InfraLensInfraLens
IS CodesIRCToolsSORHandbookQA/QCPMCFormatsCPHEEOMapsProjectsDCRRulesAbout Join Channel
Join
IS CodesIRCToolsSORHandbookQA/QCPMCFormatsCPHEEOMapsProjectsDCRDesign RulesBIMAbout Join WhatsApp Channel
InfraLensInfraLens
IS CodesIRCToolsSORHandbookQA/QCPMCFormatsCPHEEOMapsProjectsDCRRulesAbout Join Channel
Join
IS CodesIRCToolsSORHandbookQA/QCPMCFormatsCPHEEOMapsProjectsDCRDesign RulesBIMAbout Join WhatsApp Channel

IS 8409 : 1977Criteria for Design of Rubble Mound Breakwaters

PDFGoogleCompareBIS Portal
Link points to Internet Archive / others. Not hosted by InfraLens. Details
The Rock Manual (2007) · CEM 1110-2 · PIANC MarCom WG 40 (2003)
CurrentSpecializedGuidelinesWater Resources · Coastal and Marine Engineering
PDFGoogleCompareBIS Portal
Link points to Internet Archive / others. Not hosted by InfraLens. Details
OverviewValues5InternationalTablesFAQ3

IS 8409:1977 is the Indian Standard (BIS) for criteria for design of rubble mound breakwaters. This standard provides criteria and guidelines for the hydraulic design of rubble mound breakwaters. It focuses on determining armour unit stability against wave action using the Hudson formula, and provides recommendations for the geometric design of the breakwater's cross-section, including crest, slopes, and filter layers.

Specifies criteria for the design of rubble mound breakwaters, including design waves, stability, and material requirements.

Overview

Status
Current
Usage level
Specialized
Domain
Water Resources — Coastal and Marine Engineering
Type
Guidelines
International equivalents
The Rock Manual (2007) · CIRIA, CUR & CETMEF (UK, Netherlands, France)CEM 1110-2-1100 (2011) · US Army Corps of Engineers (USACE), USAPIANC MarCom WG 40 (2003) · PIANC (The World Association for Waterborne Transport Infrastructure), International
Also on InfraLens for IS 8409
5Key values1Tables3FAQs
Practical Notes
! This standard is outdated and has been superseded by IS 16474. It should be used for reference purposes only.
! The core of this code is the Hudson formula, which is known to be less accurate for breaking waves or steep slopes. Modern designs often use the Van der Meer formulas or physical model testing for optimization and verification.
! The selection of the Stability Coefficient (Kd) from Table 1 is the most critical and sensitive parameter in the design. It requires significant engineering judgment based on armour shape, placement method, and wave conditions.
Frequently referenced clauses
Cl. 4Design DataCl. 5Armour Unit StabilityCl. 6Cross-Section of BreakwaterCl. 7Foundation and Toe
Pulled from IS 8409:1977. Browse the full clause & table index below in Tables & Referenced Sections.
rockarmour stonequarry runconcrete

