Multispectral imaging, Puyallup River

Science Center Objects

In the past, levees have been built along the river banks of the Puyallup River to prevent floodwater from damaging roads, buildings, farms, and other areas in the floodplain. Because levees can worsen flooding by creating backwater effects or reducing floodplain storage, Pierce County is planning to remove current levees and build new ones further away from the river channels.

To help Pierce County evaluate the effects of levee relocation, the USGS is studying the shape and structure of river channels using advanced technologies that include airborne multispectral imaging and LIDAR mapping.

9722-BI8 - The integration of multispectral imaging and LIDAR to evaluate the geomorphic changes associated with a levee setback along the Puyallup River, WA - Completed FY2005

Problem - The Puyallup River originates from the Puyallup glacier of Mount Rainier, in the Cascade Range, and empties into Puget Sound at Commencement Bay. The Puyallup River has two major tributaries, the White and Carbon Rivers. The White River enters the Puyallup River near the city of Puyallup and the Carbon River enters about 18 river miles from the mouth of the Puyallup, between Puyallup and Orting. Local flooding along the Puyallup River has traditionally been addressed by constructing levees along the river banks to prevent floodwater from flowing into areas where they could damage roads, buildings, agricultural fields, or other developed areas of the floodplain. Levees, however, can worsen flooding upstream because of backwater effects or downstream because of a reduction in floodplain storage. Levees constrain streamflow during floods, which can produce deeper flows with higher velocities. Pierce County has begun a series of levee setback projects. These projects involve the removal of existing levees and the construction of new ones located further away from the active river channels. These setbacks are intended to alleviate local flooding and improve habitat conditions along some of its rivers. Pierce County has asked the U.S. Geological Survey (USGS) to help them evaluate the geomorphic changes resulting from a proposed levee setback.

Objectives - This study will:

  1. document and verify current geomorphic conditions in three study reaches: the proposed levee setback reach on the Puyallup River, a historic levee setback reach on the Puyallup River, and a control reach on the Carbon River using a remote sensing multispectral imaging system ,
  2. verify existing LIDAR data for the study reaches, and
  3. compare current geomorphic conditions within the proposed levee setback reach with those of a previously restored reach on the Puyallup and a control reach on the Carbon River

Relevance and Benefits - This project will help Pierce County evaluate the effects of levee removal for both flood hazard reduction and aquatic habitat improvement. The project will use new approaches including multispectral imaging and a portfolio of water-surface profiles for evaluating floodplain restoration. In addition to the benefits to Pierce County, this study directly addresses the objectives laid out in the USGS Washington Science Centers’ Science Plan. The proposed study directly evaluates the effectiveness of new technologies for characterizing geomorphic changes and there impact on flood hazards. The remote sensing tools that will be used to evaluate changes in flood hazard will also simultaneously evaluate changes in instream habitat conditions which directly effect salmon, an endangered species within the study area.

Approach - To address the first objective, four tasks will be performed. These tasks include the collection of multispectral imaging, a portfolio of water-surface profiles, and a riffle stability analysis. To address the second objective, LIDAR data collected in the spring of 2004 within the study areas will be verified and calibrated by field crews during the summer of 2004. To address the third objective, traditional empirical and graphical approaches will be used to compare the accuracy of field measurements with those of the multispectral images collected for the study reaches.