Analysis of climate elements in western Istria for the purpose of determining the need for irrigation of olives

Posljedica klimatskih promjena je sve češća pojava suše, koja se u Hrvatskoj pojavljuje svake treće do pete godine, a ovisno o intenzitetu i duljini trajanja tijekom vegetacijskog razdoblja može smanjiti prinos poljoprivrednih kultura i do 90%. U diplomskom radu razmatra se procjena utjecaja suše na redukciju prinosa masline. Cilj rada je odrediti manjak vode u tlu u prosječnoj i sušnoj godini te odrediti redukciju prinosa masline u prosječnoj i sušnoj godini. Za izradu diplomskog rada korišteni su višegodišnji klimatski podaci u nizu za 30-to godišnje razdoblje (1986.-2015.) s meteorološke postaje u Poreču, te je temeljem tih podataka izračunata referentna evapotranspiracija i bilanca vode u tlu u prosječnoj i sušnoj godini (vjerojatnost pojave oborina u 75% slučajeva). Referentna evapotranspiracija je izračunata metodom Penman-Monteith, računalnim programom "Cropwat", dok je bilanca vode u tlu određena metodom Palmera, korigiranoj i kalibriranoj prema Vidačeku, pomoću računalnog programa "Hidrokalk". Reakcija masline na manjak vode u tlu i redukcija prinosa određena je prema metodi Doorenbos i Kassam. Nedostatak vode u prosječnoj godini je iznosio 64 mm, a u sušnoj 83 mm. Redukcija prinosa masline u zapadnoj Istri u prosječnim godinama iznosila je 13.5%, dok je u sušnim iznosila 17%.The consequence of climate change is an increasing frequency of drought, which occurs in Croatia every third to fifth year, and depending on the intensity and duration during the vegetation period can reduce crop yields by up to 90%. The thesis discusses the assessment of the impact of drought on the reduction of olive yield. The aim of this study is to determine the water deficit in the soil in the average and dry year and to determine the reduction of olive yield in the average and dry year. For the preparation of the master’s thesis, multi-year climate data for 30 years (1986-2015) from the meteorological station in Poreč is used, and based on the data, reference evapotranspiration and soil water balance is calculated for the precipitation in average and dry year (probability of precipitation in 75% of cases). The reference evapotranspiration is calculated by the Penman-Monteith method, the computer program "Cropwat", while the soil water balance is determined by the Palmer method, corrected and calibrated according to Vidaček, using the computer program "Hidrokalk". The reaction of the olive to the lack of water in the soil and the reduction of the yield is determined according to the method of Doorenbos and Kassam. The lack of water in an average year was 64 mm, and in the dry 83 mm. The reduction in olive yield in western Istria in average years was 13.5%, while in dry years it was 17%