Application of an unstructured 3D finite volume numerical model to flows and salinity dynamics in the San Francisco Bay-Delta

Martyr-Koller, Rosanne; Kernkamp, Herman; Dam, Arthur van; Wegen, Mick van der; Lucas, Lisa V.; Knowles, N. Richard; Jaffe, Bruce E.; Fregoso, Theresa A.

doi:10.1016/j.ecss.2017.04.024

Cited by 69 publications

(48 citation statements)

References 37 publications

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“…In contrast to the typically poor salinity predictions in the interior Delta, comparisons to USGS transects in Figure 4 show good prediction of salinity from the Golden Gate to Rio Vista, located in the western Delta. This is consistent with good calibration results achieved with the in other applications, most recently for the two simulation years documented in [32].…”

Section: Hydrodynamic Model Calibrationsupporting

confidence: 91%

The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model

Gross

Andrews

Bergamaschi

et al. 2019

Water

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Transport time scales are common metrics of the strength of transport processes. Water age is the time elapsed since water from a specific source has entered a study area. An observational method to estimate water age relies on the progressive concentration of the heavier isotopes of hydrogen and oxygen in water that occurs during evaporation. The isotopic composition is used to derive the fraction of water evaporated, and then translated into a transport time scale by applying assumptions of representative water depth and evaporation rate. Water age can also be estimated by a hydrodynamic model using tracer transport equations. Water age calculated by each approach is compared in the Cache Slough Complex, located in the northern San Francisco Estuary, during summer conditions in which this region receives minimal direct freshwater inflow. The model's representation of tidal dispersion of Sacramento River water into this backwater region is evaluated. In order to compare directly to isotopic estimates of the fraction of water evaporated ("fractional evaporation") in addition to age, a hydrodynamic model-based property tracking approach analogous to the water age estimation approach is proposed. The age and fractional evaporation model results are analyzed to evaluate assumptions applied in the field-based age estimates. The generally good correspondence between the water age results from both approaches provides confidence in applying the modeling approach to predict age through broader spatial and temporal scales than are practical to assess using the field method, and discrepancies between the two methods suggest aspects of both approaches that may be improved. Model skill in predicting water age is compared to skill in predicting salinity. Compared to water age, salinity observations are shown to be a less useful diagnostic of transport in this low salinity region in which salt inputs are poorly constrained.

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Section: Hydrodynamic Model Calibrationsupporting

confidence: 91%

The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model

Gross

Andrews

Bergamaschi

et al. 2019

Water

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“…While several caveats and opportunities for improvement remain, the approach and results presented demonstrate the ability to directly evaluate hydroclimatic scenarios derived from GCM outputs, and to provide flow estimates at the daily time scale. The translation of daily GCM outputs into corresponding daily managed flow estimates allows mutually consistent forcing of downstream models such as D‐Flow FM (Martyr‐Koller et al, ). That is, the managed flows presented here will be physically mutually consistent in terms of relative signal magnitudes and lags with other D‐Flow FM inputs that have been derived from the same GCM runs through other methods, such as hourly sea level (Cayan et al, ) and daily meteorology (Pierce et al, ; see Figure ).…”

Section: Discussionmentioning

confidence: 99%

Responses of Unimpaired Flows, Storage, and Managed Flows to Scenarios of Climate Change in the San Francisco Bay‐Delta Watershed

