20260717 11565500 1.0 FALSE MARIN_HYDROLOGY_RAINFALL_DEPTH_1YR_1HR 002 Projected GCS_North_American_1983_HARN Linear Unit: Foot_US (0.304801) NAD_1983_HARN_StatePlane_California_III_FIPS_0403_Feet <ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/3.6.0'><WKT>PROJCS["NAD_1983_HARN_StatePlane_California_III_FIPS_0403_Feet",GEOGCS["GCS_North_American_1983_HARN",DATUM["D_North_American_1983_HARN",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",6561666.666666666],PARAMETER["False_Northing",1640416.666666667],PARAMETER["Central_Meridian",-120.5],PARAMETER["Standard_Parallel_1",37.06666666666667],PARAMETER["Standard_Parallel_2",38.43333333333333],PARAMETER["Latitude_Of_Origin",36.5],UNIT["Foot_US",0.3048006096012192],AUTHORITY["EPSG",2872]]</WKT><XOrigin>-115860599.99997142</XOrigin><YOrigin>-93269499.999989957</YOrigin><XYScale>36797.272356159439</XYScale><ZOrigin>0</ZOrigin><ZScale>1</ZScale><MOrigin>0</MOrigin><MScale>1</MScale><XYTolerance>0.00021740741875018061</XYTolerance><ZTolerance>0.001</ZTolerance><MTolerance>0.001</MTolerance><HighPrecision>true</HighPrecision><WKID>2872</WKID><LatestWKID>2872</LatestWKID></ProjectedCoordinateSystem> 20260803 14163900 20260803 14163900 500000 5000 FGDC Esri ArcGIS 13.6.3.59530 Marin County Rainfall Depth for 1 Year Recurrence Interval and 1 Hour Duration This layer provides geospatially distributed design storm rainfall depths in inches for the 1-year recurrence interval and 1-hour duration in Marin County. It is intended for use in calculations to determine sizing for bioretention systems (green stormwater infrastructure - GSI) to meet water quality and trash capture requirements under the stormwater permit issued by the State of CA Water Resources Control Board. <DIV STYLE="text-align:Left;">The data are derived from precipitation gauge station point data from across Marin County, including the Marin OneRain network (primary source), as well as selected data from National Centers for Environmental Information (NCEI) and NOAA Atlas 14. The 1-year, 1-hour rainfall depth is defined as the 1-hour rainfall accumulation that is expected to be equaled or exceeded an average of once per year. The 1-year, 1-hour rainfall depths for the OneRain and candidate NCEI rain gauges were computed using an algorithm developed by Dubin Environmental for this project; NOAA Atlas 14 rainfall statistics were downloaded directly from the Precipitation Frequency Data Server. The rainfall depth point data were interpolated across the County using the Empirical Bayesian Kriging method. The distance from a location to rain gauges, along with raster layers of mean annual precipitation and elevation as correlation variables, were inputs to the Kriging analysis that estimated the 1-year, 1-hour rainfall depths across the County as a raster layer produced with 500-foot pixels. The rainfall depths vary from 0.50 inches to more than 0.85 inches, with a distribution that is consistent with the values computed from the rain gauge data and mean annual rainfall values. The raster data pixels were converted to polygons with no smoothing, and the 1-year, 1-hour rainfall depth values were rounded to 2 decimal places. The polygons were dissolved on the rainfall depth value to group adjacent cells with the same value and reduce the total number of polygons to produce this dataset. The data are intended to support design calculations for full trash capture bioretention systems. Project designers can look up project location-specific 1-year, 1-hour rainfall depths, and then use these depths for bioretention sizing calculations. Data users may request a copy of the original raster dataset (32 bit floating point GeoTIFF) by contacting MCSTOPPP at <A href="mailto:mcstoppp@marincounty.gov" STYLE="text-decoration:underline;">mcstoppp@marincounty.gov</A> .</DIV> Dubin Environmental Consulting, LLC; MCSTOPPP Environment Climate and Weather Water - Inland Precipitation Polygon Marin County Marin Countywide Stormwater Pollution Prevention Program MCSTOPPP Stormwater Green Stormwater Infrastructure Bioretention Enterprise Geodatabase Feature Class dataset EPSG 6.3(9.0.0) 0 Simple FALSE 0 TRUE FALSE MARIN_HYDROLOGY_RAINFALL_DEPTH_1YR_1HR Feature Class 0 OBJECTID OBJECTID OID 4 10 0 Internal feature number. Esri Sequential unique whole numbers that are automatically generated. Marin_001YR_1HR 1yr-1hr Rainfall Depth, inches Double 8 38 8 Shape Shape Geometry 8 0 0 Feature geometry. Esri Coordinates defining the features. Shape.STArea() Shape.STArea() Double 0 0 0 Shape.STLength() Shape.STLength() Double 0 0 0 20260803