David E Rheinheimer

• Ph.D.
• Water Resources Engineer at Colorado River Board of California

Inter‐annual precipitation in California is highly variable, and future projections indicate an increase in the intensity and frequency of hydroclimatic “whiplash.” Understanding the implications of these shocks on California's water system and its degree of resiliency is critical from a planning perspective. Therefore, we quantify the resilience o...

Article published at Water Resources Research: https://doi.org/10.1029/2023WR035966 Inter-annual precipitation in California is highly variable, and future projections indicate an increase in the intensity and frequency of hydroclimatic “whiplash.” Understanding the implications of these shocks on California's water system and its degree of resili...

Reservoir-based hydropower systems represent key interactions between water and energy systems and are being transformed under policy initiatives driven by increasing water and energy demand, the desire to reduce environmental impacts, and interacting effects of climate change. Such policies are often guided by complex system models, whereby diverg...

This Project developed CenSierraPywr, a hydropower optimization modeling framework to consider institutional and physical constraints placed on hydropower operations. This framework – which integrates models, modules, routines, algorithms, wholesale electricity prices and data – has the capability of running various climate change scenarios. The mo...

Environmental flow management in watersheds with multi-objective reservoirs is often presented as an additional constraint to an already strained and over-allocated stream system. Nevertheless, environmental flow legislation and regulatory policies are increasingly being developed and implemented globally. In California, USA, recent legislative and...

Freshwater aquatic ecosystems are highly sensitive to flow regime alteration caused by anthropogenic activities, including river regulation and atmospheric warming-induced climate change. Either climate change or reservoir operations are among the main drivers of changes in the flow regime of rivers globally. Using modeled unregulated and simulated...

Freshwater aquatic ecosystems are highly sensitive to flow regime alteration caused by anthropogenic activities, including river regulation and atmospheric warming-induced climate change. Either climate change or reservoir operations are among the main drivers of changes in the flow regime of rivers globally. Using modeled unregulated and simulated...

Water systems modelers have developed multiple, independent, model- and study-area specific tools to store, query, visualize, and share their data. This fragmentation makes difficult comparisons, and synthesis within or across study areas. This paper identifies the common components of four existing tools for data storage, web visualization, and re...

Climate change and other changes to external conditions may jeopardize the future ability of the San Francisco Public Utilities Commission’s (SFPUC’s) Regional Water System (RWS) to meet the desired level of service. To help better understand the potential vulnerability of the RWS to uncertain future conditions, SFPUC partnered with The Water Resea...

Developing simulation and optimisation models for resource networks like water or energy systems increasingly involves integrating multiple data sources and software. Connecting multiple models and managing data accessed by different groups of analysts is a software challenge. Many resource systems are represented in computer models as networks of...

Sediment management, including supply and continual redistribution of sediments for channel maintenance and channel forming, is critical for effective environmental water programs. Many tools have been developed to more effectively manage sediment in rivers for ecosystem maintenance and improvement. This chapter reviews some of these tools, includi...

To help achieve energy security, many South Asian countries are increasingly turning towards the rivers of the Himalaya for their vast hydropower potential, as hydropower provides a relatively clean and renewable source of energy. However, hydropower development in the Himalayas is faced with numerous risks and uncertainties that challenge its cont...

Water year types (WYTs), whereby years are classified by river runoff quantity compared to historical runoff, are one tool to help make major water management decisions. Increasingly, these decisions include instream flow requirements (IFRs) below dams for river ecosystem management. However, WYTs are typically based on assumptions of stationarity,...

We assessed the potential value of hydrologic forecasting improvements for a snow-dominated high-elevation hydropower system in the Sierra Nevada of California, using a hydropower optimization model. To mimic different forecasting skill levels for inflow time series, rest-of-year inflows from regression-based forecasts were blended in different pro...

Preferential flow is significant for its contribution to rapid response to hydrologic inputs at the soil surface and unsaturated zone flow, which is critical for flow generation in rainfall-runoff (RR) models. In combination with the diffuse and source-responsive flow equations, a new model for water infiltration that incorporates preferential flow...

In this study, a meta-heuristic technique called harmony search (HS) algorithm is developed for reservoir operation optimization with respect to flood control. The HS algorithm is used to minimize the water supply deficit and flood damages downstream of a reservoir. The GIS database is used to determine the flood damage functions. The efficacy of H...

India is endowed with enormous amount of hydropower potential and ranks 5th globally, in terms of the exploitable potential which is nearly 1, 48,700 MW and ranks 7th in terms of hydro installed capacity which is about 41,000 MW. Uttarakhand, a state in Northern India, is one such region with considerable hydropower potential of about 18,000 MW out...

Descriptive modelling of water resource systems requires the representation of different aspects in one model: the physical system including hydrological inputs and engineered infrastructure, and human management, including social, economic and institutional behaviours and constraints. Although most water resource systems share some characteristics...

Selective withdrawal systems can take advantage of thermal stratification in reservoirs to manage downstream temperatures. Selective withdrawal might also help adapt operations to environmental changes, such as increased stream temperatures expected with climate change. This exploratory study develops a linear programming model to release water fro...

Alterations to flow regimes from regulation and climatic change both affect the biophysical functioning of rivers over long time periods and large spatial areas. Historically, however, the effects of these flow alteration drivers have been studied separately. In this study, results from unregulated and regulated river management models were assesse...

