Determination of optimal sampling frequency for water quality attributes at River Tisza, Szolnok (Hungary)

摘要

The assessment and monitoring of ecological quality of freshwater is of central importance today (Ruop-pola et al. 2003). Hungary has had a long tradition of objective water qualification (Felfoldy 1974), and an ecological approach of the water qualification was developed by Devai and his co-workers in the early 1990s (Devai et al. 1992a, 1992b, 1992c). The complex qualification procedure was tested during the study of Boroszlo-kerti-Holt-Tisza in 1997 (Devai et al. 1999). Our paper is related to the implementation of EU Water Framework Directive (WFD) in Hungary. We analysed the influence of sampling frequency to the result of classification of water bodies and determined the minimum sampling intensity to produce ecologically relevant classification of the chemical status of the water bodies (Directive 2000). During this study we analysed the data set of the Water and Sewage Works Franchising Joint Stock Company of Szolnok in Hungary. This water supply intake provides the drinking water of Szolnok city and their neighbouring villages (more than 120 000 people) based on the River Tisza. The Company controls the chemical water quality once every two hours. Our paper is based on the analysis of this data set.