# Aktu Irrigation and Water Resource Engineering KCE-078 Btech Short Question, Quantum Book Pdf

Study the B.Tech AKTU Quantum Book Short Question Notes on Irrigation and Water Resource Engineering. Dive into water management principles, irrigation methods, and sustainable water resource utilisation.

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## Unit-I: Hydrology (Short Question)

Q1. Define the term hydrology.

Ans. Hydrology is the science that studies the occurrence, distribution, and flow of water on Earth, including water in the atmosphere and beneath the earth’s surface.

Q2. Explain hydrological system.

Ans. The hydrologic cycle refers to the earth’s water circulatory system, which is in constant circulation from the earth to the atmosphere and back to the earth.

Q3. What is hydrologic cycle ? Write different components of hydrologic cycle.

Ans. Hydrologic Cycle: It is the process of transferring moisture from the atmosphere to the earth in the form of precipitation, transporting the precipitated water via streams and rivers to oceans and lakes, and returning the water to the atmosphere via evaporation.

Components: Following are the components of hydrologic cycle:

• i. Evaporation and transpiration.
• ii. Precipitation (P).
• iii. Runoff (R).

Q4. Discuss the evaporation and transpiration.

Ans. Evaporation: Evaporation is the process through which water evaporates from the surfaces of the ocean, rivers, lakes, and moist soil.

Transpiration: It is the process of water being lost from the leaves of the plants from their pores.

Q5. State various types of precipitation.

Ans. Following are the various types of precipitation:

• i. Orographic precipitation.
• ii. Cyclonic precipitation.
• iii. Convectional precipitation.

Q6. What are the various methods of computing average rainfall over a basin ?

Ans. Following are the methods of computing the average rainfall:

• i. Arithmetic average method.
• ii. Thiessen polygon method.
• iii. Isohyetal method.

Q7. What are the advantages of recording rain-gauges?

Ans. Following are the advantages of recording type rain-gauge over the non-recording type:

• i. The rainfall is recorded automatically.
• ii. The recording rain-gauge also gives the intensity of rainfall at any time.
• iii. Possibility of human error is obviated.

Q8. What are the different factors on which the rate of evaporation depends?

Ans. The rate of evaporation depends on the following factors:

• i. Vapour pressure at the water surface and air above.
• ii. Air and water temperatures.
• iv. Wind speed.
• v. Atmospheric pressure, etc.

Q9. What is water budget equation ?

Ans. Water budget equation or hydrological budget equation for surface flow refers to the continuity equation defined in terms of several stages of the hydrological cycle.

For a given catchment in a time ∆t,

Inflow – Outflow = Storage (Continuity equation).

Q10. What is evapotranspiration ?

Ans. It is the sum of the water lost to the atmosphere by plants via transpiration and the water evaporated from the soil, water, or body of water surrounding the plant.

Q11. Differentiate between PET and AET.

Ans. Potential Evapotranspiration (PET): If there is always enough moisture available to suit the needs of the flora completely covering the region, the resulting evapotranspiration is known as potential evapotranspiration (PET).

Actual Evapotranspiration (AET): The real evapotranspiration occurring in a specific situation is called actual evapotranspiration (AET).

Q12. What is transpiration ? What are different factor that affect transpiration ?

Ans. Transpiration: It is the process of water being lost from the leaves of the plants from their pores.

Factors: The following factors influence transpiration: air vapour pressure, temperature, wind, light intensity, and plant features such as root and leaf systems. Factors that influence free-water evaporation also influence transpiration in a given plant.

Q13. What is effective rainfall ?

Ans. The component of a storm hyetograph that is neither retained on the ground surface nor infiltrates into the soil is known as effective rainfall. It is sometimes referred to as excessive rainfall.

Q14. What do you mean by infiltration ?

Ans. It is the flow of water into the ground through the soil surface.

Q15. The recorded numbers of 3 cm /hr storm in three different rain gauge stations were 3,1 and 4 for the periods of records, which were 25,30 and 35 years respectively. Using the stations per year method, find the recurrence interval of the storm at any given point in the area.

