1 of 28

Preparing California Water Policy for the Future – CALVIN hydro-economic optimization model

Jay R. Lund

University of California - Davis

​

calvin.ucdavis.edu

CaliforniaWaterBlog.com

2 of 28

Real work done by

Dr. Mimi Jenkins Professor Richard Howitt

Dr. Kenneth W. Kirby Dr. Andrew J. Draper

Dr. Stacy K. Tanaka Prof. Josue Medellin-Azuara

Prof. Manuel Pulido Prof. Julien Harou

Dr. Siwa M. Msangi Prof. Sarah Null

Prof. Mustafa Dogan Prof. Randall Ritzema

Brad D. Newlin Prof. Guilherme Marques

Melanie Taubert Dr. Arnaud Reynaud

Prof. Tingju Zhu Brian J. Van Lienden

Kristen B. Ward Pia M. Grimes

Dr. Inês Ferreira Prof. Marcelo Olivares

Wyatt Arnold Rachel Hersh-Burdick

Matthew D. Davis Prof. Kaveh Madani

Christina Connell Prof. Leopoldo Mendoza

2

2

2

calvin.ucdavis.edu

3 of 28

3

3

Main ideas

  • Water problems are complex, messy, multi-objective
  • Most pivotal objectives are economic
  • Hydro-economic models integrate hydrologic, infrastructure, and economic aspects and decisions
  • This is mostly how real water systems work
  • Organize, analyze, and find better water decision portfolios – supplies, demands, and infrastructure
  • Framework for understanding promising portfolios, trade-offs, uncertainty, and adaptation
  • Organize problems better for discussion & solutions

4 of 28

What is a Hydroeconomic Model?

  • Water sources
  • Demand locations
    • Agriculture, urban, hydropower
  • Infrastructure
    • Reservoirs, aqueducts
    • Water and wastewater treatment
    • Pumps and hydropower
  • Economic performance
    • Water scarcity costs
    • Operating costs
  • Environmental flows
  • Wide range of decisions

Explore portfolios of water management actions

4

4

City A

City B

Agriculture

Presa

Aquifer

Basin

River

$

$

$

$

5 of 28

5

5

Hydro-economic model objectives:

Framework to organize, find, and discuss better water decision portfolios – supplies, demands, and infrastructure

6 of 28

What is CALVIN?

  • Economics-driven engineering optimization model
      • Economic values for Agricultural, Urban, & Hydropower Uses
      • Constraints for Mass, Environment, Capacities, and Policies
  • Entire inter-tied California water system
  • Surface and groundwater supplies + infrastructure
  • Supply and demand management options
  • Prescribes monthly system operation over a 82-year representative hydrology

Forces quantitative understanding of integrated water and economic system and decisions

6

6

6

7 of 28

California’s Water System

7

7

7

155 Major surface reservoirs

Extensive groundwater

Vast conveyance network

Vast irrigated acreage

40 million people

About 3,000 governments

8 of 28

Tulare Basin, California

8

8

9 of 28

9

9

Agricultural Water Values (SWAP)

  • Profit-maximizing agricultural production and crop mix model
  • Estimates value of agricultural production from water use

10 of 28

CALVIN data flow

​

Solver

​

11 of 28

Some CALVIN Applications

11

11

11

Application

References

Integrated water management and portfolio optimization

Draper et al. 2003; Jenkins et al. 2001, 2004; Ragatz 2010; Ragatz 2013; Khadem et al 2018; Nover 2019

Capacity expansion economic value

Draper et al. 2003; Jenkins et al. 2004; Nover et al. 2019; Dogan et al. 2019; Arnold 2021

Hetch Hetchy restoration

Null 2004; Null and Lund 2006

Perfect and Limited Foresight

Draper 2001; Nelson et al 2016; Khadem et al 2018, 2020; Arnold 2021

Climate Change and sustained drought

Lund et al. 2003; Tanaka et al. 2006, 2008; Medellin et al. 2008a, 2009; Connell et al 2009; Harou et al. 2010; Sicke et al 2013; Dogan et al 2018, 2019

Colorado River, Baja California

Medellin-Azuara et al. 2006; 2007; 2008b; 2009

Environmental water supply

Hersh-Burdick 2008; Null et al 2014; Singh 2015

Groundwater overdraft management

Harou and Lund 2008; Nelson et al 2016; Dogan et al 2019; Hersh-Burdick 2008; Arnold 2021

