Watershed impacts of climate and land use changes depend on magnitude and land use context

Abstract

Human population growth and urban development are affecting climate, land use, and the ecosystem services provided to society, including the supply of freshwater. We investigated the effects of land use and climate change on water resources in the Yadkin-Pee Dee River Basin of North Carolina, United States. Current and projected land uses were modeled at high resolution for three watersheds representing a forested to urban land use gradient by melding the National Land Cover Dataset with data from the U.S. Forest Service Forest Inventory and Analysis. Forecasts for 2051-2060 of regional land use and climate for scenarios of low (B2) and moderately high (A1B) rates of change, coupled with multiple global circulation models (MIROC, CSIRO, and Hadley), were used to inform a distributed ecohydrological model.Our results identified increases in water yields across the study watersheds, primarily due to forecasts of increased precipitation. Climate change was a more dominant factor for future water yield relative to land use change across all land uses (forested, urban, and mixed). When land use change was high (27% of forested land use was converted to urban development), it amplified the impacts of climate change on both the magnitude and timing of water yield.Our fine-scale (30-m) distributed combined modeling approach of land use and climate change identified changes in watershed hydrology at scales relevant for management, emphasizing the need for modeling efforts that integrate the effects of biophysical (climate) and social economic (land use) changes on the projection of future water resource scenarios.

Rainfall partitioning varies across a forest age chronosequence in the southernAppalachianMountains

“…Many of the fastest growing metropolitan areas in the region, including cities such as Atlanta, GA, and Charlotte, NC, draw on water from the southern Appalachian Mountains, which supply water to more than 18 million people (Caldwell et al, 2014). These mountain watersheds also serve as headwaters for a number of river basins that are ecologically vulnerable due to either past or predicted flow alterations (Brantley et al, 2017;Martin et al, 2017;Petes et al, 2012;Suttles et al, 2018). Although many of the fluxes reported here are small relative to transpiration, the aggregate effect of variations in interception should not be ignored.…”

Legacy Nutrient Dynamics at the Watershed Scale: Principles, Modeling, and Implications

“…However, many mechanistic models usually ignore the impacts of historical nutrient inputs and landuse management measures on nutrient and hydrological residence times (Martin et al, 2017). The measured riverine nutrient concentration is a 27 Legacy Nutrient Dynamics at the Watershed Scale mixture of nutrient having different ages, and very often the residence time of nutrient in landscapes is much longer than the temporal extent of the calibration data available Meals et al, 2010).…”

Cumulative Effects of Low Impact Development on Watershed Hydrology in a Mixed Land-Cover System

“…Our findings suggest a clear need for the evaluation of the influence and benefits of LID in the context of other watershed land uses and their associated management [68]. For example, the incremental influence of LID on overall watershed responses, relative to management targets at different locations along the stream network, should be assessed.…”