The runoff coefficient as the key to moisture recycling

Moisture recycling by evapotranspiration from vegetation is probably the most important mechanism sustaining rainfall on continental catchments, particularly in semiarid areas. A very simple and very useful parameter to evaluate moisture recycling is the annual runoff coefficient C-R. On continents, the proportion of rainfall recycled equals 1 - C-R, whereas the average number of times that a moisture particle returns as rainfall equals 1/C-R. Since the runoff coefficient is widely mapped, it is a very handy indicator to evaluate the importance of landuse practices in rainfall recycling. It is further stated that the idea of some water resources engineers that a high runoff coefficient is an asset for water resources development is a misconception. For the water resources management of continental areas, the most efficient use of water is made by minimizing runoff.