Odense – A City with Water Issues

Abstract

In the City of Odense we have plenty of water issues, but we do not have any real “burning platforms” that can turn the focus of our politicians and other relevant people in our direction. We experience pressure from all sides: Annual mean precipitation have increased 100 mm (15%) during the last 140 year. Extreme rains occur more often and they are becoming more intense. Surface runoff causing flooding in streams and rivers or from storm surges in the fjord area. Sometimes both occur at the same time. Rising groundwater level caused by increased recharge, diminishing needs for potable water / lesser water abstraction and by reducing the amount of excessive waters, e.g by restoring leaky sewers, which hereby stop acting as drains. In this article, we will highlight some of the issues we encounter as seen from two different parties with their own points of view. On one side there is the municipal authority and on the other the water and wastewater company. One of the greater issues during the last several decades is the rising groundwater level beneath the city. The quality of this groundwater is also slowly deteriorating. This is of growing concern for both parties. The cause of these problems stem from many different activities that either interact or counteract each other. They can be divided into natural conditions and those caused by human activities. Examples of natural conditions are geology, geography, climate and relief difficulties. The human activities are urban development, exploitation of resources (groundwater abstraction, gravel excavation, drainage), infiltration, SUDS. One of the key elements is that the natural conditions and the human activities often act in conjunction, causing greater problems rather than less problems. The rapid and expanding urbanization during the 20th century, have forced a deployment of well fields from early urban locations to more rural locations. This have affected the groundwater level beneath the city, so it is significantly higher today. Urbanization also affects the natural water cycle by increasing and accelerating the surface runoff, which puts further strain on the older joint sewage system under the central parts of the city, causing local flooding during heavy rains. When you consider the predicted climate changes in the future with increased intensity and volumes of water, these problems will only become worse. We believe that the solution to many of these problems are a greater awareness because when interfering with the natural water cycle, will cause a wide array of consequences. Therefore, it is imperative to reduce the gap between two different worlds - the underground specialists on one side and the surface planners, decision makers and politicians on the other. There is a strong need for positive interaction and sharing of knowledge between all involved parties. It is important to acknowledge the given natural conditions and work closely together to develop a smarter city, preventing one solution causing even greater problems for other parties.