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. By coupling physical hydrology and 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.  Examples of this are shown for a US municipal water utility- Denver Water; and an application in the Vu-Gia and Dak-Mi River Basin of Central Vietnam.

Climate-Informed Decision Support for Denver Water

Figure 1.  The adaptation option appraisal process.
Figure 1.  The adaptation option appraisal process.

There is a growing recognition that planning for adaptation to climate change must proceed despite the limited predictability of hydro-climatic changes on temporal and spatial scales relevant for water resource planning (Yates and Miller 2011; Deser et al. 2012a,b). However, conventional “top down” adaptation approaches are poorly suited to the task. This approach involves downscaling future climate scenarios, generating input data for impact models, evaluating the consequences relative to present climate, and finally considering adaptation responses. Typically, large uncertainties attached to climate model scenarios accrue into even larger uncertainties in downscaled regional climate change scenarios and impacts. An alternative is to turn the traditional top-down framework upside down, placing greater emphasis on identifying and appraising adaptation choices from the outset (Wilby and Dessai 2010). In this configuration, the scenario is used later in the process to evaluate the performance or “stress test” adaptation decisions.  For work with Denver Water we have adopted this so-called "bottom-up" approach, where the collaborative decision support process comprises four key elements (Figure 1):

  1. identifying management strategies or adaptation option(s) to be evaluated;
  2. modeling the water supply through physical representation of the hydrologic cycle;
  3. modeling the water collection and distribution systems in the context of the hydrologic cycle and the legal water rights; and
  4. stress-testing the system using scenarios of future climate and non-climatic conditions to explore the performance of the adaptation option(s) in supporting overall water-management objectives.

RAL scientists, working under funding from NCAR’s Assessment Program, have developed the  WEAP-Denver Water (WEAP-DW)  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-DW 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 and Denver Water’s systems on the East side of the continental divide, including of the major water diversions from Dillion Reservoir through the Roberts Tunnel and diversions from the Fraser River.

FY2017 Accomplishments include:

  • Advanced the WEAP-DW 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.
  • 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.
  • Inclusion of detailed water demand components within the Water
  • Training of Denver Water staff on the use and application of the WEAP-dW model. Training was conducted in July 2017.

Plans for FY2018:

  • Continued training session for Denver Water staff in the use of WEAP-DW
  • Develop a peer review paper with Denver Water on seasonal forecasting work; and the use of the WEAP-DW model in their integrated water resource planning process (IWRP).
  • Continue to work with Denver Water to advance the WEAP-DW 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 2017.
  2. Addition of the water infrastructure of the new elements of the South Platte Basin, such as local reservoirs and diversions.
  3. An initial 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 2.  Example of the WEAP-DW domain.
Figure 2.  Example of the WEAP-DW 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 3 Outline of the Colorado River Basin modeled in this study.
Figure 3 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 [Herman et 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 4. Components of the Colorado Decision Support System (adapted from [Colorado Water Conservation Board, 2010]).
Figure 4. Components of the Colorado Decision Support System (adapted from [Colorado Water Conservation Board, 2010]).

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.

Piloting Cross-Border River Basin Flood Resilience in Vietnam through an Object-Oriented Water Management Decision Support System

Figure 5: Screenshot of the Vu Gia – Thu Bon River Basin in Quang Nam and Da Nang provinces in WEAP showing the geographic domain and daily precipitation time series for a select catchment.
Figure 5. Screenshot of the Vu Gia – Thu Bon River Basin in Quang Nam and Da Nang provinces in WEAP showing the geographic domain and daily precipitation time series for a select catchment.

