Nearshore New Development Impact, 2005-2010/2011 - Hawaii

This layer represents a proxy for sediment input to the nearshore marine environment from recent construction sites. Data are derived from the NOAA Coastal Change Analysis Program (C-CAP) High Resolution Change dataset from 2005 to 2010, except for Oahu and Lanai where data are for 2005 to 2011 (http://coast.noaa.gov/ccapftp/). The Ocean Tipping Points (OTP) project extracted pixels that changed from any undeveloped class to an impervious surface during the time period and calculated the area of new impervious surface within National Hydrography Dataset (NHD) HU12 watershed polygons. A Focal Statistics tool was used to calculate the mean area of new development within a 1.5-km circular radius of each offshore pixel. This area was dispersed offshore using a Gaussian decay function with distance from shore. Finally, values were linearly rescaled from 0-1 as this layer is a unitless proxy.