Explanation: Irrigation becomes imperative in regions experiencing less rainfall, as it helps supplement the water needs of crops. Additionally, non-uniform rainfall patterns can leave certain areas parched, requiring irrigation. Commercial crops often demand precise water management, making irrigation essential for their successful cultivation. Therefore, the correct answer is (d) all of the above, as all these factors contribute to the necessity of irrigation in agriculture.
Explanation: Intensity of irrigation refers to the proportion of cultivable land that is planned for irrigation in a given period, expressed as a percentage. It is a crucial parameter in water resource management and agricultural planning. Option (a) correctly defines intensity of irrigation, making it the correct answer.
Explanation: Hygroscopic water refers to the moisture present on the surface of soil particles that cannot move by gravity or capillary action. It can only be expelled through the application of heat. This type of water is crucial for plant growth as it influences soil structure and nutrient availability.
Explanation: Capillary water is the portion of soil water that is held in the soil against the force of gravity. Plants primarily utilize capillary water for their growth and metabolic processes. It moves upward through the soil due to capillary action and is essential for maintaining plant turgor pressure.
Explanation: The top of the capillary zone is the level in the soil where capillary rise occurs. Importantly, it is situated above the water table, allowing water to move upwards through the soil against the force of gravity. This capillary action supports the availability of water to plants in the root zone.
Explanation: During the infiltration of water below the ground surface, the predominant process is absorption. Absorption refers to the movement of water into the soil and its uptake by soil particles and plant roots. This is a critical phase in the water cycle, contributing to groundwater recharge.
Explanation: An arid zone is characterized by a severe lack of natural water resources for agriculture. In such regions, precipitation is minimal, and the available water is often insufficient to support successful crop cultivation without the aid of artificial irrigation.
Explanation: The semi-arid zone represents an area with moderate water availability, allowing for the cultivation of certain crops without the necessity of irrigation. While not as arid as true desert regions, these areas still require careful water management for successful agriculture.
Explanation: An artesian aquifer is characterized by water being confined between two impermeable layers, creating pressure. When a well is drilled into such an aquifer, the water can rise to the surface without external pumping due to the natural pressure within the aquifer.
Explanation: An unconfined aquifer is often referred to as a free aquifer. In this type of aquifer, the water table is not confined by impermeable layers, allowing water to move freely in response to natural gradients.
Explanation: A well that experiences a decrease in discharge by the designed amount is termed a sick well. This reduction in discharge may be attributed to various factors, such as changes in the aquifer or well conditions.
Explanation: When drilling a tube well in compacted rock materials, the percussion method is commonly employed. This method involves the use of repetitive blows or impacts to break the rock and facilitate drilling.
Explanation: Percolation loss, which refers to the downward movement of water through the soil, is generally lower in black cotton soil compared to sandy or silty soils. The clayey nature of black cotton soil restricts rapid water movement.
Explanation: Silt, when present in soil, can act as a fertilizing agent. It contributes to soil fertility by enhancing its structure, retaining moisture, and providing essential nutrients for plant growth.
Explanation: Safe yield represents the maximum quantity of water that a reservoir can reliably supply during the worst dry period. It ensures sustainable water management and helps in planning for water availability under challenging conditions.
Explanation: Culturable Command Area (CCA) is the area that can be effectively irrigated. It is calculated by subtracting the area occupied by crops that don’t require irrigation (barren land) from the Gross Command Area (GCA). Therefore, CCA = GCA – barren land = 400 Ha – 50 Ha = 350 Ha. The correct answer is (d) 350 Ha.
Explanation: Effective precipitation for a crop refers to the water stored in the soil within the root zone of the crop. It is the water available to the crop for its growth and development. Therefore, the correct answer is (a).
Explanation: In situations with water scarcity and high pressure, sprinkler irrigation is a suitable method. It involves spraying water over the crops, making efficient use of limited water resources. Therefore, the correct answer is (d) sprinkler irrigation.
Explanation: In undulating sandy fields, where uniform water distribution is essential, sprinkler irrigation is the most suitable method. It ensures that water is evenly applied over the crops, promoting optimal growth. Therefore, the correct answer is (c) sprinkler irrigation.
Explanation: Drip irrigation is the most appropriate method during a low quantity of water. It involves delivering water directly to the root zone of plants, minimizing water wastage and ensuring efficient use. Therefore, the correct answer is (b) drip irrigation.
Explanation: The most commonly adopted method of irrigation for cereal crops is check flooding. This method involves dividing the field into smaller sections or checks, allowing water to be applied evenly across the entire field. Therefore, the correct answer is (c) check flooding.
Explanation: Basin irrigation is the method where land is surrounded by natural or artificial banks, and water is flooded into the enclosed area. This method is often used in orchards or for crops that benefit from controlled flooding. Therefore, the correct answer is (c) basin irrigation.
Explanation: Irrigation with sewage from a town is referred to as effluent irrigation. It involves using treated or untreated wastewater for agricultural purposes. Therefore, the correct answer is (a) effluent irrigation.
Explanation: On rolling land, the most suitable method of applying water is check flooding. This method allows for controlled water distribution on slopes, preventing excessive runoff and ensuring uniform coverage. Therefore, the correct answer is (a) check flooding.
Explanation: Kharif crops are sown at the beginning of the south-west monsoon season. These crops are typically sown in the rainy season and harvested in the winter. Therefore, the correct answer is (c) at the beginning of the south-west monsoon.
Explanation: Leguminous crops have the ability to fix atmospheric nitrogen in the soil through a symbiotic relationship with nitrogen-fixing bacteria in their root nodules. Therefore, the correct answer is (c) leguminous crop.
Explanation: A crop that takes more than 4 months to mature is termed a long crop. This category includes crops with an extended growth period before reaching maturity. Therefore, the correct answer is (b) long crop.
Explanation: Crop ratio is the ratio of the area irrigated in the rabi season to the area irrigated in the kharif season. It provides insights into the distribution of irrigation across different crop seasons. Therefore, the correct answer is (a) in rabi season to kharif season.
Explanation: Groundnut is not a Rabi crop; it is a Kharif crop. Rabi crops are sown in the winter season and harvested in the spring. Therefore, the correct answer is (b) groundnut.
Explanation: Groundnut is a leguminous crop. Leguminous crops have the ability to fix atmospheric nitrogen through symbiotic relationships with nitrogen-fixing bacteria in their root nodules. Therefore, the correct answer is (c) groundnut.
Explanation: Rabi crops are sown in the winter season and harvested in the spring. Groundnut and sugar cane are Kharif crops, while bajra is a Kharif or summer crop. Therefore, none of the options listed is a Rabi crop.
Explanation: Waterlogging can occur due to over-irrigation, inadequate drainage, or seepage from adjoining reservoirs. All the options mentioned contribute to the potential for waterlogging.
