The Marcellus Disappearing Lake: Contribution of surface runoff to two flooding events in 2010
Summary
The karst-related flooding of a valley called Disappearing Lake in New York State, USA has posed a threat to the valley's inhabitants and their properties. Though previous studies have focused on this phenomenon, mechanisms behind the flooding are unknown. Theories have been posted that surface water runoff in combination with other quickflow components and groundwater upwelling contribute to the floods. The fact that floods occur in winter and spring suggests a relation with snowmelt. For this research, a rainfall-runoff model that handles interception, infiltration and depression storage is constructed to quantify the surface runoff component. Two flooding events in January and March 2010 are simulated assuming impermeable conditions for the floodplain, swamps and urban areas. Resulting cumulative runoff volumes show that only 5% of the flood can be contributed to surface runoff. When the floodplain and swamps areas are modelled as unsaturated, the contribution drops below 1%, meaning that the majority of the surface runoff is saturated overland flow. These relatively small runoff contributions could be attributed to high measured values for the saturated hydraulic conductivity. These high values explain the insensitivity of the model to changes in infiltration related parameters. The flooding of the Disappearing Lake does not appear to be surface runoff driven. Other sources of water play a more important role in this phenomenon. Though a high water table appears to be a criterion for floods to occur, further research is necessary to determine the role of groundwater upwelling or other quickflow processes.