Method for fast estimation of terrace earthwork in the hilly regions and its application

In the land consolidation project planning, it is significant to estimate the earthwork in the design, cost estimation and investment budgeting of a project. A new method was advanced in this study to calculate the earthwork of terraces in the hilly regions. Its principle ideas and the computational formulae were detailed. The earthwork volumes under different slopes to construct a terrace of the given pattern were integrated with the weighed function of the distribution function of areas to get the total earthwork volume. An actual exemplary project was used to verify the method. The relative errors of the earthwork estimated with this method compared with that computed with GIS were 5.4% and 3.9% for slope gradients of 5° and 2°, respectively. This indicates a very high accuracy of the method for earthwork estimation, with improved accuracy with smaller slope intervals used. The method is convenient to use for fast earthwork determination, which can be used to determine the earthwork even before project design as long as the patterns of terraces were given. This method not only supplies the engineers with a robust but useful tool for earthwork computation during their project design, but also improves the efficiency and enhances the output of project assessment.