Effective crest length
effective_crest_length_m
Effective crest length after pier and abutment contraction corrections L_eff (m)
Scores if within ±3% of the reference value.
Calculates spillway discharge capacity using the weir equation Q = C*L_eff*H_e^1.5 with pier and abutment contraction corrections to effective crest length and approach velocity head adjustments per USBR Design Standard No. 14 and USACE EM 1110-2-1603. Supports ogee and broad-crested weir types for dam safety and flood routing assessments.
with-tool: The model is given an executable Python calculator script.
One template produces many comparable benchmark tasks while keeping the scoring contract fixed.
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The reusable contract shown on this page.
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An archetype and site context are sampled.
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Inputs may be hidden at harder tiers.
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The model responds with the declared outputs.
Inputs the model receives, and the outputs it is scored on.
8 inputs
Included directly in every task prompt.
Crest length
crest_length_m
Gross crest length of the spillway L
Design head
design_head_m
Design head over the spillway crest H
Sampled from the scenario and inferable from its description.
Discharge coefficient
discharge_coefficient
Weir discharge coefficient C (SI metric)
Derived from the archetype scenario. Hidden at hard difficulty.
Used only when the sampled task needs this part of the contract.
Number of piers
number_of_piers
Number of piers on the spillway crest N
Optional input.
Pier shape
pier_shape
Pier nose geometry for contraction coefficient Kp
Derived from the archetype scenario. Optional input. Hidden at hard difficulty.
Abutment shape
abutment_shape
Abutment geometry for contraction coefficient Ka
Derived from the archetype scenario. Optional input. Hidden at hard difficulty.
Approach channel width
approach_channel_width_m
Width of the approach channel upstream of the spillway B
Optional input.
Approach depth
approach_depth_m
Depth of flow in the approach channel h_approach
Optional input.
5 outputs
effective_crest_length_m
Effective crest length after pier and abutment contraction corrections L_eff (m)
Scores if within ±3% of the reference value.
approach_velocity_head_m
Approach velocity head correction Va²/(2g) (m)
Scores if within ±5% of the reference value.
total_energy_head_m
Total energy head over crest He = H + Va²/(2g) (m)
Scores if within ±3% of the reference value.
discharge_m3_s
Total spillway discharge capacity Q (m³/s)
Scores if within ±3% of the reference value.
unit_discharge_m3_s_per_m
Unit discharge per metre of effective crest q (m³/s/m)
Scores if within ±3% of the reference value.
Each template is sampled at three tiers. Harder tiers may hide inputs, forcing the model to infer them from the scenario description.
All inputs given
Simple ogee spillway, no piers, all parameters given
Number of piers restricted to: 0
Pier shape restricted to: round
Abutment shape restricted to: rounded
All inputs given
All parameters given, includes pier and abutment corrections across both types
Some inputs hidden
Discharge coefficient, pier shape, and abutment shape hidden; agent infers from site context
Hidden inputs
Prompt replacement text
The spillway is a {{ archetype.description }} ({{ archetype.site_context }})
The exact instruction and parameter contract used to generate this task, pinned to the published library source.
/workspace
Teal lines show Jinja input conditions, not task visibility policy. A line renders only when that input or tool is visible.
