Get reliable science

The USC Wrigley Institute for Environmental Science consists of a 14 acre facility near Two Harbors on Catalina Island. The island is home to American Bison (Bison bison), Black Buck Antelope (Antelope cervicarpa) and Mule Deer (Odocoileus hemionus) that graze on the native range on the undeveloped parts of the island. Development on the island is primarily occuring in the basins, and we wanted to show what impact recent development in a single basin had had on the flow within its watershed. The watershed that contains the Wrigley Institute was analysed in ArcMap 10.2 for changes in flow that have occurred as a result of the expansion of the Institute since 2006.  A digital surface model with 5 foot resolution from LiDAR data was run through a tool we created for model builder to determine stream order. We updated the DSM with data collected within the watershed using a Trimble GeoXH 6000 and an external 2m GNSS receiver. This new data was then used to update the DSM for 2013 and our model was rerun to incorporate the new elevations. Our model showed that the addition of a new building complex has altered the flow of water up to 627 ft from the building site.  One of the biggest overall changes we observed was the change in stream order. Between 2006 and 2013, magnitude 5 streams have more than doubled in number from 25 to 62.