SSYE uses a raster-based GIS layer of specific suspended-sediment yield (SSY, t/km2/y) from New Zealand’s rivers and streams has been generated based on gauged sediment yields at over 200 river stations and an empirical model. The model relates sediment yield per unit area to mean annual rainfall and to an ‘erosion terrain’ classification, and has been calibrated off the river-gauging data. The erosion terrains were defined by Landcare Research on the basis of slope, rock type, soils, dominant erosion processes, and expert knowledge. The resulting map of sediment delivery to rivers and streams has been adjusted over the gauged catchments so that the sediment yield predicted by the empirical model matches the gauged yields. The layer can be used to estimate suspended-sediment delivery to rivers and streams from within any defined catchment boundary. It was developed as a series of GRID files within the ARC GIS system.
A New Zealand national GIS ‘layer’ to enable reconnaissance-scale estimation of suspended-sediment yields from New Zealand’s rivers and streams. It has been developed by NIWA in collaboration with Landcare Research. Predicting long-term average suspended-sediment loads in rivers and streams is useful for dealing with a variety of issues. These include sediment entrapment rates in potential reservoirs and the vulnerability of estuarine and coastal marine habitats to sediment influxes from the land.
|State of Development||Stable Release|
|Current Development Activity||None|
|Management Domains||Land, Coastal, Natural Hazards, Biodiversity|
|Subdomains||Contaminant Losses, Erosion/Sediment, Coast, Hazards|
|Intended End Users||Researchers, Regional Coucil staff, environmental consultants|
|Temporal Resolutions||Not applicable|
|Steady State or Dynamic||Steady State|
|Level of Integration||Environmental|
|Key Input Data||Select location (river) of interest|
|Input Data Formats||User-selected map location|
|Key Output Data||River sediment yield past selected location|
|Output Data Formats||Image File(s) Screen output|
|Open/Closed Source||Closed Source|
|Licence Type||No Licence|
|Software Needed||Web browser|
|User Interface||Unknown Any PC|
|Ease of Use||Easy|
Help page on web-site Pilot version available for download: http://www.niwa.co.nz/our-science/freshwater/tools/suspended-sediment-yield-estimator
|Methods included for calibration and validation||NA|
|Methods included for managing uncertainty||NA|
Model identifies cachment upstream of selected river reach on River environment Classification channel network, then integrates sediment yield over a yield per unit area surface masked by the catchment boundary.
|Keywords||sediment, sediment yield, river, stream|
|Linkages to other Models||
Yields from this model have been incorporated as part of the P component of CLUES On-line map where load predictions can be accessed - see Water Resources Explorer NZ (http://wrenz.niwa.co.nz/webmodel/)
Hicks, D.M.; Shankar, U.; McKerchar, A.I.; Basher, L.; Lynn, I.; Page, M.; Jessen, M. (2011). Suspended sediment yields from New Zealand rivers. Journal of Hydrology (New Zealand) 50(1): 81.