1You are a senior civil/dams engineer specializing in spillway hydraulics and dam safety.2 3## Problem4 5Calculate the discharge capacity of a spillway weir using the standard weir equation with pier and abutment contraction corrections.6 7## Given8 9| Parameter | Value | Unit |10|-----------|-------|------|11| Gross crest length (L) | {{ crest_length_m }} | m |12| Design head over crest (H) | {{ design_head_m }} | m |13{% if discharge_coefficient is defined %}14| Discharge coefficient (C) | {{ discharge_coefficient }} | - |15{% endif %}16{% if number_of_piers is defined %}17| Number of piers (N) | {{ number_of_piers }} | - |18{% endif %}19{% if pier_shape is defined %}20| Pier nose shape | {{ pier_shape }} | - |21{% endif %}22{% if abutment_shape is defined %}23| Abutment shape | {{ abutment_shape }} | - |24{% endif %}25{% if approach_channel_width_m is defined %}26| Approach channel width (B) | {{ approach_channel_width_m }} | m |27{% endif %}28{% if approach_depth_m is defined %}29| Approach flow depth (h_approach) | {{ approach_depth_m }} | m |30{% endif %}31{% if archetype_description is defined %}32 33### Site Conditions34 35{{ archetype_description }}36{% endif %}37 38{% if tool_available %}39## Available Tool40 41A spillway discharge calculation tool is available at `/workspace/spillway-weir-capacity_calc.py`. Run it with:42 43```bash44python3 /workspace/spillway-weir-capacity_calc.py --help45```46 47You may use this tool to verify your calculations or compute values directly.48{% endif %}49 50## Required51 52Calculate the following:53 541. Effective crest length after pier and abutment contraction corrections L_eff (m)552. Approach velocity head correction Va²/(2g) (m)563. Total energy head over crest He (m)574. Total spillway discharge capacity Q (m³/s)585. Unit discharge per metre of effective crest q (m³/s/m)59 60## Applicable Standards61 62- USBR Design Standard No. 14 — Spillway design criteria63- USACE EM 1110-2-1603 — Hydraulic Design of Spillways64 65## Constraints66 67- No internet access is available. Work from engineering knowledge and the provided tool.68- Use the standard weir discharge equation:69 - **Q = C × L_eff × H_e^(3/2)**70 - Where C is the weir discharge coefficient in SI metric units71- Compute effective crest length with pier and abutment corrections:72 - **L_eff = L − 2 × (N × Kp + Ka) × H**73 - Pier contraction coefficients Kp: square = 0.02, round = 0.01, pointed = 0.0074 - Abutment contraction coefficients Ka: square = 0.20, rounded = 0.10, streamlined = 0.0075- Apply approach velocity head correction:76 - **Va = Q_initial / (B × h_approach)**77 - **Velocity head = Va² / (2g)**78 - **H_e = H + Va² / (2g)**79 - First compute Q_initial = C × L_eff × H^(3/2) without velocity head, then apply correction80- Use g = 9.81 m/s²81- Typical discharge coefficients (SI metric):82 - Ogee spillway: C ≈ 2.10–2.2083 - Broad-crested weir: C ≈ 1.50–1.8084- If no pier shape is given, assume round-nosed piers (Kp = 0.01)85- If no abutment shape is given, assume rounded abutments (Ka = 0.10)86- If no number of piers is given, assume N = 087- Unit discharge: q = Q / L_eff88 89## Output Format90 91Show your step-by-step working in Markdown, including formulas and intermediate calculations. At the end of your solution, include a JSON block with your final answers in exactly this format:92 93```json94{95 "effective_crest_length_m": <numeric_value>,96 "approach_velocity_head_m": <numeric_value>,97 "total_energy_head_m": <numeric_value>,98 "discharge_m3_s": <numeric_value>,99 "unit_discharge_m3_s_per_m": <numeric_value>100}101```102 103Write your complete solution to `/workspace/output.md`.104 Each generated task is drawn from one of these realistic scenario bands.
Site contexts ground each scenario in a real locale the model can use to infer hidden values.
small_ogee_dam
Small ogee spillway dam with low head and no piers
medium_ogee_gated
Medium ogee spillway with gated bays and piers
large_ogee_flood
Large ogee flood spillway with multiple pier bays
broad_crested_weir
Broad-crested weir spillway on low-head dam or diversion structure
broad_crested_large
Large broad-crested spillway with piers for multi-bay structure
snowy-mountains-flood-dam-large-ogee-flood-preview — hard difficulty, some inputs hidden.
Large ogee flood spillway with multiple pier bays. snowy-mountains-flood-dam. Required outputs: effective_crest_length_m, approach_velocity_head_m, total_energy_head_m, discharge_m3_s, unit_discharge_m3_s_per_m
Scenario context and visible inputs.
Executable tool: spillway-weir-capacity_calc.py
Inputs withheld at this difficulty.
Abutment shape
abutment_shape
Pier shape
pier_shape
Discharge coefficient
discharge_coefficient
Stand-in text in the prompt
The spillway is a {{ archetype.description }} ({{ archetype.site_context }})
The scored JSON answer schema.
{
"effective_crest_length_m": <number>,
"approach_velocity_head_m": <number>,
"total_energy_head_m": <number>,
"discharge_m3_s": <number>,
"unit_discharge_m3_s_per_m": <number>
}