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SWEEP Report #49b

Land Reshaping of Lowland Clay Soils:
II. Modelling Report

Researchers: 
Andrew H. Marshall in association with Can-Ag Enterprises, Guelph, Ontario

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View / Download Final Report [2270 KB pdf]

Associated SWEEP/LSP Research

 

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Completed: May, 1992

Key Words:

clay soils, model, phosphorus, land planing

Executive Summary

The land planing studies, which were carried out by Can-Ag Enterprises Limited, were mathematically modelled using a modified version of the Chemicals, Runoff and Erosion from Agricultural Management Systems (CREAMS, Ver. 1.7) model. This modelling assignment focused on the first phase of model application, the prediction of overland flow episodes, and was based on a procedure which encompassed five areas of model development and application. These areas included problem identification, stated objective, development of method, results and evaluation of results.

Based on this procedure, 116 out of 130 observed episodes of overland flow were predicted for the twelve fields in the land planing studies for the time period from April '89 to September '90. In addition, 38 predictions were made which could not be explained, i.e. the failure of monitoring equipment. These results were dependent on a number of factors including the proximity of an agricultural field to precipitation measurement as well as the seasonal variation in infiltration characteristics of heavy clay soils.

The predictions of overland flow episodes resulted from a novel approach of applying the CREAMS Ver. 1.7 model to agricultural fields across seasons. This approach provided a solid basis for the next phase of modelling application: an emphasis on the prediction of flow quantities and sediment and phosphorus concentrations and loadings. The framework for such an emphasis could easily be patterned on the framework developed in this assignment, the first phase of model application.

 

Evaluation Summary

(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)

The modelling was done using data from sites monitored in the SWEEP project, Land Reshaping of Lowland Clay Soils. A modified version of the field scale model for Chemicals, Runoff, and Erosion from Agricultural Management Systems (CREAMS) was used. The objective of the study was to develop a method of estimating the empirical values for the field parameters used by the model and evaluate its ability to predict occurrences of surface runoff and subsurface drainage flows.

The analysis was completed on field data for surface runoff events only. The Land Reshaping project did not measure tile flow; therefore, that component could not be incorporated into the model. The success of the model was based on its ability to predict an event occurrence. The analysis did not evaluate the model's ability to quantify runoff volume of each event. An adaptation was incorporated in the model to allow for a seasonal variation in the hydraulic conductivity parameter.

The model successfully predicted the occurrence of 116 out of 130 observed events of overland flow. The model did not find any difference in the event occurrence between planed and unplaned fields. From the measured data of overland run-off for a five month period, the unplaned fields showed a lower amount of run-off than planed fields.

Comments:

The project successfully completed its main objective of predicting overland flow events. This report would be of little interest to anyone who does not understand modelling.

Associated SWEEP/LSP Research:

Future Research: ( ) indicates reviewers suggestion for priority, A - high, C - low.

(C) The model should be further evaluated quantitatively making use of the parameter selection technique developed. At the same time, the phosphorous loss component of the model should be evaluated using this modified technique.

 

 

 

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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 03:37:58 PM