USE OF CAESIUM-137 AS A TRACER OF EROSION AND SEDIMENTATION: hANDBOOK FOR THE APPLICATION OF THE..

Part 1. Methodology Chapter 1. Soil erosion - The problem and its assessment 1.1 The impacts of soil erosion 1.1.1 On-site impacts on agricultural productivity 1.1.2 Off-site impacts of eroded sediment 1.2 The data requirement 1.2.1 Data required to assess the impact on productivity 1.2.2 Data required to assess the off-site impact 1.2.3 Data required to target conservation resources 1.3 Current methods of erosion assessment and the resultant data 1.3.1 Long term monitoring of experimental plots 1.3.2 Field survey of erosion features 1.3.3 Erosion modelling 1.4 Meeting the data requirements 1.5 The potential of the Caesium-137 technique Chapter 2. The Caesium-137 technique 2.1 The basis of the Caesium-137 technique 2.2 The source of Caesium-137 in the environment 2.3 Deposition of Caesium-137 2.3.1 Bomb-derived Caesium-137 2.3.2 Chernobyl-derived Caesium-137 2.4 Caesium-137 adsorption by mineral sediment 2.4.1 Experimental studies 2.4.2 Field studies 2.5 Sediment-associated redistribution of Caesium-137 2.5.1 Field evidence 2.6 Use of Caesium -137 measurements in erosion assessment 2.7 Establishment of a reference inventory 2.8 Measurement of the Spatial distribution of Caesium -137 2.9 Identification of Caesium -137 redistribution 2.10 Development of 'calibration' procedures 2.11 Estimation of erosion and aggradation rates Chapter 3. Sample collection, preparation and analysis 3.1 Sample collection 3.1.1 Sample collection methods 3.1.2 Sample collection equipment 3.2 Sampling reference sites 3.3 Sampling study sites 3.3.1 Individual slope transects 3.3.2 Field recording 3.4 Definition of an optimum sampling strategy Prediction of tillage fluxes 3.5 Sample preparation 3.6 Sample analysis 3.6.1 Equipment required 3.6.2 Analytical procedure 3.7 Analytical precision 3.8 Time-scales for an investigation Chapter 4. Estimation of erosion rates from Caesium-137 data 4.1 Introduction 4.1.1 Use of empirical relationships 4.1.2 Theoretical models and accounting procedures 4.2 Simulation of Caesium -137 deposition and redistribution 4.2.1 Outline of the profile model for cultivated land 4.3 Fallout inputs of Caesium-137 4.3.1 Differential of 'old' and 'new' Caesium -137 4.4 Rill and inter-rill erosion 4.4.1 Particle size selectivity of erosion 4.5 Loss of 'old' Caesium -137 4.6 Loss of 'new' Caesium -137 4.6.1 The initial depth distribution of Caesium -137 4.6.2 Loss of 'new' Caesium -137 by inter-rill erosion 4.6.3 Loss of 'new' Caesium -137 by rill erosion 4.7 Change in Caesium -137 inventory of an eroding profile 4.8 Caesium -137 content of eroded soil 4.9 Simulation of an aggrading profile 4.9.1 Change in Caesium-137 inventory of an aggrading profile 4.10 Simulation of tillage mixing 4.10.1 An eroding profile 4.10.2 An aggrading profile 4.11 The impact of tillage displacement 4.11.1 Simulating the impact of tillage erosion 4.11.2 Simulating the impact of tillage aggradation 4.12 Formulation of a calibration curve 4.13 Sensitivity analysis 4.14 Overview 4.15 References 4.16 Software listings 4.16.1 Profile model: FORTRAN-77 programme 4.16.2 Example of data file : 'dfile' 4.16.3 Atmospheric fallout data file : 'mod.dat' Chapter 5. Simulation of Caesium -137 redistribution along slope transects 5.1 The limitations of the soil profile approach 5.2 The importance of tillage displacement in the simulation of Caesium -137 redistribution 5.3 A slope transect approach 5.4 5.4.1 Tillage perpendicular to the contour 5.4.2 Contour ploughing 5.5 Estimation of soil erosion and deposition using the transect approach Chapter 6. Further data analysis: Presentation, evaluation and extrapolation 6.1 Presentation of erosion rate data 6.1.1 Data from transect sampling 6.1.2 Spatial data 6.2 Evaluation of on-site erosion 6.2.1 Rates of on-site erosion 6.2.2 Process -related impacts of on-site erosion 6.2.3 Identification of erosion processes 6.3 Evaluation of the on-site impact 6.4 Evaluating of the off-site impact 6.5 Increasing Spatial coverage 6.6 Data extrapolation procedures 6.6.1 Model-based extrapolation procedures 6.6.2 Classification-based extrapolation procedures 6.7 Sample collection for verification 6.8 Overview Part 2. Case study 1 - A Yuan area of the losses plateau near Xifeng , Gansu province , China 7.1 The Collaborators 7.2 The context 7.3 The Nan Xiaohe gully study area 7.3.1 The basin 7.3.2 The Yuan surface 7.3.3 The gully 7.3.4 The upper gully slopes 7.3.5 The lower gully slopes 7.4 Sampling strategy 7.5 Methodology 7.6 Summary of the Caesium -137 data 7.7 The erosion rates derived from Caesium-137 data for the uncultivated slopes 7.8 The erosion rates derived from Caesium -137 data for the cultivated terraces 7.8.1 The evidence of Spatial distributions 7.8.2 Integrated values from low-density sampling Chapter 8. Case study 2. - Soil erosion on agriculture land near Harare, Zimbabwe : Rates and controls 8.1 The collaborators 8.2 The context 8.3 The selection of study areas 8.4 Sampling strategy 8.4.1 The Borrowdale site 8.4.2 The Chinamora site 8.5 Methodology 8.6 Summary of the erosion rate data 8.6.1 The magnitude of the erosion rates 8.6.2 Edaphic and management controls 8.6.3 Land-use controls Chapter 9. Case study 3 -Soil erosion on cultivated land in the Lesotho Lowlands 9.1 Collaborator 9.2 The context 9.3 The Sofonia catchment 9.4 The sampling strategy 9.5 Erosion rate data for transect 1 9.5.1 Soil redistribution at the field scale 9.5.2 Soil erosion at the transect scale 9.6 Extrapolation of erosion rates 9.6.1 Net erosion estimation based on field characteristics 9.6.2 On-site erosion mapping based on surface and low-density sampling Part 3. Overview - The value of the Caesium -137 technique

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