LiDAR DEM and HEC-RAS On-Grid Rainfall Hydrograph Model for Irrigation System

Abstract

The capacity of the Saddang River Irrigation Canal will be increased by 30% to accommodate long-term irrigation discharge needs. Analysis of the hydraulic model of the irrigation and discharge channels is examined in this study. High resolution LiDAR Digital Elevation and HEC-RAS Model are used to estimate the flow depth and velocities in the event of rain with extreme intensity. HEC-RAS Model solves the 2-D depth-averaged St.Venant equations that are mainly used for river simulation. The HEC-RAS model uses on-grid precipitation hydrograph and flexible meshes that may contain arbitrarily quadrilateral and triangular cells. A hybrid mesh may achieve the best compromise between solution accuracy and computing demand. The HEC-RAS model solved variables include water surface elevation, water depth, depth averaged velocity, Froude number, and bed shear stress. The optimization of the model is useful for improving the drainage modulus, lining channel, drain time period and the performance of the irrigation and drainage channels.