuge?

Ans- It is an geological formation which is neither porous nor permeable, is known as aquifuge.

40. What is aquitard?

Ans- The geological formation that does not yield water freely to wells, due to its lesser permeability, is known as aquitard.