Ans. Given: Recorded numbers = 3, 1 and 4; Periods of records = 25,30 and 35 years.

To Find: Recurrence interval (Using the station per year method).

Number of events 3 + 1 + 4 = 8 in total.

Years of records = 25 + 30 + 35 = 90 years.

The event is equaled to or exceeded 8 times in 90 years of record.

Hence, recurrence interval, T = (90 + 1)/8 = 11.375 = 11 years.

Q16. What do you mean by infiltration capacity ?

Ans. The infiltration capacity of a soil is the maximum rate at which water will enter the soil in a given condition.

Q17. Define infiltration rate.

Ans. The rate at which water actually enters the soil during a storm is equal to the infiltration capacity or the rainfall rate, whichever is less.

Q18. What are the effects of infiltration ?

Ans. Following are the effects of infiltration:

• i. It reduces the magnitude of the flood.
• ii. It delays the time of arrival of water to the channel.
• iii. It recharges the ground water reservoir.
• iv. It reduces soil erosion, etc.

Q19. Give the factors affecting the infiltration capacity of an area.

Ans. Infiltration capacity is affected by following factors:

• i. Condition of entry surface.
• ii. Temperature.
• iii. Intensity and duration of rainfall.
• iv. Quality of water.
• v. Size and characteristics of soil particles.
• vi. Catchment parameters, etc.

Q20. Define ϕ-index.

Ans. The ϕ-index is defined as that rate of rainfall above which the rainfall volume equals the runoff volume. The ϕ-index is relatively simple and all losses due to infiltration, interception and depression storage are accounted for; hence,

Q21. Describe W-index.

Ans. The W-index is the average infiltration rate during the time rainfall intensity exceeds the infiltration capacity rate, i.e.,

where,

P = total rainfall.

Q = surface runoff.

S = effective surface retention.

tR = duration of storm during which i >Ft

Ft = total infiltration.

## Unit-II: Surface Runoff (Short Question)

Q1. Define runoff.

Ans. In contrast to water retained in depressed storage and water dissipated in the atmosphere, the phrase runoff refers to water that is on the move or flowing. The runoff of a catchment area in any given period is the total amount of water that drains into a stream or into a reservoir during that time period.

Q2. Classify the runoff.

Ans. Runoff is broadly classified into three types:

• i. Surface runoff.
• ii. Sub-surface runoff.
• iii. Base flow.

Q3. What are the factors affecting the runoff from a catchment area ?

Ans. The principal factors affecting the flow from a catchment area are:

• i. Precipitation characteristics.
• ii. Shape and size of the catchment.
• iii. Topography
• iv. Geological characteristics.
• v. Storage characteristics, etc.

Q4. List methods for computing runoff from a catchment.

Ans. Following are the methods for computing the runoff:

• i. By linear or exponential regression.
• ii. By empirical equations and tables.
• iii. By infiltration method.
• iv. By unit hydrograph.
• v. By rational method.

Q5. Explain the hydrograph.

Ans. A hydrograph is a graph that depicts the fluctuations in discharge over time at a specific place in a stream. It depicts the time distribution of total runoff at the measurement point.

Q6. Write down the methods of determining the direct runoff from a given storm hydrograph.

Ans. The following two methods are used for determining the direct runoff from a given storm hydrograph:

• i. Method of superposition.
• ii. Summation curve (or S-curve) method.

Q7. What is a unit hydrograph ?

Ans. A unit hydrograph (or unit-graph) is the direct runoff hydrograph produced by one cm of excess rainfall distributed uniformly across a catchment area at a steady rate for an effective duration.

Q8. List the assumptions involved in the unit hydrograph theory.

Ans. Following are the assumptions made for unit hydrograph theory:

• i. During the effective storm period of D hours, the excess rainfall has a constant intensity (WD cm/hr).
• ii. Excess rainfall is evenly distributed throughout the catchment basin.
• iii. The length of direct runoff caused by a given amount of surplus rainfall is constant.

Q9. Explain synthetic and S-hydrograph.

