Wednesday, November 15, 2006
294-6

Modelling Polyacrylamide Transport in Water Delivery Canals.

Li Chen, Jianting Zhu, Michael Young, and Rick Susfalk. Desert Research Institute, 755 E Flamingo Rd, Las Vegas, NV 89119

In the western United States, polyacrylamide (PAM) is being considered as a tool to reduce water seepage loss and to improve water conservation.  However, the benefits and environmental impacts of PAM as a water conservation tool have not been fully evaluated.  As a key step to examining the use of PAM and its associated impacts, the mass partition of PAM in the canal water, in the substrate soil and to the downstream open water body needs to be evaluated.  In this study, we have developed a PAM transport model that incorporates numerous known physical and chemical subprocesses, such as convection, dispersion, dissolution, flocculation, settling, adhesion, resuspension, infiltration and degradation. These subprocesses are all included in the numerical model that solves the convection-dispersion equation with source terms. All source terms are modeled based on physical and chemical mechanisms as well as laboratory or field determined parameters. The model requires the PAM concentration at the entrance of study reach and specific flow characteristics in the canal, and predicts the PAM concentration in the canal water, in the substrate soil, and downstream at a point designated by the user for any time period. The model solves the governing equation with modern numerical techniques with small numerical effect. The model provides a useful tool for predicting PAM fate and transport in water delivery canals, and can play an important role in evaluating the efficacy of this method as a water conservation tool and the fate of PAM in the environment.

 


Handout (.pdf format, 100.0 kb)