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Past Questions — 2025
Which formula is used to calculate the velocity of flow in an open irrigation canal?
A)
Bernoulli’s equation
B)
Chezy’s formula
C)
Darcy’s law
D)
Reynolds number
Step-by-step reasoning:
1. The question asks for the formula used to calculate the velocity of flow in an open irrigation canal. Open channel flow is driven by gravity and is characterized by a free surface.
2. Chezy's formula is one of the fundamental equations used in hydraulics to calculate the mean velocity (V) of flow in an open channel. It is expressed as V = C√(RS), where C is the Chezy coefficient, R is the hydraulic radius, and S is the slope of the energy grade line (or bed slope).
3. Manning's formula is a more common derivation of Chezy's formula, but among the given options, Chezy's is the only one applicable to open channel velocity.
Analysis of other options:
- a. Bernoulli’s equation: This is a general energy conservation equation for fluid flow along a streamline, used to find pressure or velocity at a point, but not specifically for calculating the average velocity of an open canal based on its geometry and slope.
- c. Darcy’s law: This describes the flow of a fluid through a porous medium (like soil or sand), not open channel flow.
- d. Reynolds number: This is a dimensionless quantity used to determine whether a flow is laminar or turbulent; it is not a formula to calculate the velocity of flow itself.
Contour lines that are very close together indicate:
A)
Flat terrain
B)
A steep slope
C)
A river valley
D)
A depression in the land
In surveying, a contour line is an imaginary line connecting points of equal elevation. The horizontal distance between two contour lines represents the change in elevation over that distance.
1. **Steep Slope:** When contour lines are drawn very close together, it means that the elevation is changing rapidly over a very short horizontal distance, which characterizes a steep slope.
2. **Flat Terrain:** Conversely, when contour lines are spaced far apart, it indicates that the elevation changes slowly over a large distance, representing flat or gentle terrain.
3. **River Valley:** A river valley is typically represented by V-shaped contours with the apex pointing upstream (towards higher ground).
4. **Depression:** A depression is indicated by closed contour lines with hachure marks (small ticks) pointing inwards toward the center of the depression.
If a river has a cross-sectional area of 30 m² and the velocity of flow is 2 m/s, what is the discharge?
A)
30 m³/s
B)
50 m³/s
C)
60 m³/s
D)
90 m³/s
To find the discharge of a river, we use the Continuity Equation for steady flow.
1. **Formula**: Discharge (Q) is the product of the cross-sectional area (A) and the average velocity of flow (v).
Formula: Q = A × v
2. **Given Data**:
- Cross-sectional area (A) = 30 m²
- Velocity of flow (v) = 2 m/s
3. **Calculation**:
Q = 30 m² × 2 m/s = 60 m³/s
4. **Analysis of Options**:
- Option (a) 30 m³/s: Incorrect; this only considers the area without multiplying by velocity.
- Option (b) 50 m³/s: Incorrect; result of an incorrect calculation.
- Option (c) 60 m³/s: Correct; matches the calculated discharge.
- Option (d) 90 m³/s: Incorrect; result of an incorrect calculation.
Which is the most water-efficient irrigation method?
A)
Furrow irrigation
B)
Sprinkler irrigation
C)
Drip irrigation
D)
Flood irrigation
Water efficiency in irrigation is measured by the percentage of water that actually reaches the root zone of the plant versus the amount applied.
1. **Drip Irrigation (c):** This is the most efficient method (often >90% efficiency). It delivers water slowly and precisely to the root zone through a network of valves, pipes, and emitters. This minimizes losses due to evaporation, surface runoff, and deep percolation.
2. **Sprinkler Irrigation (b):** While more efficient than surface methods, it is less efficient than drip irrigation (typically 70-85%). Water is lost to wind drift and evaporation as it travels through the air.
3. **Furrow Irrigation (a):** A type of surface irrigation where water flows in small parallel channels. It is less efficient (typically 40-60%) due to significant losses from deep percolation and runoff at the end of the furrows.