Ans. Synthetic unit hydrograph: UHs for other places on the stream in the same watershed or other watersheds with similar features are developed using synthetic unit hydrograph processes.

S-hydrograph: A S-hydrograph is simply a hydrograph produced by continuous effective rainfall occurring at a constant rate for an unlimited period of time. It is called an S-hydrograph because the shape of the hydrograph resembles the letter S, albeit slightly warped.

Q10. State various components of a single peaked hydrograph.

Ans. There are three essential components of a single peaked hydrograph resulting from an isolated storm:

• i. The rising limb.
• ii. The peak as crest element.
• iii. The recession limb.

Q11. What is irrigation ?

Ans. Irrigation is the process of artificially delivering water to soil in order to grow crops. It is the science of planning and designing a low-cost, economical irrigation system to match natural conditions.

Q12. Explain the flow irrigation.

Ans. Flow Irrigation: Flow irrigation is a method of irrigation in which the available irrigation water is at such a level that gravity flow transports it to the field.

Q13. Describe lift irrigation.

Ans. Lift Irrigation: Lift irrigation is used when the water supply is insufficient to run by gravity onto the land. Water is hauled up by mechanical means in such cases.

Q14. Define intensity of irrigation.

Ans. It is defined as the proportion of culturable commanded area proposed to be irrigated throughout a crop season or over the course of a year.

Q15. What are the advantages of irrigation ?

Ans. Following are the advantages of irrigation:

• i. Increase in food production.
• ii. Protection from famine.
• iii. Cultivation of cash crops.
• iv. Elimination of mixed cropping.
• v. Addition to the wealth of the country.

Q16. What is crop rotation ?

Ans. Crop rotation is the practise of producing a variety of crops in the same place over the course of several seasons. It reduces soil erosion while increasing soil fertility and agricultural productivity.

Q17. What are the various considerations for alignment of irrigation canals ?

Ans. Irrigation canals can be aligned in any of the following three ways:

• i. As watershed canal or ridge canal.
• ii. As contour canal.
• iii. As side-slope canal.

Q18. List the different parts of a canal system.

Ans. The canal system consists of following parts:

• i. Main canal.
• ii. Branch canals.
• iii. Distributaries, also called major distributaries.
• iv. Minors.
• v. Water courses.

Q19. Describe the field capacity.

Ans. The moisture content of the soil after free drainage has removed the majority of the gravity water is referred to as the field capacity. The concept of field capacity is particularly helpful in determining how much water is accessible in the soil for plant usage.

Q20. List various methods of irrigation.

Ans. Following are the various methods of irrigation:

Q21. Define Duty and Delta.

Ans. 1. Duty: It represents a unit volume of water’s irrigation capability. It is the relationship between the irrigated area of a crop and the amount of irrigation water required for the full growing season of that crop.

2. Delta: It is the total depth of water required by a crop during the entire period; the crop is in the field and is denoted by the symbol ∆.

Q22. What is crop period ?

Ans. Crop period is the time (in day) that a crop takes from the instant of its sowing to that of its harvesting.

Q23. Explain base period.

Ans. Base Period: It refers to the entire period of cultivation, beginning with the initial application of irrigation water to prepare the ground for planting the crop and ending with the last watering before harvesting.

Q24. Define time factor and capacity factor.

Ans. Time Factor: The time factor of the distributary is the ratio of a distributary’s actual operational period to the crop season.

Capacity Factor: The capacity factor of a canal is the ratio of a canal’s mean supply discharge over a period to its design full capacity.

Q25. What is irrigation efficiency

Ans. It is the proportion of crop water use to crop water provided through irrigation.

Q26. What is meant by border flooding ?

Ans. The land is split into a number of strips by modest levees known as borders in this manner. The land areas limited in each strip range from 10 to 20 metres in width and 100 to 400 metres in length.

Q27. Give the different types of irrigation channels.

Ans. Following are the various types of irrigation channels:

• i. Alluvial channels.
• ii. Non-alluvial channels.
• iii. Rigid boundary channels.

Q28. What are the causes of flooding?

