Use of standardized precipitation indices for the determination of drought and water excess in the region of Donji Srem

Abstract

The Surčin plane is very important both for agriculture and for water supply Agricultural production is constrained by water shortage, water excess, or soil salinity. For better planning of the maintenance and planning further developments of irrigation and drainage systems, problems such as drought or water excess occurrence must be analyzed, to assess the intensity of drought and its impact on field crop yields. The objective of this endeavor is to determine the intensity and frequency of occurrence of drought and water excess on the Surcin low land, by making use of the Theory of runs Standardized precipitation index (SPI), and Recognition of Drought Indices (RDI). The application of the method of runs has shown that droughts periods were very short (a season or two), with a calculated cumulative deficit of 130 mm of water for the period of vegetation, and 82 mm and 63 mm for the cold period of the year; in consequence, the intensity of drought could not be determined. The SPI method indicated a clearly cyclic nature of precipitation in the region. Drought occurred only during 7 vegetation seasons out of the 55 analyzed, and very severe drought only 5 times randomly distributed. In the cold period of the year drought came about 8 times, of which 3 times severe ones. The results showed that there were more wet seasons than droughts (4 times in the vegetation seasons and 11 times in the cold period of year), yet few of them were extremely wet. Results by RDI are very similar to those ones obtained by SPI. Analysis showed that more threat could come from water excess than from drought. In conclusion, the maintenance of drainage canals should get priority over that of the ones for irrigation. Further development of field crop irrigation must be economically justified.

Surčinsko donje polje ima veliki značaj sa aspekta poljoprivrede i vodosnabdevanja. Na njemu se javljaju mnogi problemi vezani za vode i zemljište. U cilju boljeg planiranja razvoja melioracija kao i redovnog održavanja potrebno je sa više aspekata analizirati učestalost sušnog perioda, intenzitet suše, uticaj suše na smanjenje prinosa. Cilj ovoga rada je da se primenom metoda nizova, standardizovanog indeksa padavina (SPI) i indeksa suše (RDI) utvrdi intenzitet i učestalost suše na Surčinskom donjem polju. Primenom teorije nizova utvrđeno je da je trajanje suše veoma kratkotrajno (1 do 2 sezone) a kumulativni deficit iznosi 130 mm za vegetacioni period, i 82 i 63 mm za vanvegetacioni period. Na osnovu dobijenih rezultata nije bilo osnove za određivanje intenziteta suše. Standardizovani indeks padavina jasnije pokazuje cikličnost kišnog odnosno sušnog perioda. Suša se javlja samo u toku 7 vegetacionih sezona od 55 analiziranih a jaka suša samo 5 puta i to veoma neregularno. U van-vegetacionom periodu suša se javila 8 puta, a jaka suša 3 puta. Dobijeni rezultati ukazuju da se javljaju i veoma prevlažene godine. U vegetacionom periodu osmotrene su 4 vrlo vlažne sezone, a u vanvegetacionom čak 11 vlažnih sezona od kojih 3 veoma vlažne. Ako se analiziraju sve osmotrene godine, može se primetiti da ima više vlažnih od sušnih godina i u vegetacionom i u vanvegetacionom periodu. Rezultati dobijeni primenom RD indeksa jasno ukazuju da postoji značajna veza između padavina i potencijalne evapotranspiracije jer se trendovi podudaraju sa standardizovanim indeksom padavina. Veći broj kišnih perioda ukazuje da održavanje drenažnih kanala ima prioritetan značaj u melioracijama, dok izgradnja sistema za navodnjavanje za ratarske useve mora da bude opravdana ekonomskom analizom.