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title: "Terminology and Background"
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## 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

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

- Wischmeier, W.H. and Smith, D.D. (1978). Predicting rainfall 
  erosion losses. *USDA Agricultural Handbook*, No. 537.

- McGregor, K.C. and Mutchler, C.K. (1976). Status of the R 
  factor in northern Mississippi. *Soil Erosion: Prediction and 
  Control*, 135-142.