The Three Gorges Reservoir (TGR), located on the Yangtze River in China, is operated for hydropower, flood control and navigation, with minimal environmental releases. This study explored the potential trade-offs between better environmental releases from the TGR and hydropower generation using three performance indicators. Spearman's rank correlat...

Increasing water needs for agriculture, industry and cities mean effective and flexible water resource system management tools will remain in high demand. Currently many regions or countries use simulators that have been adapted over time to their unique system properties and water management rules and realities. Most regions operate with a preferr...

Operating rules have been widely used to handle the inflows uncertainty for reservoir long-term operations. Such rules are often expressed in implicit formulations not easily used by other operators and/or reservoirs directly. This study presented genetic programming (GP) to derive the explicit nonlinear formulation of operating rules for multi-res...

Water systems in snowmelt-dominated hydroregions such as California's Sierra Nevada mountains are sensitive to regional climate change, hydropower systems in particular. In this study, a water resources management model was developed for the upper west slope Sierra Nevada to understand the potential effects of regional climate warming on hydropower...

The U.S. Federal Energy Regulatory Commission has yet to mandate incorporation of anticipated climate change effects on hydropower system operations when assessing environmental impacts from the renewal of hydropower licenses. One stated reason is the lack of specific project-level specificity in future impacts. We demonstrate how a hydropower syst...

Understanding the trade-offs between water for the environment and water for hydropower in regulated rivers can inform decision making about hydropower system planning, policy and operations, especially with anticipated climate warming–induced changes in runoff. This study used a multireservoir optimisation model to assess the hydropower effects of...

Wetland ecosystems furnish human societies with services such as recreational uses, climate regulation, fisheries, and water for crop production. However, the health of these valuable ecosystems is increasingly threatened with environmental pressures primarily created by human activities (e.g. urbanization, industrial development, etc.) around the...

To develop appropriate, multi-decadal water resources management plans that incorporate competing interests, including recreation and ecosystem protection, climate warming should be considered in the analyses. This approach will improve understanding of local sensitivity to climate change, quantify the effects of hydropower operations on other wate...

Climate warming is altering the flow and temperature regimes in California's Sierra Nevada mountain range by reducing snowpack, causing earlier runoff and raising stream temperatures. Managing reservoir releases for downstream temperatures is a promising adaptation option. In this study, we developed a linear programming model to optimally release...

Within Mediterranean-montane ecosystems, the spring snowmelt recession is a distinct feature of the natural annual hydrograph, providing an ecologically significant bridge between the physical disturbance of winter high flows and the biologically stressful conditions of summer low flows. In regulated systems, the snowmelt recession is often absent...

Whitewater recreation is an aesthetic ecosystem service potentially affected by climate warming alterations to runoff. In California's Sierra Nevada, climate change is likely to reduce water availability with warmer air temperatures and stationary or decreasing precipitation, which will likely alter whitewater recreation opportunities. In this stud...

Watersheds of the Cosumnes, American, Bear and Yuba (CABY) Rivers in the Sierra Nevada, California, are managed with a complex network of reservoirs, dams, hydropower plants and water conveyances. While water transfers are based on priorities among competing demands, hydropower generation is licensed by the Federal Energy Regulatory Commission (FER...

Catchments of California’s Sierra Nevada have been managed for hydropower, water supply, recreation and the environment, during which regional freshwater ecosystems have experienced extirpations of anadromous fishes, widespread loss in amphibian abundance and increases in non-native species. California’s Mediterranean-montane climate is expected to...

Game theory can provide valuable insights into strategic water resources conflicts. In this chapter, non-cooperative game theory solution concepts are used to determine the possible outcomes of the Nile River Basin conflict. This conflict is the result of the desire of the main riparian countries, namely Egypt, Sudan, Ethiopia, and other upstream n...

Managing rivers is becoming more challenging with increasing demand for better environmental flow regimes, just as demand for water for hydropower and water supply are increasing and water supplies are changing due to climate change. Restoration of freshwater ecosystems, such as in the Yuba River in California's Sierra Nevada, will require flows th...

We report here on a major effort to define and quantify metrics of vulnerability to climate change for the west-slope of California's Sierra Nevada. We have defined the vulnerability of flowing surface waters used for human and ecological purposes as a function of exposure and sensitivity to anticipated hydrologic alteration mediated by regional cl...

The Nile River has been the center of water resources development tensions among four main riparian actors: Egypt, Sudan, Ethiopia, and other upstream nations. Each player has a desire to meet its national demands under increasingly stressed limited resources. Egypt, the most powerful of the actors, strives to maintain the status quo: securing the...

A membrane bioreactor (MBR) was investigated for denitrification of nitrate (NO3(-)) contaminated drinking water. In the MBR, NO3(-) contaminated water flows through the lumen of tubular microporous membranes and NO3(-) diffuses through the membrane pores. Denitrification takes place on the shell side of the membranes, creating a driving force for...

A key component of the River Continuum Concept, which conceptualizes a riverine ecosystem as a continuous gradient from headwaters to mouth, is the physical template, including climate and hydrologic regime. The Grande Ronde River basin in northeastern Oregon is characterized by snowfed streams from the Wallowa Mountains in the southern part of the...