Retracing Rivers and drawing swamps: Using a drawing tablet to reconstruct an historical hydroscape from army corps survey maps

Abstract

This article presents a novel geospatial approach to reconstructing and analyzing environmental change over extensive spatial and temporal scales, even in systems such as rivers and streams that are comparatively difficult to digitize. We used a drawing tablet and stylus to digitize features found on historical Army Corps maps across the spatially extensive landscape of the Lower Wabash River’s riparian zone, in Indiana and Illinois, USA. The methodology allows for an efficient reconstruction of sinuous and irregular environmental features, such as sloughs, and demonstrates the utility of digitizing historical maps to understand the evolution of surface water quantity and location across a landscape. We then compared these historical data to contemporary environmental datasets for the same study area to understand what changes have occurred over a 100 year period. This reveals that the hydroscape of the Lower Wabash River has been significantly altered by past human activity, notably through the reduction of swamps, wetlands, and sandbars, and the increase in drainage ditches and overall stream area. Notably, many of these historical alterations are not captured within current environmental datasets.