Flood protection Nöthnitzbach Small stormwater overflow basins to protect the urban area of Dresden

As a compensatory measure for a nearby technical rainwater retention basin in the upper reaches of the Nöthnitz in 2006, the project was concretely planned and structurally implemented between 2010 and 2012 on behalf of the state capital Dresden (Environmental Agency).
The aim of the measure was to create additional retention space along the small watercourse in the south of Dresden, which has strong water level fluctuations due to its catchment area, particularly during heavy rainfall events. Adjacent to the watercourse, the retention area was to be filled by flooding over a wide overflow sill at the watercourse edge during a 1-year flood event.
Following the slightly sloping topography of the site, the system consists of 3 basins connected in series by overflow sills. At the downstream end of the last basin, the system is reconnected to the watercourse by an overflow so that stronger floodwaters flow completely through the system.
The landscape design proposal was supplemented by a water level calculation and a calculation of the drag forces on the overflow sills, which are extensively paved by grass seeding.
In 3 small, extra 30 cm deepened depressions, the water often stands for months and first dragonflies have been detected here.
A first flooding still during the construction phase occurred in the course of a heavy rain event unintentionally. A flooding in 2012 in the course of a heavy thunderstorm has proven the functionality and was still documented during the heavy rain by pictures and film recordings.
About the construction project was reported in detail in the DWA_Members_Rundbrief_43_October 2013. The newsletter is available for download. (see below)