Topography refers to the percent slope and the pattern or frequency of slopes in different directions in a field. The steeper the slope, the less suitable the field is for potato production. Surface runoff occurs when the amount of water from rainfall or an irrigation application exceeds the rate of infiltration, which is strongly influenced by soil texture. The risk of soil loss is proportional to the length of the slope and the severity of the grade. Medium and fine textured soils are most susceptible to water erosion in sloping landscapes.