# Sediment Budget Analysis System (SBAS)

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This tool is funded by (RSM)

## A Visualization and Calculation Tool for Sediment Budgets

The Sediment Budget Analysis System is a free sediment budget creation, visualization and calculation tool set for ESRI ArcGIS, with versions compatible with ArcMap 10.x versions and ArcGIS Pro. Once installed, this toolbox allows users to define a conceptual budget visually by creating a series of cells and arrows that represent fluxes into and out of cells (sources and sinks). Sand placement, P, and removal, R, within cells can be accounted for. SBAS can then create quantitative "micro" (local) and "macro" (regional) sediment budgets, using a pre-defined sediment-budget equation.

The SBAS ArcMap toolset is available for download along with additional information from the RSM Website in the "Tools & Databases" dropdown. SBAS for ArcGIS Pro will be made available in the coming year. Legacy versions of the SBAS were developed as standalone executables for PC. For questions regarding older versions of SBAS please reach out to the contacts listed at the end of this article.

## Background (modified from Rosati and Kraus, 1999)

Sediment budgets provide a conceptual and quantitative model of sediment-transport magnitudes and pathways for a given time period. Sediment budgets are a framework for understanding complex coastal systems, whether natural or engineered. Often, the natural condition is studied to gain background information necessary for evaluating the inlet and adjacent beach response to coastal engineering projects (see Komar 1996, 1998 for an overview of concepts and applications).

## Theory

SBAS calculates cell balances based on a conservation of volume (or volume flux) equation,

 ${\displaystyle \Sigma Q_{source}-\Sigma Q_{sink}-\Delta V+P-R=Residual}$ (1)

where
${\displaystyle Q_{source}}$ = input of sediment into a cell

${\displaystyle Q_{sink}}$ = loss of sediment from a cell

${\displaystyle \Delta V}$ = volume change within a cell

${\displaystyle P}$ = placement into a cell (e.g., beach fill or dredged material)

${\displaystyle R}$ = removal from a cell (e.g., dredging or mining)

${\displaystyle Residual}$ = 0 for a balanced cell

Units are fluxes or volumes (e.g., cu yd/year, cu m/year, cu yd, cu m) representative of the period of interest.

## Applications

Sediment budgets can enter at any of four stages in project development:

1. Existing Condition. A sediment budget for the existing condition is the most common type. This budget forms the basis for evaluating the impacts of planned engineering activities and the natural evolution of the coast.
2. Historical (pre-engineering activity) Condition. This budget is typically constructed for comparison with the existing-condition budget. A common application of the two budgets for inlet systems is a so-called "Section 111" or similar study, in which the impacts of inlet-related engineering activities (at Federal navigation projects) on the adjacent beaches are estimated.
3. Forecast Future Condition. Adapting and extrapolating the existing-condition sediment budget can assess the potential response to future projects or modifications.
4. Intermediate Condition. Sediment budgets representing other periods create a model of coastal evolution through time, which may lend insight to interpreting present or future evolution. As examples, intermediate-condition sediment budgets may document evolution of an inlet from initial formation to a quasi-equilibrium state, or they may reveal a picture of long-term natural bypassing through a cycle of channel migration and welding of a portion of the ebb-tidal shoal to the adjacent beach.

## Versions

SBAS Version Latest Update Software Compatability Documentation
SBAS Pro July 2020 ESRI ArcGIS Pro SBAS User's Guide Wiki
SBAS Arc10 July 2018 ESRI ArcMap v. 10.x SBAS ArcGIS 10 User's Guide (PDF)
SBAS-A 2007 ESRI ArcView v. 8.x CHETN-XIV-7
SBAS 1991 Windows 95, 98 & NT CETN-IV-20
The legacy SBAS standalone PC executable window