Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 6/15/2003
Publication Date: 7/30/2003
Citation: TEMPLE, D.M., COOK, K.R., NEILSON, M.L., YENNA, S.K. DESIGN OF GRASS-LINED CHANNELS: PROCEDURE AND SOFTWARE UPDATE. 2003. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. PAPER No. 03-2099. Interpretive Summary: Grass is extensively used to protect water conveyance channels from erosion. This form of protection has both economic and aesthetic advantages over structural channel liners for channels that experience flow only occasionally and for short periods of time. Applications include agricultural waterways and highway drainage channels. Because the flowing water interacts with the grass, the equations used in design of these grass-lined water conveyance channels are best solved by desktop computer. Changes in computer technology have resulted in the present design tools becoming outdated and improved understanding of the flow behavior has allowed the design relations to be slightly refined. Therefore, a new design tool in the form of an updated computer application was developed and documented.
Technical Abstract: The allowable erosionally effective stress design procedures of Agricultural Handbook #667 are widely used for design of grassed waterways and other grass-lined channels. However, the design aids, including computational software, provided in that publication have become outdated. It has also been observed that for trapezoidal channels with flat bank slopes, direct application of the traditional n-VR curves results in over-sensitivity of flow resistance to changes in bank slope at flow depths near vegetal overtopping. The nature of the transition from unsubmerged to submerged flow conditions in these channels is discussed and software using a computational procedure that appropriately accounts for this action is presented.