Figure 1. SBAS alternative window (left); topology window (right)

cetniv-20
Page Navigation
3

CETN IV-20

September 1999

whether a cell is balanced or not. Systematic balancing of individual cells within the

macrobudget is a central property of the SBAS methodology.

Figure 1. SBAS alternative window (left); topology window (right)

Sediment budget cells, arrows expressing directions of net, left-, and right-directed transport

rates, and notation of P- and R-values comprise the sediment budget topology. The topology

window can be expanded to scroll to the right and left (for an east-west sediment budget) or up

and down (for a north-south sediment budget). The SBAS automatically formulates and

substitutes the quantities from the topology window into the sediment budget equation

(Equation 1) based on the origin, terminus, and direction of arrows representing rates. This

visual procedure allows an integrated quantitative budget to be formed based on the conceptual

budget. At any time, the user can conveniently check the macrobudget to ensure it is balanced

before proceeding with detailed calculations.

The basic SBAS procedure is discussed in an on-line format within the Tutorial file (provided

with the installation package) and is performed as follows:

Draw arrows through and between cell boundaries, defining the sources and sinks for each

cell (establish the sediment budget topology).

Define engineering activities P and R for each cell.

Assign best-estimate and uncertainty values to volumes, transport rates, and engineering

activities within each cell.

Balance the budget of each cell and the total system (macrobudget) by reducing the residual

to zero.

The residual term in Equation 1 allows the user to explore the consequences of adding,

removing, changing the magnitude of, or changing the pathways of sources, sinks, and

engineering activities within SBAS.