HEC-5 and 5Q

Criterion

Explanation

Model name/version

HEC-5: Simulation of Flood Control and Conservation Systems
HEC-5Q: System Water Quality Modeling

General Description

HEC-5: Model simulates sequential operation of reservoir system for short-interval flood events and/or long periods of non-flood events based on control point set demands and operational constraints (i.e. channel flows, diversion requirements, energy requirements, maximum non-damaging flows, and reservoir release rate-of-change).
HEC-5Q: Using 6-hour, daily or monthly flow data from HEC-5, model simulates temperature, conservative and non-conservative constituents in a water system. This is a companion module to HEC-5 that directs HEC-5 to change water flows and releases to improve downstream water quality.

Model Domain

General

Developer

United States Army Corps of Engineers – Hydrologic Engineering Center

Hardware computing requirements

HEC-5: Eight (8) MB or more of RAM are recommended.
HEC-5Q: 32 MB RAM or higher recommended, Pentium based microprocessor or higher.
Note: programs created for DOS, may need emulator or virtual OS to run.

Code language

HEC-5 and HEC-5Q: FORTRAN

Original application

HEC-5: Originally applied to flood control operation of single flood events.
HEC-5Q: Original module developed to incorporate water quality capabilities to HEC-5.

Public/proprietary and cost

HEC-5 and 5Q are proprietary of the United States Army Corps of Engineers, Hydrologic Engineering Center. Conditions of use can be found in user guides CPD-5 and CPD-5A (USACE, 1998 and 1986).

Physically or empirically based

HEC-5 and HEC5Q: Physically based using geometric representation and mass transport mechanisms.

Mathematical methods used

HEC-5: Model defines a water system through a dendritic network of reservoirs, channels and control points specified by the user (control points are non-reservoir where demands and operational constraints can be implemented). Incremental local flows calculated in user specified time intervals (minutes, hours, one month) are used to perform simulations between control points.
Flow data is provided by HEC-5 to run HEC-5Q water quality simulations.
HEC5Q: Reservoirs and its stratification are represented geometrically using a series of one dimensional horizontal slices characterized by area, thickness and volume. Streams (aka channels) are geometrically represented as linear network of segments or volume elements characterized by length, width, cross sectional area, hydraulic radius, Manning's n and the relationship between flow and depth. Mass transport mechanisms (evaporation, inflow, outflow, vertical advection, effective diffusion consisting of molecular diffusion, turbulent [wind, flow induced] diffusion and convective mixing) are used to simulate water quality constituent movement to and from geometric representations and stratifications. Outflow allocation determined by WES withdrawal method, inflow placement determined by Debler inflow allocation method, effective diffusion calculated using Stability method. Water quality can be modeled using two options; called the variable constituent option and phytoplankton option. In order to simulate in the variable constituent option, temperature must be simulated with addition of up to 3 conservative constituents and up to 3 non-conservative constituents. The phytoplankton option requires water temperature, total dissolved solids, nitrate-nitrogen, ammonia-nitrogen, phosphate-phosphorous, phytoplankton, carbonaceous biological oxygen demand and dissolved oxygen to all be simulated. Temperature is simulated using a dynamic heat differential equation and water quality constituents are simulated using a modified dynamic heat differential equation that defines the constituents as a function of temperature, time and space; various modifications are made dependent on constituent modeled (see section 2.5.1 Physical and Chemical Constituents in CPD-5Q (USACE, 1986)). A Gaussian reduction scheme is used to solve water quality equations in the reservoirs, a linear programming algorithm is used for solving equations in streams.
Flow alteration routines in HEC-5Q are used to manipulate flows and release rates in HEC-5 to better satisfy user specified water quality at control points; this is accomplished either by a port selection algorithm to determine open/closed ports and flow rates through the port or by a flow alternation routine.