International Equivalents

Similar International Standards
The Rock Manual (2007)CIRIA, CUR & CETMEF (UK, Netherlands, France)
HighCurrent
The use of rock in hydraulic engineering (2nd edition)
Comprehensive guide covering all aspects of rubble mound design, acting as a de facto international standard.
CEM 1110-2-1100 (2011)US Army Corps of Engineers (USACE), USA
HighCurrent
Coastal Engineering Manual (CEM), Part VI, Chapter V-3: Design of Rubble-Mound Structures
Authoritative US manual providing detailed design procedures for rubble mound breakwaters and revetments.
BS 6349-7:1991British Standards Institution (BSI), UK
HighWithdrawn
Maritime structures. Guide to the design and construction of breakwaters
Directly equivalent national standard, though now outdated, covering rubble mound breakwater design.
PIANC MarCom WG 40 (2003)PIANC (The World Association for Waterborne Transport Infrastructure), International
MediumCurrent
State-of-the-Art of Designing and Constructing Berm Breakwaters
Focuses on a specific, advanced type of rubble mound structure (berm breakwaters) not detailed in IS 8409.
Key Differences
≠IS 8409 exclusively uses the Hudson formula for armor stability, whereas modern international standards (Rock Manual, CEM) primarily use the more advanced Van der Meer formulae, which account for wave period, storm duration, and wave plunging/surging characteristics.
≠The Indian standard uses a deterministic design approach. In contrast, modern practice, guided by The Rock Manual and CEM, strongly incorporates probabilistic or reliability-based design methods to account for uncertainties in wave loads and structural resistance.
≠IS 8409 provides very limited guidance on wave overtopping. International standards provide detailed methods (e.g., from the EurOtop Manual) to predict mean overtopping discharge and link these values to safety limits for people, vehicles, and structures behind the breakwater.
≠The scope of IS 8409 is limited to traditional, statically stable, multi-layered breakwaters. It does not cover modern concepts like dynamically stable berm breakwaters, reef breakwaters, or composite structures, which are extensively covered in documents like The Rock Manual and PIANC reports.
Key Similarities
≈The fundamental design principle of using the mass of individual armor units (rock or concrete) to resist wave forces is the same across all standards.
≈The basic structural cross-section concept, comprising a core of fine material, one or more underlayers, and a primary armor layer, is a common feature in both IS 8409 and international standards.
≈All standards recognize the stability of the breakwater toe as a critical design element for the overall stability of the main armor slope and prescribe specific design considerations for it.
≈The calculation for armor layer thickness is conceptually similar, typically defined as two nominal armor stone diameters (n=2), although the notation and calculation of the nominal diameter may differ slightly.
≈Although outdated, the Hudson formula and its associated stability coefficient (K_D), which are central to IS 8409, are still referenced in modern international manuals like the CEM as a tool for preliminary design or for specific simple cases.
Parameter Comparison
ParameterIS ValueInternationalSource
Primary Armor Stability FormulaRelies solely on Hudson Formula: W = (γ_r * H^3) / (K_D * (S_r - 1)^3 * cot(α))Primarily uses Van der Meer formulae, which are more complex and account for wave period and breaking type.The Rock Manual (2007)
Stability Coefficient K_D (Rough angular rock, trunk, breaking)K_D = 2.0K_D = 2.0 (for preliminary design). Note: Modern design focuses on damage level 'S' and storm duration 'N' in Van der Meer's formula instead of a single K_D.USACE CEM 1110-2-1100
Armor Layer Thicknesst = n * k_Δ * (W / γ_r)^(1/3), where n=2 (number of layers)t = n * k_t * D_n50, where n=2 and D_n50 is the nominal diameter. The concept is identical.The Rock Manual (2007)
Minimum Crest WidthSufficient for 3 armor units side by side.Minimum width of 3 nominal armor stone diameters (3 * D_n50).USACE CEM 1110-2-1100
Seaward Slope (cot α)Recommended range is 1.5 to 3.0.Typical range is 1.5 to 4.0, chosen based on stability calculations rather than a fixed recommendation.The Rock Manual (2007)
Underlayer Stone SizingWeight of underlayer stones is W/10 to W/15 of the armor stone weight (W).Based on geometric filter criteria to prevent washing out of finer material, e.g., D_15(Filter) / D_85(Base) < 5.The Rock Manual (2007)
Design WaveSpecifies use of significant wave height (H_s) and average period (T_z).Uses full spectral parameters (H_m0, T_p, T_m-1,0) and spectral shapes (e.g., JONSWAP) for more accurate modelling.The Rock Manual (2007)
⚠ Verify details from original standards before use

Key Values5

Quick Reference Values
Specific weight of sea water (γw)1.025 t/m³
Typical Stability Coefficient (Kd) for rough angular quarry stone (2 layers, trunk)2.0
Typical armour layer slope (cot α)1.5 to 2.0
Specific weight of rock (γr)2.65 t/m³
Porosity of armour layer37-40 %
Key Formulas
W = (γr * H³) / (Kd * (Sr - 1)³ * cot α) — Hudson's formula for Armour Unit Weight (W=weight, γr=unit wt of rock, H=wave height, Kd=stability coeff, Sr=specific gravity of rock, α=slope angle)

Tables & Referenced Sections

Key Tables
Table 1 - Stability Coefficient, Kd
Key Clauses
Clause 4 - Design Data
Clause 5 - Armour Unit Stability
Clause 6 - Cross-Section of Breakwater
Clause 7 - Foundation and Toe

Frequently Asked Questions3

What is the primary formula used to determine the size of armour stones?+
The Hudson formula, W = (γr * H³) / (Kd * (Sr - 1)³ * cot α), is used to calculate the required weight (W) of an individual armour unit (Clause 5.2).
What is a typical value for the Stability Coefficient (Kd) for natural quarry stone?+
For rough, angular quarry stone placed in two layers on a breakwater trunk, a Kd value of 2.0 is recommended (Table 1).
How is the crest width of the breakwater determined?+
The crest width should be determined by the number of armour units, with a minimum of three stones, to resist wave action and provide construction/maintenance access (Clause 6.3).

QA/QC Inspection Templates

📋
QA/QC templates coming soon for this code.
Browse all 300 templates →