Flood modeling and analysis is often been done using more physically oriented river basin models that can make use of topographic data to describe hydraulic flow paths in detail, thus allowing for analysis of flood stage and inundation. These types of models are good at representing physical processes across the watershed, but lack flexibility and ease-of-use- to be effective as water resource management tools. Water basin managers need to be able to explore alternative infrastructure and operational conditions that can determine the co-benefits of the basin, including such things as water provision, hydropower production, environmental protection, and flood control. This project aims to explore how the object-based water management model- the Water Evaluation and Planning system (WEAP)- can be used to represent riverine and inundation flooding across a watershed in Da Nang, Vietnam. In a previous project, a WEAP model was developed for the region and was used to explore the broader water balance of the region and salinity impacts, and this pilot represents an advancement of this capability.

The Flood Resilience Challenge. River management is complicated by administrative jurisdictional boundaries that dissect basins and limit coordinated action. Processes for inclusive, cross-jurisdictional information sharing, collaboration, and joint decision-making do not exist across much of Southeast Asia. Technical efforts to understand river risk are usually sector focused with no integration across departments. Though policy frameworks and laws allowing the formation of River Basin Organizations (RBOs) for the inter-administrative management of river systems exist in most of the Southeast Asian countries, the few attempts to use these platforms to date have failed. These risk mitigation efforts lacked both adequate clarity of purpose and the platforms required to initiate and sustain cross-departmental or inter-provincial collaboration. Previous attempts were also absent of key stakeholders, including reservoir operators and at-risk communities. These challenges of river basin management are exemplified in central Vietnam, where rapid urbanization and population densification are intensifying along river systems and in coastal floodplains. Typical of the challenges that arise, are those experienced in the Thu Bon and Vu Gia river basin, which is shared by Da Nang and Quang Nam provinces.  Novel water management tools could prove useful in helping address these challenges.

Figure 6: WEAP Training in Da-Nang, Vietnam
Figure 6: WEAP Training in Da-Nang, Vietnam

Platform for Cross-Border River Management for Flood Resilience. This effort proposes to advance an already existing WEAP application of the study basin in support of a participatory platform for the co-production of a novel, integrated hydrologic-hydraulic model for flood risk management across two provinces – Da Nang and Quang Nam – in central Vietnam. Based on our previous experience in Da Nang, our hypothesis is that the production of a modeling tool provides both the focused purpose and the information needed to underpin an effective collaborative platform that can function as a RBO. Such a collaborative platform, the Da Nang WEAP model, focused on integrating departmental actions in Da Nang, was successfully completed in 2013. This effort’s success could serve as a template for similar river basins and could leverage current RBO institutional structures within Vietnam and across Southeast Asia for scale. Though such efforts would naturally fit national contexts more easily, we foresee that improving inter-provincial river management across the region would ultimately lead to exploration of using this method across national boundaries where many current and emerging challenges are being experienced (e.g. Mekong Basin).

Potential for scaling-up. Throughout Vietnam and other Southeast Asian countries, communities are exposed to changing flood risks similar to those in Da Nang and Quang Nam; success in Da Nang will have a wide audience, spurring interest in replication elsewhere. Da Nang is one of Rockefeller’s 100 Resilient Cities, and has highlighted this project in their Resilience Strategy as a top priority (www.100resilientcities.org). As one of the first round of cities, their success in implementing their Strategy will be watched, and success disseminated by Rockefeller and 100RC platform partners.  More broadly, the proposed process for resilience includes: 1) a generalizable process for shared learning where dialogue and integration of information with narratives provides the context for resilience-enhancing, cross-silo communication; 2) a clear delineation of the basic information and data needed to build such an effort; and 3) the capacity to extend the to new partnerships elsewhere allowing the process to grow beyond this current activity. 

The WEAP model is being advanced to include the representation of floodplain inundation, allowing for the representation of the entire river basin floodplain and its infrastructure into one modeling tool and allow for integrated planning and decision-making. The pilot project has:

  1. Engaged in focused dialogue between stakeholders across jurisdictions;
  2. Used the modeling platform and output to draw out understanding and shared knowledge, and;
  3. Include at-risk populations and their advocates throughout the process.

FY-18 Activities

We will conduct an additional WEAP training on the application of the model for conducting trans-basin negotiations around reservoir operations, environmental flow development, and analysis of tradeoffs.