Explanation: In waterlogged lands, the soil pores are saturated up to the surface, leading to reduced oxygen availability for plant roots. This condition can negatively impact plant growth.
Explanation: A land is considered waterlogged when the permanent wilting point is reached, gravity drainage has ceased, and the capillary fringe reaches the root zone of plants. All these factors contribute to waterlogging.
Explanation: Waterlogging can be reduced by providing canal lining, intercepting drains, and controlling the intensity of irrigation. These measures help in better water management.
Explanation: Waterlogging of fields can lead to plant diseases, the growth of water weeds, and the rise of salt in the surface layer. All these factors are disadvantages associated with waterlogging.
Explanation: As the salinity of water increases, the electrical conductivity also increases. Salts in water conduct electricity, and higher salinity leads to higher electrical conductivity.
Explanation: An electrical conductivity between 750 to 2250 micro mhos/cm is classified as high salinity water. This indicates a relatively high concentration of salts.
Explanation: A sodium-absorption ratio between 10 to 18 is classified as medium sodium water. This ratio provides information about the sodium content in relation to other cations.
Explanation: The sodium absorption ratio (SAR) is defined as Na+ / √[(Ca++ + MG++) / 2]. It measures the proportion of sodium ions relative to calcium and magnesium ions in the soil.
Explanation: The classification is based on the sodium-absorption ratio (SAR). In this case, the SAR falls between 10 to 18, categorizing it as medium sodium water.
Explanation: The concentration of boron in irrigation water should be limited to 2 ppm to avoid adverse effects on plants. Excessive boron can be toxic to many crops.
Explanation: Sodium carbonate in water can be harmful for cultivation purposes. It contributes to the salinity of water and may negatively impact soil quality.
Explanation: The fertility of the soil is adversely affected when the pH value is more than 11. Extremely high pH levels can limit nutrient availability to plants.
Explanation: For irrigation purposes, the pH value of water should ideally be between 6 and 8.5. This range is considered suitable for most crops.
Explanation: The consumptive use of water for a crop is measured in terms of the depth of water on the irrigated area. It represents the amount of water utilized by the crop during its growth cycle.
Explanation: Crop water consumption is proportional to evapo-transpiration, which includes the sum of water transpired by plants and evaporated from the soil surface. Effective rainfall and seepage can also contribute to crop water availability.
Explanation: The ratio of the total volume of water delivered to a crop to the area on which it has been spread is known as duty. It is a measure of water distribution efficiency.
Explanation: The time for which a crop occupies a field to attain its maturity is known as the base period. It is a critical factor in determining the water requirements of the crop.
Explanation: The base period for any crop is typically measured in days. It represents the duration from sowing to harvesting when the crop is actively growing and utilizing water.
Explanation: The numerical value of the base period is generally less than the total crop period. It specifically refers to the period when the crop is actively growing and water is a critical factor.
Explanation: The relation between duty (D) and base period (B) is given by Δ = 8.64 B / D, where Δ represents delta.
Explanation: Delta (Δ) can be calculated using the formula Δ = 8.64 B / D. Substituting B = 110 days and D = 1400 he/cumec, Δ = 8.64 * 110 / 1400 = 0.68 m or 68 cm.
Explanation: The duty is largest on the field, representing the efficiency of water use at the point of application to the crops.
Explanation: The outlet discharge factor is the duty at the head of the watercourse, indicating the efficiency of water delivery to the field.
Explanation: The outlet factor is calculated as the product of kor depth and kor period. In this case, it is 19 cm * 14 days = 266 hectares/m³/sec. The correct answer is not provided in the options.
Explanation: Delta (Δ) can be calculated using the formula Δ = 8.64 B / D. Substituting B = 100 days and D = 432 he/cumec, Δ = 8.64* 100 / 432 = 2 m or 200 cm.
Explanation: The average delta for a rice crop, considering various conditions, is approximately 120 cm.
Explanation: In rice, the depth of the root zone is generally around 90 cm.
Explanation: The optimum depth of kor watering for a rice crop is considered to be around 19 cm.
Explanation: The optimum depth of kor watering for wheat in the plains or terai is considered to be around 13.5 cm.
Explanation: Water application efficiency is the ratio of the quantity of water stored in the root zone of the crops to the quantity of water actually delivered in the field.
Explanation: Leaching is the process that washes out salts from the upper zone of the soil, helping in the removal of excess salts.
Explanation: Reclamation is the process by which unculturable soil is made culturable, often involving the improvement of soil fertility and structure.
Explanation: Efflorescence is the phenomenon where salts come up in solution and form a layer of crust on the soil surface after the evaporation of water.
Explanation: In an ion exchange process where ions are transported from water to a solid, and the ion-exchange media is either a fixed or fluidized bed, the process is termed as demineralization.
Explanation: In a barrage, the crest level is typically kept low with large gates to control and regulate water flow.
Explanation: A hydraulic structure is designed to withstand various factors, including seepage, hydraulic jump, and hydraulic pressure.
Explanation: The most suitable location of a canal headwork is generally at the trough stage of the river, where the water level is relatively stable.
Explanation: Diversion headworks are constructed to regulate the intake of water into the canal from a river or source.
Explanation: The main function of the diversion headworks of a canal from a river is to raise the water level, facilitating the diversion of water into the canal.
Explanation: The distributory head regulator serves multiple functions, including regulating the supply, controlling silt entry, and serving as a meter for discharge measurement.
Explanation: A fish ladder is a device provided near weirs or dams to facilitate the migration of fish upstream or downstream around the barriers.
Explanation: A regulator provided with under sluices for the escape of washout of sand-laden bottom water can be referred to as a silt regulator, silt extractor, or silt ejector.
Explanation: A silt regulator located at the head of a channel, designed to exclude or prevent silt entry, is called a silt excluder.
Explanation: After entering the canal, sediments are removed by the silt excluder, which is designed to exclude or prevent the entry of silt into the canal.
Explanation: Silt excluders are constructed on the river bed downstream of the head regulator to prevent the entry of silt into the canal.
Explanation: When two canals take off from each bank of a river, there will be one divide wall and two under sluices to control and regulate the flow.
Explanation: The correct sequence of the parts of a canal system is head works, branch canal, main canal, and distributary.
Explanation: The supply passing down the parent channel is controlled by the distributary head regulator, which regulates the flow into the distributary.
Explanation: A cross regulator is provided on the main canal downstream of the offtake to control the flow and regulate the water supply.
Explanation: The canal head regulator is provided at the head of the offtaking canal to regulate water supply, control silt entry, and prevent river floods from entering the canal.
Explanation: Tail race is a channel conducting water away from a water wheel, has a gradient steeper than that of the canal, and is the channel between the silt extractor and the river through which escape water is discharged.
Explanation: The angle between the head regulator and the water is generally kept at 110° for the smooth entry of water into the canal.
