Rancocas Creek Watershed: Flood and Drought Conditions

        While flooding along the Rancocas Creek isn’t a common occurrence, there is a long history of changing flood conditions due to major tropical storms impacting local communities. The highest crests cluster around tropical systems, notably hurricane Irene in 2011 and heavy rainfall events in June 2019, 1971, 1939, and 1938. More modern records include events of crests below three feet, a pattern that is reflective of short-term stability provided by storm management, but also may be influenced by regional dry spells and low soil moisture. When soil and groundwater levels are depleted, even heavy storms can produce different runoff responses and should not be interpreted as reduced flood risks as these spaces can easily become overwhelmed by heavy rain, not allowing for steady ground infiltration and instead causing flooding conditions. 

        Recent drought conditions across the Rancocas Creek have stressed streams, wetlands, and groundwater supplies, lowering baseflows and exposing shallow wetlands that depend on the Kirkwood-Cohansey aquifer. Reduced streamflow concentrates pollutants, harms aquatic habitats, and limits recreational uses such as paddling and fishing. These conditions also put pressure on municipal wells and can prompt higher pumping that further depresses water tables. For agricultural areas along the watershed, cranberry operations that rely on managed hydrology are met with complications due to droughts and sudden flooding conditions making bog management difficult and competitive for limited water supplies. Recent droughts also raise wildfire risks in dry Pinelands which are difficult to gain access to due to lack of trails in protected lands and the watershed blocking land access. Resilience efforts must include systems built for both episodic floods and prolonged low flow, drought periods caused by changing weather patterns.

        Below are different sections of the Rancocas Creek Watershed with images displaying flood hazard layers and charts ranking crest heights and date, categorizing them based on flood impact level.

North Branch Rancocas Creek at Pemberton

Along the North Branch Rancocas Creek at Pemberton, there are multiple flood impact levels:

• At 2.5ft: Some minor flooding begins in Eastampton and Southampton
• At 3.5ft: Lee Street, Joe Road, and Jill Court in Southampton are subject to evacuations. Old Georges Lane and the Rancocas Trail in Southampton are also flooded. In Eastampton, flooding spreads West 
• At 4.2ft: Homes along Lee Street, joe Road, Jill Court take in water. Residents along Old Georges Lane and Rancocas Trail are subject to evacuation

North Branch Rancocas Creek at Mount Holly

Along the North Branch Rancocas Creek at Mount Holly, there are multiple flood impact levels:

• At 9ft: Spillway at mill dam is around 9 feet
• At 11.7ft: Flooding begins between Creek and Monroe Street
• At 13ft: Mill dam is overtopped. Flooding occurs in downtown Mt. Holly. Road closures and detours put in place
• At 14ft: Significant flooding occurs in downtown. Mt. Holly residents, businesses, and facilities take on water. Roads impassable. 

Greenwood Branch at New Lisbon 

Along the Greenwood Branch at New Lisbon, there are multiple flood impact levels:

• At 5ft: Greenwood Bridge Road floods and is impassable 
• At 9ft: Residential basements along Four Mile Road flood
• At 12ft: Structural damage to Greenwood Bridge Road is possible. Four Mile Road floods and shuts down

McDonald's Branch

    Take note of the satellite imagery being used in comparison to the other locations. McDonald's Branch lacks residential developments in nearby areas. Flooding is less impactful in this location as it is further into the New Jersey Pinelands, away from urbanization. There is only one flood level in this area, at 1.7ft it is under the action category, that streams are rising in water level but there are no road closures, residential impacts, or evacuations needed. Historically, there is very little flooding conditions in this area, and no significant impacts have been reported. 

