| This research investigated the effectiveness of anionic polyacrylamide (PAM) application in unlined irrigation canals. In the field test, PAM slurry was injected into a flowing canal. Flow data suggest PAM treatment produced a mean 21% increase in water loss over the test reach. Soil physical properties and low in-stream PAM concentrations likely contributed to the increase. In the laboratory, column and flume experiments tested three PAM application methods in uniform sand with and without added suspended solids. Hydraulic conductivity reduction (HCR) and treatment longevity proceeded in the order: granular turbid>granular>slurry surface>>liquid injection turbid>liquid injection. HCR was likely achieved by extensional viscosity, polymer aggregate filtration, or PAM gel formation, depending on the application method and suspended solids concentration. Within 42 hours, hydraulic conductivity returned to control-adjusted background levels in all laboratory tests except granular surface applications with added suspended solids and at high mass loading rates. |
