Oetter, D., L. Ashkenas, S. Gregory and P. Minear. 2004. GIS Methodology for Characterizing Historical Conditions of the Willamette River Flood Plain, Oregon. Transactions in GIS 8:367–383.

Flood plain restoration along the Willamette River has become a priority to absorb flood waters and increase wildlife habitat. To maximize limited resources, authors created a GIS that will allow decision-makers to prioritize floodplain restoration sites. Using historical flood maps, photographs, General Lands Office surveys, U.S. Army Corps of Engineers river maps and digital orthophotography, the GIS maps floodplains, active channels, side channels, islands and tributaries for four different time periods. It also includes historic (pre-European settlement) and current land cover data. Findings demonstrate that channel length has decreased by 26% since 1850 and nearly 58% of former side channels have been disconnected. Finally, due to conversion for agricultural and urban land uses, 72% of the basins’ floodplain forests have been lost. The final GIS is a conglomerate of data that represents spatial and temporal variations. This information can be used to identify sections of the floodplain that are good targets for restoration, those that are not overdeveloped and were historically complex.

Mapping the historical extent of the river channel