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Projects

Our research deals with geomorphology and hydrology in a variety of ancient and modern landscapes. We seek to better understand how geomorphology and geomorphic processes influence or inform landscape stability and change, stream physical and biological integrity, water quality, and river corridor management. Contact Pete if you are interested in pursuing graduate work on these or related topics.

  • Oblique aerial image from Google Earth showing stream valleys extending into glaciated upland

    Continental glaciation tends to "reset" large areas of a landscape with low-relief hummocky topography characterized by little or no integration into a surface-water drainage network. Over time channels carve into these landscapes and connect previously-noncontributing areas into the drainage network, either by headward erosion of headwater channels and ravines or by scour during seasonal overflow of ephemeral wetlands. In other words, drainage networks could develop from the "bottom up" or the "top down", or some combination of the two. The rates and controls on these processes might be different, and could lead to distinct drainage morphologies.

  • Graduate student preparing to make measurements on debris-covered glacier

    In many parts of the upper midwest, the greatest extent of the Late Wisconsinan ice sheet advance is marked by broad belts of high-relief hummocky landscape. This kind of terrain is thought to have formed as the slow-moving or stagnant ice margins melted non-uniformly beneath a thickening blanket of supraglacial sediment. Similar processes may be occurring on some modern valley glaciers, whose recent thinning has been accompanied by mass wasting from newly-exposed valley walls. We have sought to model the coupled heat transfer and short-range sediment transport processes in these settings to better understand wastage of debris-covered ice and its paleoclimatic and contemporary water-resource implications.

  • large wood in a bend in Ioway Creek

    While much of the midwest is prairie and cropland, forest has been historically widespread on steep valley slopes and in riparian areas. When trees are introduced into the channel through bank erosion, storm mortality, or beavers, many physical and biological aspects of streams can be affected. While large wood has been studied extensively in mountainous gravel and cobble-bed streams in the northwestern U.S., little is known about the impacts of large wood in low-gradient midwestern streams with sand and gravel beds and deciduous riparian trees. We are investigating the role of large wood in channel morphology, sediment transport and biotic integrity in wadeable streams of Iowa and neighboring states.

  • eroding streambank

    Stream bed and bank erosion are thought to represent a significant contribution to sediment and nutrient loads Iowa’s streams, sometimes exacerbating downstream eutrophication and turbidity impairments. The size of these contributions are not well known in time or space, and may depend on many factors including watershed land use, stream channelization history and hydrological regime, soil composition and texture. While upland in-field and edge-of-field practices for soil loss and nutrient reduction have shown promise for reducing sediment and nutrient loads in streams, they have little or no impact on sediment and nutrients derived from within the stream corridors themselves.

  • Stream restoration is a growing field in the state of Iowa, and one that is sometimes motivated by different values or concerns than those that motivate restoration in salmon or timber country. Stream restoration in Iowa also faces somewhat different challenges, including diverse private property ownership, historic channelization and hydrological modification. As Iowa develops best practices for stream restoration efforts in the state, the Applied Geomorphology lab is seeking to understand how and when restoration practices can provide the most benefit given our particular geologic settings, management histories, and social/cultural dynamics.