4. **Flood Irrigation (d):** The least efficient method. Water is applied over the entire field surface, leading to massive losses through evaporation and deep percolation (typically 30-50% efficiency).
What is the significance of the Base Period of a crop?
A)
It determines the time between sowing and harvesting
B)
It is the total period from first to last irrigation
C)
It defines the period of highest water demand in a crop cycle
D)
It represents the time taken for root development
In irrigation engineering, the 'Base Period' (B) is formally defined as the time elapsed between the first watering of a crop and the last watering of that crop. It is a critical parameter used to calculate the 'Delta' (total depth of water required by a crop) and the duty of water.
Analysis of options:
- Option (a) is incorrect because the time between sowing and harvesting is known as the 'Crop Period'. The base period is usually shorter than the crop period because irrigation is not required immediately after sowing or immediately before harvesting.
- Option (b) is correct as it matches the technical definition of the Base Period.
- Option (c) is incorrect because the period of highest water demand is referred to as the 'critical period' or 'peak demand period'.
- Option (d) is incorrect as root development is a biological growth phase and not a measurement of the irrigation schedule duration.
Why are clayey soils more prone to waterlogging compared to sandy soils?
A)
Clayey soils have larger pore spaces
B)
Clayey soils allow faster infiltration
C)
Clayey soils have lower permeability
D)
Clayey soils absorb more oxygen
Waterlogging occurs when the soil becomes saturated and water cannot drain away efficiently. The ability of soil to transmit water is known as permeability (or hydraulic conductivity).
1. **Clayey Soils:** These soils consist of very fine particles that pack closely together. While they have a high total porosity (more total void space), the individual pores are microscopic (micropores). These small pores create high friction and capillary forces that significantly restrict the movement of water, resulting in low permeability. Consequently, water accumulates in the root zone, leading to waterlogging.
2. **Sandy Soils:** These consist of larger particles with larger interconnected spaces (macropores). This allows water to move rapidly through the soil profile via gravity, resulting in high permeability and a lower risk of waterlogging.
Evaluating the options:
- **Option a** is incorrect because clayey soils have smaller individual pore spaces (micropores) compared to sandy soils.
- **Option b** is incorrect because clayey soils have much slower infiltration rates due to their fine texture.
- **Option d** is incorrect because waterlogging actually displaces oxygen from the soil, leading to anaerobic conditions; clayey soils do not 'absorb more oxygen' to prevent waterlogging.
Why does the duty of water increase as it moves downstream?
A)
Water loss due to infiltration
B)
Water use efficiency improves
C)
Reduction in seepage losses
D)
None of the above
To solve this question, we must first understand the definition of 'Duty'. In irrigation engineering, Duty (D) is defined as the area of land that can be irrigated by a constant unit discharge of water flowing throughout the period. The formula is Duty = Area / Discharge.
As water moves downstream in a canal system, it is subject to losses due to evaporation and seepage (infiltration into the ground). Consequently, the actual discharge (Q) available at the downstream end is less than the discharge at the head of the canal.
Since Duty is inversely proportional to the discharge required to irrigate a unit area (D = 8.64B / Δ), if we consider a fixed volume of water released at the head, the amount of water actually reaching the downstream fields is reduced. To irrigate the same area downstream, a higher discharge is required at the head to compensate for these losses. Therefore, the 'Duty' (the area irrigated per unit of water delivered at the source) actually DECREASES as water moves downstream because more water is 'wasted' to reach the destination.
Analyzing the options:
- Option (a): Water loss due to infiltration/seepage causes the duty to decrease, not increase.
- Option (b): Water use efficiency generally does not improve simply by moving downstream; in fact, conveyance losses reduce overall system efficiency.
- Option (c): Seepage losses typically occur throughout the canal; they do not 'reduce' in a way that would increase the duty of the water.
