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The aim of this study was to evaluate hydrologic impacts of potential climate and land use changes in a mountainous watershed in South Korea. The climatic data predicted by MIROC3.2 HiRes GCM A1B for three time periods (2010-2039, 2040-2069, and 2070-2099) were prepared using a change factor statistical downscaling method. The future land uses were predicted using the Conservation of Land Use and its Effects at Small regional extent (CLUE-s) model by establishing logistic regression model for five land use types with 11 driving forces represented by spatial information. By applying the climate and land use predictions to the Soil and Water Assessment Tool (SWAT), the watershed hydrologic components (including evapotranspiration, surface runoff, groundwater recharge, and streamflow) were evaluated. For the predicted 2070-2099 temperature and precipitation changes (+4.8°C and +34.4%), and 6.2% decrease in forest areas and 1.7% increase in urban areas, the combined land use with climate change scenario resulted in more streamflow change (+55.4%) than the single climate and single land use change scenario (+39.8% and +10.8%), respectively. The predicted large increase in future precipitation and the corresponding decrease in forest land are predicted to have substantial impacts on watershed hydrology, especially on surface runoff and streamflow. Therefore, to mitigate negative hydrologic impacts and utilize positive impacts, both land use and climate changes should be considered in water resource planning for the Chungju dam watershed.

Hydrologic variables in the Great Lakes region have been altered relative to pre-settlement conditions in response to major land use changes during the past 150 years. One of the goals of the present work is to develop a baseline scenario relative to which the impacts of land use changes on hydrological and environmental processes can be evaluated. In addition, this study can help in quantifying the potential impacts of future projected changes in land use in order to mitigate the negative impacts of these changes, especially in regard to a shift toward urbanization and second-generation bioenergy crop production derived from lignocellulosic crops. The present study explores the relationship between land use changes and hydrologic indicators within the agricultural regions of Michigan and Wisconsin. Two sets of land use data, the circa 1800 county base and the 2001 National Land Cover Dataset, were used to set up the Soil and Water Assessment Tool (SWAT) model. First, sensitivity analyses were performed based on both pre-settlement and current land use scenarios. Results showed that parameter sensitivity analysis may not always explain how the variation in model output can be attributed to different sources of variation in the model input. Therefore, effort should be made to determine the true importance of sensitive parameters by considering their placement in model algorithms. The model was then calibrated against measured daily streamflow data obtained from eight U.S. Geological Survey gauging stations. The impacts of land use changes were studied at three scales: subwatershed, watershed, and basin. At the subwatershed scale, most of the hydrologic behavior can be described by percent change in land cover. However, the trend was more apparent for land use conversion from mixed forest to urban and agriculture lands than for other land use conversions. At the watershed scale, significant differences were observed based on the long-term average hydrologic variables under the current and pre-settlement scenarios. In addition, an increase in evapotranspiration (up to 16.5%) and surface runoff (up to 93.9%) contribution to streamflow, a decrease in recharge to aquifers (up to -51.5%) and baseflow (up to -50.1%), and mixed impacts on water yield (-21.5% to 24.6%) were detected. However, at the basin scale, more than 70% of the study area experienced decreased lateral subsurface flow and recharge to aquifers, while 65% of the area experienced increased overland flow and minor changes in evapotranspiration and water yield.

High streambank erosion and failure rates on streams in the Ozark ecoregion of Oklahoma may be attributed to land use change and degradation of riparian areas. Numerous benefits may be achieved from streambank stabilization, but methods are needed to determine the most critical reaches for investing limited funds. Rapid geomorphic assessments (RGAs) have been used to aid in prioritizing stream reaches. This research (1) applied an existing RGA, the channel sta- bility index (CSI), on several reaches along the Barren Fork Creek and Spavinaw Creek, and (2) modified the existing RGA to create an ecoregion-specific RGA called the Oklahoma Ozark streambank erosion potential index (OSEPI) for larger-order streams in the area. Aerial photography (2003 to 2008) was used to document recent lateral bank retreat for evaluating the RGA scores. Whereas the CSI provided a relatively simple, inexpensive way to identify reaches that should be further evaluated for stability, it failed to disaggregate unstable stream reaches. Limitations included not considering the streambank's cohesion and the difficulty in assessing some metrics. The OSEPI, which included parameters to account for the streambank's cohesion and stream curvature, had higher correlation (R 2 = 0.29 for all reaches; R 2 = 0.45 for reaches with similar soils) with recent streambank erosion. These results indicate promise for its use in prioritizing reach- es for future stabilization projects in the Ozark region of Oklahoma. Additional research is needed to further test the ge- neric and ecoregion-specific RGAs and to determine the conditions that necessitate ecoregion-specific indices.