RSICC CODE PACKAGE CCC-671

1. NAME AND TITLE

CHNSED: Code System to Model Sediment & Contaminant Transport.

2. CONTRIBUTORS

Oak Ridge National Laboratory, Oak Ridge, Tennessee, through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM360 (C00671I306000).

4. NATURE OF PROBLEM SOLVED

CHNSED is an expanded model of hydrologic response of a watershed. It includes the simulation of trace contaminant transport through the watershed. Within the stream channel system trace contaminant is transported in dissolved and adsorbed form. CHNSED includes both SEDTRN, a model of sediment transport through a rectangular stream channel system, and the Wisconsin Hydrologic Transport Model, WHTM, a processes model. Processes considered in CHNSED include particulate mobilization (sheet erosion and overland transport) and dissolved contaminant transport (associated with run off, interflow, and base flow inputs to the channel system). An ion exchange submodel simulates the soil-contaminant-water interaction at the land surface, and sediment transport and partitioning of trace contaminant between water and sediment in the channel system are also included. Following its entry into the channel system, dissolved contaminant transport is derived from flow routing algorithms of the WHTM. Routing of the adsorbed fraction is controlled by sediment transport dynamics, which are governed by bedload and suspended load sediment transport.

5. METHOD OF SOLUTION

The sediment transport formulation is an extension of that described by R. A. Bagnold in 1966, and includes Manning's equations to determine flow rate and modification to Stokes' law to allow calculation of particulate fall velocity in both the viscous and inertial particle settling regions. Sediment is separated into three components: resident sediment in the stream bed, sediment in transit as bedload, and sediment in transit as suspended load. Each of these components is partitioned into as many as 12 size classes of logarithmically varying ranges. The partitioning of a contaminant between water and sediment is based on the assumption of an equilibrium distribution being attained within each simulation interval.

6. RESTRICTIONS OR LIMITATIONS

Current computer storage allocation allows a watershed to be divided into three segments while the channel system is broken down into seven separate reaches.

7. TYPICAL RUNNING TIME

A test simulation of a one-year real time duration for a two-segment watershed and three-reach channel system required approximately 5 minutes of CPU time on the IBM System 360/91.

8. COMPUTER HARDWARE REQUIREMENTS

350K bytes of storage were required on an IBM 360/91, and FORTRAN logical units 1 through 4 are utilized for temporary files during problem execution.

9. COMPUTER SOFTWARE REQUIREMENTS

CHNSED ran under the OS/360 operating system.

10. REFERENCES

a) included in documentation:

D. E. Fields, "CHNSED - Simulation of Sediment and Trace Contaminant Transport with Sediment/Contaminant Interaction," ORNL/NSF/EATC-19 (March 1976).

b) background information:

D. E. Fields, D. M. Hetrick, "HOTSED: A Discrete Element Model for Simulating Hydrodynamic Conditions and Adsorbed and Dissolved Radioisotope Concentrations in Estuaries," NUREG/CR-0440, ORNL/NUREG/TM-266 (March 1979).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document in (10.a) and a diskette which includes the Fortran source, assembler source, overlay and sample case written in a self-extracting compressed DOS file.

12. DATE OF ABSTRACT

May 1999.

KEYWORDS: HYDRODYNAMICS