Ans. Causes of Flooding: Following are the causes of flooding:

• 1. Intense precipitation.
• 2. Prolonged rainfall.
• 3. Snow melt or ice thaw.
• 4. Storm surges.
• 5. Landslides.
• 6. Volcanic eruptions.
• 7. Changes in land use.
• 8. Urbanization.
• 9. Climate change.
• 10. Poor dam construction.

Q29. Write down the relation between duty and delta.

Ans. Relation between duty and delta is given by,

Delta, ∆ = 8.64 (BID) metres

where,

B = Base periods in days

D = Duty in ha/cumec

Q30. Find the delta for a crop if the duty for a base period of 110 days is 1400 hectares/cumec.

Ans. Given: Base period, B= 110 days, Duty, D = 1400 ha/cumec

To Find: Delta, ∆

## Unit-III: Sediment Transport (Short Question)

Q1. Explain Lacey’s silt factor.

Ans. Silt factor is connected to the average particle size. It is given by,

where,

dmm = Average particle size in mm

Q2. What do you understand by schedule of area statistics ?

Ans. The design of the channel cross-section from km to km is done in a tabular format known as the schedule of area statistics and channel dimensions.

Q3. What are the factors responsible for the selection of a particular type of lining ?

Ans. Following are the factors responsible for selection of a particular type of lining:

• i. Size and importance of the canal.
• ii. Canal slopes and alignments.
• iii. Climate of the area.
• iv. Availability of materials.
• v. Initial expenditure.

Q4. What is water logging?

Ans. A land is said to be water logged when the pores of soil within a plant’s root zone get saturated and the plant’s regular growth is hampered due to limited air circulation.

Q5. Mention the effects of water logging.

Ans. The crop yield is considerably reduced in a water logged area due to the following adverse effects of water logging:

• i. Absence of soil aeration.
• ii. Difficulty in cultivation operations.
• iii. Weed growth.
• iv. Accumulation of salts.

Q6. Describe the drainage of irrigated lands.

Ans. The removal of excess water and salts from adequately irrigated agricultural regions is referred to as drainage. Drainage is required to sustain soil productivity because to deep percolation losses from appropriately watered levels and seepage from reservoirs, canals, and water courses.

Q7. Write down the preventive measures of water logging.

Ans. Following are the preventive measures of water logging:

• i. Adoption of tolerant crops.
• ii. Restricting canal supplies close to crop water needs.
• iii. Switch over to drip irrigation.
• iv. Conjunctive use of surface and ground water.
• v. Incentives for reclamation of land.

Q8. State the Kennedy critical velocity ratio (m).

Ans. Kennedy realized the importance of silt grade on critical velocity and introduced a factor (m) known as critical velocity ratio (CVR) in his equation. The equation is given by:

V0 = 0.55 mD0.64

Q9. Write down the drawbacks in Kennedy’s theory.

Ans. Following are the drawbacks in Kennedy’s theory:

• i. Kennedy did not notice the importance of B/D ratio.
• ii. He aimed to find out only the average regime conditions for the design of a channel.
• iii. Silt grade and silt charge were not defined.
• iv. Kennedy did not give any slope equation, etc.

Q10. Define silting and scouring.

Ans. Scouring: Scouring occurs as a result of surface flow of water, particularly at high velocity or during significant flood discharge. It erodes the soil and takes it downstream with the passage of water.

Silting: After the scouring event, a state occurs in which the eroded material or soil settles at the bottom of the flow. This is referred to as silting or particle settling at the bed.

Q11. Explain the lining of canals in short.

Ans. Canal lining is the technique of decreasing irrigation water seepage loss by applying an impervious layer to the trench’s margins. Lining refers to the use of impermeable material to protect the canal prism. The lining of a canal might be hard, semi-rigid, or flexible. Lining a canal can also help to keep water out of low-lying areas of the canal.

Q12. Write any two advantages of lining of canal.

• i. The increased velocity minimizes the losses due to evaporation.
• ii. Lining makes the canal banks more stable.

Q13. Discuss the economic liability of lining of canal.

