A Numerical Solution for Bi-level Drainage Design

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

A Numerical Solution for Bi-level Drainage Design
Author:Mohammad Reza Nouri <nouri1351@yahoo.com> (Chamran University)
Presenter:Mohammad Reza Nouri <nouri1351@yahoo.com> (Chamran University)
Date: 2006-06-18     Track: Special Sessions     Session: Groundwater Optimal Management Session

Knowledge of the water level and rate of drawdown is important in water and soil management. Several equations in literature are used to make a relation between soil characteristic, drain information, the declination rate of the water table and other related factors. Almost all of these equations are based on the Bossinesq equation with Dupuit-Forchheimer assumptions. In this study the Bossinesq equation with appropriate initial and boundary conditions was solved numerically to predict a fall in the water table for a level and a bi-level drainage system. Almost identical values of spatial and temporal distribution of water table heights were obtained. In order to compare the capability of both systems, the model was run for a real drainage system project in the Khuzestan region, with a drainage network spacing of 40, 60 and 80(m) in distance. The results show that for a sub-region with 40(m) spacing network, 30 (cm) drawdown in maximum water table elevation (MWTE) takes about 6 and 7 days time in the level and bi-level system, respectively. The same results for a sub-region with 60(m) space is 10.5 and 12 days and those of 80(m) are 12 and 14 days. In additional to the bi-level system with time (Simultaneous falling water table) position of MWTE shifts from the mid- point towards the shallow drain.We conclude that in this spatial project the cost of installation of subsurface drainage system can be reduced about 10.6 percent by using a bi-level system instead of a level system with similar spacing network. Keywords: Numerical methods, Finite Volume, Bi-level drainage