Sensitivity of Reference Evapotranspiration and Soil Evaporation to Climate Change in the Eastern Mediterranean Region

Abstract

Climate data generated by a regional climate model (RCM) under the A2 scenario were used to quantify the evaporative demand of the atmosphere in the Mediterranean region of Turkey in a baseline period (1994–2003) and the future (2070–2079). The daily reference evapotranspiration and bare soil evaporation were computed using the FAO-56 Penman-Monteith and E-DiGOR models, respectively, for both periods. The sensitivity of Penman-Monteith type equations to the major climatic variables was determined. Based on decadal averages, solar radiation, air temperature, and wind-speed were projected to increase from 16.084 to 16.324 MJ m−2 day−1, from 19.3 °C to 20.7 °C, and from 0.75 to 0.77 m s−1 respectively, by the period of 2070–2079 compared with the baseline period. By contrast, the relative humidity is expected to decrease from 68.1 to 67.5% (equivalent to a 0.9% reduction). The reference evapotranspiration (Eto) and potential soil evaporation (Ep) are projected to increase by 92.0 mm year−1 and 68.6 mm year−1 respectively by the 2070s. Conversely, the actual soil evaporation (Ea) is expected to decrease by 49.6 mm year−1 by the same period due to the decrease in rainfall and soil wetness.