DOI: 10.7280/d10q29
title: Tools for assessing hydrologic challenges and restoration potential of reservoir deltas: case studies from Southern California

description: California has lost nearly all its natural riparian ecosystems. Reservoir
 deltas represent an under-explored opportunity to restore these lost
 riparian forests across the west. However, flood magnitude, duration,
 frequency, timing, and rate of change are all modified along reservoir
 deltas, with varying impacts on key riparian species that support
 wildlife. I analyzed daily water elevation data from five reservoirs as
 case study sites and combined hydrologic and topographic data to delineate
 areas where riparian vegetation could become established. I compiled plant
 height data from a wide range of riparian restoration projects to evaluate
 the ability of riparian species to resist flood mortality. Finally, a case
 study illustrates challenges and lessons learned to guide future projects.
 Four of the five sites, while hydrologically highly modified, have
 portions of the drawdown zone where forest re-planting could be a feasible
 approach to expanding available habitat. Using these case studies, I
 developed a stepwise decision tree for integrating hydrologic data into
 site selection and restoration design. The framework illustrated in this
 report can be easily replicated to identify additional locations across
 the state where restoration has a higher likelihood of success and where
 additional data collection can further refine techniques.
description: Data from 23 River Partners
 restoration project sites in 8 counties across California were included in
 this dataset (Figure 4), representing a range of soil types and
 environmental conditions. Projects had been planted in 11 different years
 ranging from 2003 to 2018, representing a variety of precipitation and
 climate conditions. Plant propagules were either seed (ex.,
 <i>Quercus</i> spp.), 18-inch cuttings buried to 12-inches
 (ex., <i>Salix</i> spp.), or one-gallon container plants.
 During the establishment phase, plants were maintained using horticultural
 restoration methods including highly aggressive mechanical or chemical
 weed control, and frequent supplemental watering using drip or flood
 irrigation based on soil conditions and evapotranspiration demand.  Height
 measurements were taken in 12 different years from 2005 to 2020, within 12
 to 43 months after planting. To select plants for measurement, we
 randomly established 20m x 50m monitoring plots in each restoration
 project at a rate of one plot per 5-20 acres. Plots were at least 10
 meters from the project boundary, and oriented with the long axis (50m)
 facing north. All trees and shrubs within the plot were measured. Height
 was measured by placing a Stadia rod at the plant base and recording the
 tallest branch height.
description: Please see attached ReadMe file. Other
 datasets referenced here are publicly available: Department of Water Resources.
 (2019). Daily SWP Reservoir Elevation and Storage Data. https://data.ca.gov/dataset/daily-swp-reservoir-elevation-and-storage-data [accessed on Nov 16, 2019] U.S. Geological Survey. 2018. Digital Elevation Model - USGS National Map 3DEP Downloadable Data Collection: U.S. Geological Survey. https://portal.opentopography.org/usgsDataset?jobId=usgs1588274974053