Defining Furrow Cross Section

Descriptions of the furrow cross section are required in many formulations that have been developed to model furrow irrigation performance. Researchers have presented techniques for measuring the furrow cross section in the field, and have described the effect of furrow cross-sectional shape on furrow irrigation performance. This technical note outlines several techniques to analyze furrow cross-sectional data to arrive at some of the commonly used empirical descriptions of the furrow cross section. The furrow can have an assumed shape, triangular or parabolic, or the observed cross-section measurements can be used numerically. In most cases the observed cross-section data should be numerically integrated to develop a data set from which the desired empirical shape descriptions can be estimated. Then, nonlinear regression analyses should be used to develop relationships between the shape descriptions. An example furrow is used to show that simple shape assumptions can impact the resulting empirical shape description.