Modelling catchment processes

River Channel Management

“…Ecological modelling was developed somewhat separately from hydrological, hydraulic and geomorphological modelling, but the need remains to provide comprehensive models embracing all aspects of the hydrosystem. Considerable recent progress, aided by developments in topographic specification, including that by GIS, has enabled refinement of three types of catchment-scale model, namely: integrated component process models, watershed analysis and conceptual models (see Downs and Priestnall, 2003). Considerable recent progress, aided by developments in topographic specification, including that by GIS, has enabled refinement of three types of catchment-scale model, namely: integrated component process models, watershed analysis and conceptual models (see Downs and Priestnall, 2003).…”

“…http://www.science.calwater.ca.gov/vision.shtml (last accessed 19 October 2003)). Also, as indicated in Chapter 6, technological advances in developing spatial databases using remote sensing data and Geographical Information Systems have provided consistent, detailed data over large spatial extents to permit integrated, basin-wide research studies to be practicable for the first time, leading for instance, to the prospect of catchment-scale models of sediment transport behaviour (review in Downs and Priestnall, 2003). Continuing challenges relate to downscaling GCMs to provide reliable local hydrological information (Schulze, 1997;Wilby and Wigley, 1997), while further issues arise because river flows are a second-order environmental change following from predicted changes in precipitation, temperature and vegetation growth (Arnell, 1996;Arnell and Reybard, 1996).…”

“…Suitable long-term data would be obtained from flow gauging, sediment transport gauging, periodic repeat surveys of monumented cross-sections and channel long profile, and repeat aerial and oblique photography from monumented positions. Frameworks for 'watershed analysis' have been drafted (Montgomery et al, 1995, technological advances are allowing catchmentscale models with relevance to fluvial geomorphology to be developed (Downs and Priestnall, 2003) and the philosophical and practical issues related to real cumulative impacts analysis are being addressed (Reid, 1998). Of these requirements, the likelihood is that only flow gauging records may exist close to any particular site of concern.The data are pivotal for determining change in the river channel environment and for providing an appropriate spatial and temporal context to evaluation (p. 229).…”

“…Initiate the ecosystem knowledge about individual drainage collation of basins and highlights linkages that limit scientific management and assist in identifying knowledge geospatial gaps that can be addressed through databases process-oriented research (National Research Council, 1999).This demands a commitment to long-term data collection, monitoring efforts, dedicated geographic databasing entities, improved catchment modelling capabilities founded on high quality terrain data acquisition and representation, justified methods of data abstraction, improved geomorphological process models of drainage basin operations and investment in the collection of validation data, especially for sediment transport (Downs and Priestnall, 2003). Initiate the ecosystem knowledge about individual drainage collation of basins and highlights linkages that limit scientific management and assist in identifying knowledge geospatial gaps that can be addressed through databases process-oriented research (National Research Council, 1999).This demands a commitment to long-term data collection, monitoring efforts, dedicated geographic databasing entities, improved catchment modelling capabilities founded on high quality terrain data acquisition and representation, justified methods of data abstraction, improved geomorphological process models of drainage basin operations and investment in the collection of validation data, especially for sediment transport (Downs and Priestnall, 2003).…”

The Sustainability of Restored Rivers: Catchment‐Scale Perspectives on Long Term Response

“…Achieving such process understanding often requires spatial data related to the relational and extrinsic composition of the catchment (Table 13.2): this includes the elements and spatial arrangement of terrain and elevation features, channel network and subcatchment topographical units within the entire catchment, as affected by differences in soils, bedrock and alluvial sediments, vegetation and land use. In this regard, the advent of 1 m resolution commercial satellite data from the IKONOS satellite, 2-4 m resolution airborne data using CASI (Compact Airborne Spectrographic Imager), 5 m resolution using interferometric SAR (Synthetic Aperature Radar) and decimetre elevation data precision using airborne LiDAR (Light Detection And Ranging) is likely to promote a signifi cant evolution in DEM-based process models in the next decade (issues in Downs and Priestnall, 2003). Firstly, it is increasingly likely that some spatially comprehensive data will already exist for a catchment where river restoration is being contemplated, that it will be easily available via the internet and (critically) that the data will be formatted to allow easy transfer and viewing using proprietary GIS software such as ArcGIS 'shape' fi le types.…”