Explanation: A canal designed to irrigate throughout the year is known as a perennial canal.
Explanation: Canals taken off from ice-fed perennial rivers are referred to as perennial canals.
Explanation: A canal constructed by the side of and generally parallel to the parent canal with a different bed slope is called a ditch canal.
Explanation: A canal aligned at right angles to the contour is known as a side slope canal.
Explanation: The group of canals which avoid cross drainage work includes side slope and watershed canals.
Explanation: Single bank canal is another name for a contour canal.
Explanation: Canals taking off from a river with or without a head regulator and used for the diversion of floodwaters are called inundation canals. These canals help manage excess water during periods of high flow.
Explanation: An inundation canal is typically used for the diversion of floodwaters from a river. It helps control and manage the excess water during periods of flooding.
Explanation: A drain canal is used to drain off water from waterlogged areas, helping to improve the drainage conditions in those areas.
Explanation: The most desirable alignment of an irrigation canal is along the ridge line. This alignment helps in efficient water distribution and management.
Explanation: A contour canal is aligned parallel to the contour of the area, making it suitable for hilly terrain. It helps in irrigation on both sides, enhancing water distribution.
Explanation: In a gravity canal, the Full Supply Level (F.S.L) is typically maintained a few centimeters above the ground level. This ensures a consistent and controlled flow of water.
Explanation: The dead storage in a reservoir is provided to accumulate sediment, mitigate floods, and increase the useful life period of the reservoir. It serves multiple purposes.
Explanation: As the coefficient of friction increases, the velocity of water in a canal decreases. Increased friction results in a reduction in the speed of water flow.
Explanation: The mean velocity that prevents silting or scouring in a channel throughout the year is known as critical velocity.
Explanation: The maximum velocity in a circular channel occurs when the depth of flow is approximately 0.81 times the diameter (0.81d).
Explanation: Bed bars in a canal are provided to observe and monitor the general behavior of the canal. They help assess the flow conditions and detect any irregularities.
Explanation: Bed bars in a canal can be made of either cement concrete or brick masonry, depending on the design and requirements.
Explanation: Borrow pits, used for obtaining construction materials, are preferably located in the central half section of the canal. This helps maintain balance and stability during construction.
Explanation: A spoil bank is formed when the volume of excavation exceeds the volume of embankment filling during canal construction.
Explanation: Extra excavated earth from canals is utilized to provide spoil banks on both the left and right sides. This helps manage excess soil and provides stability to the canal embankment.
Explanation: A counterbalance in canal construction refers to a vertical benching provided on the inner edge of the bank. It helps stabilize the canal banks.
Explanation: A counter berm is a horizontal benching provided on the outer slope of the canal bank. It aids in preventing erosion and adds stability.
Explanation: Freeboard is the difference in level between the top of a canal bank and the full supply level. It provides a safety margin to prevent overtopping.
Explanation: The width of “Dowels” in canal construction is typically kept between 32 to 60 cm, and the height above the road level should be more than 30 cm for stability.
Explanation: Lime concrete lining is used when the velocity of flow is below 2 m/sec, in irrigation channels with capacities up to 200 cumecs, and where economic considerations are important.
Explanation: Lining of an irrigation channel decreases the waterlogging area by preventing seepage into the surrounding soil, thereby enhancing water use efficiency.
Explanation: The thickness of concrete lining for canal discharge up to 200 cumecs typically varies from 10 to 15 cm, providing the necessary strength and durability.
Explanation: The mean velocity of the canal should never be less than the critical velocity to avoid issues such as sediment deposition.
Explanation: In a concrete-lined canal, the permissible velocity of water is typically around 2 m/sec to maintain stability and prevent erosion.
Explanation: In a stone masonry-lined canal, the permissible velocity of water is generally around 1 m/sec to avoid damage to the lining.
Explanation: A minimum of 90 cm freeboard is provided when the discharge in the canal is over 60 cumecs, ensuring additional safety against overtopping.
Explanation: Roughness of the bed and sides of a channel can be reduced by removing sandbars, fallen trees, and other snags, as well as preventing cropping on the river bed near banks.
Explanation: The most suitable section of a lined canal depends on the canal’s size. Triangular sections with a circular bottom are suitable for small canals, while trapezoidal sections with rounded corners are preferred for larger canals.
Explanation: Boulder lining is useful where the groundwater level is above the bed of the canal and when prevention of erosion is required.
Explanation: The shape of the lined canal recommended by ISI is typically trapezoidal, providing a practical and stable cross-section for efficient water flow.
Explanation: Total losses in the canal typically amount to around 10% of the total discharge, encompassing various factors such as seepage, evaporation, and other hydraulic losses.
Explanation: Evaporation loss in a canal is typically in the range of 1 to 2 percent of the water entering the canal, influenced by climatic conditions.
Explanation: According to Manning’s formula, the velocity in an open channel is inversely proportional to the rugosity coefficient, hydraulic mean depth (HMD), and gradient.
Explanation: The rugosity coefficient for silt clay is typically around 0.025, and it is a key parameter in Manning’s formula for calculating open channel flow.
Explanation: A rectangular channel is considered wide if its width is more than ten times the depth of the flow. This classification is important for hydraulic analysis.
Explanation: Weed growth in a canal tends to obstruct the flow, leading to a decrease in discharge and potentially causing other issues.
Explanation: The tractive force on the canal bed can be calculated using the formula τ0 = WR, where W is the unit weight of water, R is the hydraulic radius, and S is the average bed slope.
Explanation: The ratio of average shear stresses on the bed to those on the banks in a channel is typically more than 1, indicating that the bed experiences higher shear stress.
Explanation: When building an embankment on unreliable soil, a sand core is often used to provide stability and reduce percolation.
Explanation: A revetment is a facing of dry stone pitching or other materials laid on a sloping face of earth to maintain the slope and protect it from erosion.
Explanation: Lining an irrigation channel provides several advantages, including a reduction in water loss due to seepage, economical use of land, and the ability to withstand higher velocities with a proportional reduction in cross-sectional area.
Explanation: The balancing depth of a canal cross-section is the depth at which the quantity of excavation is equal to the earthwork required for the banks.
Explanation: A stilling basin is a structure designed to dissipate the energy of flowing water, reducing its velocity and preventing erosion downstream.
Explanation: The velocity at which eddies in the flow die out is referred to as the lower critical velocity.
Explanation: Critical depth is the depth at which the flow in a channel transitions to critical flow, and it corresponds to the critical velocity.
Explanation: Critical flow occurs when the total energy head is minimum for a given discharge, and it is associated with the Froude number being equal to unity.
Explanation: The silt-carrying capacity of water in a canal depends on factors such as the silt charge, discharge, and surface slope.
