Paper presents comparison of the daily reference crop (grass vegetation cover) potential evapotranspiration results calculated by the two modifications of the Penman-Monteith type equation. The first modification was published in FAO recommendation (Allen at al., 1998), PM-FAO, the second is modification according to Budagovskiy (1964) and Novák (1995), PM-BN. Both are used in soil water simulation models HYDRUS-1D and GLOBAL. Calculations were performed for frost-free seasons of the years 2000-2009, using the meteorological station Gabčíkovo (South Slovakia) meteorological data and canopy characteristics. The results indicate significant differences in daily and seasonal potential evapotranspiration. Reasons for those differences are discussed; they should be in different net radiation and aerodynamic resistance estimation methods.
Transient infiltration into a swelling, cracked fine-textured soil was calculated using the originally designed FRACTURE submodel (version B) of the HYDRUS-ET simulation model. The model permits changes in the dimensions of the cracks during the infiltration process. Modeling results obtained with the new model were compared with those from FRACTURE submodel (version A) assuming a stable crack system. It is shown that deforming cracks lead to higher rates of infiltration during precipitation events as compared with stable cracks. A difference of about 20 percent was estimated in our illustrative example. and Práca obsahuje výsledky matematického modelovania infiltrácie vody do pôdy s puklinami, meniacimi svoje rozmery pocas procesu, (verzia B) v závislosti na vlhkosti pôdy, ktoré sú porovnané s výsledkami, získanými pomocou modelu s konštantnými rozmermi puklín (verzia A) pocas infiltrácie zrážok. Submodel FRACTURE - verzia B, ktorá kvantifikuje infiltráciu vody do pôdy s deformujúcimi sa puklinami je súcastou modelu HYDRUS–ET. Porovnanie výsledkov modelovania pomocou oboch submodelov ukázalo, že pocas zrážkovej udalosti v tomto ilustratívnom príklade rýchlost infiltrácie do pôdy s deformujúcimi sa puklinami je asi o 20 % väcšia ako do pôdy so stabilnými puklinami. Treba poznamenat, že meranie charakteristík infiltrácie vody do pôdy s puklinami a súcasné meranie deformácií siete puklín nie je v prírode prakticky možné, preto matematické modely môžu byt použité aj ako nástroje vedeckého výskumu v numerických experimentoch.