Over the past two centuries, the Mississippi River system (MRS) has been dramatically altered to facilitate commercial navigation and provide flood control. Because of its long history of modification, rigorous measurements including maps, charts, surveys, and other data concerning the MRS are available from the past 200 years or longer. Comparison between historical reference conditions and modern conditions can document changes related to natural processes, human impacts, and river management practices and policies.
To show these changes, we have assembled a hydrologic database of approximately 7 million measurements and a geospatial database consisting of 4878 map sheets dating back to 1765. The databases include nearly all available data sources for the navigable Mississippi River, the lower Missouri River, and the Illinois River (>4500 kilometers of waterways; see Figure 1, in the electronic supplement to this Eos issue; http://www.agu.org/eos_elec). We have digitized all 81 map sets and georeferenced 48 of those map sets, meaning that the maps have been referenced in physical space for use in a geographic information system. The purpose for constructing these databases is to centralize and standardize these data sources and to make them broadly available for research and management. In this article we describe the data, the databases, and their dissemination.