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Characterizing, Quantifying, and Optimizing Groundwater Recharge in Dedicated MAR Basins at the Moorpark Water Reclamation Facility, Ventura County, CA
  • +4
  • Craig Ulrich,
  • Sebastian Uhlemann,
  • Baptiste Dafflon,
  • Michelle Newcomer,
  • Peter Fiske,
  • Peter Nico,
  • Susan Pan
Craig Ulrich
Lawrence Berkeley National Laboratory

Corresponding Author:[email protected]

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Sebastian Uhlemann
Lawrence Berkeley National Laboratory
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Baptiste Dafflon
Lawrence Berkeley National Laboratory
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Michelle Newcomer
Lawrence Berkeley National Laboratory
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Peter Fiske
Lawrence Berkeley National Laboratory
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Peter Nico
Lawrence Berkeley National Laboratory
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Susan Pan
Ventura County Waterworks District #1
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Abstract

As a result of climate change, California is experiencing the impact of more extreme weather patterns including longer drought periods and atmospheric rivers resulting in extreme snow pack and heavy flood flows. CA faces a significant challenge to mitigate these impacts while simultaneously providing resilient sources of water under uncertain future conditions. One approach that addresses both flood mitigation and water storage is the use of Managed Aquifer Recharge (MAR). Ventura County Waterworks District #1 (VCWWD) is designing a MAR recharge facility to divert flood flows in the adjacent Arroyo Las Posas to a series of engineered basins, where water will infiltrate and replenish the local aquifer (estimated recharge: 3000 acre-feet annually). However, large uncertainties in percolation rates and an inability to predict or improve percolation (measured: 5 and 16 cm/day) places large uncertainties on the facility’s ultimate performance (and impact) on VCWWD’s overall strategy for sustainable groundwater management. The goals of this project are to use a suite of geophysical techniques, point sensors and novel modeling approaches to measure the basin(s) spatial recharge rates, where and how the water is infiltrating (fast paths) and how will basin modification improve recharge rates. Selected basins will first be characterized using electromagnetic methods and electrical resistivity tomography (ERT) coupled with soil cores to estimate the distribution of subsurface permeability in order to design the infiltration monitoring layout. During managed flooding events Spontaneous Potential will be used to monitor subsurface leakage from the basins back into the river. Within a basin, novel vertical Distributed Temperature Profiling sensors will measure diurnal temperature fluxes to calculate spatially distributed 1-D vertical recharge rates and 3D time-lapse ERT to monitor and measure the spatially dynamic recharge. ERT results will be coupled with multi-point geostatistical simulations to estimate soil permeability field scenarios and with novel joint inversion codes to estimate volumetric recharge and rates, offering a powerful suite of tools for water managers to quantify, and potentially improve basin recharge rates and develop operational and maintenance plans to maximize recharge.