Explanation: The proportion of silt, water, and the size of silt particles carried in a water channel depends on factors such as the slope, nature of the surface soil, and rainfall in the catchment area.
Explanation: The minimum size of a stone that will remain at rest in a channel is given by 11 times the hydraulic mean depth (R) multiplied by the slope (S).
Explanation: Silting in a channel can occur due to various factors, including a defective outlet, defective head regulator, or the channel not being in regime (not in a stable or normal condition).
Explanation: Manning’s formula for open channel flow is expressed as V = 1/n (S1/2R2/3), where V is the velocity, n is Manning’s roughness coefficient, S is the slope, and R is the hydraulic radius.
Explanation: Darcy’s formula relates the rate of flow in a porous medium to the hydraulic gradient, expressing that the flow is proportional to the hydraulic gradient.
Explanation: The formula V = 0.55 mD0.64 is associated with Kennedy, expressing the velocity (V) in terms of hydraulic mean depth (D).
Explanation: The overflow portion of a dam that allows surplus discharge to flow from the reservoir to the downstream is known as a spillway.
Explanation: In an ogee-shaped spillway, the discharge is proportional to the total head (H) raised to the power of 3/2.
Explanation: The discharge coefficient of an ogee spillway is typically around 2.02.
Explanation: The discharge coefficient of an ogee spillway depends on factors such as the depth of approach, upstream slope, downstream apron, and submergence.
Explanation: For an earthen dam, the ogee spillway is typically the least suited spillway type.
Explanation: In a chute spillway, the flow is generally turbulent.
Explanation: In a syphon spillway, the discharge is proportional to the square root of the total head (H).
Explanation: The effective head in a syphon spillway is measured as the difference in levels of water upstream and downstream of the spillway.
Explanation: In situations where space is limited due to topography, a shaft spillway is often considered the most suitable option.
Explanation: An aquifer is a water-bearing stratum that can store and transmit groundwater, feeding wells and springs.
Explanation: The overflow of a spillway with a double or s-curve shape, convex at the top and concave at the bottom, is called an ogee spillway.
Explanation: The SHAFT spillway is the same as a morning glory spillway.
Explanation: The flow of water after spilling over the spillway is typically at a right angle and parallel to the weir crest.
Explanation: The crest level of an emergency spillway is generally kept at the full reservoir level.
Explanation: To remove waterlogging of land, measures may include reducing percolation from canals and watercourses and increasing outflow from the groundwater reservoir.
Explanation: The number of dams in Bandhra irrigation may vary and could be equal to, between 1 and 3, or greater than 2.
Explanation: The area velocity method is used to measure the discharge in a channel.
Explanation: The weir method is commonly used to measure the discharge of water in open channels.
Explanation: The surface float method is used to measure the velocity of water flow in a channel.
Explanation: The Pitot tube is a device used to measure the velocity of fluid flow, including water in a channel.
Explanation: The surface float method is used for velocity measurement, while the current meter is used for the measurement of water velocity in a channel.
Explanation: A multipurpose reservoir is planned and constructed to serve various purposes, such as irrigation, hydropower generation, and water supply.
Explanation: A retarding reservoir, also called a detention reservoir, is designed to temporarily hold and control the flow of water without specific water control devices. These reservoirs help manage downstream flooding by detaining excess water during peak flow periods and gradually releasing it.
Explanation: The normal type of storage used in a reservoir is “useful storage.” This refers to the volume of water stored between the minimum pool level and the normal pool level. Useful storage is actively utilized for various purposes such as water supply, irrigation, or hydropower generation.
Explanation: Useful storage refers to the portion of water in a reservoir that is actively utilized for various purposes. It is the volume of water stored between the minimum pool level (lowest operational level) and the normal pool level (optimal operational level).
Explanation: Dead storage is the volume of water in a reservoir that is below the minimum pool level and is not typically utilized for water supply or other purposes.
Explanation: Dead storage refers to the volume of water in a reservoir that is below the minimum pool level. This portion is not actively used for water supply or other purposes.
Explanation: Surcharge storage represents the volume of water stored in a reservoir between the normal pool level and the maximum pool level. It is an important component for managing water levels during peak demand or flood conditions.
Explanation: In a flood control reservoir, the effective storage is the sum of useful storage, surcharge storage, and the exclusion of valley storage. This configuration allows for optimal flood management.
Explanation: Trap efficiency, in the context of a reservoir, is determined by the ratio of its capacity to inflow. It reflects the reservoir’s ability to capture and retain sediment inflows.
Explanation: To minimize sediment deposits in a reservoir, multiple measures such as providing vegetal cover, avoiding sediment-prone sites, and implementing soil conservation practices in the catchment area should be employed.
Explanation: Sediment deposition in a reservoir is influenced by various factors, including sediment size, the shape of the reservoir, and the slope of the river valley.
Explanation: In the full reservoir condition, providing top width for the roadway causes the resultant force to shift towards the heel, impacting the stability of the structure.
Explanation: Siltation reduction strategies include land management, installing sluice gates, and implementing gully plugging check dams and contour bunds in the catchment area.
Explanation: The useful life of the reservoir, considering sediment deposition, is calculated by dividing the dead storage by the annual sediment deposition: 12 million cubic meters / 0.1 million cubic meters per year = 120 years.
Explanation: The flow-mass curve graphically represents the cumulative discharge volume over time in chronological order, aiding in the analysis of water flow patterns.
Explanation: If the demand line drawn from a ridge in a flow-mass curve does not intersect the curve again, it indicates that the demand cannot be met by the available inflow.
Explanation: The primary purpose of mean water training for rivers is to maintain the channel’s shape by effectively disposing of suspended and bed load, ensuring its stability and navigability under normal water conditions.
Explanation: River training work involves considerations of discharge, depth of water, and the amount of sediment. It encompasses a comprehensive approach to manage and control river behavior.
Explanation: Achieving the desired depth in river training is accomplished through the use of groynes and bandalling. These structures help regulate and control the flow, preventing excessive sedimentation.
Explanation: Various methods, including groynes, guide banks, and pitched banks, are employed for river training. These structures aid in shaping and stabilizing the river channel.
Explanation: River training becomes essential when the river exhibits meandering behavior, requiring interventions to control and shape its course for improved stability.
Explanation: The primary cause of meandering in rivers is the excess total discharge during floods, leading to the development of turbulence and alterations in the river’s course.
Explanation: A meandering river is characterized by the dominant discharge, representing the prevailing flow conditions that influence the river’s meandering pattern.
Explanation: Meandering of rivers results from factors such as excessive discharge during floods, widening of the river, and significant deposition. These contribute to the development of meanders.
Explanation: Meandering of the river increases its length during cut-off events, leading to a decrease in the overall length. Cut-off events are associated with changes in the river’s course.
Explanation: The width and length of meanders in rivers vary approximately with the square root of discharge. This relationship reflects the influence of flow dynamics on the characteristics of meandering.