Knowles

Cronkite-Ratcliff

Pierce

et al. 2018

Water Resources Research

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Projections of meteorology downscaled from global climate model runs were used to drive a model of unimpaired hydrology of the Sacramento/San Joaquin watershed, which in turn drove models of operational responses and managed flows. Twenty daily climate change scenarios for water years 1980–2099 were evaluated with the goal of producing inflow boundary conditions for a watershed sediment model and for a hydrodynamical model of the San Francisco Bay‐Delta estuary. The resulting time series of meteorology, snowpack, unimpaired flow, reservoir storage, and managed flow were analyzed for century‐scale trends. In the Sacramento basin, which dominates Bay‐Delta inflows, all 20 scenarios portrayed warming trends (with a mean of 4.1 °C) and most had precipitation increases (with a mean increase of 9%). Sacramento basin snowpack water equivalent declined sharply (by 89%), which was associated with a major shift toward earlier unimpaired runoff timing (33% more flow arriving prior to 1 April). Sacramento basin reservoirs showed large declines in end‐of‐September storage. Water‐year averaged outflows increased for most scenarios for both unimpaired and impaired flows, and frequency of extremely high daily unimpaired and impaired flows increased (increases of 175% and 170%, respectively). Managed Delta inflows were projected to experience large increases in the wet season and declines in the dry season. Changes in management strategy and infrastructure can mitigate some of these changes, though to what degree is uncertain.

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“…We apply the open source Delft3D‐Flexible Mesh software (http://www.deltares.nl/en/software/delft3d-flexible-mesh-suite/, version 1.1.162.43444) to compute water temperatures for the water years 2011 and 2012. The model of the current study builds upon the model by Martyr‐Koller et al (), covering the Sacramento‐San Joaquin Delta up to the approximate upstream limit of tidal influence and extending seaward to North Bay, Central Bay, South Bay, and the coastal Pacific Ocean (Figure ). The unstructured grid consists of approximately 75,000 elements in the horizontal and allows for computation of model results at a spatial resolution down to 10–100 m in the Delta and a time resolution of minutes.…”

Section: Methodsmentioning

confidence: 99%

“…The southwestern part of the Delta has the highest yearly averaged temperature. In North Bay (consisting of San Pablo Bay, Carquinez Strait, and Suisun Bay), salinity stratification influences the hydrodynamics (Martyr‐Koller et al, ). During low river flow conditions, salinity intrudes into the confluence of the Sacramento and San Joaquin Rivers near Antioch (ANH), whereas high river flow pulses may shift salinity intrusion tens of kilometers seaward into San Pablo Bay (Jassby et al, ).…”

Section: Introductionmentioning

confidence: 99%

What Determines Water Temperature Dynamics in the San Francisco Bay‐Delta System?

Vroom

Wegen

Martyr-Koller

et al. 2017

Water Resources Research

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Water temperature is an important factor determining estuarine species habitat conditions. Water temperature is mainly governed by advection (e.g., from rivers) and atmospheric exchange processes varying strongly over time (day‐night, seasonally) and the spatial domain. On a long time scale, climate change will impact water temperature in estuarine systems due to changes in river flow regimes, air temperature, and sea level rise. To determine which factors govern estuarine water temperature and its sensitivity to changes in its forcing, we developed a process‐based numerical model (Delft3D Flexible Mesh) and applied it to a well‐monitored estuarine system (the San Francisco Estuary) for validation. The process‐based approach allows for detailed process description and a physics‐based analysis of governing processes. The model was calibrated for water year 2011 and incorporated 3‐D hydrodynamics, salinity intrusion, water temperature dynamics, and atmospheric coupling. Results show significant skill in reproducing temperature observations on daily, seasonal, and yearly time scales. In North San Francisco Bay, thermal stratification is present, enhanced by salinity stratification. The temperature of the upstream, fresh water Delta area is captured well in 2‐D mode, although locally—on a small scale—vertical processes (e.g., stratification) may be important. The impact of upstream river temperature and discharge and atmospheric forcing on water temperatures differs throughout the Delta, possibly depending on dispersion and residence times. Our modeling effort provides a sound basis for future modeling studies including climate change impact on water temperature and associated ecological modeling, e.g., clam and fish habitat and phytoplankton dynamics.

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Application of an unstructured 3D finite volume numerical model to flows and salinity dynamics in the San Francisco Bay-Delta

Cited by 69 publications

References 37 publications

The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model

The Use of Stable Isotope-Based Water Age to Evaluate a Hydrodynamic Model

Responses of Unimpaired Flows, Storage, and Managed Flows to Scenarios of Climate Change in the San Francisco Bay‐Delta Watershed

What Determines Water Temperature Dynamics in the San Francisco Bay‐Delta System?

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