HR: 1340h
AN: H33G-1708    [Abstracts]
TI: Polyacrylamide Transport in Water Delivery Canals
AU: * Chen, L
EM: lchen@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Zhu, J
EM: jianting.Zhu@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Young, M
EM: michael.young@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AB: Linear, anionic polyacrylamide (PAM) is being considered in the western United States as a technology to reduce seepage in unlined water delivery canals. A broad laboratory and field testing program has been undertaken to understand the benefits and potential environmental impacts of PAM use. The ability to predict the fate and transport of PAM in water delivery canals could prove to be a useful planning tool for PAM application. However, one key area of uncertainty of this type of canal treatment is the hydration, reaction, and settling rates of PAM after the dry powder is added to the canal water. In this study, we have developed a model that incorporates a number of known physical and chemical processes that can affect PAM transport, such as convection, dispersion, dissolution, flocculation, and settling, while solving the governing convection-dispersion transport equation. The model uses a mixed analytical and advanced numerical approach, and implements a transient partitioning of PAM mass between the canal water, the substrate soil, and potentially to open water bodies downstream of the application point. All source terms are modeled based on physical and chemical mechanisms as well as laboratory or field determined parameters. To more closely simulate field treatment of some canals, where PAM application moves upstream in time, the model is capable of implementing either a fixed or mobile upper boundary. In the latter treatment, the PAM can be added discretely or continuously in both time and space. A number of test situations have been simulated thus far, including theoretical and hypothetical cases for a wide range of conditions. The model also performed well when predicting PAM concentrations from a full-scale canal treatment experiment. The model provides a useful tool for predicting PAM fate and transport in water delivery canals, and therefore can play an important role in evaluating the efficacy of PAM application for water resources management. Moreover, the model could also be used to simulate the transport of many other reactive particle in open channels, thereby widening its potential use to a lot of environmental situations.
DE: 1800 HYDROLOGY
DE: 1842 Irrigation
DE: 1847 Modeling
DE: 1880 Water management (6334)
SC: Hydrology [H]
MN: 2007 Fall Meeting