Quantifying Effects of Humans and Climate on Groundwater Resources - - PowerPoint PPT Presentation

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Quantifying Effects of Humans and Climate on Groundwater Resources - - PowerPoint PPT Presentation

Sep 27, 2023 382 likes •597 views

Quantifying Effects of Humans and Climate on Groundwater Resources Through Modeling of Volcanic-Rock Aquifers of Hawaii Volcanic rock University of Hawaii Freshwater Saltwater Kolja Rotzoll, Scot K. Izuka, Tracy Nishikawa, Michael N.

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Quantifying Effects of Humans and Climate on Groundwater Resources Through Modeling of Volcanic-Rock Aquifers of Hawaii

University

  • f Hawaii

This information is preliminary and is subject to revision. It is being provided to meet the need for timely best science. The information is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from the authorized or unauthorized use of the information.

Freshwater Volcanic rock Saltwater

Kolja Rotzoll, Scot K. Izuka, Tracy Nishikawa, Michael N. Fienen, and Aly I. El-Kadi

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Challenges Limited capacity to store fresh groundwater Sharp contrasts in climate, geology, and hydrology Scope

  • Current condition of the Hawaii volcanic aquifers
  • Effects of human activities
  • Responses to future stresses

USGS Water Availability & Use Science Program

Hawaii Volcanic-Rock Aquifer Study

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SLIDE 3

160º 22º 21º 20º 19º 159º 158º 157º 156º 155º 40 MILES 40 KILOMETERS

Kauai Oahu Molokai Maui Hawaii (Big Island) Lanai Kahoolawe Niihau

HAWAIIAN ISLANDS

Framework, groundwater budget, conceptual model, whole-island numerical model Framework, groundwater budget, conceptual model Not included in this study

Preliminary Information—Subject to Revision. Not for Citation.

USGS Water Availability & Use Science Program

Hawaii Volcanic-Rock Aquifer Study

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SLIDE 4

Izuka, S.K., Engott, J.A., Bassiouni, M., Johnson, A.G., Miller, L.D., Rotzoll, K., and Mair, A., in press, Volcanic aquifers of Hawai‘i — hydrogeology, water budgets, and conceptual models: U.S. Geological Survey Scientific Investigations Report 2015-5164

USGS Water Availability & Use Science Program

Hawaii Volcanic-Rock Aquifer Study

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SLIDE 5

160º 22º 21º 20º 19º 159º 158º 157º 156º 155º 40 MILES 40 KILOMETERS

Kauai Oahu Molokai Maui Hawaii (Big Island) Lanai Kahoolawe Niihau

HAWAIIAN ISLANDS

Framework, groundwater budget, conceptual model, whole-island numerical model Framework, groundwater budget, conceptual model Not included in this study

whole-island numerical model Simulate steady-state groundwater flow and 50% salinity interface (MODFLOW/SWI2)

  • 2001-2010 conditions
  • Pre-development conditions
  • Future scenarios (Oahu only)

Preliminary Information—Subject to Revision. Not for Citation.

USGS Water Availability & Use Science Program

Hawaii Volcanic-Rock Aquifer Study

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SLIDE 6

Script-Based Modeling

Instantaneous execution Readable files: Easy to catch and correct errors Reproducibility: A script is a record of the entire modeling or data-analysis process Python: Free and open-source computer language

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SLIDE 7

Basalt Structural Contours

Preliminary Information—Subject to Revision. Not for Citation.

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Elevation of Basalt Surface

Preliminary Information—Subject to Revision. Not for Citation.

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Sediment Thickness

Preliminary Information—Subject to Revision. Not for Citation.

Surface Elevation – Basalt Elevation = Caprock Thickness

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Boundary Conditions

0 = ocean 1 = confined 2 = unconfined

Preliminary Information—Subject to Revision. Not for Citation.

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SLIDE 11

Preliminary Information—Subject to Revision. Not for Citation.

drains general head wells

Boundary Conditions

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Average 2001-2010 Withdrawals & Recharge

Total basalt

  • recharge: 560 Mgal/d
  • withdrawal: 197 Mgal/d

Preliminary Information—Subject to Revision. Not for Citation.

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SLIDE 13

Integer Grid of Aquifer Zones

Preliminary Information—Subject to Revision. Not for Citation.

1

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SLIDE 14

Hydraulic Conductivity

Preliminary Information—Subject to Revision. Not for Citation.

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SLIDE 15

Simulated Drain Fluxes

Preliminary Information—Subject to Revision. Not for Citation.

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Simulated High-Level Water Levels

ft rel. to msl

Preliminary Information—Subject to Revision. Not for Citation.

ft rel. to msl

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SLIDE 17

Simulated Freshwater-Lens Water Levels

ft rel. to msl

Preliminary Information—Subject to Revision. Not for Citation.

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Simulated Midpoint of the Transition Zone

50% Seawater-Salinity Depth

Preliminary Information—Subject to Revision. Not for Citation.

ft rel. to msl

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Outlook

  • Statistical parameter estimation: PEST
  • Run the calibrated model
  • with pre-development recharge and without withdrawals
  • future climate scenarios

(future land cover & rainfall -> future recharge, future withdrawals)

  • Assess changes in
  • water levels
  • discharge to streams and ocean
  • freshwater volume (50% salinity interface to water table)
  • Compare results of Kauai, Oahu, and Maui
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Quantifying Effects of Humans and Climate on Groundwater Resources Through Modeling of Volcanic-Rock Aquifers of Hawaii

University

  • f Hawaii

This information is preliminary and is subject to revision. It is being provided to meet the need for timely best science. The information is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from the authorized or unauthorized use of the information.

Freshwater Volcanic rock Saltwater

Kolja Rotzoll, Scot K. Izuka, Tracy Nishikawa, Michael N. Fienen, and Aly I. El-Kadi