(SEM VII) THEORY EXAMINATION 2023-24 SOIL & WATER CONSERVATION ENGINEERING

OE078 – SOIL & WATER CONSERVATION ENGINEERING

B.Tech (SEM VII) – Theory Examination
Time: 3 Hours | Max Marks: 100

SECTION A

(Attempt all questions in brief – 2 × 10 = 20 marks)

a. Name some methods of reducing the impact of flooding.

Methods include construction of dams and reservoirs, levees and embankments, flood forecasting and warning systems, river channel improvement, afforestation, and proper land-use planning.

b. Define vegetation management in brief.

Vegetation management is the practice of growing and maintaining plants, grasses, and trees to protect soil, reduce erosion, improve infiltration, and conserve water resources.

c. Name the types of soil erosion due to water.

Types of soil erosion due to water are:                             Splash erosion

Sheet erosion                                                                    Rill erosion

Gully erosion                                                                     Stream bank erosion

d. Give the universal soil loss equation.

The Universal Soil Loss Equation (USLE) is:

A=R×K×L×S×C×PA = R \times K \times L \times S \times C \times PA=R×K×L×S×C×P

Where A = average annual soil loss, R = rainfall erosivity factor, K = soil erodibility factor, L = slope length factor, S = slope steepness factor, C = crop management factor, P = conservation practice factor.

e. Discuss the effects of erosion.

Soil erosion reduces soil fertility, decreases crop yield, causes siltation of rivers and reservoirs, leads to flooding, degrades land productivity, and damages infrastructure.

f. Name the biological methods of soil erosion control.

Biological methods include afforestation, strip cropping, contour farming, grassed waterways, cover crops, and pasture development.

g. Define evaporation losses in brief.

Evaporation losses refer to the loss of water from soil, reservoirs, canals, and water bodies into the atmosphere due to heat and wind action.

h. Define aquifer with example.

An aquifer is an underground water-bearing layer of permeable rock or soil that stores and transmits groundwater.
Example: Sandstone aquifer.

i. Name some fertilizers and pesticides.

Fertilizers: Urea, DAP, NPK
Pesticides: DDT, Malathion, Carbaryl

j. Define soil loss estimation in brief.

Soil loss estimation is the process of predicting the amount of soil removed from land due to erosion using empirical or mathematical models such as USLE.

SECTION B

(Attempt any three – answers provided for ALL)

2(a). Discuss the methods of soil erosion control in detail.

Soil erosion control methods are broadly classified into agronomic, mechanical, and biological 

methods.
Agronomic methods include contour farming, strip cropping, mulching, and crop rotation. Mechanical methods involve terracing, contour bunding, check dams, and gully plugging. Biological methods include afforestation, grass planting, and vegetative barriers. These methods reduce runoff velocity, improve infiltration, and protect soil from erosive forces.

2(b). What are the sources of agricultural water pollution? Explain in detail.

Agricultural water pollution is caused by excessive use of fertilizers, pesticides, herbicides, animal waste, irrigation runoff, and soil erosion. Nutrient runoff leads to eutrophication of water bodies, pesticides contaminate groundwater, and sediments reduce water quality, affecting aquatic life and human health.

2(c). Discuss the need of planned utilization of water resources in detail.

Planned utilization of water resources is necessary to meet increasing demands for agriculture, industry, and domestic use. It ensures equitable distribution, prevents over-exploitation, reduces floods and drought impacts, improves irrigation efficiency, and promotes sustainable development through integrated water resource management.

2(d). Discuss the mechanism of soil erosion in detail with the help of diagram.

Soil erosion begins with detachment of soil particles by raindrop impact (splash erosion), followed by transportation through surface runoff (sheet and rill erosion), and finally deposition in low-lying areas or water bodies. Increased slope, rainfall intensity, and lack of vegetation accelerate erosion.
(Neat diagram of erosion process to be drawn in exam)

2(e). What do you understand by groundwater recharge through wells? Explain in detail.

Groundwater recharge through wells involves directing surface water into recharge wells to replenish aquifers. It increases groundwater availability, prevents depletion, improves water quality, and is widely used in rainwater harvesting systems.

SECTION C

3(a). What do you understand by hydrologic cycle? Explain in detail with the help of diagram.

The hydrologic cycle is the continuous movement of water between the earth’s surface and atmosphere. It includes evaporation, transpiration, condensation, precipitation, infiltration, runoff, and groundwater flow. This cycle maintains water balance on earth.
(Hydrologic cycle diagram to be drawn)

3(b). Discuss the soil erosion due to wind and its control in detail.

Wind erosion occurs in dry, loose, and bare soils when strong winds detach and transport soil particles. It causes loss of fertile topsoil and damages crops. Control measures include shelter belts, windbreaks, mulching, strip cropping, and maintaining soil moisture.

4(a). Discuss some of the river training works in detail.

River training works are structures constructed to guide river flow and protect banks. These include levees, groynes, guide banks, spurs, and revetments. They help in flood control, bank protection, navigation improvement, and prevention of erosion.

4(b). Define sediment deposition in rivers in detail.

Sediment deposition occurs when the velocity of flowing water decreases, causing suspended particles to settle. It leads to siltation of riverbeds, reservoirs, and canals, reducing water-carrying capacity and increasing flood risk.

5(a). What do you understand by soil erosion? Discuss its causes and types.

Soil erosion is the detachment and removal of soil particles by water or wind.
Causes: Rainfall, wind, deforestation, overgrazing, improper farming practices.
Types: Water erosion (sheet, rill, gully) and wind erosion.

5(b). Define grassland management in detail with the help of suitable diagram.

Grassland management involves proper use and maintenance of grass-covered lands for grazing and soil conservation. It includes controlled grazing, reseeding, fertilization, and erosion control measures. Proper management improves fodder yield and prevents land degradation.
(Grassland management diagram to be drawn)

6(a). Define soil loss estimation in detail. Also give USLE and MUSLE.

Soil loss estimation predicts erosion rates to plan conservation measures.

USLE:

A=R×K×L×S×C×PA = R \times K \times L \times S \times C \times PA=R×K×L×S×C×P

Modified USLE (MUSLE):

A=11.8(Q×qp)0.56KLSCPA = 11.8 (Q \times q_p)^{0.56} K L S C PA=11.8(Q×qp​)0.56KLSCP

Where Q = runoff volume, qpq_pqp​ = peak runoff rate.

6(b). What do you understand by gullies? Give its classification and stages of development.

Gullies are deep channels formed by concentrated runoff.
Classification: Small, medium, and large gullies.
Stages: Formation, development, stabilization, and healing.

7(a). What do you understand by wind erosion? What are the factors affecting wind erosion?

Wind erosion is the removal of soil by wind action.
Factors: Wind velocity, soil texture, soil moisture, vegetation cover, surface roughness, and field length.

7(b). What do you understand by land capability classification? Explain in detail.

Land capability classification groups land into classes based on suitability for agriculture without permanent damage. Classes range from I (best land) to VIII (unsuitable for cultivation). It helps in sustainable land-use planning.