http://www.uv.es/EBRIT/macro/macro_5000_74_165.htmlEvaporation in all desert regions is a factor of great significance....
The total annual evaporation everywhere exceeds total precipitation significantly, and, indeed, this relationship can be considered one of the climatic hallmarks of the arid regions...
Geologic factors such as rock type and structure, the character of the soil, and the porosity and permeability of surface materials in general also can affect the hydrology in two ways. If water will readily seep to the subsurface because of the presence of rock fissures and fractures or of highly permeable materials, then the runoff from a given amount of precipitation will be less than normal because of water losses. On the other hand, this same set of conditions may promote recharge (the addition of water) of the groundwater reservoir in the area. Where geologic factors inhibit the downward percolation of water, runoff following a storm may be enhanced, but, ultimately, greater evaporation may result.
In many desert regions, there is a lot of clay in the soil and when the water runoff caused by OHV ruts collects in ponds, it doesn't soak in, it evaporates, thus depriving the ecosystem of adequate moisture.
http://mojavedesert.net/plants/biological-soil-crusts/Soil loss due to rainfall and water movement is increased when cyanobacterial connections are broken. This is particularly problematic when the impact is in a continuous strip, such as a vehicle or bicycle track, because channels for water flow are quickly formed, especially on slopes.