The thesis deals with a general explanation of water balance, its components, and SIMPEL software designed for water balance calculations. The aim of the creators of the software was to reduce the complexity of calculations and to create a hydrological program designed for a wide range of users.
In the first part of the thesis, there is a general explanation of water balance and its components and a description of SIMPEL software. We described the necessary input data as well as where and in what form to insert them. Then metods for calculating evapotranspiration (ETp) e.g. the Haude, Thornthwaite, Blanex/Criddle, Turc, Penman, Makkink, Wendling for costal areas, Penman/Monteith for coniferous woods and Penman/monteith – EPIC are descriped. The bucket model which is the basis for calculation of the surface runoff is also introduced.
In the practical part of the thesis we calculated water balance for the catchment of Tolminka river using SIMPEL software. We compare the calculated values of ETp and surface runoff for one ‘wet’ year 2009 and one ‘dry’ year 2011. We compared measured and calculated values and assessed the predictive power of the model with Nash-Sutcliffe coefficient. The results demonstrate that model for calculations of ETp returned satisfactory results. However, it is difficult to satisfactory calibrate the model of surface runoff, which is often the problem of hydrological models.