Explanation: Rivers on alluvial plains are typically stable, as they have reached an equilibrium where the sediment deposition equals the sediment erosion.
Explanation: An aggrading river is characterized by building up its beds through sediment deposition, resulting in an elevation of the riverbed.
Explanation: A river resulting from a deficit of sediments in flowing water tends to erode its bed, making it a degrading type of river.
Explanation: An aggrading river is characterized by the accumulation of sediment, making it a silting river.
Explanation: These structures, groynes and spurs, are constructed transverse to the river flow to control erosion and sedimentation.
Explanation: Groynes can lead to the accumulation of sediment in their vicinity, creating a slack flow and causing siltation.
Explanation: Groynes are typically provided transverse to the river to control its flow and manage sedimentation.
Explanation: A groyne with a curved head is known as a Hockey groyne.
Explanation: Groynes are generally provided to deflect the flow of the river and control erosion.
Explanation: Crops typically require maximum water during the initial stages of growth when they have grown a few centimeters.
Explanation: A repelling groyne is strategically aligned pointing upstream to divert the water flow away from the bank. This orientation helps in mitigating bank erosion by directing the flow away from vulnerable areas.
Explanation: Attracting type spurs are designed to induce sediment deposition and stabilize the riverbed. They are aligned pointing downstream to encourage the accumulation of sediments, promoting riverbed stability.
Explanation: A divide wall is strategically placed to separate the under sluices from the weir proper. This separation helps in preventing interference between the controlled release of water through sluices and the operation of the weir structure.
Explanation: A divide wall is typically provided at a right angle to the axis of the weir. This orientation helps in effectively separating the under sluices from the main weir structure, contributing to the efficient functioning of both elements.
Explanation: The degree of sinuosity is defined as the ratio between the curved length along the river channel and the straight air length between the endpoints of the meander. It provides insights into the river’s meandering pattern.
Explanation: In alluvial soil, a river bend often exhibits silting on the convex side and scouring on the concave side. This dynamic interaction is influenced by sediment transport and erosion patterns.
Explanation: Tortuosity measures the sinuousity or curviness of a meandering river and is represented by the ratio of the curved length along the channel to the direct axial length of the river reach.
Explanation: Tortuosity is typically expressed as a value greater than one, indicating the extent of meandering in the river’s course.
Explanation: A marginal bund or levee is an earthen dam constructed roughly parallel to the river. It serves to protect against flooding and helps in managing water flow along the riverbanks.
Explanation: Bell bunds are guide bands constructed at the site of a bridge or weir to direct the river’s flow through the designated waterway in the structure.
Explanation: A toe wall is a longitudinal shallow retaining wall constructed near ground level to provide support for the pitching on the face of an earthen embankment. It helps in stabilizing the structure.
Explanation: An excavation in the base of a dam or other structures filled with relatively impervious material is known as both a cut-off trench and a key trench. This feature helps reduce percolation and enhance the dam’s stability.
Explanation: Guide banks constructed at the site of a bridge or weir for training a river are referred to as bell bunds. These structures guide the flow through the designated waterway in the bridge or weir.
Explanation: A guide bank is a protective and training bank constructed at the site of a bridge or weir to guide the river’s flow through the designated waterway in the structure.
Explanation: The water face of guide banks is typically protected by one layer of stone pitching. This protective layer helps prevent erosion and enhances the stability of the guide banks.
Explanation: A curtain wall is a structure built across the stream under the floor of a hydraulic structure, extending from the upstream to downstream ends of the pavement. Its purpose is to prevent scour, protect floors, abutments, and other components of the structure.
Explanation: A flarred wall is a retaining wall with a profile that gradually changes from one slope to another. This design is often used for stability and aesthetic purposes.
Explanation: A head wall is a wall built across a small channel, equipped with a regulating arrangement to control the flow and head up water on the upstream side.
Explanation: A training wall is constructed along the bank of a river, parallel to the flow direction. Its purpose is to guide fast-flowing water from a sluice or spillway, preventing erosion of the river or canal banks.
Explanation: A retaining wall that extends from the abutment both upstream and downstream is referred to as both a flank wall and a wing wall.
Explanation: The economic height of a dam corresponds to the height that minimizes the overall cost per unit of storage. This height is determined through economic feasibility studies.
Explanation: In the analysis of an elementary profile of a gravity dam under an empty reservoir condition, the primary forces considered include water pressure acting on the dam structure.
Explanation: The main overturning force in a gravity dam is the water pressure exerted by the reservoir. This force acts to overturn the dam structure.
Explanation: The elementary profile of a dam is often represented as a right-angled triangle. This simple geometric shape is used for analytical purposes in the initial design stages.
Explanation: A low gravity dam is characterized by a height where the maximum principal stress is less than the allowable crushing strength, and the upstream face is designed to be vertical for stability.
Explanation: The uplift pressure on the face of a drainage gallery in a dam is calculated as a combination of hydrostatic pressures at the toe and heel, with a ratio of two-thirds at the toe and one-third at the heel.
Explanation: The major resisting force in a gravity dam is the self-weight of the dam structure. The mass of the dam provides stability against external forces.
Explanation: When the reservoir is full, the maximum compressive force in a gravity dam is produced at the toe of the dam. This is a critical consideration for ensuring stability.
Explanation: In a gravity dam, tailwater (water downstream of the dam) can cause a decrease in principal stress and shear stress, impacting the structural stability of the dam.
Explanation: The uplift pressure acting on a dam can be controlled by employing various measures, including pressure grouting in the foundation, constructing drainage channels between the dam and its foundation, and building a cutoff under the upstream face.
Explanation: The total force resulting from wave pressure in a gravity dam acts at a specific height above the still water level. This height is calculated as 0.375 times the height of the wave (hw). Proper understanding of wave forces is essential for designing dams to withstand dynamic water conditions.
Explanation: Achieving an economical design for a gravity dam involves considering the shear friction factor. A value around 0.65 is often considered optimal for balancing construction costs and ensuring structural stability. This factor is crucial in determining the resistance to sliding along the dam base.
Explanation: The construction height of an earthen dam depends on the suitability of the foundation. When the foundation is deemed suitable, an earthen dam can be constructed up to a height of 200 meters. Foundation assessment is a critical aspect of dam engineering.
Explanation: To prevent the development of tension at the base of a gravity dam, engineers consider the maximum permissible eccentricity. In this context, the recommended maximum eccentricity is typically defined as B/6, where B represents the base width of the dam.
Explanation: The primary cause of maximum failure in earthen dams is often associated with overtopping. This occurs when the height of the dam is insufficient to handle the water level, leading to potential breaches and failures. Adequate height is crucial for the overall safety of earthen dams.
