A comprehensive assessment of surface water quality for irrigation in the Pannonian Plain’s agroecological conditions: a case study of the Danube‑Tisa‑Danube hydrosystem area (Serbia)

The Danube-Tisa-Danube hydrosystem area is recognized as one of the most important agricultural regions in Southeastern Europe. This area is rich in soil resources and surface water resources, which is the main source of water for irrigation. An assessment of water quality for irrigation was made using frequently used indices and agronomic classifications (SAR, %Na, RSC, KI, PI, MH, PS, Stebler’s IC, USSL, Nejgebauer and FAO classifications, and IWQI). Most watercourses belonged to the Ca-Mg-HCO3 water type, except for the Zlatica River, which belonged to the Na-HCO3 water type. According to Stebler’s IC, most locations belonged to the “good” class, while eight stations were assessed as “permissible”. According to Nejgebauer’s classification, water quality ranged from excellent to unsuitable. The results of the USSL classification show that all surface waters in the area fall into the C2-S1 and C3-S1 classes. FAO classification mostly refers to the problem of the presence of HCO3−. Applied classifications and multivariate techniques (PCA and CA) single out six watercourses where water quality from the irrigation aspect is rated as questionable to poor. These watercourses include canal sections that are under significant anthropogenic influences (wastewater from settlements, industry, and agriculture) and small watercourses that are affected by topographical conditions, climatic conditions, and transboundary waters. The analyses show that using surface water resources for irrigation during the growing season is generally safe, except for a few small watercourses, where it is recommended to monitor the quality of applied water and salt accumulation in soil.