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Daily mean water level regression model for the Sacramento-San Joaquin Delta, USA


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Created: Aug 31, 2023 at 12:24 a.m.
Last updated: Mar 14, 2024 at 8:11 p.m.
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Abstract

Water levels in deltas and estuaries vary on multiple timescales due to coastal, hydrologic, meteorologic, geologic, and anthropogenic factors. These diverse factors increase uncertainty of and may bias relative sea level rise (RSLR) estimates. Baranes et al. (in review) evaluates RSLR in San Francisco Bay and the Sacramento-San Joaquin Delta, USA by applying a physics-based, nonlinear regression to 50 tide gauges. We estimate the spatially varying controls on daily mean water level for water years 2004-2022. Results show that median river flow causes water level variations of 10 mm-1.3 m, and high summertime pumping rates lower water level by up to 0.35 m. High (95th percentile) coastal water level perturbations, tidal-fluvial interaction, and wind forcing cause water level variations of -50-50, 0-70, and 0-60 mm, respectively. Removal of these interfering factors greatly improves RSLR estimates, narrowing 95% confidence intervals by 89-99% and removing bias due to recent drought. Results show that RSLR is spatially heterogeneous, with rates ranging from -2.8 to 12.9 mm y-1 (95% uncertainties <1 mm y-1). RSLR exceeds coastal SLR of 3.3 mm y-1 in San Francisco at 85% of stations. Thus, RSLR in the Delta is strongly influenced by local vertical land motion and will likely produce significantly different future flood risk trajectories. Datasets and scripts provided here can be used to run the regression model at Delta gauges.

Subject Keywords

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
Place/Area Name:
Sacramento-San Joaquin Delta
North Latitude
38.7669°
East Longitude
-120.9979°
South Latitude
37.3068°
West Longitude
-123.1760°

Temporal

Start Date:
End Date:

Content

readme.txt

Author: Hannah Baranes
Gulf of Maine Research Institute
hbaranes@gmri.org 
Created 30 August 2023 

Run kj3_regression_fit_exp_coef.m to calculated modeled daily mean water level and model 
coefficients, exponents, and statistics using the  regression approach described in Baranes 
et al. (in review). This script uses the function kj3_regression.m and data file 
daily_MWL_kj3_regression_vars.mat.  

The input data file daily_MWL_kj3_regression_vars.mat contains the following variables 
(see Baranes et al., in review for details): 
	
	station:  Names of tide gauge stations
	
	info:     Metadata variable containing station latitude and longitude, staiton code, 
	          data source, time zone, datum info, and units 
	
	dqIxFlag: Indices of stations where Baranes et al. found the regression did not perform 
	          well 
	
	zone:     Geographic zone of the station, where 1=bays and straits west of the 
			  Sacramento-San Joaquin Rivers confluence; 2=northern Delta; 3=southern Delta.
			  The zone determines the regression formulation used for the station. 
	
	dng:	  Vector of daily times in MATLAB's datenum format. Variables DWL, Q, E, T, C, 
	          and W all correspond to this time vector. 
	
	DWL:      Measured daily mean water level in meters, calculated by applying a 45-hour 
			  Lanczos filter to hourly gauge data, then taking the water level at 12:00 
			  each day(to remove bias from tides because the tidal period is not an exact 
			  multiple of 24 hours) 
	
	Q:		  Daily mean river discharge in m^3/s. Q{1}=Net Delta Outflow Index, from 
			  California Department of Water Resources Dayflow model; Q{2} = Net Delta 
			  Outflow Index minus exports (see E term); Q{3}=Sacramento River at Freeport
			  (USGS station 11447650); Q{4}= San Joaquin River near Vernalis (USGS station 
			  11303500)
			  
	E:		  Daily mean exports in m^3/s, from Dayflow model 
	
	T:		  Daily higher high water minus daily lower low water in meters at Point Reyes 
			  (NOAA station 9415020) 
	
	C: 		  Daily mean non-tidal coastal water level at Point Reyes in meters, calculated 
	          by detrending and detiding the hourly NOAA tide gauge record 
			  
	W:		  Daily mean wind speed at Port Chicago (NOAA station 9415144) in m/s; winds with
		      azimuths from 315º through 135º are set to 0

Reference: 
Baranes, H., S. A. Talke, D. A. Jay & S. L. Dykstra (in review), Sea level
rise and the drivers of daily water levels in the Sacramento-San Joaquin 
Delta. Scientific Reports. 

How to Cite

Baranes, H., S. L. Dykstra, D. Jay, S. Talke (2024). Daily mean water level regression model for the Sacramento-San Joaquin Delta, USA, HydroShare, http://www.hydroshare.org/resource/60a77d2b6df446d8bb4390cd94712459

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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