Explanation: To control seepage through the foundation of an earthen dam, the provision of an impervious cut off is a common practice. This barrier helps prevent excessive water flow through the foundation, ensuring the stability and safety of the dam.
Explanation: Controlling seepage through the embankment of an earthen dam involves the use of drain trenches. These trenches help channel and manage water flow, reducing the risk of erosion and ensuring the integrity of the dam structure.
Explanation: The central impervious core of a zoned embankment type dam requires a material that minimizes seepage. A mixture of clay and fine sand is considered the most suitable, providing the necessary impermeability to control water flow and enhance the dam’s stability.
Explanation: An impervious wall constructed inside an earthen dam to reduce seepage can be referred to by different names, including core wall, diaphragm wall, and pug wall. These structures play a crucial role in minimizing water infiltration and enhancing the dam’s impermeability.
Explanation: The upstream face of an earthen dam is defined by the phreatic line, representing the water table or flow line under steady-state conditions. Understanding the characteristics of the upstream face is essential for assessing water levels and ensuring the dam’s stability.
Explanation: The most adverse condition for the stability of the slope on the upstream face of an earthen dam occurs during sudden drawdown. This refers to a rapid lowering of the reservoir water level, leading to potential instability and increased risk of slope failure. Proper design and analysis are essential to mitigate the effects of sudden drawdown on the dam’s stability.
Explanation: Earthen dams, as compared to gravity dams, generally require less skilled labour for construction. This is because the materials used, such as earth and rock fill, are more readily available and can be handled with less technical expertise. This characteristic contributes to the cost-effectiveness of earthen dams.
Explanation: Horizontal acceleration during an earthquake induces hydrodynamic pressure on the dam and inertia forces within the dam body. These combined effects can lead to additional stresses on the dam structure. Earthquake engineering principles consider these factors to ensure the dam’s stability under seismic events.
Explanation: Vertical acceleration during an earthquake can result in both an increase and a decrease in the effective weight of the dam. This dynamic loading condition is a crucial consideration in earthquake engineering, as it impacts the overall stability and response of the dam structure.
Explanation: Hydrodynamic pressure resulting from an earthquake acts at a specific height above the dam base. This height is calculated as 4H / 3π, where H represents the height of the dam. Understanding the distribution of hydrodynamic pressure is vital for designing dams to withstand seismic forces.
Explanation: According to Lacey’s theory, the silt factor is directly proportional to the square root of the average particle size. This factor is a critical parameter in Lacey’s regime theory, influencing the transport of sediment in rivers and channels.
Explanation: In Lacey’s regime theory, a channel is said to be in its regime when it satisfies multiple conditions, including constant discharge, constant silt grade, and silt charge. Additionally, the channel should be flowing in incoherent unlimited alluvial soil of the same nature as that being transported.
Explanation: In Lacey’s theory, silt supporting eddies are generated from both the bottom and the sides of the channel. These eddies play a crucial role in the transport of sediment and the maintenance of the channel regime. Understanding the origin of these eddies is essential in river engineering.
Explanation: In Lacey’s regime theory, the flow velocity in a channel is proportional to (Qf2)1/6, where Q is the discharge and f is the silt factor. This relationship helps in understanding the velocity characteristics of water flow in different channel regimes.
Explanation: According to Lacey’s theory, the bed slope in a channel is given by the expression f5/3 / 3340Q1/6, where f is the silt factor and Q is the discharge. This formula is crucial for determining the slope required to maintain a specific regime in the channel.
Explanation: The wetted perimeter of a regime channel, given a discharge Q, is calculated as 4.75Q1/2 according to Lacey’s theory. This parameter is essential for understanding the hydraulic characteristics of the channel and its suitability for different flow conditions.
Explanation: In Lacey’s theory, the depth of scour in the case of a right-angle bend is determined to be 2 times the normal depth (2D). This estimation is crucial for assessing the potential impact of bends on channel stability and sediment transport.
Explanation: According to Lacey’s theory, the scour depth (R) of a river in flood is given by the equation R = 0.47(Q/f)1/3, where Q is the discharge and f is the silt factor. This relationship helps in estimating the potential scour depth under varying flow conditions.
Explanation: Kennedy’s equation for the critical velocity is given by 0.55mD0.64, where m is a constant and D is the diameter of the sediment particle. This equation is significant in sediment transport studies, providing insight into the velocity required to initiate particle motion.
Explanation: According to Kennedy’s theory, silt supporting eddies are primarily generated due to the roughness of the bed. The irregularities and roughness on the bed surface create conditions conducive to the formation of eddies that support the transport of silt. Understanding these mechanisms is essential for predicting sediment transport in rivers.
Explanation: Weirs designed and constructed on Bligh’s theory were prone to failure due to the undermining of the sub-soil. This phenomenon resulted in the instability of the weir structure, especially in the region beneath the floor. The failure mechanism often involved the erosion and removal of the sub-soil material, compromising the foundation’s integrity.
Explanation: According to Khosla’s theory, the undermining of the floor of a weir typically starts from the tail end. This implies that the erosion and removal of material beneath the floor initiate at the downstream portion of the weir. Understanding the point of initiation is crucial for designing and maintaining stable weirs.
Explanation: According to Khosla’s theory, the exit gradient is dependent on the b/d ratio, where ‘b’ is the width of the weir and ‘d’ is the depth of flow. The ratio of b/d plays a significant role in determining the exit gradient, influencing the hydraulic performance of the weir.
Explanation: According to Khosla’s theory, the exit gradient in the absence of a downstream cutoff is considered to be infinity. This implies that without proper measures to prevent erosion and scouring downstream of the weir, the exit gradient can become unbounded. Implementing cutoffs is essential to control exit gradient and prevent undermining.
Explanation: The discharge through a channel is maximum when the hydraulic mean depth (m) is equal to half of the channel bottom width (b/2). This condition results in optimal flow efficiency and is a key consideration in channel design and hydraulic engineering.
Explanation: The discharge through a channel is maximum when the hydraulic mean depth (m) is equal to half of the flow depth (d/2). Achieving this relationship enhances the efficiency of flow and contributes to maximizing the discharge capacity of the channel.
Explanation: Separation of flow occurs when the boundary layer adjacent to the channel bed comes to rest or reverses its direction. This phenomenon is often associated with changes in channel geometry, such as reductions in cross-sectional area or alterations in flow conditions.
Explanation: The discharge through a trapezoidal channel is maximum when half of the top width is equal to the length of the sloping side. Achieving this relationship optimizes the flow characteristics in the trapezoidal channel, leading to enhanced discharge capacity.
Explanation: The maximum discharge through a circular channel occurs when the depth of flow is approximately 0.95 times the diameter of the channel. This relationship is a critical parameter in optimizing the hydraulic performance of circular channels.
