Determination of Evaporation Based On Stable Isotope Measurements.

In April 2009 a field experiment started to investigate the different elements of the soil water balance, esp. evaporation and deep percolation using isotope and conventional methods.
In April 2008 investigations started at an agro-meteorological station in Gross-Enzersdorf, Austria (48° 12' 10'' N, 16° 33' 3'' E). Average annual precipitation amounts to 547 mm with an average annual temperature of 9.9 C. From April to October daily potential evapotranspiration rates were measured by using a CGI 3000 evaporation pan.
In weekly intervals water samples from this pan were taken. Additionally rainfall was measured and sampled event based. From all water samples stable isotopes (d²H and d¹⁸O) were determined in the IAEA Hydrology Lab using laser spectroscopy. A relationship between measured data and change of isotope concentration in evaporation pan was developed to calculate evaporation rates.