Although important, data regarding the spatial distribution of evaporation are scarce. With the development of a small reference atmometer (RAM), studying the spatial distribution of evaporation was made more feasible and consequently carried out at the hilltops (TOP), wadi beds (WADI) and along the northern (NF), southern (SF), eastern (EF) and western (WF) aspects within a second order drainage basin in the Negev Desert Highlands during June 2004 to May 2006. Evaporation rates showed high variability in accordance with season and aspect following the order: TOP > SF ≥ EF ≥ WF > WADI > NF. The data showed (a) an increase in evaporation with elevation; (b) that the average evaporation rates of the stations located at the slopes and the wadi beds were respectively ∼14% and ∼23% lower than that of the hilltop stations; (c) that while insignificant differences characterized the eastern and the western aspects during summer and winter, significant differences characterized the northern and the southern aspects, and (d) that the ratio obtained between the northern and southern aspects is significantly different from that calculated based on direct-beam shortwave radiation. The findings were explained by the effects of sun and wind upon evaporation, with each factor explaining up to ∼45-50% of the results. The findings are in agreement with the dense vegetation at the north-facing footslope and at the wadi bed, and may have important implications towards the understanding of microorganism and plant distribution as well as geomorphological and pedological topics such as weathering rates and soil forming processes.
Bibliographical noteFunding Information:
The study was supported by Grant 1358/04 of the Israel Science Foundation (ISF) . We warmly would like to thank Avraham Starinsky for his support, making the research available, Ariel Cohen for his helpful advice, and to Israel Einot for his valuable statistical assistance. We would like to thank Jaacov Mishaeli, Talia Horovitz and Elad Shilo from the Israel Meteorological Society, Rafi Kronenfeld and Shmuel Melamed from Kibbutz Sede Boqer for providing essential meteorological equipment and data, Shimon Tal for his valuable technical assistance and Carol A. Kidron for the editing. Special thanks to the anonymous reviewers for their very helpful comments.
- Drainage basin
- Evaporation rates
- Negev Desert
- Reference atmometer
ASJC Scopus subject areas
- Water Science and Technology