Since the duty of water decreases (not increases) as it moves downstream due to conveyance losses, none of the provided reasons explain an 'increase' in duty. Therefore, the correct option is 'None of the above'.
Which of the following is an effective way to control waterlogging?
A)
Applying excessive fertilizers
B)
Constructing deep drainage channels
C)
Using excessive irrigation
D)
Eliminating all organic matter from soil
Waterlogging occurs when the soil becomes saturated with water, displacing air from the soil pores and hindering root respiration. To control this, the excess water must be removed from the root zone. Constructing deep drainage channels (surface or subsurface drainage) lowers the water table by providing a path for gravity-driven water flow away from the field.
Analysis of other options:
- Option (a): Applying excessive fertilizers does not remove water; in some cases, high salt concentrations from fertilizers can actually degrade soil structure and worsen drainage.
- Option (c): Using excessive irrigation is the primary cause of waterlogging, not a solution.
- Option (d): Organic matter improves soil structure and porosity, which actually helps in water infiltration and drainage; eliminating it would likely worsen the soil's physical properties.
A field with a gentle slope requires which type of drainage system to prevent waterlogging?
A)
Deep sub-surface drainage only
B)
Contour surface drainage channels
C)
No drainage is needed on gentle slopes
D)
Excess irrigation to balance water levels
Step-by-step reasoning: 1. Analysis of the field condition: A 'gentle slope' means the land is not perfectly flat, but the gradient is low enough that water may still accumulate or cause erosion if not managed. 2. Objective: The goal is to prevent waterlogging (excess water saturation in the root zone). 3. Evaluating Option (b): Contour surface drainage involves constructing channels along the contour lines (lines of equal elevation). This allows excess surface water to be collected and diverted safely away from the field without causing severe soil erosion, which is the primary risk on sloped lands. 4. Evaluating Option (a): Deep sub-surface drainage is typically used for high water tables in flat terrains or specific soil types, but for surface water management on slopes, surface channels are more immediate and effective. 5. Evaluating Option (c): This is incorrect because even gentle slopes can experience waterlogging in depressions or due to low soil permeability. 6. Evaluating Option (d): Excess irrigation would exacerbate waterlogging, not prevent it. Therefore, contour surface drainage is the most appropriate engineering solution for managing surface runoff and preventing waterlogging on gently sloping terrain.
If a river has a cross-sectional area of 30 m² and the velocity of flow is 2 m/s, what is the discharge?
A)
30 m³/s
B)
50 m³/s
C)
60 m³/s
D)
90 m³/s
To calculate the discharge (Q) of a river, we use the Continuity Equation for steady flow: Q = A × V, where 'A' is the cross-sectional area of the flow and 'V' is the average velocity of flow.
Given:
- Cross-sectional area (A) = 30 m²
- Velocity of flow (V) = 2 m/s
Calculation:
Q = 30 m² × 2 m/s = 60 m³/s.
Therefore, the discharge is 60 cubic meters per second.
- Option (a) 30 m³/s is incorrect as it only considers the area.
- Option (b) 50 m³/s is mathematically incorrect.
- Option (d) 90 m³/s is mathematically incorrect.
Contour lines that are very close together indicate:
A)
Flat terrain
B)
A steep slope
C)
A river valley
D)
A depression in the land
In surveying, contour lines are imaginary lines connecting points of equal elevation. The spacing between these lines represents the rate of change in elevation over a horizontal distance (the slope).
1. **Steep Slope:** When contour lines are very close together, it means the elevation is changing rapidly over a short horizontal distance, which indicates a steep slope.
2. **Flat Terrain:** Conversely, when contour lines are widely spaced, the elevation changes slowly over a large distance, indicating flat or gentle terrain.
3. **River Valley:** A river valley is typically represented by V-shaped contours with the apex of the 'V' pointing upstream.
4. **Depression:** A depression is indicated by closed contour lines with hachure marks (small ticks) pointing inwards toward the center of the depression.
