Arroyos and Washes
Arroyos and Washes
Arroyos and washes are desert drainageways where water flows after a heavy rainstorm, but which are otherwise dry. Arroyos usually indicate that there is no local groundwater connection to the valley bottom. However, they sometimes mark areas where groundwater is closer to the surface than in the surrounding landscape. Infrequently, these channels may have sections that serve as ”recharge windows” where a portion of the surface flow seeps down through the streambed to the groundwater aquifer. Arroyos and washes are two types of impermanent, or ephemeral, water bodies found in New Mexico. They only flow occasionally in response to heavy rain storms. Playa lakes are another type of ephemeral water body found in arid landscapes like the desert southwest. Playa lakes form in depressions and generally have their own local watershed. Most playas form in response to precipitation, but some in New Mexico are supported by shallow groundwater. Open water appears in precipitation-driven playas after rain events. In many places, playas recharge a groundwater aquifer, but only very slowly since it depends on rainfall.
