Relationships Among Nutrient and Sediment Fluxes, Hydrological Variability, Fire, and Land Cover in Coastal California Catchments

Aguilera, Rosana; Mélack, John M.

doi:10.1029/2017jg004119

Cited by 22 publications

(17 citation statements)

References 78 publications

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“…As the major carrier of nutrients/sediment, surface runoff and discharge are crucial for beach ecosystems in the study region (Myers et al, 2019;Aguilera and Melack, 2018). Nutrients and sediment build up over land surface and in channels during the dry season and get flushed with the initiation of the wet season (Scott and Williams, 1978;Keller and Capelli, 1992;Bende-Michl et al, 2013;Aguilera and Melack, 2018).…”

Section: Impacts and Uncertainty Analysismentioning

confidence: 99%

“…Nutrients and sediment build up over land surface and in channels during the dry season and get flushed with the initiation of the wet season (Scott and Williams, 1978;Keller and Capelli, 1992;Bende-Michl et al, 2013;Aguilera and Melack, 2018). The nutrients/sediment fluxes are positively correlated with hydrologic variability, and the majority of them occurs at the beginning of the wet season (Aguilera and Melack, 2018;Homyak et al, 2014). Therefore, both timing and magnitude of runoff and discharge will impact the nutrients/sediment export to the coastal ecosystems.…”

Section: Impacts and Uncertainty Analysismentioning

confidence: 99%

“…Some studies have been performed to investigate uncertainties mentioned above at both variable scales (for example, Wilby and Harris, 2006;Vetter et al, 2015;Valentina et al, 2017;Kay et al, 2009;Eisner et al, 2017;Su et al, 2017;Schewe et al, 2014;Hagemann et al, 2013;Asadieh and Krakauer, 2017;Chegwidden et al, 2019;Hattermann et al, 2018;Addor et al, 2014;Vidal et al, 2016;Giuntoli et al, 2018;Alder and Hostetler, 2019). Most previous studies treated hydrologic models as a whole package.…”

Section: Introductionmentioning

confidence: 99%

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Identifying uncertainties in hydrologic fluxes and seasonality from hydrologic model components for climate change impact assessments

Feng

Beighley

2020

Hydrol. Earth Syst. Sci.

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Abstract. Assessing impacts of climate change on hydrologic systems is critical for developing adaptation and mitigation strategies for water resource management, risk control, and ecosystem conservation practices. Such assessments are commonly accomplished using outputs from a hydrologic model forced with future precipitation and temperature projections. The algorithms used for the hydrologic model components (e.g., runoff generation) can introduce significant uncertainties into the simulated hydrologic variables. Here, a modeling framework was developed that integrates multiple runoff generation algorithms with a routing model and associated parameter optimizations. This framework is able to identify uncertainties from both hydrologic model components and climate forcings as well as associated parameterization. Three fundamentally different runoff generation approaches, runoff coefficient method (RCM, conceptual), variable infiltration capacity (VIC, physically based, infiltration excess), and simple-TOPMODEL (STP, physically based, saturation excess), were coupled with the Hillslope River Routing model to simulate surface/subsurface runoff and streamflow. A case study conducted in Santa Barbara County, California, reveals increased surface runoff in February and March but decreased runoff in other months, a delayed (3 d, median) and shortened (6 d, median) wet season, and increased daily discharge especially for the extremes (e.g., 100-year flood discharge, Q100). The Bayesian model averaging analysis indicates that the probability of such an increase can be up to 85 %. For projected changes in runoff and discharge, general circulation models (GCMs) and emission scenarios are two major uncertainty sources, accounting for about half of the total uncertainty. For the changes in seasonality, GCMs and hydrologic models are two major uncertainty contributors (∼35 %). In contrast, the contribution of hydrologic model parameters to the total uncertainty of changes in these hydrologic variables is relatively small (<6 %), limiting the impacts of hydrologic model parameter equifinality in climate change impact analysis. This study provides useful information for practices associated with water resources, risk control, and ecosystem conservation and for studies related to hydrologic model evaluation and climate change impact analysis for the study region as well as other Mediterranean regions.

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Section: Impacts and Uncertainty Analysismentioning

confidence: 99%

Section: Impacts and Uncertainty Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Identifying uncertainties in hydrologic fluxes and seasonality from hydrologic model components for climate change impact assessments

Feng

Beighley

2020

Hydrol. Earth Syst. Sci.