Therefore, closely spaced contours are the definitive characteristic of a steep slope.
The most common type of error in levelling is:
A)
Instrumental error
B)
Gross error
C)
Collimation error
D)
Systematic error
In leveling, errors are generally classified into three categories: Instrumental, Personal (Gross), and Natural. Among these, the 'Collimation Error' is the most common and significant instrumental error. It occurs when the line of sight of the telescope is not perfectly horizontal (parallel to the axis of the bubble tube) when the instrument is leveled. This causes the line of sight to incline slightly upwards or downwards, leading to incorrect staff readings. While it is a type of systematic error, 'Collimation error' is the specific, most frequent technical error encountered in leveling operations.
Breakdown of other options:
- Instrumental error: This is a broad category. Collimation error is a specific type of instrumental error, making 'c' a more precise answer.
- Gross error: These are caused by human mistakes (e.g., misreading a number) and are avoided by careful work, not inherent to the process.
- Systematic error: This is a general category of errors that follow a mathematical law (including collimation error and curvature/refraction). Again, 'Collimation error' is the most common specific instance in leveling.
The key difference between plane and geodetic surveying is-
A)
The use of electronic instruments
B)
The type of data collected
C)
The consideration of earth’s curvature
D)
The number of surveyors required
In surveying, the fundamental distinction between plane surveying and geodetic surveying is based on how the shape of the Earth is treated:
1. **Plane Surveying**: This method assumes that the Earth's surface is a flat plane. The curvature of the Earth is neglected. This is acceptable for small areas (typically where the area is less than 250 square kilometers) because the error introduced by ignoring the curvature is negligible.
2. **Geodetic Surveying**: This method takes into account the true ellipsoidal or spherical shape of the Earth. It is used for large-scale surveys, high-precision work, and establishing control points over vast distances where the curvature of the Earth significantly affects measurements.
Analysis of other options:
- Option (a): Both plane and geodetic surveying can use electronic instruments (like Total Stations or GPS).
- Option (b): The type of data (distances, angles, coordinates) is essentially the same; only the mathematical treatment of that data differs.
- Option (d): The number of surveyors depends on the project scale, not the surveying methodology.
What is the primary purpose of agricultural drainage?
A)
To increase soil erosion
B)
To remove excess water and prevent waterlogging
C)
To increase soil acidity
D)
To promote water stagnation
Agricultural drainage is the removal of excess water from the soil surface or the root zone to create an optimal environment for plant growth.
1. Why option (b) is correct: Excess water in the soil fills the pore spaces, displacing oxygen (aeration). This leads to anaerobic conditions, which can suffocate plant roots, inhibit nutrient uptake, and cause waterlogging, which stunts crop growth or kills the plant. Drainage systems (surface or subsurface) are designed specifically to mitigate this.
2. Why other options are incorrect:
- Option (a): Soil erosion is a negative process where topsoil is lost; drainage is intended to manage water, not to increase erosion (in fact, poor drainage management can sometimes lead to erosion, but it is never the 'purpose').
- Option (c): Increasing soil acidity is generally detrimental to most crops. Drainage is used to manage the water table, not to intentionally alter pH levels toward acidity.
- Option (d): Water stagnation is the exact problem that agricultural drainage is designed to solve. Promoting stagnation would lead to root rot and crop failure.
Which factor does NOT directly influence the crop water requirement?
A)
Soil type
B)
Crop type
C)
Wind speed
D)
Crop market price
Crop water requirement (CWR) is the total quantity of water required by a crop for its growth from sowing to harvesting. It is primarily determined by the Evapotranspiration (ET) rate and the water needed to moisten the soil.
1. **Crop type (Option b):** Different crops have different root depths, growth stages, and transpiration rates (represented by the crop coefficient Kc), directly affecting water needs.
2. **Wind speed (Option c):** Wind increases the rate of transpiration and evaporation by removing the boundary layer of moisture from the leaf surface, thereby increasing the water requirement.