Input data requirements

HEC-5: Input into model are in the form of records that define: reservoir information (storage levels, outflow characteristics, control point connections, areas, dimensions, elevation, cost, power plant), computational information, flow data, program outputs, system energy, control point information (static or variable channel capacity, routing criteria, diversion type and schedules, elevation, cost), flood events and damage, flow data, start date of simulation and computation interval.
HEC5Q: Input into model are in the form of records that define: simulation operation (simulation length in time, number of control points, water temperature units, water quality constituents to be modeled), initial reservoir properties and operation (reservoir size and dimensions, temperature, water quality profile, modeling coefficients), stream properties (channel geometry, inflows, cross sections, non-conservative constituent decay rates, water quality objectives at control points), water temperature at inflow points, water surface heat exchange, constituent objective functions and relative weights and gate operation inflow rates.
Publicly available reservoir, dam, water flow, waterbody characteristics, water quality, chemical properties, meteorological databases are easily obtainable.

Outputs

HEC-5: Outputs include computed incremental local flow, maximum flows, storage levels and elevations for reservoir and non-reservoirs, reservoir releases, actual flow at control points, diversions and diversion shortages, flood control storage, flood events and damage cost, system costs, net benefits and a computer error check report. Output is provided in the format of tables and plots, arranged sequentially in time. User can specify output time intervals, output upon completion of simulations or at some point intermediate in the simulation.
HEC5Q: Outputs include computed water temperature, total dissolved solids, nitrate-nitrogen, ammonia-nitrogen, phosphate-phosphorous, phytoplankton, carbonaceous biological oxygen demand, dissolved oxygen profiles and distributions for reservoirs and streams. Simulation outputs are in time frame of one year or more and can be displayed as time series plots, animated vertical plots and longitudinal profiles.

Pre-processing and post-processing tools

HEC-5 and 5Q: program files provided.

Representation of uncertainty

HEC-5: Uncertainty is incorporated into model framework using Contingency Factors that can be specified by user for each control point, these factors represent uncertainty in flow data and flow forecasting.
HEC5Q: No uncertainty procedures directly incorporated into model framework. Some uncertainty in model predictions compared to measure results are presented by Bartholow (2005).

Prevalence

HEC-5 and 5Q: Both models widely applied by groups and individuals at private, government and academic entities. Common applications have included water supply analysis, flood control, water quality objective planning and water management planning.
HEC-5 and 5Q models have been used for water temperature modeling in the Sacramento and San Joaquin Rivers (RMA, 2003; USBR, 2011, 2013). No previous modeling examples specific to the San Francisco Bay – Sacramento-San Joaquin Delta (Bay-Delta) found.

Ease of use for public entities

HEC-5 and 5Q: Easy to moderate, no special training required.

Ease of obtaining information and availability of technical support

HEC-5 and 5Q: User guides are available at http://www.hec.usace.army.mil/publications/. Training is provided by the United States Army Corps of Engineers and information can be obtained at http://www.hec.usace.army.mil/training/default.aspx. Technical support is available through various sources to users and non-users, with possible associated costs (http://www.hec.usace.army.mil/software/support_policy.aspx).

Model and Source code availability

Model programs are available through the United States Army Corps of Engineers and can be found at http://www.hec.usace.army.mil/software/legacy/hec5/ and http://www.hec.usace.army.mil/software/legacy/hec5Q/.
Source code is available upon request to United States Army Corps of Engineers. Any modifications made to the modules and programs must be approved by the United States Army Corps of Engineers, Hydrologic Engineering Center.

Status of model development

HEC-5 and 5Q: Both models available for immediate use. HEC-5 model has been replaced with new updated HEC-ResSim model. Status for HEC-5Q future updates unclear.

Model limitations

HEC-5: Maximum number of components currently allowed in model – forty reservoirs, eighty control points. Detailed list of operational limitations can be found in section 1.3 Dimension Limits of the CPD-5 (USACE, 1998).
HEC5Q: Maximum number of components currently allowed in model – twenty reservoirs, forty control points. Detailed list of operational limitations can be found in section 2.1 General Capabilities and Limitations of the CPD -5Q (USACE, 1986). Additional limitations include no apparent methods accounting for heat exchange between the subsurface and water, major aqueous reactions that may affect constituents, and in the context of the Bay-Delta, organic carbon as an important water quality constituent.

Challenges for integration

HEC-5 and 5Q: The proprietary nature and limited conditions of use for these programs may present difficulties for integration.