Long-term impacts of land cover changes on stream channel loss.
Land cover change and stream channel loss are two related global environmental changes that are expanding and intensifying. Here, we examine how different types and transitions of land cover change impact stream channel loss across a large urbanizing watershed. We present historical land cover in the 666-km(2) Lake Thunderbird watershed in central Oklahoma (USA) over a 137 year period and coinciding stream channel length changes for the most recent 70 years of this period. Combining these two datasets allowed us to assess the interaction of land cover changes with stream channel loss. Over this period, the upper third of the watershed shifted from predominantly native grassland to an agricultural landscape, followed by widespread urbanization. The lower two-thirds of the watershed changed from a forested landscape to a mosaic of agriculture, urban, forest, and open water. Most channel length lost in the watershed over time was replaced by agriculture. Urban development gradually increased channel loss and disconnection from 1942 to 2011, particularly in the headwaters. Intensities of channel loss for both agriculture and urban increased over time. The two longest connected segments of channel loss came from the creation of two large impoundments, resulting in 46 km and 25 km of lost stream channel, respectively. Overall, the results from this study demonstrate that multiple and various land-use changes over long time periods can lead to rapid losses of large channel lengths as well as gradual (but increasing) losses of small channel lengths across all stream sizes. When these stream channel losses are taken into account, the environmental impacts of anthropogenic land-use change are compounded.
Texas State University, Department of Geography, 601 University Drive, ELA 139, San Marcos, TX 78666, United States. Electronic address: Jason.Julian@txstate.edu.
Jason P
JP
Julian
University of Oklahoma, Department of Geography & Environmental Sustainability, 100 East Boyd St., Norman, OK 73019, USA.
Nicholas A
NA
Wilgruber
University of Oklahoma, Department of Geography & Environmental Sustainability, 100 East Boyd St., Norman, OK 73019, USA.
Kirsten M
KM
de Beurs
U.S. Environmental Protection Agency, National Health and Environmental Effects Research Lab, Western Ecology Division, 200 SW 35th Street, Corvallis, OR 97333, USA.
Paul M
PM
Mayer
Yarmouk University, Department of Geography, P.O. Box 21163, Irbid, Jordan.
Rana N
RN
Jawarneh
Historical land use; Landscape planning; River discontinuity; Stream channel loss; Urban ecosystem impacts; Watershed hydrology