Alaska Section

Tom Douglas, Alaska Section AWRA Northern-Region Director

This is a tentative list of winter speakers for AWRA, Northern-Region Section. Dates and locations vary and are subject to change for the 2003 talks, and we will make every attempt to keep you informed of any changes as they occur. We plan to send an email out the Monday prior to each talk, so if you have not been receiving E-mails and wish to, please contact Tom Douglas at (907) 353-9555 or Thomas.A.Douglas@erdc.usace.army.mil. Brownbag talks are from 12:00 pm to 1:00 pm on the second Wednesday of each month. We meet in the conference room at the Department of Natural Resources, 3700 Airport Way (across from the Airport Way Fred Meyer Store).

Unusual Wintertime Flooding of the Tanana River and Piledriver Slough Near Salcha, Alaska: Possible Causes and Solutions

Flooding in low-lying areas along the Tanana River and Piledriver Slough near Salcha has been a reoccurring problem during the winter of 2002-2003. Unusually high surface and ground water levels in the area have flooded portions of the Old Richardson Highway and inundated residential basements. The high water has also occasionally restricted access to numerous residences bordering Piledriver Slough.

It is possible the present flooding is linked to the unseasonably warm fall temperatures which prevailed across Alaska and led to a late and prolonged freeze-up of interior rivers. A general temperature sequence of "freeze-thaw-freeze" caused river ice that formed during October to break-up and form local ice jams as temperatures warmed in early November. Subsequent freezing temperatures in mid and late November likely preserved some of the ice jams - essentially creating ice dams. It is speculated that ice dams are at least partially obstructing the main channels of the Tanana River and diverting flow into the far eastern channel, which parallels the Old Richardson Highway. Alternatively, this area has seen a noticeable increase in spring and fall flooding events in recent years and the current flood event may simply be related to long-term channel migration of the Tanana River.

Future flooding continues to pose a significant concern for residents, as well as local, state, and federal agencies because of the impact to area roads and private property. This presentation will provide a background of the unique winter flood event and a brief history of flooding and erosional problems in this area. The seminar will then be open for discussion of probable causes and possible solutions for the prevention and mitigation of flooding along the Tanana River and Piledriver Slough near Salcha.

Alaska Section, American Water Resources Association