Appendix F: Long-Term Fate (LTFATE) of Dredged Material Model

Appendix F

Long-Term Fate (LTFATE)

of Dredged Material Model

Introduction

This appendix provides information on the computer program used to execute

the Long Term FATE (LTFATE) model. LTFATE is a site-evaluation tool that

estimates the dispersion characteristics of a dredged material placement site over

long periods of time, ranging from days for storm events to a year or more for

ambient conditions. Simulations are based on the use of local wave and currents

input to the model. Local, site-specific hydrodynamic input information is

developed from numerical model-generated databases; however, user-supplied

data files can be substituted for the database-generated files described in this

report.

LTFATE has the capability of simulating both noncohesive and cohesive

sediment transport. In addition, avalanching of noncohesive sediments and

consolidation of cohesive sediments are accounted for to accurately predict

physical processes that occur at the site. It should be emphasized that LTFATE,

although demonstrated to accurately simulate mound movement, is still under

development. Modifications are underway that will improve the basic descrip-

tion of sediment processes. These additions include modifications for mounds

on a sloped bottom bathymetry and layering of sediments to account for the

decrease in cohesive sediment resuspension potential with depth. Also, addi-

tional field and laboratory work are necessary to fully understand (and thus be

able to model) cohesive sediment erosion and deposition processes under high

shear stresses. LTFATE is designed to lend itself easily to code modification to

include new processes.

This appendix provides an overview of the theoretical background on which

the model is based, the personal computer (PC) requirements to run the model,

required input, and typical output. Details on all of these aspects can be found in

Scheffner et al. 1995.

Appendix F LTFATE Model