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Potential evapotranspiration for the distributed modeling of Belgian catchments

Abstract:

To support a sensitivity analysis in the framework of catchment modeling, three potential evapotranspiration (ET<inf>p</inf>) scenarios were generated by means of two Food and Agriculture Organization (FAO) approaches, namely, the FAO-24 and the FAO-56 approaches. The crop ET<inf>p</inf>, was estimated as a function of the reference evapotranspiration (ET<inf>o</inf>) by means of the k<inf>c</inf>-ET<inf>o</inf>, approach. Scenario A was generated with the standard FAO-24 approach; Scenario B considered also the FAO-24 approach, but with some nonstandard parameters. Scenario C considered the standard FAO-56 approach. The ET<inf>o</inf> data were compared to point-scale ET<inf>o</inf> constraints. The annual cumulative value of ET<inf>o</inf> from Scenario A was on average approximately 200 mm larger than the values from Scenarios B and C. The research revealed similar ET<inf>o</inf>, estimates for Scenarios B and C. The research also assessed the performance of the angstrom approach for estimating incoming solar radiation (R<inf>s</inf>). In this context, a set of angstrom coefficients was derived by means of an optimization process that considered available R<inf>s</inf> data.