Field measurement of soil erosion and runoff

by N. W. Hudson Silsoe Associates Ampthill, Bedford United Kingdom

Food and Agriculture Organization of the United Nations

Rome, 1993

Table of contents

Foreword

List of figures

List of plates

List of tables

Acknowledgements

Chapter 1 Experimental design

OBJECTIVES

PRACTICALITIES

AVOID 'BEFORE AND AFTER' EXPERIMENTS

STATISTICS

Sampling

Differences

Replications

ANOMALOUS RESULTS AND EXTRAPOLATION

CONCLUSION

Chapter 2 Reconnaissance methods

ADVANTAGES

Interference

ACCURACY

Heresay evidence

MEASURING CHANGE OF SURFACE LEVEL

Point measurements

Erosion pins

Paint collars

Bottle tops

Pedestals

Tree mounds and tree roots

Profile meters

VOLUMETRIC MEASUREMENTS

Rills and roads

Gullies and streambanks

Catchpits

Landslips and landslides

Chapter 3 Field plots

OVERVIEW

A catalogue of disasters

WHEN TO USE RUNOFF PLOTS

STATISTICAL DESIGN

Replication

Bias

Standard designs

TYPES OF RUNOFF PLOTS

Natural or simulated rainfall

Bounded or unbounded plots

Size of plots

Watershed/catchment studies

CONSTRUCTION

Plot size

Plot shape

Plot boundaries

Collectors

Tanks and Divisors

OPERATION

Frequency of recordings

Estimating soil loss

Recorders and automation

Record keeping and analysis

Chapter 4 Streamflow

VOLUMETRIC METHODS

VELOCITY/AREA METHOD

RATING A GAUGING STATION

EMPIRICAL FORMULAS FOR ESTIMATING VELOCITY

GAUGING WEIRS

Sharp-crested weirs

Broad-crested weirs

MEASURING FLUMES

The Parshall flume

H flumes

Washington State College (WSC) flume)

Using existing structures

WATER-LEVEL RECORDERS

Chapter 5: Sediment transport

ESTIMATING SUSPENDED LOAD

Grab samples

Depth-integrating samplers

Point-integrating samplers

Pumping samplers

Continuous sampling

ESTIMATING BEDLOAD

Direct measurements

Samplers

Radio-active tracers

Empirical estimations

ESTIMATING TOTAL LOAD

ESTIMATES FROM DEPOSITION IN RESERVOIRS

Chapter 6 Rainfall simulators

OBJECTIVES AND APPLICATIONS

Advantages and disadvantages

Opportunities

Construction

TYPES OF SIMULATOR

Desirable characteristics of simulated rain

Making artificial rainfall

Water pressure for spraying nozzles

PRACTICAL CONSIDERATIONS

OPERATION

Chapter 7 Estimating from models

ESTIMATING RUNOFF

Maximum runoff rates

_{Runoff quantity, or yield}

_{ESTIMATING SOIL LOSS}

_{Empirical models for estimating soil loss}

Erosion parameters

References

Further reading