Baccharis Consulting LLC

Water Inundation in Brandywine Creek Watershed, Delaware (2002-2017)

 

Picture of Brandywine Creek

      Brandywine Creek near tidal head at Market Street Bridge looking downstream

Discussion of Brandywine Creek Watershed

Brandywine Creek is the lowermost tributary of the Christina River.  The tidal section run from its confluence with the Christina River to just upstream of Market Street bridge in Wilmington, Delaware.  Most of the stretch is developed or highly disturbed.  More information on the watershed can be found at this link.

Tidal exposure is similar to the Christina River in miniature.  But like the others, it is a riverine watershed.  This means that precipitation events have an outsize influence on the inundation numbers.  For instance, you can have a heavy rainfall event in the upper parts of Brandywine Creek and have the water flow in the tidal sections and have nowhere to go but up.  There is not enough area for the water to spread out.  In these watersheds (riverine) it is best to look at the trends rather than the actual numbers.

Brandywine Creek Water Inundation

(2002-2017)

 

Table 1. Brandywine Creek Watershed Tidal Water (2002-2017) in acres
Year ETRW ECOW Total Tidal Water
2002 7.42 50.18 57.60
2007 7.30 49.92 57.22
2012 7.26 51.34 58.60
2017 7.34 52.36 59.70

ETRW = Estuarine Tidal Riverine Water (Salinity < 0.5 ppt)

ECOW = Estuarine Coastal Oligohaline Water (Salinity 0.5-5 ppt)

Table 1 shows that the amount of tidal water in the watershed has risen over time with a regression in the 2002-2007 period. However, compared to a lot of watersheds the amount of rise is slight.  This could be due to development on the shore and the steep creek banks.

Table 2. Average Rate of Brandywine Creek Watershed Tidal Water Inundation 

(2002-2017) in acres/year

2002-2007 -0.08
2007-2012 +0.28
2012-2017 +0.22

Table 2 shows that the inundation rate after regressing in the 2002-2007 period has been consistently upward.  This is an unusual result when compared to other watersheds.

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