ICAR AICE-JRF/SRF (PhD) — Agricultural Engineering subjects 38–43 · India · National Testing Agency for ICAR
Original practice questions written to the published syllabus · not past papersEstimating erosion and designing the bunds, terraces, waterways, spillways, ponds and dams that control it.
In the exams: GATE AG Section 4 Soil & Water Erosion; ICAR AIEEA-PG Unit VII; ICAR AICE subject 40 Unit 5; NCEES PE erosion; PRC ABE land and water (32%); state PSCs
ICAR AICE-JRF/SRF (PhD) — subject 40 Soil and Water Conservation Engineering
PG-depth understanding: RUSLE and MUSLE factor derivation and limits, sediment delivery and trap efficiency, drop-spillway energy dissipation, earthen dam seepage and stability under drawdown, wind erosion equation factors and shelterbelt design, and the role of remote sensing and GIS in erosion mapping.
How our questions for ICAR AICE-JRF/SRF spread across the units of Soil & Water Conservation Engineering. Difficulty: 2 easy, 21 medium, 20 hard.
| Soil loss estimation: USLE, RUSLE and MUSLE | 7 | |
| Earthen dams: seepage and stability | 6 | |
| Drop, drop-inlet and chute spillways | 5 | |
| Wind erosion mechanics | 5 | |
| Sediment yield | 4 | |
| Wind erosion control and shelterbelts | 4 | |
| Mechanics of water erosion | 3 | |
| Grassed waterways | 3 | |
| Contour and graded bunds | 2 | |
| Bench and broad-base terraces | 2 | |
| Gully control | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A storm has two uniform-intensity parts: 20 mm at 40 mm/h (30 minutes) followed by 10 mm at 10 mm/h (60 minutes). With e = 0.119 + 0.0873 log10 I (MJ/ha/mm), the storm's EI30 is closest to:
C. 289.6 MJ·mm/(ha·h)
Energy of part 1 = 20 × (0.119 + 0.0873 log10 40) = 5.177; part 2 = 10 × (0.119 + 0.0873 log10 10) = 2.063; E = 7.240 MJ/ha. The wettest 30 minutes delivered 20 mm, so I30 = 40 mm/h. EI30 = 7.240 × 40 = 289.6. Using the storm average intensity (20 mm/h) gives 144.8, treating all 30 mm as falling at 40 mm/h gives 7.766 × 40 = 310.6, and stopping at E gives 7.24.
Further reading: Wischmeier and Smith (1978), USDA Agriculture Handbook 537
A small watershed produces a storm runoff volume of 5,000 m³ with a peak rate of 1.2 m³/s. With K = 0.03, LS = 1.5, C = 0.2 and P = 0.6, MUSLE (Y = 11.8 (Q qp)^0.56 K LS C P) gives a storm sediment yield closest to:
D. 8.3 t
Q·qp = 5000 × 1.2 = 6000; 6000^0.56 = 130.5. Y = 11.8 × 130.5 × 0.03 × 1.5 × 0.2 × 0.6 = 8.3 t. Adding Q and qp (5001.2^0.56) gives 7.5 t, dropping the exponent gives 382 t, and the US-units coefficient 95 with SI inputs gives 67 t.
Further reading: Williams (1975)
For an actively advancing gully with a large runoff-producing catchment above it, the first engineering step is to:
A. divert or control runoff above the gully head and stabilise the head
Gullies advance by head-cutting, so stopping runoff over the head and stabilising it comes first, alongside catchment treatment. Check dams and planting follow once the flow is controlled.
Further reading: Schwab et al. / Fangmeier et al., Soil and Water Conservation Engineering
A straight drop spillway discharges 1.5 m³/s per metre of crest over a drop of 2.0 m. Using the drop number D = q²/(g h³) and Rand's relation L_d = 4.30 h D^0.27, the distance from the drop wall to where the nappe strikes the apron is closest to:
B. 3.30 m
D = 1.5²/(9.81 × 2³) = 2.25/78.48 = 0.0287. D^0.27 = 0.3833. L_d = 4.30 × 2.0 × 0.3833 = 3.30 m. Omitting h gives 1.65 m; using q instead of q² in D gives 2.95 m. Dropping the 0.27 exponent gives 4.30 × 2.0 × 0.0287 = 0.247 m.
Further reading: Chow, V.T., Open-Channel Hydraulics
A dry, cohesionless embankment fill has an angle of internal friction of 32°. For an infinitely long slope of 2.5:1 (horizontal:vertical), the factor of safety against sliding is closest to:
B. 1.56
tan β = 1/2.5 = 0.4. F = tan φ / tan β = 0.6249/0.4 = 1.56. Dividing by 2.5 instead of by 0.4 gives 0.25; using sin φ instead of tan φ gives 1.32; quoting tan φ alone (0.62) ignores the slope.
Further reading: Das, Principles of Geotechnical Engineering
Wind speed measured 2 m above a bare field is 8 m/s. The roughness length is 0.01 m and κ = 0.4. From the logarithmic profile u = (u*/κ) ln(z/z0), the friction velocity is closest to:
C. 0.604 m/s
u* = κ u / ln(z/z0) = 0.4 × 8 / ln 200 = 3.2/5.298 = 0.604 m/s. Using log10 gives 1.39; inverting κ gives 3.77.
Further reading: Morgan, R.P.C., Soil Erosion and Conservation
In the Wind Erosion Equation E = f(I, K, C, L, V), the factor L represents:
A. the unsheltered distance across the field along the prevailing erosive wind
I is soil erodibility, K ridge roughness, C the climatic factor, L the unsheltered field length along the wind direction and V vegetative cover. Windbreaks and strip cropping act by reducing L.
Further reading: Woodruff and Siddoway (1965)
For the longest effective zone of protection against wind erosion, a windbreak should have:
C. moderate porosity, roughly 40–50%
A solid barrier gives strong reduction just behind it but produces turbulence and a short sheltered zone. A moderately porous barrier lets some air through, reducing turbulence and extending protection. Gaps near the ground cause jetting under the canopy.
Further reading: Morgan, R.P.C., Soil Erosion and Conservation
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