The Effect of Hydrological and Anthropogenic Factors on the Chemical Properties of Water in the Canal Network of Southeastern Srem - page 01

Contrary to irrigation, exceptional attention is being devoted in Serbia to drainage. A farmland area of about two million hectares is covered by some form of drainage. In the past, protection of farmland from water-logging by drainage has most often been provided in parallel with flood protection. As a result, there is an extensive network of drainage canals in place, which could be used to provide irrigation water. In the past 15 years, insufficient maintenance of drainage systems has been the main reason for their low efficiency. Dredging on a rather low scale has resulted in a growing sedimentation problem and the operation of the drainage systems was seriously threatened at times.

It is clear that future irrigation development priorities in Serbia will be to rehabilitate existing irrigation systems and assess the feasibility of using the large drainage network for both drainage and irrigation purposes. In order to assess the practicability of using the drainage network for irrigation as well requires research and analyses, which include both hydrological and technical aspects. Hydrological research should address the quantity and quality of water in the existing drainage network. Namely, in the summer, when the water demand of plants is at its highest, the water available in the drainage network is generally insufficient to cover the irrigation water deficit. The technical component of the assessment should include the possibility of injecting fresh water into the drainage system, from rivers that serve as recipients of excess water during active drainage periods. Water quality analyses are particularly important in Serbia because, similar to other countries, there is increasing pollution of surface water and groundwater. Water is largely polluted by unchecked wastewater discharges, improper use of fertilizers and pesticides in farming, or dumping of waste in watercourses (Dragović et al., 2012).

Pollutants can thus enter the food chain through the polluted water/soil/plant system and lead to significant health problems for those who consume the products of contaminated plants (Song et al., 2006). Consequently, many countries have resorted to irrigation water quality control. The use of polluted water in EU countries is restricted by EU directives (including the Water Framework Directive), which call for very stringent control of food quality and safety, in collaboration with the European Food Safety Authority (EFSA).

Water quality testing in Serbia is limited and insufficient. One of the problems is a debate about which of the numerous available methods should be used to assess irrigation water quality (Belić et al., 2003).

Such assessments should certainly include an in-depth study of the possible consequences of using this water (i.e. the potential effect on plant quality in terms of food safety and the effect of irrigation water on soil productivity and components of the irrigation system). Namely, water quality assessments should be based on ecological, agronomic, technical and economic criteria(Bezdnina, 1989). In this regard, Serbia has regulated the maximumpermissible concentrations of hazardous and harmful substances in soil and irrigation water, which can damage or alter soil productivity and irrigation water quality (the Water Law, Official Gazette of the Republic of Serbia, nos. 30/2010 and 93/2012; Regulation on Permissible Concentrations of Hazardous and Harmful Substances in Soil and Irrigation Water, OG RoS no. 23/94; and Administrative Order on Soil Quality Monitoring Program, Indicators for Soil Degradation Risk Assessment, and Methodology for Developing Remediation Programs, OG RoS no. 88/2010).

At the time large irrigation systems were built in Serbia, the water quality of nearby rivers or drainage canals was generally satisfactory. However, this quality has deteriorated over the past 20 years, as reported in the hydrological almanacs of the National Hydrometeorological Service of Serbia. Namely, at some monitoring points the quality of water falls into Category IV, which restricts the use of such water for irrigation.

The objective of the present research was to determine water quality and water levels in the drainage network of southeastern Srem, with a view to finding out whether the water could be used for crop irrigation. Consecutive analyses of water quality and water levels at selected locations, over a three-year period, will serve to assess the rate of change in the relevant parameters and their correlation and interaction with the precipitation regime and various anthropogenic drivers. The anthropogenic drivers include land uses in the drainage areas of the studied canals (farming or presence of manufacturing facilities discharging wastewater into the canals), as well as any pumping stations and radial wells that might affect water levels. The water level assessment will indicate the availability of water in the canals in the summer, when there is a demand for irrigation water. The water quality analyses will show whether the water complies with irrigation standards and identify potential polluters, which is a precondition for any action or prevention of future pollution.