Systems for Evaluating Nonpoint Source Pollution -- An Overview

The approach of the US working group to the development of a hierarchy of mathematical models dealing with non-point-source pollution at the field level is described. The objective of the group is to use this system of models for assessing non-point-source pollution, quantifying responses from alternative management practices, and evaluating the best ones. Each model should be simple, but physically based. The following phenomena are described consecutively, with discussions of approaches to their modeling: surface and subsurface flow, deep percolation, erosion, sediment transport, and dissolved and adsorbed chemical output due to use of fertilizers and pesticides. The system is not considered to be an end in itself, but a first step towards the development of user-oriented comprehensive models

European and United States Case Studies in Application of the CREAMS Model

Several countries require investigation of the complex environmental consequences of agricultural management; therefore, IIASA decided to transfer the physically based CREAMS model program (developed by the US Department of Agriculture) to the Institute. The model was made operational on the Institute's computer and used by scientists from the following countries: Czechoslovakia, FRG, Finland, Poland, Sweden, United Kingdom, United States, and the USSR. The main objective of this work was to perform the quantitative evaluation of the consequences of the agricultural management in different countries. The collateral objective was to make validation studies of the CREAMS model where possible. These studies are completed now, and some of them are included in this volume. They can be divided into three categories: 1. Those where some observed data are available for model validation (Finland, England); 2. Those where some observed data are available for model validation with model extension for simulation (CSSR, FRG, USA); and 3. Those without observed data and only model simulations are generated to examine possible problems associated with management (Sweden, USSR, Poland)