tailieunhanh - Water Pollution Control - A Guide to the Use of Water Quality_15

Các lưu vực sông Danube là trung tâm của miền Trung và Đông Âu (Hình ). Các sông chính là một trong dài nhất (xếp hạng 21) trên thế giới và dài thứ hai ở châu Âu. | Water Pollution Control - A Guide to the Use of Water Quality Management Principles Edited by Richard Helmer and Ivanildo Hespanhol Published on behalf of the United Nations Environment Programme the Water Supply Sanitation Collaborative Council and the World Health Organization by E. F. Spon 1997 WHO UNEP ISBN 0 419 22910 8 Case Study IX - The Danube Basin This case study was prepared by Ilya Natchkov Introduction The Danube river basin is the heartland of central and eastern Europe Figure . The main river is among the longest ranked 21 in the world and the second longest in Europe. It has a total length of 2 857 km from its source at a height of 1 078 m in the Black Forest Germany to its delta on the Black Sea Romania. The watershed of the Danube covers 817 000 km2 and drains all or significant parts of Germany Austria the Czech Republic the Slovak Republic Hungary Croatia Slovenia Bulgaria Romania Moldova Ukraine and parts of the Federal Republics of Yugoslavia Bosnia and Herzegovina. The watershed represents 8 per cent of the area of Europe Figure . Between the source and the delta the main Danube river falls a total height of 678 m and its character varies therefore from a mountain stream to a lowland river. Upstream of the Danube delta the mean flow of the river is about 6 550 m3 s-1 with maximum and minimum discharges of 15 540 m3 s-1 and 1610 m3 s-1 respectively. About 120 rivers flow into the Danube such as the Tisza and Sava which have their own significant flow. The contribution from the main tributaries is given in Figure . The mean altitude of the river basin is only 475 m but the maximum difference in height between the lowland and alpine peaks is over 3 000 m. However the basin can be conveniently divided into an upper middle and lower region according to its geological structure and geography and the Danube delta. The range of mean monthly temperature increases in an easterly direction from 21 C in Vienna to 23 C in Budapest and .