What are the uses of water storage

Water storage and flood protection

Dammed water as the key to regulated supply and protection against flooding

The flow of water in the Rur and its tributaries is inherently difficult to calculate: on the one hand, the soils of the northern Eifel poorly absorb the existing water, on the other hand, heavy rainfall and periods of drought cause irregular water levels. Smaller rivers in the lower reaches of the Rur in particular could “dry out” over the course of the year - that is, they could no longer carry any water. In the past, frequent floods and months of water shortages were the very existence of the people who lived by and with the river.

At the end of the 19th century, the necessary technical knowledge was established and the construction of dams began: Our Urft dam was completed in 1905 and was the first dam in the network. At that time it was considered the largest on the entire continent and literally triggered a “dam construction boom”. The accumulation of stream or river water became a recipe for success for the region, as it solved many problems at the same time:

  • Flood protection
  • Provision of raw water for the public drinking water supply
  • Process water supply for industry and agriculture
  • Generating energy through hydropower

Over time, the reservoirs that were created also became popular places for local recreation, meeting points for hikers and water sports enthusiasts. This became the “engines” of the region’s tourism development.

Function and construction

A dam is usually a large, solid wall in a river - this becomes a lake through the artificially created barrier. The water on this side is then higher and, if necessary, can be discharged at the bottom outlets at the bottom of the wall in the section of the river below, the lower course. In this way one can influence the water level in the further course of the river, and an effective flood protection becomes possible. In addition, an important water reservoir is being created for the region. In addition to the bottom outlets, dams can also have so-called service outlets: From these, the dam water is transported to a hydropower plant to generate electricity, for example, or to a drinking water supplier's waterworks. The bottom outlets of large dams always have two closures - the "regulating device" controls the amount of water that should flow through the pipe when it is released. Another lock serves as a "backup" of the regulating body and thus security.

Dams are available in different designs: The most common type of dam is the gravity dam - a good example of this is the Urft Dam. Gravity dams consist of solid concrete or large rubble stones connected with mortar and brace themselves with their own weight against the pent-up water masses. Other variants, such as the so-called pier dam, are rarer - our Oleftalsperre is the only one of its kind in Germany. It is hollow on the inside and directs the water pressure through its pillars into the ground. Which type of construction is ultimately used depends, among other things, on the prevailing terrain conditions.

Dams are not always built as dams, however: another form of construction is the dam. Its components - earth, rubble, clay and loam - usually form a supporting and a sealing part. Due to the construction method, care must be taken with dams that they are not flooded, as the water flow would wash them out and destroy them.

Since flooding is of course not wanted in any dam, each dam has a flood relief system that can drain away water in a controlled manner in an emergency.

Operation and management

There are complex calculations behind the smooth operation of our dam system: Our dam management is based on a comprehensive data archive. The daily runoff amounts for the past 115 years serve as a basis for calculation when developing our control strategy for controlling the dam system. With the help of numerical models, we can simulate the different variants of the dam control and thus determine the optimal balance in the event of competing usage requirements: Flood protection and the simultaneous use of the dam for water storage are not mutually exclusive. Ideal factors for cultivation on the Rur are an even minimum of 5 cubic meters of water per second and, in the event of a flood, compliance with the upper limit of 60 cubic meters per second.

Optimal balance - a win for everyone

Our central reservoir in the dam system is the Rur dam - according to our statistical calculations, it may only overflow or empty completely less than once in 100 years. But how do we determine our respective traffic jam target in the dams? And how can we hold it? Our models have to make decisions for the future possible, even if extreme dry periods, even over several years, or a series of flood events cannot be predicted. Briefly defining half the storage volume of a dam as the target water level would be too short - with this small amount of water, flood protection would be easy, but dry phases lasting several months or even several years would not be able to be survived in this way. The calculated values ​​mentioned above apply here again. Against this background, it is easy to see: temporarily low damming volumes in dry seasons are just as little a management error on our part as the rare flood charges from the dam system. The latter often only become a problem for neighbors when other, uncontrollable flood runoffs occur from the tributaries along the Rur. On the contrary, the dams cushion flood peaks for the people along the Rur by around 50 percent and thus protect them from major damage.

Dam control system: Your safety at a glance

Our specialists in dam management bear a high level of responsibility for the safety of people in the region and monitor the complex structures and systems of the dam network with a digital, networked control system. In this way, they are always in a position to identify loads and developments at an early stage, including on the dam itself, and to react accordingly. The control system records, controls and manages, among other things, measured values ​​for seepage, structural movements, pore water pressure, precipitation, air, water and building material temperatures as well as electricity generation.