Terminology and Background

Key Terms and Definitions

Rainfall Intensity (I)

The rate of rainfall expressed in millimetres per hour (mm/hr). It describes how fast rain falls during a storm event.

Maximum 30-minute Intensity (I30)

The maximum rainfall intensity recorded over any 30-minute period during a storm. Expressed in mm/hr. This is a key parameter in soil erosion prediction.

Kinetic Energy (E)

The energy delivered by raindrops to the soil surface. Calculated from rainfall intensity using empirical equations such as Brown & Foster (1987), Wischmeier & Smith (1978), or McGregor & Mutchler (1976).

Erosivity Index (EI30)

The product of total storm kinetic energy (E) and maximum 30-minute intensity (I30). It quantifies the erosive power of a rainfall event:

EI30 = E x I30

Erosivity

The ability of rainfall to cause soil erosion. Higher erosivity means greater potential for detaching and transporting soil particles.

Breakpoint Rainfall Data

Rainfall data recorded at irregular or regular time intervals where each record represents the depth of rain (mm) that fell during that interval.

USLE — Universal Soil Loss Equation

An empirical model used to estimate average annual soil loss from a field. EI30 is the rainfall erosivity factor (R factor) in the USLE.

RUSLE — Revised Universal Soil Loss Equation

An improved version of the USLE incorporating updated equations and additional factors for better soil loss prediction accuracy.

Hydrological Analysis

The study of water movement, distribution, and quality in the environment. Rainfall intensity and erosivity are key inputs in hydrological modeling.

References