By Tarika Hanawalt
While many governments and organizations use the geospatial data we provide, what the public sees is often just a detailed map or two. And if they do make all the datasets public, it can take months, if not years, before others can access it.
But that’s not the case for Sonoma County, Calif. The forward-thinking agency quickly took LiDAR-derived high resolution, detailed hydrology datasets we delivered in February 2016, and made them publicly available in early March on its Sonoma Veg Map site.
Sonoma County is using this Quantum Spatial dataset, and many others we provided – including bare earth elevation models, tree canopy height models and one-foot elevation contours – to expand its countywide vegetation and habitat assessment map project. The map assists with natural resource planning, conservation, climate change, sustainability planning, hydrologic evaluations, watershed assessment, to name a few uses.
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For the hydrologic data survey, Quantum Spatial defined more than 9,260 miles of stream flowlines and 1.065 million acres of bare earth and hydrology raster coverage, and watershed boundaries. The results of our high resolution LiDAR survey included:
Hydro-enforced bare earth ground models of nearly 10 times greater resolution than current publicly available ground models. -
Flowlines capturing the drainage pathways of virtually every catchment basin in the county, whether continuously flowing or ephemeral.
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Nested watershed boundary delineation from hydrologic unit 2 (region) up to hydrologic unit 14 (sub watershed – all sub-basins 10,000 acres or less).
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Flow direction and accumulation rasters capturing the direction of surface runoff for every three foot by three foot pixel, and defining accumulated flow out of all drainage areas greater than five acres.
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Supporting vector datasets that identify locations where hydro-enforcement of underground or blocked flow paths was necessary in the ground model, as well as locations of all stream junctions.
Among the public data available on the Sonoma Veg Map site are vector hydrologic products (available as file geodatabases), including stream centerlines, hydro-enforcement burn locations, confluence points and watershed boundaries. Sonoma County also made available raster hydrologic products (as watershed downloads), including a hydro-enforced digital elevation model, flow direction and flow accumulation.
Our work continues with Sonoma County. We are now in the process of modeling the extent of potential flood inundation for all 68 miles of the Russian River within the county. This data will provide critical information to planners and emergency responders in the event of a flood.
We applaud Sonoma County for its approach providing key geospatial data available to the public, and making use of it in unique ways. We know many agencies and organizations face challenges – from the resources and time to digest the data, to budget constraints – that may prevent them from getting the most out of LiDAR surveys. Sonoma County sets a great example of how that can be done quickly, and provides the community with valuable information as they plan for the future and prepare for potential natural disasters.
By Tarika Hanawalt
Tarika is a team leader in the commercial program at Quantum Spatial, and brings 5 years of experience working with LiDAR data and conducting geospatial analytics and hydrologic modeling projects. He has a Bachelors of Science degree in environmental engineering from Portland State University and lives in Portland, Oregon, where he is an active volunteer for river restoration and advocacy, an avid hiker, mountain climber, boat builder, and fisherman.