3. **Soil type (Option a):** Soil texture (sandy vs. clayey) determines the water-holding capacity and infiltration rate, which directly influences how much irrigation water is needed to maintain the root zone moisture.
4. **Crop market price (Option d):** This is an economic factor. While it may influence a farmer's decision on *whether* to plant a crop or how much to invest in irrigation, it has no biological or physical effect on the actual amount of water the plant requires to survive and grow.
What are the primary components of a sub-surface drainage system?
A)
Open ditches and barriers
B)
Perforated pipes and drains
C)
Wind barriers and ridges
D)
Artificial reservoirs
Sub-surface drainage (also known as underground drainage) is designed to remove excess water from the root zone of the soil to prevent waterlogging and salinity. The primary components of such a system are perforated pipes (laterals) placed below the soil surface, which collect the seepage water and transport it to a main drain or outlet.
Analysis of options:
- Option (a) 'Open ditches' are components of surface drainage, not sub-surface drainage.
- Option (b) 'Perforated pipes and drains' are the standard engineering components used to intercept and remove groundwater in sub-surface systems.
- Option (c) 'Wind barriers and ridges' are used for erosion control or surface water management, not for sub-surface drainage.
- Option (d) 'Artificial reservoirs' are used for water storage (irrigation), which is the opposite function of a drainage system.
GIS is mainly used for:
A)
Mapping and analyzing spatial data
B)
Measuring distances with high accuracy
C)
Estimating soil properties
D)
Conducting hydrographic surveys
GIS stands for Geographic Information System. It is a conceptualized framework that provides the ability to capture, store, manipulate, analyze, manage, and present all types of geographical or spatial data.
1. Why Option (a) is correct: GIS integrates hardware, software, and data to visualize, question, analyze, and interpret data to understand relationships, patterns, and trends. Its primary function is the management and analysis of spatial data (data linked to a specific location on Earth).
2. Why Option (b) is incorrect: Measuring distances with high accuracy is the primary function of surveying instruments like Total Stations, EDM (Electronic Distance Measurement), or Steel Tapes, not the GIS software system itself.
3. Why Option (c) is incorrect: Estimating soil properties is the domain of Geotechnical Engineering and Soil Mechanics, involving laboratory tests and field sampling (e.g., Standard Penetration Test).
4. Why Option (d) is incorrect: Conducting hydrographic surveys involves the use of Echo Sounders, Sonar, and specialized marine surveying equipment to map the bottom of water bodies. While the results of a hydrographic survey can be imported into a GIS for analysis, the act of 'conducting' the survey is a field operation, not a GIS function.
A field has a length of 300 meters and a width of 150 meters. If 5 cm of irrigation water is applied, calculate the total volume of water required (in cubic meters).
A)
2250 m³
B)
1500 m³
C)
2500 m³
D)
3000 m³
To calculate the total volume of water required for irrigation, we use the formula: Volume = Area × Depth of water.
Step 1: Calculate the area of the field.
Area = Length × Width
Area = 300 m × 150 m = 45,000 m²
Step 2: Convert the depth of irrigation water from centimeters to meters to maintain unit consistency.
Depth = 5 cm = 5 / 100 m = 0.05 m
Step 3: Calculate the total volume.
Volume = 45,000 m² × 0.05 m
Volume = 2,250 m³
Therefore, the total volume of water required is 2,250 cubic meters. Option (a) is correct. Options (b), (c), and (d) are incorrect as they do not match the calculated volume based on the provided dimensions and depth.
What is sub-surface drainage?
A)
A system that removes excess water from below the root zone
B)
A method to increase irrigation water
C)
A method to reduce fertilizer application
D)
A way to improve plant growth by adding chemicals
Sub-surface drainage refers to the removal of excess water from the soil profile (specifically from the root zone or below it) to maintain an optimal balance of air and water for plant growth. This is typically achieved using perforated pipes, tiles, or gravel drains installed underground.