Explanation: The Chazy’s coefficient has the dimensions of L1/2T-1, where L represents length and T represents time. This coefficient is a dimensional parameter used in the Chazy formula for determining the velocity distribution in open channel flow.
Explanation: The most economical section for an open channel is one that maximizes the discharge for a given cross-sectional area, slope of the bed, and coefficient of resistance. Achieving maximum discharge is a key objective in designing efficient and cost-effective open channels.
Explanation: The obstruction constructed across a river to raise its water level and divert water into a canal is called a weir or anicut. Weirs are hydraulic structures designed to control and regulate the flow of water in rivers for various purposes, including irrigation.
Explanation: Weirs are generally aligned at a right angle to the direction of the main river flow because it provides better discharge capacity, requires less length of weir, and is considered economical. This alignment optimizes the hydraulic performance of the weir.
Explanation: The top of the weir is referred to as the crest. It is the highest point of the weir structure and plays a crucial role in controlling the water flow. The crest design is essential for achieving the desired water levels and discharge characteristics.
Explanation: The crest of the undersluice portion of the weir is typically kept at a lower level compared to the crest of the normal portion. This design facilitates the controlled release of water through the undersluice, allowing for specific flow regulation and operational flexibility.
Explanation: The discharge capacity of the undersluice in a weir is determined by various factors, and it is often the greatest among different scenarios. It can be twice the maximum discharge of the off-taking canal, 20% of the maximum flood discharge, or the maximum winter discharge, depending on the specific conditions and design considerations.
Explanation: In a gravity weir, the uplift pressure is primarily resisted by the weight of the floor. The self-weight of the floor acts as a stabilizing force against the uplift pressure, contributing to the overall stability and integrity of the weir structure.
Explanation: In a non-gravity weir, where the structure is not entirely reliant on its self-weight, the uplift pressure is resisted by the bending action of the reinforced concrete floor. The design and material properties contribute to the structural strength and ability to counteract uplift forces.
Explanation: A weir with a tail water level higher than the weir crest, influencing the discharge, is referred to as a submerged weir. The submergence affects the flow characteristics over the weir and is an important consideration in hydraulic engineering.
Explanation: A weir in which the tail water remains below the crest is known as a free weir. The flow over the weir is not significantly influenced by the submergence of the downstream water, and the weir operates under free-flow conditions.
Explanation: A weir constructed to divert part or all of the water from the stream into a different course is called an intake weir. Intake weirs are designed to facilitate the diversion of water for specific purposes such as irrigation or water supply.
Explanation: The necessity of cross-drainage works arises in various situations, including when canals are aligned on the watershed across multiple drainages, when canals are directed away from the watershed due to unsuitability, and when there is a need to link multiple canal systems.
Explanation: Achieving a drain over the irrigation canal can be done by providing either a siphon or a super passage. Both options involve structures that allow drainage over the canal, ensuring proper water management in the irrigation system.
Explanation: When the irrigation canal and drain are at the same level, cross-drainage works can be achieved by providing either a level crossing or an inlet and outlet. Both options are suitable for managing water flow and ensuring effective drainage.
Explanation: In the case of a canal siphon, the bed of the canal is lowered to facilitate the passage of water. This design allows for the creation of a siphon structure, ensuring the controlled flow of water across the canal.
Explanation: A structure provided where natural drainage and a canal meet at the same level is called a level crossing. This type of cross-drainage structure allows for the passage of water from the natural drainage to the canal without significant changes in elevation.
Explanation: In syphon aqueducts, the highest flood level of the drain is typically designed to be much above the canal bed. This elevation ensures that the aqueduct can accommodate high flood levels without compromising the structure.
Explanation: When the bed level of the canal is higher than the highest flood level (HFL) of the drainage, the cross-drainage work is known as an aqueduct. Aqueducts are designed to carry water over the canal, preventing interference with the canal bed.
Explanation: The floor of an aqueduct is subjected to uplift pressure due to both the seepage of water from the canal to the drainage and the subsoil water table in the drainage bed. These factors contribute to the forces acting on the aqueduct floor.
Explanation: In a syphon aqueduct, the maximum uplift pressure on the floor occurs when the canal is empty, and the water table in the stream rises to the canal bed. This specific condition leads to increased uplift forces on the aqueduct floor.
Explanation: When the canal runs below the drain, the cross drainage work provided is called a super passage. A super passage allows the drainage water to flow over the canal, providing a passage for both water bodies without interference.
Explanation: In a canal syphon, the flow is characterized as pipe flow. The water flows through a pipe structure, and the operation of the syphon involves the principles associated with pipe flow.
Explanation: The structure constructed to allow drainage water to flow under pressure through an inverted syphon below a canal is called a syphon aqueduct. It combines elements of both a syphon and an aqueduct, providing a controlled passage for drainage water beneath the canal.
Explanation: When the RL (Reduced Level) of the canal bed level is higher than the highest flood level (HFL) of the drainage, the cross drainage work is referred to as an aqueduct. An aqueduct allows water from the drainage to flow over the canal.
Explanation: When the RL of the canal bed level is higher than the HFL of the drainage, the cross drainage work is termed a syphon aqueduct. This structure facilitates the controlled flow of drainage water through an inverted syphon beneath the canal.
Explanation: The aqueduct or super passage type of cross drainage headworks is typically employed when the high flood drainage discharge is large and continues for an extended period. These structures are designed to handle substantial and prolonged water flow.
Explanation: Depending on the specific conditions, cross drainage works may have inlets or outlets. When the cross drainage flow is small, an inlet is constructed. Similarly, when canal flow is small, an outlet is constructed. The number of outlets and inlets may vary based on design considerations.
Explanation: The retrogression of the bed level of a river downstream of a weir or barrage can occur due to a lower percentage of silt in the river water. Silt deposition is a key factor influencing bed levels, and a reduced silt percentage can contribute to retrogression.
Explanation: The proportion of silt per unit volume by weight in water is known as silt charge. It represents the concentration of silt in the water and is a crucial parameter in understanding sediment transport and deposition in rivers and canals.
Explanation: Fall is provided in the canal of a ridge. The design and construction of falls in canal beds, particularly on ridges, are aimed at maintaining proper flow conditions and preventing issues such as sediment deposition and water stagnation.
Explanation: A fall in a canal bed is generally provided when the ground slope exceeds the designed bed slope. This design choice helps in achieving proper flow conditions and preventing issues related to excess slope in the ground.
Explanation: The design and construction of a fall in a canal are intended to satisfy multiple conditions. These include ensuring that the velocity of approach is minimum, allowing for variations in water levels in the canal, and ensuring the safety of the bed, bank, and downstream position against erosion due to excess flow energy.
Explanation: The sudden and turbulent passage of water from a low level critical depth to a high level above critical depth, accompanied by a transition from supercritical to subcritical velocity, is known as a hydraulic jump. This phenomenon is a common occurrence in open-channel flow.