South Branch Rancocas Creek at Vincentown

Along the South Branch Rancocas Creek at Vincentown, there are multiple flood levels:

• At 6ft: The creek floods onto adjacent land
• At 7ft: Mill Street in Vincentown floods. Flooding occurs downstream in Lumberton depending on tide levels
• At 8ft: Race Street in Vincentown floods. Previous flood levels worsen
• At 9ft: Main Street in Vincentown floods. Previous flood levels worsen
• At 11ft: Homes and businesses flood on Mill, Race, and Main Street. Flooding is more likely to overflow downstream in Lumberton 

South Branch Rancocas Creek at Medford

Along the South Branch Rancocas Creek at Medford, there are multiple flood levels:

• At 11ft: The creek floods adjacent to land 
• At 13ft: New Freedom Road is closed between Church and Eayerstown Road. Flooding may occur downstream in Lumberton depending on tide levels
• At 14ft: Flooding occurs in Medford. Roads are closed. Camp Dark Waters is flooded. Flooding occurs in Lumberton before the Southwest Branch merge
• At 15ft: Evacuations occur in New Freedom Road with water surrounding homes. Flooding is more likely downstream but still depending on tidal levels 
• At 17ft: Flooding occurs on Bridge Street in Lumberton. Residential locations are flooded
• At 19ft: Widespread flooding occurs between Medford and Lumberton 

Flood Reports

        Below is a video report from NBC10 Philadelphia reporting on flash flood conditions in June 2019. Repeated flash flood events caused residents to evacuate their homes by emergency rescue boats with some using their own kayaks and canoes to escape the rising water levels. Properties along the creek were severely damaged and roads became impassable as flood levels rose above the height of cars. Some roads were not as flooded, but still required larger, off-roading style vehicles to pass. Some residents became homeless and were displaced from being able to work or have a normal day to day life until water levels returned to normal and they were able to recuperate. 

   

     Below is a slideshow of different pictures provided by Burlington County Times, taken along the Rancocas Creek after hurricane Irene flooded the area in August of 2011. Take note of the locations in the captions of each picture. Flooding conditions weren't exclusive to one branch of the Rancocas Creek Watershed, flooding was seen in Mount Holly from the North Branch Rancocas Creek, Vincentown from the South Branch Rancocas Creek, and Southampton from the Rancocas Creek in Pemberton. Hurricane Irene brought record setting floods to the area, prompting better stormwater management, emergency preparedness, and flood mapping for future hurricane seasons. 

References:

National Oceanic and Atmospheric Administration. (n.d.). MEDN4 gauge — National Water Model (NWM). NOAA Water Prediction. https://water.noaa.gov/gauges/MEDN4#hg=nwm

National Oceanic and Atmospheric Administration. (n.d.). VNCN4 gauge — Official observations. NOAA Water Prediction. https://water.noaa.gov/gauges/VNCN4#hg=official

National Oceanic and Atmospheric Administration. (n.d.). MCDN4 gauge — Official observations. NOAA Water Prediction. https://water.noaa.gov/gauges/MCDN4#hg=official

National Oceanic and Atmospheric Administration. (n.d.). NLBN4 gauge — Official observations. NOAA Water Prediction. https://water.noaa.gov/gauges/NLBN4#hg=official

National Oceanic and Atmospheric Administration. (n.d.). IWPN4 gauge — Official observations. NOAA Water Prediction. https://water.noaa.gov/gauges/IWPN4#hg=official

National Oceanic and Atmospheric Administration. (n.d.). PEBN4 gauge — National Water Model (NWM). NOAA Water Prediction. https://water.noaa.gov/gauges/PEBN4#hg=nwm

Burlington County Times. (2011, August 29). Photos from Hurricane Irene. Burlington County Times. https://www.burlingtoncountytimes.com/picture-gallery/news/2011/08/29/photos-from-hurricane-irene/576167007/

NBC10 Philadelphia. (n.d.). Flooding in South Jersey, Philadelphia, Pennsylvania from storms. NBC Philadelphia. https://www.nbcphiladelphia.com/news/local/flooding-south-jersey-philadelphia-pennsylvania-storms/185873/