Ans. Lining irrigation canals to avoid seepage losses, which account for 40% of water delivered in unlined canals, is justified only on economic grounds. Lining an irrigation canal is economically viable when the cost is returned in terms of advantages obtained during the life of the lining.

Q14. Define leaching.

Ans. Leaching is a mass transfer process that occurs when a substance is extracted from a solid material that has come into contact with a liquid.

Q15. Explain Lacey silt theory.

Ans. Lacey Silt Theory: “Dimensions, width, and slope of a regime channel to carry a given discharge loaded with a given silt charge are all fixed by nature”.

It states that the silt carried by the flowing water is kept suspended by the vertical component of eddies formed from the channel’s whole wetted perimeter.

Q16. Write short note on Standard project flood (SPF).

Ans. The flood is caused by the most severe combination of climatic and hydrological elements that are realistically applicable to the basin. Extremely unusual combinations, on the other hand, are not permitted.

Q17. What is Phreatic line ? What is its use ?

Ans. The top flow line of a saturated soil mass below which seepage takes place is called phreatic line.

Use: Phreatic line is used in separating saturated and unsaturated zone.

## Unit-IV: Regulation and Controls of Canal System (Short Question)

Q1. Describe the regulation work.

Ans. Canal regulation works are structures built to govern and regulate discharges, depths, velocities, and other parameters in canals.

Q2.  Give the types of canal regulation works.

Ans. Following are the types of canal regulation works:

• i. Canal fall.
• iii. Cross regulator.
• iv. Canal escape.

Q3. What do you understand by a fall in a canal ?

Ans. A canal fall is a hydraulic structure that is built across a canal to reduce the water level. This is accomplished by negotiating the change in canal bed elevation caused by the difference in ground slope and canal slope.

Q4. What are the different types of canal falls ?

Ans. Following are the various types of canal fall:

• i. Ogee fall.
• ii. Rapid fall.
• iii. Stepped fall.
• iv. Notch fall.
• v. Vertical drop fall.
• vi. Glacis type fall, etc.

Q5. What is cistern ? Classify the cistern elements in fall.

Ans. Cistern: It is that portion of the fall downstream of the crest wall where the surplus energy of water leaving the crest is destroyed.

Classification: Following are the classification of cistern elements:

• i. Vertical-impact cisterns.
• ii. Horizontal-impact cisterns.
• iii. Inclined-impact cisterns.
• iv. Non-impact cisterns.

Q6. What do you understand by distributary head regulator ?

Ans. The distributary head regulator is built at the upstream end of a channel, where it connects to the main canal, a branch canal, or a significant distributary.

Q7. Describe the cross regulator.

Ans. A cross regulator is typically installed on the downstream side of an off-taking channel so that the water level upstream of the regulator can be adjusted as needed to allow the off-taking channel to draw its required supply even when the main channel is carrying low supply.

Q8. Define canal escape.

Ans. Canal Escape: A canal escape is a side channel built to divert excess water from an irrigation channel (main canal, branch canal, or distributary canal, for example) into a natural drain.

Q9. Give the types of canal escape.

Ans. Following are the types of canal escape:

i. Surface escape (Weir type).

ii. Sluice escape (Regulatory type).

Q10. What is an outlet?

Ans. An outlet is a masonry construction that admits water from a distributary into a water stream.

Q11. What are the general requirements of canal outlets?

Ans. Following are the requirements of a canal outlet:

• i. The outlets must be solid and simple, with no moving elements that require attention and maintenance on a regular basis.
• ii. Because a significant number of outlets must be put in an irrigation network, the cost of outlets should be low.
• iii. The outlets should be able to operate effectively even at low pressures.

Q12. Classify the canal outlets.

Ans. Following are the types of canal outlets:

• i. Non-modular outlets.
• ii. Semi-modular outlets.
• iii. Modular outlets.

Q13. What do you understand by non-modular outlets ?

Ans. Non-modular outlets are those whose discharge is determined by the difference in head between the distributary and the water stream.

Q14. Write down the various types of semi-modular outlets.

Ans. Following are the types of semi-modular outlets:

• i. Kennedy’s gauge outlet.
• ii. Open flume outlet.
• iii. Orifice semi-modules.

