New England Multi-Source Historical Flood Exposure Characterization, 2000 - 2018

This dataset includes county aggregate flood event data for multiple flood sources in New England from 2000 to 2018. Each flood source has individual cleaning and processing which is done by source, prior to aggregation across sources. Sources included in the derivation are: ----- Dartmouth Flood Observatory (DFO) ----- Global Flood Database (GFD) ----- National Weather Service Storm_Events Database ----- PRISM Precipitation ----- United States Geological Survey Stream Gages As described in the associated manuscript, this dataset includes a combination of catalog and hydrometeorological sources. Catalog sources such as the DFO, GFD, NWS have listed start and end dates. Processing was conducted to transform flood polygons (DFO), flood rasters (GFD), or non-county spatial identifiers to a county-level flood marker, and to ensure consistency in the definition of events within a county for these sources. For the hydrometeorological sources, we use thresholds of flooding. For PRISM, a 'flood' is identified where the 3-day cumulative precipitation exceeds the 99th percentile of 3-day precipitation for the region (67 mm). For USGS, a 'flood' is identified where at least one stream gage in a county is in exceedance of the median annual peak for that gage. The median annual peak is the median of annual peak discharge values for the gage during the 2000 to 2018 period. Please see the related publication for details on threshold selection, the use of alternate thresholds, and additional details. The data is provided in 3 forms, as described in the manuscript: Characterizing the Number and Nature of Historical Floods and Implications for Exposure Characterization in New England, 2000-2018 ne_flooding_allsource_daily.csv Time series of all days with flooding identified by any of the sources above. ne_flooding_allsource_non_union.csv Time series of all flood events identified by any source. No cross-source merger is happening here, so if there is an event in county 25025 for NWS from 3/1/2003 to 3/3/2003 and an event in county 25025 for PRISM from 3/1/2003 to 3/6/2003, then both will appear as separate rows. ne_flooding_allsource_upd_union.csv Time series of all flood events identified by any source. Here there is cross-source merger, so if there is an event in county 25025 for NWS from 3/1/2003 to 3/3/2003 and an event in county 25025 for PRISM from 3/1/2003 to 3/6/2003, then there will be a single row with an event from 3/1/2003 to 3/6/2003 listed with both NWS and PRISM noted as sources. This collection will be updated with the source-specific county-level flood aggregates which are in preparation for sharing.