Imagine the Devils Lake Basin as one of those bowls with the wide lips. The bowl itself is pretty much filled now so, as more water goes in, it can only spread out and spread out fast.
UND geography professor Paul Todhunter uses that analogy to explain why the Devils Lake region can expect to lose more land at a much faster rate than before.
"We're at a point in the lake level's rise where the rate of change is dramatic," he said in a university release. "As bad as things have been, we're transitioning into a period where there will be greater expansion of the lake's area for each foot of rise in its level."
Since the regional wet cycle began in 1993, Devils Lake has expanded at an average rate of less than 11 square miles a year. The 3-foot rise forecast for this spring could cause the lake
to expand by more than 50 square miles in a single year, according to Todhunter.
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The lake now covers 252 square miles compared to 70 square miles in 1993.
Rising waters have caused more than $1 billion in damage to surrounding communities and those communities and the state have spent millions to raise dikes and roads to keep up. If the lake spreads faster than before much more damage can be expected as more homes and farms end up underwater.
Todhunter, whose interests include climatology and hydrology, has studied Devils Lake since its water began rising. The lake is unusual because there is no natural outlet so water can come in, but has no way out other than overflowing into the surrounding lands. Though it hasn't happened in recorded history, there's some evidence that Devils Lake has overflowed into the Red River Basin twice in the last 10,000 years.
"The basic fact of terminal lakes is that water can only be removed from them by evaporation, which varies relatively little from one year to the next -- especially in North Dakota where summers are short," Todhunter said. "When the water level goes up sharply, it can only be brought down slowly."
The state has operated an artificial outlet on the west end of the lake since 2005, but it hasn't significantly reduced lake levels. There are plans to expand that outlet and build a new one on the east end.
