Erosion Science
- Soil Properties Particle size: 0.001-2.0mm. Cohesion: 0-15 kPa. Friction angle: 25-45°. Bulk density: 1.2-1.8 g/cm³. Permeability: 10⁻⁸-10⁻³ cm/s.
- Hydraulic Factors Flow velocity: 0.5-6.0 ft/s. Shear stress: 0.1-8.0 lb/ft². Manning's n: 0.01-0.05. Reynolds number: 500-2000. Froude number: 0.4-1.2.
- Rainfall Impact Intensity: 0.5-4.0 in/hr. Duration: 5min-24hr. Return period: 2-100yr. Kinetic energy: 200-1200 J/m²·mm. Splash distance: 0.3-1.0m.
Control Methods
- Vegetative Measures Root depth: 6-36". Coverage density: 70-95%. Establishment time: 5-60 days. Growth rate: 0.5-2.0"/day. Soil binding: 2-15 kPa.
- Structural Solutions Riprap size: D50 6-24". Mat thickness: 0.25-2.0". Geotextile strength: 95-200 lbs. Anchor depth: 12-36". Overlap: 6-12".
- Chemical Stabilizers Application rate: 0.1-0.5 gal/yd². Penetration: 1-3". Binding strength: 50-150 kPa. Longevity: 3-12 months. pH tolerance: 4-9.
Cost Analysis
- Material Expenses Seed/mulch: $1500-3000/acre. Erosion blankets: $1-3/yd². Silt fence: $3-6/lf. Check dams: $100-300/ea. Stabilizers: $2000-4000/acre.
- Installation Labor Seeding: 0.5-1.0 acre/day. Blanket laying: 2000-4000 ft²/day. Fence install: 500-1000 lf/day. Maintenance: 10-20% of install.
- Project Factors Slope factor: 1.2-2.0×. Access difficulty: 1.1-1.5×. Weather risk: 15-30%. Permit compliance: 5-10%. Monitoring: 8-15%.
Performance Monitoring
- Inspection Requirements Frequency: weekly/post-rain. Coverage check: 95% min. Sediment depth: <50% capacity. Repair response: 24-48 hrs. Documentation: photo/written.
- Success Criteria Soil loss: <2 tons/acre/year. Vegetation establishment: >80%. Turbidity: <280 NTU. Sediment retention: >85%. BMP effectiveness: >90%.
- Maintenance Needs Reseeding: 10-25% area. Blanket repair: 5-15%. Fence cleaning: monthly. Sediment removal: quarterly. Chemical reapplication: 6-12 months.