Impacts of impervious cover, water withdrawals, and climate change on river flows in the conterminous US

Abstract

Rivers are essential to aquatic ecosystem and societal sustainability, but are increasingly impacted by water withdrawals, land-use change, and climate change. The relative and cumulative effects of these stressors on continental river flows are relatively unknown. In this study, we used an integrated water balance and flow routing model to evaluate the impacts of impervious cover and water withdrawal on river flow across the conterminous US at the 8-digit Hydrologic Unit Code (HUC) watershed scale. We then estimated the impacts of projected change in withdrawals, impervious cover, and climate under the B1 "Low" and A2 "High" emission scenarios on river flows by 2060. Our results suggest that compared to no impervious cover, 2010 levels of impervious cover increased river flows by 9.9% on average with larger impacts in and downstream of major metropolitan areas. In contrast, compared to no water withdrawals, 2005 withdrawals decreased river flows by 1.4% on average with larger impacts in heavily irrigated arid regions of Western US. By 2060, impacts of climate change were predicted to overwhelm the potential gain in river flow due to future changes in impervious cover and add to the potential reduction in river flows from withdrawals, decreasing mean annual river flows from 2010 levels by 16% on average. However, increases in impervious cover by 2060 may offset the impact of climate change during the growing season in some watersheds. Large water withdrawals will aggravate the predicted impact of climate change on river flows, particularly in the Western US. Predicted ecohydrological impacts of land cover, water withdrawal, and climate change will likely include alteration of the terrestrial water balance, stream channel habitat, riparian and aquatic community structure in snow-dominated basins, and fish and mussel extirpations in heavily impacted watersheds. These changes may also require new infrastructure to support increasing anthropogenic demand for water, relocation of agricultural production, and/or water conservation measures. Given that the impacts of land use, withdrawals and climate may be either additive or offsetting in different magnitudes, integrated and spatially explicit modeling and management approaches are necessary to effectively manage water resources for aquatic life and human use in the face of global change

Simulation of Hydro Climatological Impacts Caused by Climate Change: The Case of Hare Watershed, Southern Rift Valley of Ethiopia

“…Consistent with other research [8,32,33], the climate only scenarios had a larger effect on streamflow than land use change. In 2050s, mean annual streamflow is found to increase in all the scenarios.…”

“…There was a fundamental change between the fourth and fifth assessment reports (AR4 and AR5) [8][9][10] and in order to reflect such differences as well as model variability, the study looked at two future scenarios. The first scenario considers what the future climate will be under conditions with a representative concentration path (RCP) that assumes that radiative forcing will stabilize at 8.5 W/m 2 in 2100 (RCP8.5); the second less extreme scenario assumes that radiative forcing will stabilize at 4.5 W/m 2 in 2100 (RCP4.5).…”

Projecting water yield and ecosystem productivity across the United States by linking an ecohydrological model to WRF dynamically downscaled climate data

“…The WaSSI model simulates the full monthly water (ET, Q, and soil moisture storage) and carbon balances (GPP, ecosystem respiration, and net ecosystem productivity) for each land cover class at the given watershed scale. This model has been tested in a variety of geographical regions, and widely used for quantitatively assessing combined or individual effects of climate change, land use/cover change (LUCC), and population dynamics on water supply stress and ecosystem productivity (i.e., carbon dynamic) over the CONUS (Sun et al, , 2011aLockaby et al, 2011;Caldwell et al, 2012;Averyt et al, 2013;Tavernia et al, 2013;Marion et al, 2014;Sun et al, 2015a, b). The model has also been applied internationally in Mexico, China (Liu et al, 2013b), and Africa (McNulty et al, 2016).…”

“…The WaSSI model is an integrated, water-centric processbased ecohydrological model designed for modeling water and carbon balance and water supply stress at a broad scale (Sun et al, 2011a;Caldwell et al, 2012;Sun et al, 2015a, b). It operates on a monthly time step at the 8-digit HUC or 12-digit HUC watershed scale for the CONUS.…”

Improving sub-pixel imperviousness change prediction by ensembling heterogeneous non-linear regression models

“…rainfall-runoff transformation, ground water recharge, environmental or even population health) (Arnold and Gibbons, 1996;Shahtahmassebi et al, 2014). For this reason the accurate information about ISA coverage and monitoring of its change plays an important role in many environmental studies, especially urban and hydrological ones (Caldwell et al, 2012;Dams et al, 2013;Shahtahmassebi et al, 2014;Li et al, 2016).…”