PBL rapport 550026002 Calibration and validation of the land use ...
PBL rapport 550026002 Calibration and validation of the land use ...
PBL rapport 550026002 Calibration and validation of the land use ...
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This chain includes <strong>the</strong> construction <strong>of</strong> scenarios, <strong>the</strong> modelling<br />
<strong>of</strong> sector-specific developments, <strong>the</strong> spatial integration<br />
<strong>and</strong> allocation in <strong>the</strong> L<strong>and</strong> Use Scanner <strong>and</strong>, finally, <strong>the</strong> assessment<br />
<strong>of</strong> various, <strong>of</strong>ten environmental, impacts in dedicated<br />
tools <strong>and</strong> models. Each <strong>of</strong> <strong>the</strong>se subsequent phases may<br />
introduce additional assumptions, data layers, uncertainties<br />
<strong>and</strong> errors that undermine <strong>the</strong> quality <strong>of</strong> <strong>the</strong> results. A full<br />
assessment <strong>of</strong> this issue is beyond <strong>the</strong> scope <strong>of</strong> <strong>the</strong> current<br />
analysis. The model improvement project that <strong>the</strong> Ne<strong>the</strong>rl<strong>and</strong>s<br />
Environmental Assessment Agency started in 2008,<br />
however, does pay attention to this <strong>and</strong> o<strong>the</strong>r more conceptual<br />
modelling issues.<br />
6.5<br />
Fur<strong>the</strong>r research<br />
Based on <strong>the</strong> current research we can make several recommendations<br />
for fur<strong>the</strong>r research related to: <strong>the</strong> quality <strong>of</strong> <strong>the</strong><br />
base data, <strong>the</strong> focus <strong>of</strong> <strong>the</strong> explanatory statistical analysis <strong>and</strong><br />
<strong>the</strong> consistency <strong>of</strong> <strong>the</strong> modelling chain in which <strong>the</strong> L<strong>and</strong> Use<br />
Scanner is applied.<br />
For any fur<strong>the</strong>r study on l<strong>and</strong>-<strong>use</strong> change it is highly recommended<br />
that <strong>the</strong> quality <strong>of</strong> <strong>the</strong> l<strong>and</strong>-<strong>use</strong> base data is<br />
improved. The data sets that we applied stretched over a<br />
relatively short time period, but <strong>the</strong>y already show considerable<br />
classification differences <strong>and</strong> o<strong>the</strong>r sources <strong>of</strong> error. Data<br />
sets covering <strong>the</strong> longer periods needed to perform a more<br />
fundamental calibration, are known to contain even larger<br />
methodological inconsistencies <strong>and</strong>, thus, require additional<br />
efforts in data preparation.<br />
To refine <strong>the</strong> current explanatory statistical analysis that<br />
underlies <strong>the</strong> calibration <strong>of</strong> <strong>the</strong> l<strong>and</strong>-<strong>use</strong> allocation algorithms,<br />
fur<strong>the</strong>r research should focus on longer time periods <strong>and</strong> <strong>the</strong><br />
actual l<strong>and</strong>-<strong>use</strong> changes that occur. By using a longer time<br />
period, it becomes possible to see whe<strong>the</strong>r <strong>the</strong> importance<br />
<strong>of</strong> certain location factors changes over time <strong>and</strong>, thus, to<br />
assess <strong>the</strong> robustness <strong>of</strong> <strong>the</strong> observed statistical relations. An<br />
analysis <strong>of</strong> change in l<strong>and</strong>-<strong>use</strong> patterns, ra<strong>the</strong>r than explaining<br />
current configurations, is especially interesting as it <strong>of</strong>fers<br />
<strong>the</strong> possibility to implement transition costs into <strong>the</strong> model.<br />
Such transition costs can help to improve <strong>the</strong> performance<br />
<strong>of</strong> <strong>the</strong> model. They can also be estimated in a multinomial<br />
logistic regression analysis, but require <strong>the</strong> availability <strong>of</strong> a<br />
third intermediate time-step in <strong>the</strong> base date (e.g. 1996), to<br />
be able to calibrate <strong>the</strong> model on one period (year 1-year 2)<br />
<strong>and</strong> validate it on ano<strong>the</strong>r subsequent period (year 2-year 3).<br />
Fur<strong>the</strong>r statistical analysis could benefit from <strong>the</strong> incorporation<br />
<strong>of</strong> additional independent variables. Previous research<br />
(Verburg et al., 2004) included, for example, <strong>the</strong> distance to<br />
historic city centres. The inclusion <strong>of</strong> detailed municipal plans<br />
for additional roads or residential areas, <strong>and</strong> related more<br />
general spatial planning maps, will be incorporated in future<br />
analyses <strong>of</strong> l<strong>and</strong>-<strong>use</strong> changes.<br />
Discussion 37