Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / The purpose of the investigation was to inventory and analyze riparian corridor vegetation changes throughout the Black Vermillion watershed from approximately 1857 through 2007. Three sub-watersheds were studied; North Fork, Irish Creek and Black Vermillion Main Stem. Research questions investigated were: 1) What changes in riparian corridor width have taken place since the original territory surveys done in 1857 and why? 2) How has land cover adjacent to riparian corridors changed since the original territory surveys? 3) Has woody species composition in the riparian corridors changed? The research questions were addressed using a variety of techniques and tools including aerial photography, basic GIS, and vegetation survey techniques. Territory of Kansas survey maps and notes that were completed in 1857 were used as baseline reference conditions concerning corridor width and woody species present in the riparian corridors. Inventory and analysis of the riparian vegetation change over time and adjacent land cover will aid in understanding the present ecology of these riparian corridors and are important to stream and riparian ecosystem rehabilitation. Woody riparian corridors increased in width throughout the watershed from 1857 until about 1956 (probably due to a decrease in prescribed burning and lack of grazing), which is the pre-channelization period for this watershed. After channelization (late 1960's & early 1970's), average corridor widths dropped significantly as the stream was shortened a total of 15.8 miles (25.4Km). Most often, the land cover changed from native, tallgrass prairie to cultivated cropland or pasture. Woody species composition has changed over time from established mature woodland to a pioneer successional stage. The findings of this study can influence beginning stages of design for natural habitat rehabilitation purposes in this watershed. Design decisions for land rehabilitation purposes should consider reference conditions (historic), and to understand reference conditions we must study the history of land use and land change. This study provides a template for studying the history of land use and land use change of riparian corridors for Midwestern, agricultural landscapes.

Master of Arts / Department of Geography / Richard A. Marston / The Black Vermillion River (watershed area = 1310 square kilometers) contributes runoff and sediment into Tuttle Creek Reservoir, a large federal reservoir (volume = 327 million cubic meters) northeast of Manhattan, Kansas. Tuttle Creek, completed in 1962, is filling with sediment faster than other federal reservoirs in the region. The Reservoir’s conservation pool is about 40 percent full of sediment and is predicted to fill by 2023. Debate rages over the relative contribution of sediment from upland sources (largely croplands and pasture) versus channel incision. In the Black Vermillion watershed, bedrock is overlain in most of the watershed by pre-Illinoian age easily erodible glacial till and loess. Row crop agriculture is the most common land use in the watershed and stream channels are incised and prone to frequent flooding and channel instability. This research focused on the spatial extent, timing, and causes of channel incision in the Black Vermillion watershed. I conducted a watershed-wide survey of channel cross-sections in 56 locations repeated at sites that had been surveyed 45 years ago by the Soil Conservation Service. Further, I collected channel cross sections in 2008 at a total of 51 more locations for a total of 107 study sites. Channel depths between 1963 and 2008 increased by a mean of 1.6 meters (maximum = 5.2 meters). Most channels throughout the watershed have incised, are actively incising, or incising and widening. Statistical testing between channel depths as measured in 1963 and 2008 showed that the amount of incision was related to land use/land cover, riparian buffer widths, upstream drainage area, and geology. As channels incise, they progress through six stages of channel evolution, which complicates the relationship between channelization and incision. Channel stage, as identified in the field, was statistically related to geology, occurrence and timing of channelization, land use/land cover, and upstream drainage area. Channelization has reduced channel length by a significant portion and was identified as one of the leading causes of incision. This finding suggests that planting buffers and/or expanding existing buffers along streams should be encouraged in the watershed to alleviate flooding and channel instability.