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Roger C Bales - One of the best experts on this subject based on the ideXlab platform.
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Forest thinning impacts on the water balance of Sierra Nevada mixed-conifer Headwater basins - eScholarship
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
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forest thinning impacts on the water balance of sierra nevada mixed conifer Headwater basins
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
Benjamin W Abbott - One of the best experts on this subject based on the ideXlab platform.
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unexpected spatial stability of water chemistry in Headwater stream networks
Ecology Letters, 2018Co-Authors: Benjamin W Abbott, Gerard Gruau, Jay P Zarnetske, Florentina Moatar, Lou Barbe, Zahra Thomas, Ophelie Fovet, Tamara KolbeAbstract:Understanding how water and solutes enter and propagate through freshwater landscapes in the Anthropocene is critical to protecting and restoring aquatic ecosystems and ensuring human water security. However, high hydrochemical variability in Headwater streams, where most carbon and nutrients enter river networks, has hindered effective modelling and management. We developed an analytical framework informed by landscape ecology and catchment hydrology to quantify spatiotemporal variability across scales, which we tested in 56 Headwater catchments, sampled periodically over 12 years in western France. Unexpectedly, temporal variability in dissolved carbon, nutrients and major ions was preserved moving downstream and spatial patterns of water chemistry were stable on annual to decadal timescales, partly because of synchronous variation in solute concentrations. These findings suggest that while concentration and flux cannot be extrapolated among subcatchments, periodic sampling of Headwaters provides valuable information about solute sources and subcatchment resilience to disturbance.
Phil C Saksa - One of the best experts on this subject based on the ideXlab platform.
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Forest thinning impacts on the water balance of Sierra Nevada mixed-conifer Headwater basins - eScholarship
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
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forest thinning impacts on the water balance of sierra nevada mixed conifer Headwater basins
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
Carol P Harden - One of the best experts on this subject based on the ideXlab platform.
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human impacts on Headwater fluvial systems in the northern and central andes
Geomorphology, 2006Co-Authors: Carol P HardenAbstract:Abstract South America delivers more freshwater runoff to the ocean per km2 land area than any other continent, and much of that water enters the fluvial system from Headwaters in the Andes Mountains. This paper reviews ways in which human occupation of high mountain landscapes in the Andes have affected the delivery of water and sediment to Headwater river channels at local to regional scales for millennia, and provides special focus on the vulnerability of paramo soils to human impact. People have intentionally altered the fluvial system by damming rivers at a few strategic locations, and more widely by withdrawing surface water, primarily for irrigation. Unintended changes brought about by human activities are even more widespread and include forest clearance, agriculture, grazing, road construction, and urbanization, which increase rates of rainfall runoff and accelerate processes of water erosion. Some excavations deliver more sediment to river channels by destabilizing slopes and triggering processes of mass-movement. The northern and central Andes are more affected by human activity than most high mountain regions. The wetter northern Andes are also unusual for the very high water retention characteristics of paramo (high elevation grass and shrub) soils, which cover most of the land above 3000 m. Paramo soils are important regulators of Headwater hydrology, but human activities that promote vegetation loss and drying cause them to lose water storage capacity. New data from a case study in southern Ecuador show very low bulk densities (median 0.26 g cm− 3), high organic matter contents (median 43%), and high water-holding capacities (12% to 86% volumetrically). These data document wetter soils under grass than under tree cover. Effects of human activity on the fluvial system are evident at local scales, but difficult to discern at broader scales in the regional context of geomorphic adjustment to tectonic and volcanic processes.
Christina Tague - One of the best experts on this subject based on the ideXlab platform.
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Forest thinning impacts on the water balance of Sierra Nevada mixed-conifer Headwater basins - eScholarship
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
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forest thinning impacts on the water balance of sierra nevada mixed conifer Headwater basins
Water Resources Research, 2017Co-Authors: Phil C Saksa, Martha H Conklin, John J Battles, Christina Tague, Roger C BalesAbstract:Headwater catchments in the mixed-conifer zone of the American and Merced River basins were selectively thinned in 2012 to reduce the risk of high-intensity wildfire. Distributed observations of forest vegetation thinning, precipitation, snowpack storage, soil-water storage, energy balance and stream discharge from 2010 to 2013 were used to calculate the water balance and constrain a hydro-ecologic model. Using the spatially calibrated RHESSys model, we assessed thinning effects on the water balance. In the central-Sierra American River Headwaters, there was a mean annual runoff increase of 14% in response to the observed thinning patterns, which included heterogeneous reductions in Leaf Area Index (-8%), canopy cover (-3%), and shrub cover (-4%). In the southern-Sierra Merced River Headwaters, thinning had little impact on forest structure or runoff, as vegetation growth in areas not thinned offset reductions from thinning. Observed thinning effects on runoff could not be confirmed in either basin by measurements alone, in part because of the high variability in precipitation during the measurement period. Modeling results show that when thinning is intensive enough to change forest structure, low-magnitude vegetation reductions have greater potential to modify the catchment-scale water balance in the higher-precipitation central Sierra Nevada versus in the more water-limited southern Sierra Nevada. Hydrologic modeling, constrained by detailed, multi-year field measurements, provides a useful tool for analyzing catchment response to forest thinning.
