Which term describes the degree of inclination of a surface expressed as a percentage?

The term that accurately describes the degree of inclination of a surface expressed as a percentage is "Grade." In the context of grading, drainage, and stormwater management, the grade refers to the steepness or pitch of a surface, such as a road or slope, which is typically expressed as a percentage. This percentage is calculated by taking the vertical rise over the horizontal run and multiplying it by 100.

For example, if a surface rises 10 feet over a horizontal distance of 100 feet, the grade would be 10%. Understanding grade is crucial for effective design and management in landscaping and civil engineering, particularly in ensuring proper drainage and preventing erosion. While gradient and slope are terms that may describe similar concepts, they do not specifically denote the percentage measurement as explicitly as grade does.

Inclination is a more general term and may not directly relate to the formulaic expression of steepness as a percentage. Therefore, the most suitable term in this specific context is grade, as it precisely conveys the measurement of inclination in terms of percentage.