Q15. Give the types of modular outlets.

Ans. Following are the types of modular outlets:

• i. Gibb’s rigid module.
• ii. Khanna’s rigid module.
• iii. Foote module.

Q16. Describe the term river training.

Ans. River training encompasses all actions required to control and regulate river flow and configuration. River training works are built either across or beside a river.

Q17. What are the objectives of river training ?

Ans. Following are the objectives of river training:

• i. Flood protection.
• ii. Sediment control.
• iii. Guiding the flow.
• v. Stabilization of river channel.

Q18. Define the term width of meandering and length of meander.

Ans. Meander Width: It is the transverse distance between the apex of one curve and the apex of the opposite curve.

Meander Length: It is the air distance along a river between the tangent points of two curves of the same order.

Q19. Write down the various types of river training works.

Ans. Following are the various type river training works:

• 1. Guide bank system.
• 2. Groynes or spurs.
• 3. Levees or embankment
• 4. Bank protection and pitched banks.
• 5. Pitched islands.
• 6. River training without embankmentS.
• 7. Bandalling.

Q20. What are the basic principles of regulation of a canal system?

Ans. The principle underpinning water distribution is allocating available canal supplies based on irrigable area. If water is only required on occasion, it may be supplied in accordance with the general arrangement reached between cultivators and canal administration. A canal must be run with full supplies if there is a high demand in the commanded region, with partial supplies if only a portion of the commanded area need water, and with no supplies if demand falls below a particular threshold.

Q21. What is diversion headwork ?

Ans. A diversion headwork raises the river’s water level and diverts the necessary amount into the canal.

Ans. Any hydraulic structure which supplies water to the off-taking canal is called a headwork. Headworks may be divided into two classes:

Q23. Write down the functions of head regulator.

Ans. Following are the functions of head regulator:

• i. To make the regulation of supply in the canal easy.
• ii. To control the silt entry in the canal.
• iii. To shut out river floods.

Q24. State the principles of cross regulator.

Ans. The cross regulator is provided to ensure equitable supply distribution among the distributaries and parent canal, to raise water level when supply in the parent canal is low, to release surplus water from the canal in conjunction with escapes, or to provide a means of cutting off supplies to the downstream side for repairs, etc.

Q25. What do you mean by fall and where are they located ?

OR

Why are the canal falls are constructed in an irrigation canal ?

Ans. Canal Fall: A canal fall is a hydraulic structure that is built across a canal to reduce the water level. This is accomplished by negotiating the change in canal bed elevation caused by the difference in ground slope and canal slope.

Location: When the natural slope of the ground over which the canal is to be built is greater than the canal’s specified bed slope. The slope difference is compensated for by placing various drops in the canal bed at appropriate intervals.

Q26. What is meant by a cross drainage work ?

Ans. A cross drainage work is a construction that carries a natural stream’s discharge over a canal that intercepts the stream.

Q27. Write a short note on canal syphon.

Ans. The canal water flows by gravity, revealing a canal syphon, or simply syphon. In this scenario, the levels are such that the canal’s FSL is substantially higher than the drainage trough’s bed level, resulting in syphonic action under the trough.

Q28. Why the falls are necessary in canals ?

Ans. A fall is an irrigation structure built across a canal to reduce its water level and destroy the excess energy librated by the falling water, which may erode the canal’s bed and banks.

## Unit-V: Groundwater Hydrology (Short Question)

Q1. Define the aquifer.

Ans. Aquifers are permeable formations with characteristics that allow a significant amount of water to travel through them under normal field conditions. As a result, these are the geologic formations where ground water exists.

Q2. Classify aquifers.

Ans. Aquifers are mainly of two types:

• i. Unconfined aquifer.
• ii. Confined aquifer (artesian aquifer).

Q3. What do you mean by unconfined aquifer ?

Ans. An unconfined aquifer, also known as a water table aquifer, is one in which the upper surface of the zone of saturation is a water table. It is sometimes referred to as a free, phreatic, or non-artesian aquifer.

