This book contains the proceedings of the first workshop held at Monte Verità near Ascona, Switzerland on September 24-29, 1989. The workshop was designed to survey the current understanding of water and solute transport through unsaturated soils under field conditions, and to foster research by discussing some unresolved key issues relative to transport modeling and experimentation in four "Think Tank" groups. The first part of this book consists of the reports prepared by the Think Tank groups, who discussed the following topics: modeling approaches, effective large scale properties, evaluation of filed properties, and the role preferential flow. The second part contains a selection of reviewed original contributions presented at the workshop, with topics ranging from the presentation of results from large scale experiments, to improved or new modeling approaches, and to legal or policy aspects. This book is intended for researchers in soil science, hydrology, and environmental engineering who have an interest in transport and reaction processes in the unsaturated zone. It will provide them with a representative sample of current research activities, and with a group discussion of future research directions in four important areas of water and solute transport.

Inhalt
1 Think Tank Reports.- Flow and Transport Modeling Approaches: Philosophy, Complexity and Relationship to Measurements.- Effective Large Scale Unsaturated Flow and Transport Properties.- Evaluation of Field Properties from Point Measurements.- Evaluating the Role of Preferential Flow on Solute Transport through Unsaturated Field Soils.- 2 Papers.- Spatial Variability of Water and Solute Flux in a Layered Soil.- One and three Dimensional Evaluation of Solute Macrodispersion in an Unsaturated Sandy Soil.- Assessment of Field-Scale Leaching Patterns for Management of Nitrogen Fertilizer Application.- The Effect of Field Soil Variability in Water Flow and Indigenous Solute Concentrations on Transfer Function Modelling of Solute Leaching.- Analysis of Caisson Transport Experiment by Travel Time Approach.- Field Estimates of Hydraulic Conductivity from Unconfined Infiltration Measurements.- Sprinkler Irrigation, Roots and the Uptake of Water.- The Infiltration-Outflow Experiment Used to Detect Flow Deviations.- Spatial Variability of Unsaturated Flow Parameters in Fluvial Gravel Deposits.- Quantification of Deterministic and Stochastic Variability Components of Solute Concentrations at the Groundwater Table in Sandy Soils.- Use of Scaling Techniques to Quantify Variability in Hydraulic Functions of Soils in the Netherlands.- Kriging Versus Alternative Interpolators: Errors and Sensitivity to Model Inputs.- Spatial Averaging of Solute and Water Flows in Soil.- Criteria for Evaluating Pesticide Leaching Models.- Relating the Parameters of a Leaching Model to the Percentages of Clay and other Soil Components.- Prediction of Cation Transport in Soils Using Cation Exchange Reactions.- Transport of a Conservative Tracer under Field Conditions: Qualitative Modelling with Random Walkin a Double Porous Medium.- Mass Flux of Sorptive Solute in Heterogeneous Soils.- Effective Properties for Modeling Unsaturated Flow in Large-Scale Heterogeneous Porous Media.- Transport of Reactive Solutes in Spatially Variable Unsaturated Soils.- A Perturbation Solution for Transport and Diffusion of a Single Reactive Chemical with Nonlinear Rate Loss.- Areal Solute Flux Estimation: Legal Aspects.