rainerosr

Calculate I30 (maximum 30-minute rainfall intensity) and EI30 (erosivity index) from rainfall breakpoint data for use in soil erosion modeling.

Installation

# Install from GitHub (once uploaded)
# devtools::install_github("yourusername/rainerosr")

# Or install locally
devtools::install_local("path/to/rainerosr")

Features

• I30 Calculation: Maximum 30-minute rainfall intensity from breakpoint data
• EI30 (Erosivity Index): Calculate rainfall erosivity using multiple kinetic energy equations
• Multi-Event Processing: Automatically separate and analyze multiple storm events
• Data Validation: Comprehensive checks for data quality and consistency
• Visualization: Plot rainfall patterns and intensity profiles
• Flexible Input: Works with various time interval formats

Quick Start

Basic I30 Calculation

library(rainerosr)

# Create sample data
data <- data.frame(
  datetime = as.POSIXct(c(
    "2024-01-15 14:00:00",
    "2024-01-15 14:15:00",
    "2024-01-15 14:30:00",
    "2024-01-15 14:45:00",
    "2024-01-15 15:00:00"
  )),
  rainfall_mm = c(5.2, 8.3, 6.1, 3.4, 2.0)
)

# Calculate I30
result <- calculate_i30(data, "datetime", "rainfall_mm")

print(paste("Maximum 30-minute intensity:", result$i30, "mm/hr"))
print(paste("Total rainfall:", result$total_rainfall, "mm"))

Calculate EI30 (Erosivity Index)

# Calculate erosivity index
ei30_result <- calculate_ei30(data, "datetime", "rainfall_mm")

print(paste("EI30:", ei30_result$ei30, "MJ mm ha^-1 hr^-1"))
print(paste("Total energy:", ei30_result$total_energy, "MJ ha^-1"))
print(paste("I30:", ei30_result$i30, "mm/hr"))

# Use different kinetic energy equation
ei30_wisch <- calculate_ei30(data, "datetime", "rainfall_mm", 
                             ke_equation = "wischmeier")

Process Multiple Storm Events

# Data with multiple storms
multi_data <- data.frame(
  datetime = as.POSIXct(c(
    # Storm 1
    "2024-03-10 09:00:00", "2024-03-10 09:15:00", "2024-03-10 09:30:00",
    # Storm 2 (8 hours later)
    "2024-03-10 18:00:00", "2024-03-10 18:20:00", "2024-03-10 18:40:00"
  )),
  rainfall_mm = c(6.5, 8.9, 5.2, 9.2, 7.8, 6.3)
)

# Process all events
events <- process_storm_events(
  multi_data, 
  "datetime", 
  "rainfall_mm",
  min_gap_hours = 6,        # Separate events by 6-hour gaps
  min_rainfall_mm = 12.7    # Minimum 12.7mm to be considered an event
)

print(events)

Data Validation

# Validate your data before analysis
validation <- validate_rainfall_data(data, "datetime", "rainfall_mm")

if (validation$valid) {
  print("Data is valid!")
} else {
  print("Issues found:")
  print(validation$issues)
}

if (length(validation$warnings) > 0) {
  print("Warnings:")
  print(validation$warnings)
}

Visualization

library(ggplot2)

# Plot rainfall pattern
plot_rainfall_pattern(data, "datetime", "rainfall_mm", plot_type = "both")

# Plot intensity profile with I30 highlighted
plot_intensity_profile(data, "datetime", "rainfall_mm", highlight_i30 = TRUE)

Input Data Format

The package accepts rainfall breakpoint data in the following formats:

Option 1: Time and Rainfall Depth (most common)

data <- data.frame(
  time = as.POSIXct(...),  # POSIXct datetime objects
  depth_mm = c(...)         # Rainfall depth in mm
)

The function will automatically calculate time intervals between consecutive points.

Option 2: With Explicit Intervals

data <- data.frame(
  time = as.POSIXct(...),
  depth_mm = c(...),
  interval_min = c(...)     # Time interval in minutes
)

Kinetic Energy Equations

Three equations are available for calculating kinetic energy:

1. Brown & Foster (1987) - Default, widely used
   • e = 0.29[1 - 0.72exp(-0.05i)]
2. Wischmeier & Smith (1978) - Classic USLE equation
   • e = 0.119 + 0.0873log10(i)
3. McGregor & Mutchler (1976) - For southern US conditions
   • e = 0.273 + 0.2168i - 0.0083i² (for i < 76 mm/hr)

Where e is unit energy (MJ ha⁻¹ mm⁻¹) and i is intensity (mm hr⁻¹).

Functions

Output Units

• I30: mm/hr (millimeters per hour)
• Rainfall depth: mm (millimeters)
• EI30: MJ mm ha⁻¹ hr⁻¹ (megajoules millimeters per hectare per hour)
• Energy: MJ ha⁻¹ (megajoules per hectare)
• Duration: minutes

Use Cases

• USLE/RUSLE modeling: Calculate R-factor components
• Hydrological analysis: Assess rainfall intensity patterns
• Erosion risk assessment: Quantify erosive potential of storms
• Climate studies: Analyze temporal rainfall patterns
• Engineering design: Design storm characterization

References

• Brown, L.C., & Foster, G.R. (1987). Storm erosivity using idealized intensity distributions. Transactions of the ASAE, 30(2), 379-386.

• Wischmeier, W.H., & Smith, D.D. (1978). Predicting rainfall erosion losses: A guide to conservation planning. USDA Agriculture Handbook No. 537.

• Renard, K.G., Foster, G.R., Weesies, G.A., McCool, D.K., & Yoder, D.C. (1997). Predicting soil erosion by water: A guide to conservation planning with the Revised Universal Soil Loss Equation (RUSLE). USDA Agriculture Handbook No. 703.

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

License

MIT License

Author

Your Name

Citation

If you use this package in your research, please cite:

Your Name (2026). rainerosr: Calculate Rainfall Intensity and Erosivity Indices.
R package version 0.1.0.

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