Zum Einfluß der Stauregulierung auf den Sauerstoffhaushalt der Donaustrecke Kelheim-Jochenstein Mikrobiologisch-biochemische Untersuchungen und Gütemodellrechnungen
[On the impact of impounding on the oxygen balance of the Danube from Kelheim to Jochenstein Microbiological-biochemical investigations and water quality model calculations]
Müller, Dieter; Kirchesch, Volker
published: May 6, 1987
Results of microbiological-biochemical investigations of the Danube river, which characterize the different processes influencing the oxygen balance, and results of simulation runs with a water quality model are presented and discussed. The paper describes the impact of the development of the German reach of the Danube between Kelheim and Straubing into a navigable waterway with minimum depth of 3 m needed for modern cargo ships. When considering the oxygen content, the organic load, the algal growth and the "additional oxygen consumption for pepton and glucose", the effects of the two impoundments realized so far are superimposed by the effects from new wastewater plants, which were taken into operation during the same period. The mathematical model used is of the deterministic type, calculating the growth of slowly growing organisms (nitrifiers, algae and zooplankters) according to Monod and Michaelis-Menten. The simulation shows that only the impounding of a reach of 90 km (4 impoundments) will result in some significant effects: decrease of C-BOD5 together with an increasing release of ammonium and enhanced algal growth. In the following river reach the effects are partly compensated. Thus, after the confluence with the river Inn, the Danube reaches Austria with a somewhat enhanced presence of algae and other slowly growing organisms. The slight effects of the impounding of the Danube is compared with the more remarkable effects of impounding in other rivers. In the Danube the change in morphology is small and melting water discharge of the alpine tributaries minimize the problems of low discharge in summer. The methodology of measurement is discussed. In future the parameters used will be chosen to correspond better to the needs of the quality model used.