Dew deposition and drying in a desert system: a simple simulation model

In a desert environment dew serves as an important source of moisture for plants, biological crusts, insects and small animals. A measurement programme was carried out within a sand dune area situated in the north-western Negev Desert, Israel, to acquire data on daily dew deposition amounts as well as related data of the micro-meteorological conditions during dew formation and the drying process. Dew quantities were measured using micro-lysimeters. A simple physical model was constructed to simulate the dew deposition process as well as early morning drying. Measurements carried out during September and October 1997 showed that the daily amounts of dew ranged between 0•1 to 0•2 mm per night. The early morning drying process occurs slowly due to the low matrix potential of the soil under dry conditions. The simulated results agreed well with the field data.