Civil Engineering 2021 Paper II 50 marks Calculate

Q8

(a) From the basin map of a given watershed with drainage area 3000 km², the length of the mainstream (L) is measured as 125 km. The distance (Lc) from the outlet to a point on the stream nearest the centroid of the watershed area is measured as 90 km. The regional constant C₁ for the watershed is 0·75 and C₂ = 2·75. From the unit hydrograph derived for the watershed, the following are determined : rainfall duration tR = 12 h, basin lag tpR = 34 h and peak discharge qpR = 135 m³/s. cm. Determine the coefficients Ct and Cp for the synthetic unit hydrograph of the watershed. (20 marks) (b) Describe municipal solid waste sanitary landfill with a schematic diagram showing its various components. (15 marks) (c) Briefly describe the process for the award of environmental clearance for a project according to the EIA Act 2006. (15 marks)

हिंदी में प्रश्न पढ़ें

(a) 3000 km² अपवाह क्षेत्र के दिए गए एक जल-विभाजक के द्रोणी (बेसिन) मानचित्र से मुख्य धारा की लंबाई (L) 125 km मापी जाती है। धारा पर एक बिंदु, जो जल-विभाजक क्षेत्र के केन्द्रक से समीपतम है, की निगम से दूरी (Lc) 90 km मापी जाती है। जल-विभाजक के लिए क्षेत्रीय नियतांक C₁ = 0·75 एवं C₂ = 2·75 हैं । जल-विभाजक के लिए बनाए गए एकांक जलालेख से निम्नलिखित ज्ञात किए गए हैं : वर्षा अवधि tR = 12 h, द्रोणी काल पश्चाता (बेसिन लैग), tpR = 34 h एवं चरम निस्सरण, qpR = 135 m³/s. cm. जलविभाजक के संश्लेषिक एकांक जलालेख के लिए गुणांक Ct एवं Cp निर्धारित कीजिए । (20 अंक) (b) शहरी ठोस अपशिष्ट स्वच्छ भू-भराव का, एक योजनाबद्ध चित्र से, इसके विभिन्न अंगों को दर्शाते हुए, वर्णन कीजिए । (15 अंक) (c) ई.आई.ए. अधिनियम 2006 के अनुसार एक परियोजना को पर्यावरणीय स्वीकृति प्रदान करने की प्रक्रिया का संक्षेप में वर्णन कीजिए । (15 अंक)

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How this answer will be evaluated

Approach

Calculate the synthetic unit hydrograph coefficients Ct and Cp in part (a) using Snyder's method with given basin parameters; describe the sanitary landfill components with a neat schematic in part (b); and outline the EIA 2006 clearance process stepwise in part (c). Allocate approximately 40% time to numerical calculations in (a), 30% to diagram and description in (b), and 30% to procedural explanation in (c).

Key points expected

Part (a): Correct application of Snyder's synthetic unit hydrograph equations to calculate Ct = tpR/(C₁(L.Lc)^0.3) and Cp = qpR.tR/(C₂.A)
Part (a): Accurate substitution of values: L=125 km, Lc=90 km, A=3000 km², tR=12 h, tpR=34 h, qpR=135 m³/s.cm with proper unit handling
Part (b): Description of sanitary landfill components: liner system, leachate collection, gas collection, cover system, monitoring wells
Part (b): Schematic diagram showing cross-section with proper labeling of all functional layers and drainage systems
Part (c): Sequential steps of EIA 2006: screening, scoping, public consultation, appraisal by EAC, final EC with conditions, post-clearance monitoring
Part (c): Mention of category A/B projects, TOR preparation, 30-day public hearing notice, and validity period of clearance

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	20%	10	For (a), correctly identifies Snyder's method and defines Ct as basin lag coefficient and Cp as peak discharge coefficient; for (b), accurately describes double liner system, leachate recirculation, and methane gas recovery; for (c), precisely distinguishes between Category A and B projects and identifies MoEFCC vs. SEIAA jurisdiction	Identifies basic formulas for (a) and general landfill components for (b), but confuses leachate with runoff or omits gas management; for (c), lists steps but misses scoping or public consultation details	Uses wrong method (e.g., SCS curve number) for (a); describes open dumping instead of sanitary landfill for (b); omits EIA Notification 2006 specifics and confuses with older 1994 notification for (c)
Numerical accuracy	20%	10	For (a), computes (L.Lc)^0.3 = (125×90)^0.3 = 11250^0.3 ≈ 6.81 correctly; obtains Ct = 34/(0.75×6.81) ≈ 6.65 h and Cp = (135×12)/(2.75×3000) × appropriate unit conversion yielding dimensionally consistent values; shows intermediate calculations with 3-4 significant figures	Correct formula substitution but arithmetic errors in exponent calculation or unit conversion; final values within 10-15% of correct answer; missing intermediate steps	Major calculation errors: wrong exponent (uses 0.5 instead of 0.3), omits C₁ or C₂ constants, or fails to convert units (km² to appropriate units); or completely skips numerical part
Diagram quality	20%	10	For (b), draws detailed cross-sectional schematic with: composite liner (geomembrane + compacted clay), leachate collection layer with perforated pipes, waste cells in lifts, final cover with vegetation, gas venting wells, and groundwater monitoring wells; proper dimensioning arrows and clear labels; for (a) and (c), uses well-organized tables or flowcharts where helpful	Basic schematic showing 3-4 main components but missing details like secondary liner or gas collection; labels present but some unclear; diagram occupies adequate space but lacks professional finish	No diagram for (b) despite explicit requirement; or extremely crude sketch with unidentifiable components; diagram too small or labels missing; diagram contradicts description
Step-by-step derivation	20%	10	For (a), explicitly writes Snyder's equations: tp = C₁(L.Lc)^0.3 and qp = C₂.A/tp, then shows derivation of Ct = tpR/[C₁(L.Lc)^0.3] and Cp = qpR.tR/(C₂.A) with clear algebraic manipulation; for (c), presents EIA process as numbered chronological steps with timelines; logical flow from given data to final answer	Shows main formulas and final substitution but skips derivation of how Ct and Cp relate to regional constants; steps present but some logical gaps; for (c), steps listed but not in clear sequence	Only final answers without derivation; or completely wrong formulas; for (c), random listing without process flow; jumps from input to output without showing calculation steps
Practical interpretation	20%	10	For (a), interprets Ct ≈ 6.65 h as indicating a slower-responding basin compared to standard Snyder Ct=1.0-2.0, and Cp reflecting regional peak characteristics; for (b), relates landfill design to Indian conditions (MSW Rules 2016, CPCB guidelines) and mentions biomining/legacy waste; for (c), cites specific Indian projects (e.g., Tehri Dam, POSCO Odisha) and discusses 2020 EIA draft amendments controversy	Brief mention that coefficients are empirical or that landfill prevents groundwater contamination; generic statement about EIA importance without Indian context; no connection between theory and practice	No interpretation of what coefficients mean physically; treats landfill as purely theoretical; no mention of Indian regulatory framework or real-world application; completely abstract answer

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