Reasoning for options:
- Option (a) is correct because the primary purpose of sub-surface drainage is to lower the water table and remove saturated water from below the surface to prevent waterlogging.
- Option (b) is incorrect because drainage is the removal of water, whereas irrigation is the addition of water.
- Option (c) is incorrect because while drainage can improve nutrient uptake efficiency, its primary definition is not the reduction of fertilizer application.
- Option (d) is incorrect because drainage is a physical/mechanical process of water management, not a chemical additive process.
The primary purpose of stream gauging station is-
A)
River velocity only
B)
Streamflow and discharge
C)
Rainfall intensity
D)
Groundwater table levels
A stream gauging station is a facility established at a specific point along a river or stream to monitor and measure the volume of water moving past that point over time.
1. **Streamflow and Discharge**: The primary objective of these stations is to determine the 'discharge' (Q), which is the volume of water flowing per unit of time (typically measured in m³/s or cusecs). Discharge is calculated using the formula Q = A × V, where A is the cross-sectional area of the channel and V is the average velocity of the flow.
2. **Why other options are incorrect**:
- **Option a (River velocity only)**: While velocity is measured at a gauging station, it is merely a component used to calculate the total discharge. Measuring velocity alone does not fulfill the primary purpose of gauging the stream's flow volume.
- **Option c (Rainfall intensity)**: This is measured by rain gauges (pluviometers), not stream gauging stations.
- **Option d (Groundwater table levels)**: This is measured using observation wells or piezometers, which monitor the phreatic surface of an aquifer, not the surface flow of a stream.
If a rain gauge recorded 50 mm of rainfall in 10 hours, what is the average intensity of rainfall?
A)
2.5 mm/hr
B)
5 mm/hr
C)
7.5 mm/hr
D)
10 mm/hr
The average intensity of rainfall is defined as the total depth of precipitation recorded divided by the duration of the rainfall event.
Given data:
- Total rainfall depth (P) = 50 mm
- Duration of rainfall (t) = 10 hours
Formula:
Average Intensity (I) = Total Rainfall / Duration
I = 50 mm / 10 hours
I = 5 mm/hr
Evaluating the options:
- Option (a) 2.5 mm/hr is incorrect as it would result from 25 mm of rain in 10 hours.
- Option (b) 5 mm/hr is correct based on the calculation.
- Option (c) 7.5 mm/hr is incorrect as it would result from 75 mm of rain in 10 hours.
- Option (d) 10 mm/hr is incorrect as it would result from 100 mm of rain in 10 hours.
In which situation is a contour canal preferred over a watershed canal?
A)
When the region has a flat terrain
B)
When the land has undulating topography with steep slopes
C)
When there are many natural streams in the area
D)
When the canal needs to avoid excessive excavation
In canal engineering, the choice between a watershed canal and a contour canal depends primarily on the topography of the land.
1. **Watershed Canal (Ridge Canal):** This canal is aligned along the ridge line (watershed) of the area. It allows irrigation on both sides of the canal through gravity. However, it is only feasible in regions where the ridge is relatively straight and the terrain is not excessively steep or undulating.
2. **Contour Canal:** A contour canal is aligned approximately parallel to the contours of the land. It is specifically preferred in hilly or undulating terrain where the land has steep slopes. Because it follows the natural contour, it minimizes the need for massive earthworks (cutting and filling) that would be required to maintain a ridge alignment in rugged terrain.
**Analysis of Options:**
- **Option (a):** In flat terrain, a ridge canal or a simple aligned canal is preferred; contouring is unnecessary.
- **Option (b):** Correct. In undulating topography with steep slopes, following the contour is the most practical way to maintain a steady gradient for water flow while minimizing construction costs.
- **Option (c):** The presence of natural streams affects the number of aqueducts or siphons needed, but it is not the primary deciding factor between watershed and contour alignment.
