Editor's Note

This issue of the J. Irrig. Drain. Eng. has eight papers and two technical notes on different aspects of irrigation and water resources.

The first two papers, by Zerihun et al., discuss the development and application of a surface-subsurface solute transport model for basin and border irrigation. The subsurface transport process in the model is simulated using HYRUS-ID. The third paper, by Rodriguez-Sinobas et al., discusses the development of analytical expressions relating water distribution indexes in trapezoidal drip irrigation units to design variables such as lengths and diameter of pipes, emitter and lateral spacing, etc. An example using the analytical expressions is also presented in the paper.

The fourth and fifth papers are both on groundwater. Mishra and Fahimuddin present an analysis of an unsteady-flow problem into a multiaquifer well due to stream stage changes and variable pumping rates. Then, Baura and Hoffman cover the development of equations for predicting flow into an auger hole partially penetrating a homogeneous and anisotropic confined aquifer under steady-state conditions.

The sixth paper, by Cadena and Magallanez, presents an analytical solution that accurately predicts flow for circular sliding gates which are used as diversion and flow control structures in irrigation canals. The seventh paper, by Islam et al., also deals with canals. The Saint-Venant equations are discretized using the four-point implicit Preissmann scheme to develop a system of nonlinear equations solved using the Newton-Raphson method to model steady and unsteady flows in branched and looped canal networks.

The eighth paper, by Lui et al., describes a field experiment to develop the plough sole in a paddy field by ploughing, compaction, and a combination of ploughing and compaction.

The first technical note, by Swanee and Rathie, describe the development of exact equations for critical depth in a trapezoidal channel. The second technical note, by Hendawi et al., discusses the use of a fluid dynamics software program to simulate several collector designs to access their capabilities in terms of precision in water collection under a horizontal wind for sprinkler irrigation.