Inundation patterns and fish production in the Volgaakhtuba floodplain (Russia)
Middelkoop, H. ; Wolfshaar, K.E. van de; Addink, E. ; Winter, H.V. ; Nagelkerke, L.A.J. - \ 2011
In: International conference on the Status and Future of the World's Large Rivers, Vienna, Austria, 11-14 April 2011. - - p. 253 - 253.
Linking Flow Regime, Floodplain Lake Connectivity and Fish Catch in a Large River-Floodplain System, the Volga-Akhtuba Floodplain (Russian Federation)
Wolfshaar, K.E. van de; Middelkoop, H. ; Addink, E. ; Winter, H.V. ; Nagelkerke, L.A.J. - \ 2011
Ecosystems 14 (2011)6. - ISSN 1432-9840 - p. 920 - 934.
temperate floodplain - mississippi river - pulse concept - growth - dynamics - wetland - dams
River-floodplain systems are amongst the most productive—but often severely impacted—aquatic systems worldwide. We explored the ecological response of fish to flow regime in a large river-floodplain system by studying the relationships between (1) discharge and inundated floodplain area, with a focus on spatial and temporal patterns in floodplain lake connectivity, and (2) flood volume and fisheries catch. Our results demonstrate a non-linear relationship between discharge and floodplain inundation with considerable hysteresis due to differences in inundation and drainage rate. Inundation extent was mostly determined by flood volume, not peak discharge. We found that the more isolated lakes (that is, lakes with a shorter connection duration to the river) are located at higher local elevation and at larger hydrological distance from the main rivers: geographical distance to the river appears a poor predictor of lake isolation. Although year-to-year fish catches in the floodplain were significantly larger with larger flood volumes in the floodplain, they were not in the main river, suggesting that mechanisms that increase catch, such as increased floodplain access or increased somatic growth, are stimulated by flooding in the floodplain, but not in the river. Fish species that profit from flooding belong to different feeding guilds, suggesting that all trophic levels may benefit from flooding. We found indications that the ecological functioning of floodplains is not limited to its temporary availability as habitat. Refugia can be present within the floodplain itself, which should be considered in the management of large rivers and their floodplain.
Improving geo-information reliability by centralized change detection management
Gorte, B. ; Nardinocchi, C. ; Thonon, I. ; Addink, E. ; Beck, R. ; Persie, M. van; Kramer, H. - \ 2006
In: ISPRS Commission VII mid-term symposium 2006 "Remote sensing: from pixels to processes". - Enschede : ITC - p. 602 - 607.
A consortium called Mutatis Mutandis (MutMut), consisting of three Universities and eight producers and users of geo-information, was established in the Netherlands to streamline change detection on a national level. After preliminary investigations concerning market feasibility, three actions are being taken by MutMut: (1) construction of a centralised, web based repository for collection and exchange of changes detected by various actors, (2) design and implementation of an image based, automated change detection methodology, and (3) widening the scope of the project in a European context. This paper focusses on the second action. Objects in the database are used to formulate hypotheses, for which newer imagery may or may not provide evidence. In the latter case, older imagery is considered as well. If evidence for the hypothesis could still be found there, a possible change is detected. The paper shows preliminary results of a first implementation of this methodology.