Reducing Delta exports and increasing Delta outflows

Tanaka and Lund 2003; Tanaka et al.2006, 2008; Lund et al. 2007, 2008, 2010; Dogan et al. 2019

12 of 28

Paleo-Megadrought Study (Harou et al 2010)

West Walker River

Tenaya Lake

Mono Lake

Photos by Scott Stine http://www.yosemite.org/naturenotes/

13 of 28

Paleo-drought Hydrology

  • Scott Stine (1986 - 1994)
  • Severe, sustained droughts reduced Mono Lake inflows (hydrographically closed lake) by 40-60% for ~100 years (tree-ring records with carbon dating)
  • No wet period in the droughts raised the lake enough to inundate and drown these trees
  • Droughts not unique to Mono Basin. All along the Sierra Nevada range are indications of sustained drought during these periods

14 of 28

Synthetic Paleo-drought Hydrology

  • Random re-sampling from 10 driest years of record since it seems there were no “wet” years in paleodrought(s).
  • Re-sampling produces time series of surface water inflows, groundwater inflows, local accretions (intra-basin runoff), seepage losses in rivers and environmental minimum flows.
  • 72-year synthetic drought generated.

15 of 28

Water Scarcity Results

16 of 28

Scarcity & Delivery Results

17 of 28

Scarcity Cost Results ($M/yr)

18 of 28

Monthly Groundwater Storage

19 of 28

Annual Surface Water Storage

20 of 28

Marginal Value of More Water (WTP)

21 of 28

21

21

Directions for Hydro-economic modeling

  • Data management and documentation
  • Model solver flexibility, independence from data
  • Multi-objective trade-offs
  • Multiple near-optima
  • Limited foresight
  • Adapting portfolios with uncertainty (sensitivity/robustness analyses, multi-stage analysis, Bayesian climate change)
  • Story-telling, visuals

22 of 28

Web-based database: HOBBES

  • Database for California’s water supply network
  • Data independent from model
  • Store hydrology time-series, demand curves, & physical properties of network
  • Tools to export the network in desired format
  • Visualize & animate input & output data

22

Dogan et al. 2018

hobbes.ucdavis.edu

23 of 28

Visualization

  • Animation layer to visualize inputs (inflow) and outputs (storage, demand & flows on conveyance links
  • Size of nodes & links change depending on magnitude of flow & storage

23

Change in total

groundwater storage (MAF)

  • Your own visualization?

California Water Network

https://cwn.casil.ucdavis.edu

Dogan et al. 2018

24 of 28

Linear Program Solvers

  • Python programming language & its standard scientific libraries
  • Pyomo library, a Python-based, open-source optimization modeling language
  • Solvers
    • GLPK,CBC -
    • CPLEX,Gurobi -
  • CALVIN model repository from GitHub

24

Freely available

Free for academic use only

Dogan et al. 2018

Github.com/ucd-cws/calvin

25 of 28

25

25

Multi-objective near-optima (Arnold 2021)

26 of 28

26

26

Conclusions

  • Water problems are complex, messy, multi-objective
  • Most pivotal objectives are economic
  • Hydro-economic models integrate hydrologic, infrastructure, and economic aspects and decisions
  • Model the wide range of management options
  • Organize, analyze, and find better water decision portfolios – supplies, demands, and infrastructure
  • Framework for understanding multi-objective trade-offs, uncertainty, and adaptation
  • Organize problems better for discussion & solutions

27 of 28

27

27

Further Reading

  1. Arnold, W. (2021) The Economic Value of Carryover Storage in California’s Inter-Regional Water Supply System with Limited Hydrologic Foresight, MS Thesis, UC Davis
  2. Dogan, M., et al. (2019), “Statewide Effects of Ending Long-Term Groundwater Overdraft in California,” J. Water Resources Planning and Management, Vol 149.
  3. Nover, D., et al (2019), "Does More Storage Give California More Water?" Journal of the American Water Resources Association, Vol. 55, No 3
  1. Dogan, M. et al. (2018) “An open-source Python implementation of California's hydroeconomic optimization model,” Environmental Modelling and Software, Vol. 108, pp. 8-13
  2. Harou, J., et al, “Economic consequences of optimized water management for a prolonged, severe drought in California,” Water Resources Research, Vol. 46, 2010
  3. Draper, et al. (2003), “Economic-Engineering Optimization for California Water Management.” J. of Water Resources Planning and Management.

28 of 28

28