Explanation: The hydraulic jump is often referred to as a standing wave. It is characterized by the abrupt change in flow conditions, resulting in a standing wave pattern. This phenomenon is distinct from positive and negative surges.
Explanation: The hydraulic jump is an example of rapidly varied flow. It involves a sudden change in flow conditions, including depth and velocity, over a relatively short distance. This contrasts with gradually varied flow, which involves more gradual changes in flow characteristics.
Explanation: A sudden fall of the level of the ground along the alignment of the canal joined by an inclined bed is referred to as a rapid fall. This type of fall involves a quick descent of the ground level, impacting the flow conditions in the canal.
Explanation: The fall that can be used as a meter fall is a vertical drop fall. A vertical drop fall involves a direct descent of water over a vertical structure, making it suitable for metering and controlling the flow of water in the canal.
Explanation: Falls such as a low weir fall, a trapezoidal notch fall, and a rectangular notch fall are designed to maintain their depth under varying flow conditions. These falls are suitable for applications where a consistent depth of flow is desired.
Explanation: A vertical drop fall is considered satisfactory for a drop up to 1.0 meter. Beyond this height, other types of falls or energy dissipation structures may be required to manage the flow and prevent excessive turbulence.
Explanation: Vertical drop falls are suitable for a discharge of around 15 m3/sec. The design and selection of falls depend on various factors, including the anticipated discharge and the desired hydraulic performance.
Explanation: A straight glacis fall with a baffle wall is considered suitable for any discharge. This type of fall provides flexibility and effectiveness across a range of discharge conditions.
Explanation: A straight glacis type fall with a baffle platform and a baffle wall is known as an Inglis fall. Inglis falls are designed to dissipate energy effectively and control the flow of water in the canal.
Explanation: The fall using a parabolic glacis for energy dissipation is called a Montague fall. Montague falls utilize a parabolic glacis design to dissipate energy and control the flow of water in the canal.
Explanation: The fall with the crest usually at or near the bed level, without a glacis, is referred to as a notch fall. Notch falls are designed to manage flow without the need for an extended glacis structure.
Explanation: An obstruction placed on the downstream floor of a fall to dissipate the velocity of the flowing water and maintain the standing wave on the glacis is known as a friction block. It helps control the flow dynamics and prevent excessive turbulence.
Explanation: A protection at the downstream end of a weir or fall, consisting of blocks of concrete or masonry, is called talus. Talus provides stability and erosion protection at the base of the structure.
Explanation: The design of the canal system is often determined by factors such as the difference in the downstream and upstream depths. The formula “5(D2-D1)” is a common expression used in the design process.
Explanation: For a proportional outlet, the flexibility is one. Proportional outlets are designed to maintain a consistent relationship between the outlet discharge and the upstream flow, providing a predictable and controllable water distribution.
Explanation: Gibb’s module is a type of rigid-modular outlet. It is a component used in canal systems to control and regulate the flow of water.
Explanation: The ratio of the rate of change of the discharge of an outlet to the rate of change of the discharge of the distributing channel is known as flexibility. It is a measure of how changes in outlet discharge relate to changes in the upstream flow.
Explanation: In the case of paddy cultivation, the maximum amount of water is required during the flowering stage. This is a critical stage in the growth cycle of paddy, and adequate water availability during flowering is essential for successful crop development.
Explanation: Drop structures in the canal are primarily provided for energy dissipation. They help reduce the kinetic energy of flowing water, preventing erosion and turbulence.
Explanation: Drain crossing is not considered a cross drainage work. Cross drainage works typically involve structures that allow water to flow across a drainage channel or watercourse.
Explanation: Saturation capacity refers to the amount of water required to fill up the pore spaces in soil particles by replacing all the air held in the pore spaces. It represents the maximum water-holding capacity of the soil.
Explanation: The discharge in an open channel is inversely proportional to the roughness of the section. Roughness affects the flow resistance, and a smoother section allows for a higher discharge.
Explanation: When the water table is within the root zone depth and negatively affects plant life, the land is said to be waterlogged. Waterlogging can lead to reduced oxygen availability for plant roots, negatively impacting crop growth.
Explanation: The trapezoidal section is often considered the most efficient for a channel. It provides a balance between hydraulic efficiency and structural stability.
Explanation: In irrigation canals, water losses can occur due to absorption, evaporation, and percolation. All of these factors contribute to the overall water losses in the irrigation system.
Explanation: To avoid interruption in the flow of a siphon, the air vessel is provided at the summit. The air vessel helps regulate air in the siphon, ensuring continuous flow.
Explanation: Drops in irrigation canals are needed when the natural slope is very steep. The drop structures help manage the steep slope and prevent excessive erosion.
Explanation: For the maximum velocity occurring in a canal, the hydraulic mean depth is maximized. This is a key parameter in determining the flow characteristics of an open channel.
Explanation: A deep well generally has more discharge than a shallow well. The deeper the well, the greater the potential for accessing larger aquifers and higher groundwater yields.
Explanation: A hydrograph is a graphical representation of river runoff over time. It illustrates the variation in discharge or flow rate in a river or stream in response to rainfall or other hydrological factors.
Explanation: Sprinkler irrigation typically has a higher water application efficiency compared to other methods. It involves spraying water directly onto the crops, minimizing losses due to evaporation and runoff.
Explanation: The total depth of water required by a crop during the entire period the crop is in the field is known as “Delta.” Delta is a term used in irrigation to represent the total water requirement for a specific crop.
Explanation: The water-holding capacity of clay is the highest among all soils. Clay soils have fine particles with high porosity, allowing them to retain more water.
Explanation: Irrigation distributor canals are generally aligned along straight lines. This alignment helps in efficient water distribution to different agricultural fields.
Explanation: Available moisture is defined as the difference in water content of the soil between field capacity (maximum moisture-holding capacity) and permanent wilting point.
Explanation: The trapezoidal cross-section is often considered the best hydraulic section for open channels. It provides a good balance between flow efficiency and structural stability.
Explanation: When a canal is carried over a natural drainage, the structure provided is known as an aqueduct. An aqueduct is a water-carrying structure that allows the canal to pass over the drainage.
Explanation: The consumptive use of water for a crop can be measured as the volume of water per unit area or as the depth of water on the irrigated area. It includes water supplied by both precipitation and irrigation.
Explanation: A diversion headwork is constructed to raise the water level at the head of the canal, regulate the intake of water, and reduce fluctuations in the supply level of the river.
Explanation: The main function of a diversion headwork of a canal from a river is to raise the water level, ensuring an adequate supply of water to the canal.
Explanation: The site of the headworks is considered good when a good foundation is available for the structure. A stable foundation is crucial for the durability and performance of the headworks.
Explanation: The diversion headwork is divided into eight components, each serving a specific function in the regulation and control of water diversion.