Inland Flooding

CIRCA works to enhance the State’s resilience to inland flooding. CIRCA focuses on understanding characteristics and trends of changing precipitation patterns and their influence on inland flooding in riverine communities using tested hydrologic models. In coastal areas where there are also rivers, rainfall contributes to flooding in coastal communities as well, packing a one-two punch.

Impacts of Extreme Weather and Climate Change on Inland Flooding

The 2014 National Climate Assessment (NCA) finds that hurricane intensity and intense rainfall events will increase as the climate continues to warm, both contributing to inland flooding. The NCA also states that “river flooding occurs when surface water drained from a watershed into a stream or a river exceeds channel capacity, overflows the banks, and inundates adjacent low lying areas. Riverine flooding depends on precipitation as well as many other factors, such as existing soil moisture conditions and snowmelt.” Clearly as the climate continues to change and heavy rainfall events continue, it is expected that riverine flooding will also become more frequent. Moreover, research (ASCE Magazine, 2015) indicates that riverine and coastal flooding events are occurring simultaneously much more frequently than they were half a century ago, contributing to a compound impact of coastal communities with rivers.

CIRCA and Inland Flooding

CIRCA’s work in this area includes the development of a hydrologic model that takes into account all of the river flooding factors described above with environmental conditions that are specific to Connecticut. This model can be used to predict future flood conditions in riverine systems for the state. Furthermore, the riverine flooding can be combined with CIRCA’s coastal flooding information to determine the compound impact of the two sources of flooding. Information from CIRCA can be used to determine whether Connecticut’s current and future flood control structures are designed for these scenarios and to identify areas and infrastructure at extreme risk.

CIRCA Research Projects

CIRCA’s current research projects in the area of inland flooding are listed below.

Real‐time Flood Prediction & Vulnerability Analysis of Connecticut’s Inland River Network 

The Real‐time Flood Prediction and Vulnerability Analysis of Connecticut’s Inland River Network project provides a hydrology model for Connecticut’s rivers and applies this model to determine flood vulnerabilities in current and future climate scenarios.

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Municipal Resilience Planning Assistance for Sea Level Rise, Coastal Flooding, Wastewater Treatment Infrastructure, & Policy

The Municipal Resilience Planning Assistance for Sea Level Rise, Coastal Flooding, Wastewater Treatment Infrastructure, and Policy project provides information for wastewater system vulnerability assessments, combined river and coastal flooding for pilot sites, and policy options for priority resilience projects for towns in the Sandy-impacted counties.

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Connecticut River Flooding
(Click image to enlarge) A week after Tropical Storm Irene hit New England, the Connecticut River was carrying Vermont soil down to Long Island Sound. Flooding from Irene inundated farmland in Connecticut and caused the worst flooding that Vermont had seen in 80 years. (Credit: NASA Earth Observatory, September 2, 2011)
Precipitation Map
 (Click image to enlarge) The map shows percent increases in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events) from 1958 to 2012 for each region of the continental United States. The northeast region of the United States has seen a 71% increase in these rainfall events, far outstripping the observed increase in heavy precipitation events of any other region. (Credit: NCA, 2014)

Further Reading