Olives are traditionally grown in the Mediterranean basin in arid conditions with scarce rainfall. Because of these conditions, the need to introduce irrigation methods is becoming increasingly pronounced especially in the karst landscape of coastal and island areas. On the territory of the Republic of Croatia, olives are not sufficiently irrigated which leads to oscillation of olive yields. The introduction of irrigation methods would stabilise yields and the production of olives. In this master thesis, the needs for the irrigation waters were determined for agroecological conditions of Jadrtovac area. To calculate the irrigation needs of the soil based on the soil characteristics, meteorological indicators and olive characteristics, the "Cropwat" model was used. By comparing the results obtained from the meteorological station Šibenik and the automatic meteorological station in the period from 2015 to 2017, calculated evapotranspiration was higher than the evapotranspiration from the automatic station for all months analysed. Additionally, calculated maximal and minimal evapotranspiration values coincide for the two sets of results. Furthermore, measurements of the tree growth and development parameters, as well as olive lushness, were performed. 50% ET and 75% ET treatments showed the best results compared to the control treatment. Finally, it was shown that for accurate results and further irrigation plans, longer-term measurements should be performed, taking into account all the parameters that affect the proper cultivation of olives. It is recommended that further research follows the analysis of this thesis.