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Land-cover changes to surface-water buffers in the Midwestern USA: 25 years of Landsat analyses (1993-2017)
Citation:
Lane, C., T. Berhane, S. Mengistu, J. Christensen, H. Golden, S. Qiu, AND Z. Zhu. Land-cover changes to surface-water buffers in the Midwestern USA: 25 years of Landsat analyses (1993-2017). 2019 AGU Fall Meeting, San Francisco, California, December 09 - 13, 2019.
Impact/Purpose:
Poster in AGU Session: Characterizing and Monitoring Land Change and Associated Ecosystem Responses Using Long-term Time Series Remote Sensing Data
Description:
Important biogeochemical processing and flow-attenuation occurs in the surface and near-surface inflows surrounding – or buffering – aquatic systems. Hence, modifications to the areas buffering waters can have profound impacts on the quantity, quality, and seasonal inundation in a given water body, as well as implications for the condition of downstream systems. To understand the timing, extent, magnitude, and frequency of change in the buffer areas (90-meter) surrounding waters of the Midwestern US, we analyzed the full archive of three Landsat path/row combinations totaling 31 years of data for ~100,000 km2, including areas of high urbanization (i.e., Chicago, IL, and St. Louis, MO) as well as agriculturally dominated landscapes (i.e., Peoria, IL). We used the Continuous Change Detection and Classification algorithm, which identified instances of land-cover change throughout the continuous Landsat archive for each 30-m pixel. We binned the data using the 2001 National Land Cover Dataset into six classes, trained the data from 1986-1992, and analyzed continuous change from 1993-2017. Change was consistent for the ~110,000 waterbody buffers analyzed across all three images, with substantial linear decreases in forest cover (-0.9 to -1.7%), croplands (-0.2 to -1.0%), and grass/pasture (-0.1 to -0.3%). Conversely, developed lands increased markedly over 25 years (0.5 to 2.5%). Water bodies increased in area over time, with increases ranging from 0.2 to 1.1%. The greatest change occurred most frequently in the buffers surrounding the smallest waters (<0.1 ha). Though relatively small as a change percent, the spatial extent of the modifications is substantial (e.g., nearly 850 km2 of forested and cropland became urban lands in the Chicago area, whereas nearly 300 km2 of land became water in both St. Louis and Peoria images). Incorporating water buffer dynamics into large-scale modeling and measuring studies that analyze aquatic nutrient and hydrologic dynamics will improve the physical representation of the landscape in these efforts. Ultimately, changes wrought to areas buffering waters likely affect the processes within a given water as well as cumulatively modify downstream conditions.