What little precipitation does occur in such harsh environments is not always available to the
plant and animal life. Long drought seasons create hard crusts on desert soil, resulting in runoff, characterized by flood channels and wadis. Physical, inorganic crusts have been extensively investigated because of their negative impact on arid agricultural land. What little moisture does remain in the soil undergoes excessive evapotranspiration. Deserts bordering coastal lands derive most of their moisture from moist onshore breezes. This moisture evaporates from the soil leaving behind high concentrations of NaCl.