Common Aspects of UCRAF RiverWare Models

Across all UCRAF RiverWare models there are common aspects. The following pieces of data structure, model structure, and model logic are similar across all UCRAF RiverWare models.

Data Objects for Input Data

For each UCRAF RiverWare model, observed data was collected and used as a historical record in Natural Inflow mode that subsequent model runs can be compared to. Consumptive use demands simulated by the DRC are developed for the Baseline and Changed Case modes, which are driven with computed and simulated data where the computed data is based on the observed data. Overall, the three types of data used are observed, computed, and simulated data.

RiverWare has objects that do not simulate and merely house scalar, time series, tabular, or periodic data called data objects. The three types of data outlined above is either manually copied to these objects one time or interactively through the process of developing data from the DRC. When a DRC Baseline or Change Case scenario is developed, the output is transferred to the UCRAF RiverWare model through the "DRC Baseline Inputs" or "DRC ChangeCase Inputs" data objects. This transfer brings diversion, loss, and return flow inputs (all output from the DRC) into the UCRAF RiverWare model in a time series format.

DRC Input Data Clusters

Data Objects for Output Data

Once a Baseline or Change Case simulation is made in a UCRAF RiverWare model, results are organized on output data objects. These three objects, "RW_OutputVisualization_Baseline", "RW_OutputVisualization_ChangeCase", and "DRC_OutputVisualization_ChangeCase", contain simulation data summarized in a consistent way across all models and allows visualization tools, developed in Power BI, to use data in similar format from different UCRAF RiverWare models. The data from these objects are exported in a consistent manner across UCRAF RiverWare models using RiverWare's Data Management Interface (DMI).

RiverWare Output Visualization Objects

A large portion of the physical system in the Duchesne UCRAF RiverWare model

Physical System

Within each UCRAF RiverWare model, there is a network of model objects known as the physical system that simulates water flowing through the basin. RiverWare uses objects such as river reaches (representing a segment of river), gages (representing a flow gage), reservoirs (representing a storage or power reservoir), and diversions (representing a canal or other diversion from a river). Those objects represent a basin or subbasin, and the specific objects will be different for each UCRAF RiverWare model. However, the purpose of these objects is common across all UCRAF RiverWare models. Objects are added to each UCRAF RiverWare model and linked together to simulate flow of physical water through the basin or subbasin. Each object solves its water balance individually and passes flow of water between linked objects. This simulation of flow determines the amount of physical water available on each object in the system.

Accounting System

The accounting structure available in RiverWare, known as the accounting system, sits alongside the physical system and "colors" the water into different accounts. The accounting system implemented in each UCRAF RiverWare model is of similar structure. Within each reach there are three accounts: Natural, Project (aka reservoir diversion), and Drought Mitigation. The Natural and Project accounts are used in the Baseline scenario to characterize the system's water deliveries. Natural water flows through the system as water not delivered from a piece of infrastructure. Project water, conversely, is water that originates from a reservoir and is delivered to water users to supplement demand not met by natural water. The Drought Mitigation account is used in a Change Case scenario when water needs protected (i.e., it cannot be used by other users) as it flows downstream as part of a conservation program. Water that was delivered to a water user in either the Natural account or the Project account that is part of a conservation program is returned to the river (or held in a reservoir) in a Drought Mitigation account.

Accounting structure, including the Natural, Project, and Drought Mitigation accounts, on reaches and a gage in the Duchesne UCRAF RiverWare model

Example RiverWare Policy Language (RPL) Logic

RiverWare Policy Language (RPL) Logic

RiverWare models accomplish various physical and accounting actions using logic generally called "rules." While each UCRAF RiverWare model has a large selection of individualized rules, written in RiverWare Policy Language (RPL), a selection of these rules are shared between models. These are rules or functions that accomplish similar actions within each UCRAF model. The rules and functions shared include those that prepare data to be exported, compute return flows as part of a change case, and logic that computes the charge to a conserved flow sitting on top of system (natural) flow in the river known as transit loss.

Demonstrates the mass balance calculation that determines the local inflow for a river reach

Natural and Local Inflow Computation

Observed historical data for each basin is collected for each UCRAF RiverWare model to simulate in Natural Inflow mode. In this mode, RiverWare runs in simulation mode where it solely evaluates the water balance of the physical system given observed data as inputs and solves for unknown quantities. For this data-computation run, all observed data (USGS gage data, reservoir storage data, diversion data, etc.) is entered into the model to allow it to calculate the balance (i.e., unknown) terms. These balance terms include primarily reservoir inflows (e.g., a loss in a reservoir due to groundwater interaction) and stream reach local inflows (e.g., gains in a reach of river due to ungaged confluences); these inflows can be positive or negative to indicate a gain or loss.

Transit Loss Calculation

The method of estimating incremental transit loss uses basic channel geometry to develop a relationship between flow and wetted perimeter for a given reach and then quantifies incremental loss proportional to the change in this relationship given the presence of conserved water. The method requires the following physical characteristics of each river reach through which conserved water will flow: amount of conserved water at the upstream program source, reach length, loss rate versus flow (percent loss per mile), and average wetted perimeter versus flow. The calculation process begins with the loss associated to the flow without conserved water. Then, total loss is calculated as base loss times the increase in wetted perimeter due to the addition of conserved water. Finally, the incremental loss associated to the conserved water is the difference of these two quantities. Implementation in the UCRAF RiverWare models is the same and assumes a single cross section at each gage and that channel geometry is constant between gages.

Diagram that demonstrates an increase in the wetted perimeter of a reach due to conserved water along with basic equations for calculating the transit loss attributed to the conserved water

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