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“…The region has diverse watersheds, which vary widely in the proportion of natural, agricultural and urban development (Aguilera and Melack, 2018). Steep montane slopes composed of readily eroded fractured sedimentary rock and strongly seasonal, often intense, episodic rainfall, result in large sediment loads to the ocean (Warrick et al, 2015).…”

Section: Study Areamentioning

confidence: 99%

“…An extremely hot day is defined as day with daily temperature maximum meeting or exceeding the 99%-percentile value of daily temperature maximums during the 1985-2014 historical period. (Aguilera and Melack, 2018). Therefore, increased runoff in a delayed wet season will result in changes in the timing and quantity of nutrients and sediment export to the coastal ecosystems.…”

Section: Watershed Impactsmentioning

confidence: 99%

A multidisciplinary coastal vulnerability assessment for local government focused on ecosystems, Santa Barbara area, California

Myers

Barnard

Beighley

et al. 2019

Ocean & Coastal Management

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Incorporating coastal ecosystems in climate adaptation planning is needed to maintain the well-being of both natural and human systems. Our vulnerability study uses a multidisciplinary approach to evaluate climate change vulnerability of an urbanized coastal community that could serve as a model approach for communities worldwide, particularly in similar Mediterranean climates. We synthesize projected changes in climate, coastal erosion and flooding, watershed runoff and impacts to two important coastal ecosystems, sandy beaches and coastal salt marshes. Using downscaled climate models along with other regional models, we find that temperature, extreme heat events, and sea level are expected to increase in the future, along with more intense rainfall events, despite a negligible change in annual rainfall. Consequently, more droughts are expected but the magnitude of larger flood events will increase. Associated with the continuing rise of mean sea level, extreme coastal water levels will occur with increasingly greater magnitudes and frequency. Severe flooding will occur for both natural (wetlands, beaches) and built environments (airport, harbor, freeway, and residential areas). Adaptation actions can reduce the impact of rising sea level, which will cause losses of sandy beach zones and salt marsh habitats that support the highest biodiversity in these ecosystems, including regionally rare and endangered species, with substantial impacts occurring by 2050. Providing for inland transgression of coastal habitats, effective sediment management, reduced beach grooming and removal of shoreline armoring are adaptations that would help maintain coastal ecosystems and the beneficial services they provide.

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Predicting burrowing crab impacts on salt marsh plants

2021

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Burrowing animals profoundly influence plant communities, and changes in the burrower and plant communities together with changing abiotic parameters can shift the influence of burrowers on plants. However, we lack an ability to predict when, where, and how burrowers will influence vegetation. To begin to understand how naturally, varying environmental conditions influence the impacts of burrowers, we need to examine how burrower impacts on marsh plants differ across sites differing in environmental conditions. We manipulated crab presence for multiple years and measured the responses of the dominant plants, Pacific cordgrass (Spartina foliosa) and perennial pickleweed (Sarcocornia pacifica), at three sites in northern California and two sites in southern California. Southern California (Point Conception, CA, to the U.S.–Mexico border) experiences higher air and water temperatures, lower precipitation, and higher porewater salinity levels. Combining data from these field studies with laboratory studies allowed us to generate predictions about burrowing crab effects in salt marshes. Our models included (1) an estimate of grazing pressure on marsh plants by the dominant burrowing crab (Pachygrapsus crassipes) and (2) several soil biogeochemical measurements. Crab effects varied from strongly positive to strongly negative and depended upon estimated crab grazing pressure and edaphic conditions (salinity, ammonium, and nitrate). Relative to crabs at other sites, crabs enhanced cordgrass at sites with intermediate levels of ammonium and extreme salinities. The dependence of crab effects on edaphic conditions suggests that projected interannual variability in temperature, precipitation, and nutrients could lead to more temporally variable impacts of crabs on cordgrass. Understanding the environmental controls on these interactions will help promote cordgrass productivity and stabilize salt marsh ecosystems.

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Relationships Among Nutrient and Sediment Fluxes, Hydrological Variability, Fire, and Land Cover in Coastal California Catchments

Cited by 22 publications

References 78 publications

Identifying uncertainties in hydrologic fluxes and seasonality from hydrologic model components for climate change impact assessments

Identifying uncertainties in hydrologic fluxes and seasonality from hydrologic model components for climate change impact assessments

A multidisciplinary coastal vulnerability assessment for local government focused on ecosystems, Santa Barbara area, California

Predicting burrowing crab impacts on salt marsh plants

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