the system as runoff and can contribute to erosion. In a basin with a higher vertical hydraulic conductivity, water more effectively infiltrates into the ground and does not contribute to saturated overland flow erosion, resulting in a less developed channel system and therefore lower drainage density. Relation to the mean annual flood Charles Carlston (1963) determined an equation to express the mean annual flood runoff, Q2.33, for a given drainage basin as a function of drainage density. Carlston found a correlation between the two quantities when plotting data from 15 drainage basins and determined the following equation: Where Q is in units of cubic feet per second per square mile and Dd is in units of inverse miles. From that equation, it is concluded that a drainage basin will adjust itself through erosion such that this equation is satisfied. Effect of vegetation on drainage density The presence of vegetation in a drainage basin has multiple effects on the drainage density. Vegetation prevents landslides in the source area of a basin that would result in channel formation as well as decrease the range of drainage density values regardless of soil composition. Vegetation stabilizes the unstable source area in basin and prevents channel initiation. Plants stabilize the hillslope that they grow in, which results in physical erosion processes such as rainsplash, dry ravel, or freezing and thawing processes. While there is significant variation between species, plant roots grow in underground networks that holds the soil in place. Because the soil is held in place, it is less prone to erosion from those physical methods. Hillslope diffusion was found to decrease exponentially with vegetation cover. By stabilizing the hillslope in the source area of the basins, channel initiation, channel initiation is less likely. The erosional processes that may lead to channel initiation are prevented. The increased soil strength also protects against surface runoff erosion, which hinders channel evolution once it has begun. At the basin scale, there are fewer channels in the basin and the drainage density is lower than an unvegetated system. The effect of the vegetation on decreasing the drainage density is not unbounded though. At high vegetative coverage, the effect of increasing the coverage diminishes. This effect imposes an upper limit to the total reduction in drainage density that vegetation can result in. Vegetation also narrows the range of drainage density values for basins of various soil composition. Unvegetated basins