(a) (i) Design a trapezoidal concrete lined channel to carry a discharge of 300 m³/s at a slope of 1 in 4000. The side slope of the channel may be taken as 1·5 : 1. The value of n for the lining material may be taken as 0·0125. Assume the B/D ratio a

Question

(a) (i) Design a trapezoidal concrete lined channel to carry a discharge of 300 m³/s at a slope of 1 in 4000. The side slope of the channel may be taken as 1·5 : 1. The value of n for the lining material may be taken as 0·0125. Assume the B/D ratio as 5. 10
(ii) Describe briefly different type of spillways used in dams and methods used for dissipating energy of water discharged from them. 10

(b) Mention the sources and health effects on human being of the following elements with reference to Air pollution :
Lead, Cadmium, Nickel, Mercury, Carbon Monoxide 15

(c) (i) Discuss the factors that must be considered in evaluating potential sanitary landfill sites.
(ii) How does the occurrence of gases and leachate in sanitary landfill take place ? Explain with the help of chemical reactions taking place. 15

UPSC Answer Check · Accepted Answer

The directive 'design' in part (a)(i) demands a complete hydraulic design with numerical solution, while other parts require descriptive and explanatory responses. Allocate approximately 25% time to (a)(i) for rigorous Manning's equation application with B/D=5 constraint, 20% to (a)(ii) for spillway classification and energy dissipators, 25% to (b) for systematic coverage of five pollutants with sources and health effects, and 30% to (c) for landfill site selection criteria and biochemical processes. Structure with clear sub-headings, present calculations in tabular format, and conclude with practical implications for Indian conditions.
- (a)(i) Correct application of Manning's equation with given B/D=5 ratio to solve for normal depth and base width, verification of hydraulic parameters
- (a)(ii) Classification of spillways (ogee, chute, shaft, siphon, side channel) with sketches; energy dissipation methods (hydraulic jump, ski jump, roller buckets) with Indian dam examples like Bhakra or Hirakud
- (b) Systematic presentation of five pollutants: sources (industrial, vehicular, thermal power) and specific health effects (neurotoxicity, nephrotoxicity, carcinogenicity, Minamata disease, CO poisoning)
- (c)(i) Site selection criteria: hydrogeological isolation, distance from water bodies, accessibility, soil permeability, climatic factors, social acceptance referencing CPHEEO/MSW Rules
- (c)(ii) Anaerobic decomposition phases, gas generation (CH₄, CO₂, H₂S), leachate formation chemistry with relevant equations; leachate migration and control measures

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	20%	10	Correctly identifies hydraulic radius for trapezoidal section; accurately classifies spillway types and energy dissipators; precisely describes toxicological mechanisms for all five pollutants; correctly explains anaerobic landfill phases with proper biochemical pathways	Minor errors in geometric relationships for channel; incomplete spillway classification; generic health effects without specific pathways; basic landfill concepts without phase differentiation	Fundamental errors in channel geometry; confuses spillway types with gates; incorrect health effects or missing pollutants; misunderstands anaerobic decomposition or leachate chemistry
Numerical accuracy	20%	10	Correctly solves Manning's equation with B/D=5 constraint yielding accurate normal depth (~4.8m) and base width (~24m); proper unit consistency throughout; verification of Froude number and flow regime	Correct approach but arithmetic errors in final values; inconsistent units; incomplete verification	Wrong formula application; ignores B/D constraint; order of magnitude errors; no verification
Diagram quality	15%	7.5	Neat trapezoidal channel cross-section with all dimensions labeled; clear spillway profiles (ogee crest, chute, ski jump bucket); labeled landfill gas and leachate migration diagrams; Indian dam examples illustrated	Basic sketches without proper labeling; missing critical dimensions; generic diagrams without context	No diagrams or unrecognizable sketches; diagrams contradict text description
Step-by-step derivation	25%	12.5	Systematic derivation: geometric relations (A, P, R), substitution in Manning's equation, iterative solution for D, calculation of B, verification; clear logical flow for landfill chemical reactions with balanced equations	Some steps skipped or condensed; jumps to final formula; incomplete reaction sequences	No derivation shown; only final answers; disconnected statements without logical progression
Practical interpretation	20%	10	Relates channel design to lining material selection and maintenance; cites Indian dams (Tehri, Sardar Sarovar) for spillway examples; references Indian standards (CPCB, MSW Rules 2016); discusses methane recovery from landfill gas and leachate treatment in Indian context	Generic practical remarks without Indian context; standard textbook applications; superficial environmental connections	No practical application; purely theoretical treatment; irrelevant examples

Q8

Directive word: Design

How this answer will be evaluated

Approach

Key points expected

Evaluation rubric

Practice this exact question

More from Civil Engineering 2023 Paper II