By JENN McDOWELL
The Federal Emergency Management Agency is funding an independent study on the 2006 and 2007 flooding of New Hampshire rivers.
The Suncook River is one of the prime focus areas of the study, which will look into the differences between the two flooding episodes, possible reasons for the excessive flooding and ways to reduce flood impact in the future.
The first of three public forums on the study was held at the Department of Environmental Services in Concord on Dec. 12. The study looked at whether improvements can be made to dam operations, as well as how emergency response can cut down on future flooding impact.
FEMA’s interest in the study is to reduce the magnitude of their response, said Jim Gallagher, head of the state Dam Bureau.
FEMA has spent about $30 million on responding to the flooding throughout the state according to Albie Lewis, who was FEMA’s federal coordinating officer during the May 2007 flood.
The study, which costs about $330,000, is being conducted by international engineering firm URS Corporation, and will be overseen by independent experts in water resource management.
“They’re really taking a fresh look at this,” said Gallagher about the researchers involved, who are engineers being consulted by weather experts and emergency management personnel.
Lewis said Gov. John Lynch called him personally about finding a way to fund the study through FEMA.
According to Lewis, one of the study areas will be the amount of sediment along the riverbeds. When sediment builds up along a river’s bottom, it decreases the amount of space for the water to travel through between the banks.
This is particularly important for the Suncook River, where such a buildup of sediment in Epsom caused an avulsion, or a change in the river’s course of direction, during the May flooding. This may be one of the reasons for the worse flooding and the increased amount of flood damage in Epsom and towns downstream, such as Allenstown.
The two floods were not consistent with historical flooding statistics, particularly for the Suncook River.
“Over the years, without a heavy flow of water, sediment fills in channels of the river. When that happens, water overflows its banks,” Lewis said.
The rain totals for the May 2007 event were significantly less than those from the 2006 floods, prompting questions as to why the flooding would be so much worse the second time around.
Researchers looked at high-water marks of the 2007 floods and compared them to those of the 2006 floods, finding the more recent to be higher. This points to a possible increase in the amount of sediment along the river bottoms, Lewis said.
The study will also include an analysis of the dam operations along the various rivers included in the study. Researchers will look at flow analysis, average daily flow, the height of such dams at low and high water marks, and the general operations at the dams.
The Webster Dam on the Suncook in Pembroke is of particular interest to researchers said Gallagher. Interviews will be conducted at the Webster Dam and others around the state to determine what was done at the time of the flood and how problems were addressed.
Lewis added the study will include looking at wetlands that typically absorb excess water from the rivers in question. The less water in such wetlands the more there is in the river itself, he explained.
In March, researchers will hold another public meeting to present their interim findings before compiling a final report on the study, which should be completed in May.