Tides

Tide Tables

Always check the tides before planning any activity on the tidal waters in the marshlands.  The tides in Bordentown are about the same as those in Trenton.  The tides in Watson Woods are approximately 1 hour later.

Tide tables for selected dates and locations along the Delaware

Tides at the Abbott Marshlands

Tides are daily rhythms, as dependable as day and night. Along the east coast of North America, they are semidiurnal, with two high and two low tides each day. Tides are the result of force created by the earth as it rotates on its axis and the gravitational pulls of the moon and the sun.

The ebb and flow of water along the New Jersey coast is felt in Delaware Bay and all the way up the Delaware River to Trenton. As the ocean tide rises, a large amount of water enters the bay, and as it moves the volume is constricted, and tidal water is forced up river all the way to the Falls at Trenton. Thus, as the tide rises in the Delaware, the water shifts upstream and the water level in adjoining creeks and wetlands, such as Crosswicks Creek and the Marsh, also rises.

Interestingly, this effect is amplified up river. For example on Oct 17, 2009, high tide was 6.6 feet at Hope Creek, about 0.6 mile above the beginning of the Delaware River (elevation above sea level = 3 feet), while at Trenton, 125 miles up river (elevation = 52 feet), high tide was 9.5 feet. There is considerable time lag: high tide at Hope Creek was at 10:35 AM while at Trenton it was 2:40 PM.

Some points to ponder:

• Tidal water at the Marsh is fresh water. Salty water occurs south of Philadelphia.
• There were no tides in the region 1200-1500 years ago. (Sea level was lower).
• Back and forth movement of water with tides is 12 miles, so that, for example a seed produced downstream along the Delaware River could find its way upstream into the Marsh.

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  The depths of the water at high and low tides vary seasonally, with the phase of the moon, and with position of the moon relative to the sun. Such changes are related to the earth’s orbit being elliptical and that the earth is tilted on its axis.

• It takes longer for the tidal water to flow out of the Marsh (7 hours) than to flow in (5 hours).
• Times of high and low tides shift ahead by approximately 1 hour each day.
• Tidal range at Trenton (and the Marsh) is 3 feet greater now than 70 years ago. This is attributed in part to sea level rise, but also to the filling in of wetlands along the river and to river channelization during the 1940s and 1950s making the Delaware navigable to Trenton.