Climate and Managed Water Systems

BACKGROUND

A number of projects conducted within RAL focus on assisting decision and policy-makers in better understanding how climate variability and change and extreme weather events, including floods and droughts, can affect their water systems. Using the Water Evaluation and Planning (WEAP) model, co-developed by Dr. David Yates and scientists at the Stockholm Environment Institute, we are helping to address the growing need for new tools and methods to assess the impact of future climate-predicted precipitation on water availability and quality. In addition, the importance of energy use by the water sector is also of keen interest, as organizations seek to quantify and reduce their carbon emissions, with water use often having a strong tie to energy use. This is commonly referred to as the water-energy nexus. This integration has been achieved the coupling of with WEAP’s cousin on the energy side- the Long Range Energy Analysis and Planning (LEAP) model.

Figure 1.  The water energy nexus and its application in the southwestern US.
Figure 1.  The water energy nexus and its application in the southwestern US.

The types of questions being asked of this integrating framework with water and energy planners in California include:

  1. If inter-basin transfers are reduced, what does that mean in terms of the mix of the water supply portfolio? What happens to energy use in the water sector?
  2. How dominating is climate in determining the range of the possible future outcomes relative to supply or demand side actions in the water sector, and how does this affect the energy use by the water sector?
  3. In the face of future climate what is the direction of change with regards to hydropower production? Groundwater storage (Sustainable Groundwater Act of California)? Water use and delivery? Surface water storage? Sacramento-Delta outflows?
  4. What happens to groundwater under these assumptions and how does that affect energy use for the water supply?
  5. If desalinated water is used as a ‘back-up’ source under these scenarios, when is its used triggered and by how much? How much energy does it use?
  6. Where do realistic levels of conservation and water use reduction lead us? And how much energy reduction is achieved?

The integrating framework can be used to explore water and energy use under a range of future conditions. Below we show agricultural water deliveries throughout California under a range of future climate projections and a set of 4 policy scenarios. The climate projections suggest a wide range of potential impacts, while the policy implications on energy use are dramatic. (Right figure)

Figure 2. Water-Energy Analysis for California showing the agricultural water delivery (left) under a range of future climate projections (colored bands) and 4 policy scenarios, where there are structural adaptations in the water is delivered to users throughout the state. The right figure is the energy use for all projections and each of the 4 policy scenarios.
Figure 2. Water-Energy Analysis for California showing the agricultural water delivery (left) under a range of future climate projections (colored bands) and 4 policy scenarios, where there are structural adaptations in the water is delivered to users throughout the state. The right figure is the energy use for all projections and each of the 4 policy scenarios.

The coupling of physical hydrology water planning and management information within a single framework, WEAP can be used by planners and managers to develop scenarios and strategies for more robust water management decision-making in their watershed, city or state.  In addition to the WEAP model, RAL scientists work with stakeholders to adapt regional and global climate models and datasets to their needs. Education, training, and capacity building are fundamental components of this water resource management effort.

RAL scientists have developed the  WEAP-Headwaters model of the Upper Colorado River basin (WEAP-HW)  model to simulate the current water management system under plausible scenarios of variable climate and associated changes in watershed conditions (including dust-on-snow; land use/land cover changes, etc.) both with and without specific drought mitigation policies in place.  With this capability, the WEAP-HW model has also been configured as a seasonal forecasting tool that is able to generate seasonal streamflow forecasts as inputs into the West Slope water supply decision framework for utilities such as Denver Water and Colorado Springs Utilities. We are forecasting water supply delivery to critical points on the East side of the continental divide, including the major water diversions from Upper Blue River, Dillion Reservoir through the Roberts Tunnel and diversions from the Fraser River.

FY2018 ACCOMPLISHMENTS INCLUDE:

  • Development of a Southwest US wide water –energy analysis with WEAP
  • Advanced the WEAP-HW model through the extension of the model domain to include the South Platte River Basin, its tributaries, and the water supply and demand elements in this domain. Development of detailed water demand elements along the Colorado Front Range.
  • The additional watersheds of the South Platte Basin extend to the South Platte Basin at the Kersey gage.  The new river basins include, among others, Clear Creek, Boulder Creek, the St. Vrain, the Big Thompson, the Poudre River, and other tributaries of the South Platte River.
  • If early insights can be realized, we asked how management might use these forecasts to make management decisions or adaptations.
  • Training of Denver Water and Colorado Springs Utilities staff on the use and application of the WEAP-HW model. Training was conducted throughout 2018.

PLANS FOR FY2019:

  • Advancement of the SW WEAP model for water-energy nexus analysis. We are working collaboratively with the Lawrence Berkley National LAB on this effort.
  • Continued training session for water utility staff on the use of the use of WEAP-HW
  • Develop a peer review paper with utilities on seasonal forecasting work; and the use of the WEAP-HW model in their integrated water resource planning process (IWRP).
  • Continue to work with Denver Water and Colorado Springs Utilities to advance WEAP-HW model to extend the South Platte portion of the model to the Colorado-Nebraska border. Improvements will include:
  1. An updated climate forcing dataset for the new catchments to be added to the model that extend through 2018.
  2. Addition of the water infrastructure of the new elements of the South Platte Basin and the Upper Colorado, such as local reservoirs and diversions. There is particular interest in looking at conditional water rights within the context of climate variability and change.
  3. A final calibration of the model, for the new tributaries and the South Platte mainstream, with calibration of some of the tributary flows and South Platte flows to the Nebraska Border.
Figure 3.  Example of the WEAP-HW domain.
Figure 3.  Example of the WEAP-HW domain.