- **Option (d):** While contour canals do reduce excavation compared to a forced ridge alignment in hills, the *primary situation* that necessitates their use is the topography itself (undulating/steep slopes).
In levelling, the term “backsight” refers to-
A)
The last reading taken before moving the instrument
B)
The first reading taken from a known elevation
C)
A reading taken at a change point
D)
A reading used for error correction
In leveling, a Backsight (BS) is defined as the first staff reading taken after the leveling instrument (level) is set up. This reading is taken on a point of known elevation (either a Benchmark or a previously established point) to determine the Height of Instrument (HI).
Analysis of options:
- Option (a) describes a 'Foresight' (FS), which is the last reading taken before moving the instrument to a new position.
- Option (b) is correct as it describes the fundamental purpose of a backsight: establishing the instrument's elevation relative to a known point.
- Option (c) is partially true in practice (a reading at a change point can be a BS), but the definition of a BS is specifically the reading taken *back* toward a known point, whereas the reading taken *away* from the instrument at a change point is the FS. Option (b) is the more precise general definition.
- Option (d) is incorrect; while BS is used in calculations, it is not a specific 'reading used for error correction' (that would be a check reading or a closing reading).
How does a total station improve accuracy in surveying compared to a theodolite?
A)
It reduces the need for manual calculations
B)
It can measure underground features
C)
It works without needing a reference point
D)
It automatically adjusts for atmospheric conditions
A Total Station is an electronic/optical instrument that integrates an Electronic Distance Meter (EDM) with a digital theodolite and an onboard microprocessor.
1. Why Option (a) is correct: In traditional theodolite surveying, the surveyor must manually read angles and measure distances (using a tape or chain), and then perform trigonometric calculations (like sine and cosine rules) to determine the coordinates (X, Y, Z) of a point. A Total Station performs these calculations automatically and instantaneously using its internal microprocessor, which significantly reduces human error associated with manual data recording and mathematical computation, thereby improving the overall accuracy and efficiency of the survey.
2. Why Option (b) is incorrect: Total Stations use light/infrared waves (EDM) which require a line-of-sight. They cannot penetrate the ground to measure underground features; that would require Ground Penetrating Radar (GPR) or seismic surveying.
3. Why Option (c) is incorrect: Every survey requires a reference point (benchmark or known station) to establish a coordinate system. A Total Station still needs a known starting point and orientation to provide absolute coordinates.
4. Why Option (d) is incorrect: While some high-end Total Stations allow the user to input atmospheric corrections (temperature and pressure) to adjust the EDM's speed of light calculations, they do not 'automatically' adjust for all atmospheric conditions without input or calibration; more importantly, this is a feature of the EDM component, whereas the primary systemic improvement over a theodolite is the integration of measurement and calculation.
Which of the following is NOT a preventive measure for waterlogging?
A)
Using well-planned irrigation techniques
B)
Installing drainage systems
C)
Growing water-demanding crops in all seasons
D)
Using raised beds for planting
Waterlogging occurs when the soil becomes saturated with water, displacing air from the soil pores and hindering root respiration. To prevent this, measures must focus on controlling water input or increasing water removal.
- Option (a) 'Using well-planned irrigation techniques' (such as drip or sprinkler irrigation) prevents over-watering, thus preventing waterlogging.
- Option (b) 'Installing drainage systems' (such as surface or subsurface drains) allows excess water to exit the root zone, directly preventing waterlogging.
- Option (d) 'Using raised beds for planting' improves aeration and allows excess water to drain away from the plant roots into the furrows, preventing saturation of the root zone.
- Option (c) 'Growing water-demanding crops in all seasons' is NOT a preventive measure. While water-demanding crops (like rice) can tolerate waterlogging, planting them in all seasons does not prevent the soil from becoming waterlogged; in fact, if the soil is already prone to waterlogging, this practice does nothing to mitigate the physical condition of the soil and may lead to salinity or alkalinity issues in other crop cycles.