SDE Feature Class
Tags
bioassessment, piotic integrity, streams, urbanization, modified channels, landscape stressors
Stream management goals for biological integrity may be difficult to achieve in developed landscapes where channel modification and other factors impose constraints on in-stream conditions. To evaluate potential constraints on biological integrity, we developed a statewide landscape model for California that estimates ranges of likely scores for a macroinvertebrate-based index that are typical at a site for the observed level of landscape alteration. This context can support prioritization decisions for stream management, like identifying reaches for restoration or enhanced protection based on how observed scores relate to the model expectations. This dataset is a shapefile of the model results for California that shows summarized median predictions for the California Stream Condition Index (CSCI, Mazor et al. 2016) aggregated by HUC12 watersheds. The medians indicate the most likely CSCI scores across all NHD flowlines in a watershed as a function of landscape development only. Note that these values are not the same as predicting biological condition in the absence of field data where bioassessment scores are estimated using all available data. Here we predict CSCI scores only as a function of landscape development to identify conditions that are expected given watershed alteration. All data are considered draft products that are currently under review. Details on modelling and data are in a manuscript under review in Freshwater Science.
The landscape model was developed for California using land use data, stream hydrography, and biological assessments. Stream data from the National Hydrography Dataset Plus (NHD-plus) were used to identify stream segments in California for modelling biological integrity. Stream segments designated in the NHD-plus were used as the discrete spatial unit for modelling biological integrity. Hydrography data were combined with landscape metrics available from the StreamCat Dataset to estimate land use at the riparian zone (i.e., a 100-m buffer on each side of the stream segment), the catchment (i.e., nearby landscape flowing directly into the immediate stream segment, excluding upstream segments), and the entire upstream watershed for each segment. The California Stream Condition Index (CSCI) was used as a measure of biological condition in California streams. The CSCI is a predictive index that compares the observed taxa and metrics at a site to those expected under reference conditions. A dataset of 2620 unique CSCI scores was used to calibrate and validate the landscape model.
A quantile random forest model was developed to estimate ranges of CSCI scores associated with land use gradients, such as road density or urban and agricultural land use. Measures of land use development were quantified for riparian, catchment, and watershed areas (as defined above) of each stream segment in California using the StreamCat dataset. Expected CSCI scores were modelled using estimates of canal/ditch density, imperviousness, road density/crossings, and urban and agricultural land use for each stream segment.
We applied the model to stream segments statewide to estimate the most likely (median) CSCI score at each stream reach as a function of landscape development. Median CSCI scores for all stream reaches within each HUC12 watershed were averaged and weighted by reach length.
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Extent
| West | -124.506155 | East | -113.497856 |
| North | 42.068502 | South | 32.423749 |
| Maximum (zoomed in) | 1:5,000 |
| Minimum (zoomed out) | 1:150,000,000 |