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Abstract

Many land-management decisions would be aided by an understanding of the current sediment production and transport regime in a watershed, and of the likely effects of planned land use on that regime. Sediment budgeting can provide this information quickly and at low cost if reconnaissance techniques are used to evaluate the budget. Efficient budget construction incorporates seven steps:

· careful definition of the problem to be adressed
· collection of background information
· subdivision of the project area into uniform sub-areas
· interpretion of aerial photographs
· fieldwork
· analysis
· checking of results

Methods used in fieldwork and analysis must be selected according to the types of hillslope and channel processes active and the level of precision required. Methods for evaluating erosion and sediment transport rates are described, and four examples are given to demonstrate budget applications and construction.
Retrieval terms: watershed, cumulative impact, erosion, sediment transport, sediment budget, land-use planning, watershed-analysis.

Contents (shortened)
1	INTRODUCTION
1.1	Definition and description
1.2	Relation to other methods
1.3	Misconceptions
1.4	How to use this volume
2	PROCEDURE FOR SEDIMENT BUDGET CONSTRUCTION
	▪ Step 1. Define the problem ▪ Step 2. Acquire background information ▪ Step 3. Subdivide area ▪ Step 4. Interpret aerial photographs ▪ Step 5. Conduct fieldwork ▪ Step 6. Analyze data ▪ Step 7. Check results
3	EVALUATING SEDIMENT PRODUCTION FROM HILLSLOPES AND CHANNELS
3.1	Overview of hillslope sediment production
3.2	Identification of sediment sources
3.3	Rates of discrete erosion processes: Landslides ▪ Debris flows ▪ Gullies ▪ Treethrow ▪ Animal burrows
3.4	Rates of chronic erosion processes: ▪ Sheetwash erosion ▪ Wind erosion ▪ Dry ravel ▪ Bank erosion
3.5	Other hillslope sediment transport processes
3.6	Sediment delivery from hillslopes to channels
3.7	Grain size composition
3.8	Calculation of long-term rates
3.9	Predicting future erosion rates
4	EVALUATING SEDIMENT TRANSPORT AND STORAGE IN CHANNELS
4.1	Overview of channel processes
4.2	Characterization of channels: ▪ Qualitative characterization ▪ Selection of measurement sites ▪ Slope measurements ▪ Channel geometry measurements ▪ Channel roughness ▪ Definition of flow characteristics ▪ Identification of channel changes
4.3	Grain-size distributions
4.4	Initiation of bed-material transport
4.5	Determination of scour depths
4.6	Sediment transport rates in channels: ▪ Sediment transport equations ▪ Comparison of transport predictions and measurements ▪ Applying sediment transport equations ▪ Use of field observations ▪ Evaluation of the washload component ▪ Limits of sediment transport predictions
4.7	Sediment storage: ▪ Identifying storage elements in channels ▪ Defining trends in channel-related sediment storage
4.8	Computations of sediment yield
5	EXAMPLES OF SEDIMENT BUDGET APPLICATIONS
5.1	West slope of the Sierra Nevada, California
5.2	Shinyanga Region, Tanzania
5.3	Snoqualmi River basin, Washington
5.4	Olympic Peninsula rivers, Washington
6	CONCLUSIONS
APPENDIX 1. GLOSSARY
APPENDIX 2. ADDITIONAL READING AND USEFUL COMPENDIA
▪ Background information ▪ Manuals and descriptions of particular methods ▪ Data compendia
REFERENCES