Nõlv

Nõlv is an Estonian noun meaning slope or incline. In geography and related fields, nõlv denotes the inclination of a surface relative to the horizontal, typically the ground. It describes how steeply terrain rises or falls and is a key factor in erosion, drainage, and construction.

Nõlv is commonly expressed as gradient in percent (rise per 100 units of horizontal distance) or as an angle in degrees. For example, a 10% slope corresponds to a small incline, while a slope of 45 degrees is very steep. The choice of units depends on the field: civil engineering often uses percent or grade, while geography or surveying may report angle.

Slopes are mapped using topographic data and measured in the field with clinometers or slope meters, and refined with digital elevation models. In planning and land-use management, the slope informs decisions on road alignment, building foundations, flood risk, drainage, stability of soils, and forest operations. Gentle slopes promote easier cultivation and drainage; steeper slopes are more prone to erosion and may require mitigation practices.

In Estonia and other regions, terrain variation leads to a mosaic of nõlv types from flat plateaus to steep hillsides, affecting land cover, land use, and infrastructure planning.