REFERENCES

Deser C, Knutti R, Solomon S, Phillips AS, (2012a) Communication of the role of natural variability in future North American climate. Nat Clim Change 2: 775-779. doi: 10.1038/nclimate1562.

Deser C, Phillips AS, Bourdette V, Teng H, (2012b) Uncertainty in climate change projections: The role of internal variability. Clim Dyn 38: 527-546. doi: 10.1007/s00382-010-0977-x.

WUCA (2010) Decision Support Planning Methods: Incorporating Climate Change Uncertainties into Water Planning. Report prepared for Water Utility Climate Alliance by Edward Means III, Maryline Laugier, Jennifer Daw, Marc Waage and Laurna Kaatz, January 2010. http://www.wucaonline.org/assets/pdf/actions_whitepaper_012110.pdf

Yates D, Sieber J, Purkey D, Huber-Lee A (2005) WEAP21 - A Demand-, Priority-, and Preference-driven Water Planning Model Part 1: Model Characteristics. Water Int 30: 487–500.

Yates D., Miller K. (2011) Climate Change in Water Utility Planning: Decision Analytic Approaches. The Water Research Foundation, Denver, 80pp.

A Framework for Assessing the Multi-stakeholder Vulnerabilities and Risk Management Tradeoffs Related to Future Climate Extremes in the Colorado River Basin

This project seeks to identify key risk metrics that will encompass the multi-stakeholder interests in the CRB, within Colorado. This project includes support from NOAA’s Societal Applications Research Program (SARP). The team is working with the Colorado Water Conservation Board (CWCB) and diverse sectoral stakeholders to develop example metrics for the municipal, agriculture, hydropower and environmental interests. The project is developing a decision support framework that uses existing CDSS modeling tools developed by the State of Colorado and that has the potential to be generalized and transferred to other river basins in Colorado and to broader UCRC planning. Climatically driven hydrologic models capable of generating credible natural flow states throughout the Upper Colorado River Basin (UCRB), to the State of Colorado’s infrastructure models (e.g., StateMod and StateCU) to develop an overall integrated system simulation.  The integrated simulation system will support bottom-up risk analyses within Co-Investigator Patric Reed’s Many-Objective Robust Decision Making (MORDM) framework.

Figure 4 Outline of the Colorado River Basin modeled in this study.
Figure 4 Outline of the Colorado River Basin modeled in this study.

MORDM provides a platform for constructive decision support, allowing users to interactively discover promising alternatives and potential vulnerabilities while examining conflicting objectives.  The MORDM approach has been successfully exploited in complex multi-city drought mitigation studies in the Southeast US [Hermanet al., 2014], in Colorado Springs Utilities’ integrated water resources planning [Basdekas, 2014], and in a myriad of other risk planning test cases [Kasprzyk et al., 2013; Quinn et al., 2017; Singh et al., 2015].  A primary goal is to address the relevant questions and concerns of CRB stakeholders, and allow them to explore the impacts and significance of alternative management actions and conceptions of robustness.  Our proposed multi-objective bottom up decision support framework is intended to be transparent and allow for deeper exploration of the Colorado portion of the CRB’s robustness to climate extremes.

The project is exploring decision triggers that consider changing hydrology, endangered species, water leasing, hydropower production, and regionally coordinated demand management.  Actions may include extended operations, such as releasing water from Upper Colorado River Basin storages to allow Lake Powell to stay above critical elevations, or demand management that includes municipal and agricultural conservation of water using a variety of methods such as fallowing, deficit irrigation, municipal water conservation strategies such as, efficiency improvements, and other strategies. Many possible actions and demand management strategies have been identified in the Colorado River Basin Implementation Plan, and the other Basin Implementations Plans that fall within the Colorado River Basin (Yampa, Gunnison, and Southwest Basin Implementation Plans).

Figure 5. Components of the Colorado Decision Support System (adapted from [Colorado Water Conservation Board, 2010]).
Figure 5. Components of the Colorado Decision Support System (adapted from [Colorado Water Conservation Board, 2010]).

References

The project teams continues to develop collaborative modeling capacities using the suite of models, which are non-trivial given the complexity of the Upper CRB.  In combination, they form the Colorado Decision Support System (CDSS) illustrated in the figure at right.

Basdekas, L. (2014), Is Multiobjective Optimization Ready for Water Resources Practitioners? Utility's Drought Policy Investigation, Journal of Water Resources Planning and Management, 140(3), 275-276.

Colorado Water Conservation Board (2010), Statewide Water Supply Initiative - 2010, edited by Department of Natural Resources.

Colorado Water Conservation Board (2012), Colorado River Water Availability Study Rep., Depart of Natural Resources, State of Colorado.

Hadka, D., J. Herman, P. Reed, and K. Keller (2015), An open source framework for many-objective robust decision making, Environmental Modelling & Software, 74, 114-129.

Herman, J., H. Zeff, P. Reed, and G. Characklis (2014), Beyond optimality: Multistakeholder robustness tradeoffs for regional water portfolio planning under deep uncertainty, Water Resources Research, 50(doi:10.1002/2014WR015338).

Kasprzyk, J. R., S. Nataraj, P. Reed, and R. Lempert (2013), Many-Objective Robust Decision Making for Complex Environmental Systems Undergoing Change, Environmental Modelling & Software, 42, 55-71.

Quinn, J. D., P. M. Reed, and K. Keller (2017), Direct policy search for robust multi-objective management of deeply uncertain socio-ecological tipping points, Environmental Modelling & Software, 92, 125-141.

Singh, R., P. Reed, and K. Keller (2015), Many-objective robust decision making for managing an ecosystem with a deeply uncertain threshold response, Ecology and Society, 20(3), 12.