Water balance and nitrate leaching from arable land in a changed climate
This thesis aims to present the essential background on how to perform climate change impact assessments, and to present the results from a climate impact assessment on water balance and nitrate leaching for an arable Swedish soil. The soil is a sandy soil in southwestern Sweden, grown with spring c...
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| Formato: | Second cycle, A1E |
| Lenguaje: | sueco Inglés |
| Publicado: |
2011
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| Acceso en línea: | https://stud.epsilon.slu.se/3362/ |
| Sumario: | This thesis aims to present the essential background on how to perform climate change
impact assessments, and to present the results from a climate impact assessment on water
balance and nitrate leaching for an arable Swedish soil. The soil is a sandy soil in southwestern
Sweden, grown with spring cereals. This study is meant to be a benchmark example,
and cannot be seen as a regional or national assessment for Sweden, rather as an approach
to present and analyze the most important parts of these kinds of assessments.
A dynamical simulation model (COUP, Jansson and Karlberg, 2004) was used for this
study. The model was parameterized and calibrated against data from an experimental site,
located in Mellby in Hallands county, south western Sweden. Measurements were carried
out between 1st of April 1988 and 1st of April 1991. The data set consists of daily standard
weather data and discharge, data on soil water content, soil nitrogen and nitrogen contents
in drainage water from to experimental fields grown with spring cereals. The model was
calibrated against the 4-year data set based on a GLUE-procedure in which a number of
“acceptable parameter sets” were identified. One of these parameter sets were randomly
chosen for the climate impact model runs performed in this study. The driving data for the
model are 30-year climate data, including data for precipitation, temperature, solar radiation,
relative humidity and wind speed, which enables long-term simulations of water and
nitrogen flows. Three different simulations were performed, one for present climate as a
reference scenario with climate data from 1971-2000, and two different emission scenarios
representing year 2071-2100. The driving data were constructed by the delta-change method,
which is a common way of interfacing regional climate model output with impact
models.
Results show that, for both scenarios, that nitrate leaching will increase with 41 % and
66 % respectively. This is mainly due to increased winter temperatures (increasing nitrogen
mineralization with 22 % and 32 % respectively) and increased drainage (20 % and 33
% respectively) during the period when the soil is left bare.
It is important to remember that the study includes many generalizations, both in parameterization
and in driving data. Despite that, the approach with a dynamical model driven
with long-term climate data is a very robust and valuable way of making such assessments.
Further studies need to consider crop growth characteristics and crop parameterization to
be able to simulate growth of other varieties more suitable in a changed climate. Ensemble
modeling can also be an approach to reduce biases in the modeling chain. |
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