The development of a GIS tool to assess the changes in the riverine landscape for the ecological quality of the river Rhine in the Netherlands

This study aims to evaluate the usability of ecotope maps to predict aquatic ecological consequences of floodplain landscape changes. If successful, this method will be applied to evaluate ecological rehabilitation measures that will be carried out in order to improve the ecological status of the large river plains. Ecological value is reflected in indicator metrics for fish, aquatic vegetation, and other qualities. There is a correlation between the composition of these indicators and ecotope types. In order to substantiate this correlation I have gathered information about changes in these indicators by comparing ecotope maps of different years. Recent maps, 1997-2004, are compared to see the effect of pilot rehabilitation measures, and these maps are compared to a reference situation, an ecotope map of 1850. 1850 is the last mapped situation before the normalisation of Dutch rivers caused the ecological quality to deteriorate. I have explored possibilities to translate aquatic ecotope changes – derived from intervening map changes – into changes in the fish and aquatic vegetation metric scores, i.e. indicators. The metric scores on fish and aquatic vegetation can tell if the ecological status of the river flood plain as a whole is changing; they are based on the Water Framework Directive (WFD) system of scoring. For evaluation, a Geographic Information System (GIS) approach is used. In a GIS environment, I have added information about the 'ecotope – fish' and 'ecotope – aquatic' vegetation relation to the ecotope maps of different years. Through the comparison of the ecotope maps using a GIS, changes in ecotopes type and surface area and, thereby, changes in the fish and aquatic vegetation indices became apparent, which I have presented as maps, graphs and figures. In addition to surface area related metrics, perimeter based information, too, has ecological meaning. As an indicator for the state of the river, I have chosen the shoreline index. The shoreline index can reflect whether the flow of the river is very normalised or natural. Out of the aquatic borders and shoreline type the shoreline index has been determined. This index has been divided between navigated and non-navigated waters, and furthermore into different shoreline types, such as sandy or builds up. My conclusion is that ecotope maps can be used to reflect changes in metrics for ecological quality indicators. It is argued that, for a good comparison, the ecotope maps of different years have to be normalized for the water level during the mapping of the ecotope maps from aerial photos. Adding height and depth information to the ecotope map will also improve resolution. It is also is argued that for a good insight into the fish population not only aquatic ecotopes but also adjacent ecotopes have to be included. By doing this the sometimes flooding patches are also incorporated – which is essential because they are important for the reproduction of some fish species. Calculated EQR values for current years and reference years appear to be less apart than expected. Therefore it is recommended to add other factors like area ratio and diversity composition by means or the alpha beta theory