Date of Graduation

Summer 2023

Degree

Master of Natural and Applied Science in Geography, Geology, and Planning

Department

Geography, Geology, and Planning

Committee Chair

Robert Pavlowsky

Abstract

Channel form can respond to changes in flood regime and sediment load caused by land use and climate disturbances. In the eastern United States, widespread soil and vegetation disturbances in the 1800s during agricultural expansion increased runoff rates, flood magnitude and frequency, and sediment loads often causing major changes in channel activity and floodplain sedimentation in local streams. Investigating the historical evolution of a stream channel system including its floodplains can help to advance geomorphological theory and benefit environmental managers. This study documents human impacts on historical changes in channel and floodplain widths since the early to middle 1800s in the Blue River in Kansas City, Missouri compared to a conceptual historical channel evolution model (HCEM) developed from the findings of other studies in the Midwest, U.S.A. The Blue River watershed drains the transitional area between the Ozark Plateaus in Missouri and Central Lowlands in Kansas. It has been affected by a long agricultural history as well as more recent and significant urban-industrial growth. Historical channel changes were assessed by: (i) General Land Office (GLO) surveys from 1826, 1827 and 1836 that describe pre-settlement channel conditions; (ii) Bank-line changes over time using aerial photography since the 1950s; and (iii) Locations, dates, and types of bank stabilization structures and channel modifications. Channel data combined with census data, flood records, soil maps, land use trends, and GLO surveyor notes indicate significant changes in channel width and planform of Blue River. Low-order channels responded to historical hydrological changes through incision and headward network extension. Middle watershed channels generally transitioned from a wide, shallow, multi-threaded planform to a narrower, deeper, single-channel stream. In addition, bank heights and floodplain extent increased by accelerated floodplain deposition of legacy sediment along most of the present-day channel. Lower main channel segments narrowed and possibly aggraded in response to higher sedimentation rates and artificial in-filling of urban land on the valley floor that possibly led to the need for the construction of engineered channel modifications to reduce flood risk since the 1970s.

Keywords

fluvial geomorphology, channel width adjustments, General Land Office surveys, Kansas City, legacy sediment

Subject Categories

Geology | Geomorphology | Soil Science

Copyright

© Katie Ann Grong

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