Q4. Describe the confined or artesian aquifer.

Ans. A confined aquifer, also known as an artesian aquifer, is one in which ground water is held under pressure greater than atmospheric pressure by overlying, generally impermeable strata.

Q5. Define the term aquicludes.

Ans. Aquicludes are impermeable rocks that store water but cannot transfer or supply a large amount of it.

Q6. What is aquifuge ?

Ans. Aquifuge is an impermeable formation which neither contains nor transmits any water.

Q7. What do you mean by specific yield ?

Ans. The specific yield of an aquifer is defined as the ratio expressed as a percentage of the volume of water that can be drained by gravity to its own volume after being saturated.

Q8. Explain the specific retention of an aquifer.

Ans. The specific retention (S) of an aquifer is the ratio of the volume of water that the aquifer will hold after saturation against gravity to its own volume, represented as a percentage.

where, Vr = volume of water retained.

Q9. Define the term storage coefficient.

Ans. The volume of water that an aquifer releases or takes into storage per unit surface area of the aquifer per unit change in the component of head normal to that surface is known as the storage coefficient.

Q10. What do you understand by coefficient of permeability (k)?

Ans. The velocity of flow that will occur through the total cross-sectional area of the soil (or aquifer) under a unit hydraulic gradient is defined as the coefficient of permeability.

Q11. Define coefficient of transmissibility.

Ans. At a temperature of 60° F, the coefficient of transmissibility is defined as the rate of flow of water (in m3/day or gallons/day) through a vertical strip of aquifer of unit width (1m or 1 ft.) and extending the entire saturation height under unit hydraulic gradient. Thus, the coefficient of transmissibility (T) equals to the field coefficient of permeability multiplied by the aquifer thickness (b),

T = bk

Q12. Explain well losses.

Ans. When water is pumped out of a well, the total drawdown induced comprises not only the logarithmic drawdown curve at the well face, but also flow through the well screen and axial movement within the well. The latter is referred to as well loss.

Q13. What do you understand by specific capacity ?

Ans. The specific capacity of a well is a measure of its efficacy and is defined as the well’s yield per unit drawdown.

where,

s = drawdown.

Q = well discharge or the yield.

Q14. What is water well ?

Ans. A water well is a hole or shaft constructed in the ground, usually vertically, to bring ground water to the surface.

Q15. Classify the water wells.

Ans. Wells can be mainly divided into two classes:

• i. Dug wells or open wells.
• ii. Bored or drilled wells or tube wells.

Q16. Enlist the various types of tube wells.

Ans. The tube wells may be of three types:

• i. Strainer well.
• ii. Cavity well.
• iii. Slotted well.

Q17. Explain well shrouding.

Ans. Well shrouding is the technique of inserting coarse material such as gravel and coarse sand between the well-pipe and the aquifer soil to prevent finer soil particles from clogging the strainer.

Q18. What are the various methods of well development ?

Ans. A well may be developed by one of the following methods:

• i. Development by pumping.
• ii. Development by surging.
• iii. Development by compressed air.
• iv. Development by backwashing.
• v. Development by dry ice.

Q19. Classify the open well.

Ans. An open well is classified as:

• i. Shallow well.
• ii. Deep well.

Q20. Enlist the methods for lifting of water.

Ans. The various methods for lifting water can be divided into two heads:

• i. Indigenous methods.
• ii. Mechanical methods.

Q21. What are the types of pumps suitable for deep wells ?

Ans. The following types of pumps are suitable for deep well and tube well operation:

• i. Deep well turbine pump.
• ii. Deep well jet pump.
• iii. Air lift pump.

Q22. What is Dupuit’s theory ?

Ans. In Dupuit’s theory, no observation wells (as in Thiem’s theory) are built. The main well is pumped out to achieve sufficient drawdown, and the pumping rate is then adjusted to achieve equilibrium conditions (i.e., the rate of inflow equals the rate of outflow, and the water level in the well becomes constant).

Q23. What is well efficiency?

Ans. The ratio of formation loss to total drawdown measured inside the well is defined as well efficiency.