Scenario analysis of water quantity and quality in the Havel river basin
aim of the subproject is to verify and improve existing estimations of nutrient
emission from diffuse (mainly agricultural) sources in a lowland region using a
dynamic model. Based on the results, the application of some known methods to
reduce nutrient leaching will be tested in the modelling framework.
exactly, the subproject aims are:
Estimation of nutrient
emission from diffuse sources in selected mesoscale subbasins of the Havel (e.g.
Nuthe, Rhin) by means of dynamic modelling of hydrological and ecohydrological
Scenario analysis of options
to reduce nutrient leaching from diffuse sources resulting from
modified land use and land management strategies,
estimation of nutrient retention in a large river basin (the lower Havel)
using the coupled drainage basin (SWIM) and river (HYDRAIN) modelling.
subproject in collaboration with subproject 3 should provide a tool to link
processes in the drainage basin area with those in the main river system (Havel)
and to estimate retention processes at the basin level. It is strongly linked to
subproject 6 (data and parameterization), subproject 2 (modelling of inputs),
and subproject 3 (transport in the water system).
Scheduled work and methods
ecohydrological model SWIM (Soil and Water Integrated Model), developed at PIK,
simulates hydrological processes, plant growth, nutrient cycles (nitrogen,
phosphorous) and erosion at the river basin level using regionally available
data. Another objective is the study of climate and land use change impacts on
ecohydrological processes. SWIM was already successfully validated in a number
of meso- and macroscale basins (mainly in the Elbe catchment area) and applied
for impact studies. However the detailed validation for water quantity and water
quality in a lowland basin like Havel is missing.
Validation of SWIM in a selected mesoscale subbasin of the Havel
of all, a mesoscale basin in the catchment area of the Havel has to be selected
(e. g. Rhin, Nuthe or Hammerfließ), whereby the quality of data is the
substantial criterion of choice. The following data will be used: a digital
elevation model (DEM), a land use map, a soil map and related soil parameters, a
ground water table map, meteorological data, land management (crop rotation,
fertilization regime), water discharge, measured concentrations of nitrogen in
the river and in the ground water. The model SWIM will be validated for the
selected basin with special consideration of hydrological processes and nitrogen
and phosphorous fluxes.
data already exist at PIK (e.g. a DEM, meteorological data, a land use map),
other data will be supplied by project partners (subprojects 1, 6). In this
context the improvement of spatial and temporal resolution of the input data,
such as land use, soils and hydrology, is of particular importance.
Estimation of nutrient emission from diffuse sources
the validation of SWIM nutrient emission from diffuse (mainly agricultural)
sources will be estimated. The monthly accumulated emissions will be compared
with existing estimations for the selected subbasins of the Havel (Behrendt et
al, 1999). In addition, this work will contribute to subproject 2.
C. Simulation experiments considering different scenarios of land use change
Different scenarios of
land use change will be created based on available information (LUA). Thereby
possible changes of the relative areal share (e.g. of arable land, grassland,
forest, and fallow land) or changes within the classes (e.g. of the crop
rotation within arable land, the fertilization regime, the forest management)
have to be considered.
For this purpose the results of the project MESSAGE (Mesoscale Simulation Study Assessing the Consequences of Global Change) can be adopted and transferred to the scale of land use for the districts in Brandenburg. MESSAGE is coordinated at PIK and uses the agroeconomical model RAUMIS. Other scenarios will be provided by subprojects 1 and 6. Afterwards, the analysis of options to reduce nutrient emissions from diffuse sources by modified strategies of land use and land management will be performed.
differentiated modelling of the river basin
After validation of
the model for the selected subbasin, SWIM will be applied to the total area of
the lower Havel in a spatially-distributed mode. Hydrological processes
(evapotranspiration, runoff, groundwater recharge) as well as nitrogen and
phosphorous fluxes (plant uptake, wash-off by surface runoff, leaching to
groundwater) will be simulated for existing land use and recent climate
conditions. This work will provide an input for the hydraulic model HYDRAIN
simulating river transport of nutrients. In addition, the estimation of
retention processes should be improved by linking SWIM and HYDRAIN in
cooperation with subproject 3.
A. Results of validation of the ecohydrological model SWIM in a selected subbasin of the Havel with a focus on hydrological processes and the nitrogen and phosphorous fluxes.
B. Comparison of the existing estimations of nutrient emissions from diffuse sources with those simulated dynamically by SWIM.
C. Analysis of options to reduce non-point nutrient emissions by investigating different scenarios of land use change and using the dynamic model SWIM.
D. Estimation of nutrient fluxes for the whole lower Havel (spatially-distributed) for the existing land use and recent climate.
E. Recommendation of methods to reduce nitrogen and phosphorous emissions from agriculture.
Layout: W. Lahmer