 |
| Titel |
Lake on life support: Evaluating urban lake management measures by using a coupled 1D-modelling approach |
| VerfasserIn |
Robert Ladwig, Georgiy Kirillin, Reinhard Hinkelmann, Michael Hupfer |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143604
|
| Publikation (Nr.) |
 EGU/EGU2017-7339.pdf |
|
|
|
|
|
| Zusammenfassung |
| Urban surface water systems and especially lakes are heavily stressed and modified systems
to comply with water management goals and expectations. In this study we focus on Lake
Tegel in Berlin, Germany, as a representative of heavily modified urban lakes. In the 20th
century, Lake Tegel received increased loadings of nutrients and leached heavy metals from
an upstream sewage farm resulting in severe eutrophication problems. The construction of
two upstream treatment plants caused a lowering of nutrient concentrations and a
re-oligotrophication of the lake. Additionally, artificial aerators, to keep the hypolimnion
oxic, and a lake pipeline, to bypass water for maintaining a minimum discharge, went into
operation. Lake Tegel is still heavily used for drinking water extraction by bank
filtration. These interacting management measures make the system vulnerable to
changing climate conditions and pollutant loads. Past modelling studies have shown the
complex hydrodynamics of the lake. Here, we are following a simplified approach
by using a less computational time consuming vertical 1D-model to simulate the
hydrodynamics and the ecological interactions of the system by coupling the General
Lake Model to the Aquatic Ecodynamics Model Library 2. For calibration of the
multidimensional parameter space we applied the Covariance Matrix Adaption-Evolution
Strategy algorithm. The model is able to sufficiently replicate the vertical field
temperature profiles of Lake Tegel as well as to simulate similar concentration ranges
of phosphate, dissolved oxygen and nitrate. The calibrated model is used to run
an uncertainty analysis by sampling the simulated data within the meaning of the
Metropolis-Hastings algorithm. Finally, we are evaluating different scenarios: (1)
changing air temperatures, precipitation and wind speed due to effects of climate
change, (2) decreased discharges into the lake due to bypassing treated effluents
into a near stream instead of Lake Tegel, and (3) increased nutrient elimination at
the upstream treatment plants. We are focusing on quantifying the impact of these
scenarios on lake stability as well as the abundance and distribution of nutrients. |
|
|
|
|
|
|