River Gauge Markers & GPS for Flood Fighting Seminar

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2008 brought some of the most devastating flooding that our area has seen. After the flood of 1993 we had hoped to never see another 500 year flood in our time, however with crests that were approaching the 1993 levels we had two 500 year floods in a 15 year time span.

One of the main problems encountered in the 2008 flood was the ability to determine how high to go with the protection do to lack of an effective method to relate levee height to predicted flood crest. We quickly found out that a crest prediction of 28’ at one gauge may not relate very well to other points of interest along the levee.

A simple and cost effective solution to this problem is the installation of a river marker system along the levee. This system would place a marker (a pole of sorts) every 250 yards along the levee on the river side. This marker would have a base elevation where it meets the levee, and would protrude out of the levee. From the base up there would be a 1’ incremental marker (similar to a large ruler), that would display both the actual
elevation and the elevation in relation to the river gauge.

Example:
Elevation: 500.00 ft
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Gauge Level: 22.17’

The purpose behind this is so that at any point along the river the crest predictions can be directly related to how high the river will be.

Currently Mid-West GIS, Inc. is developing this exact system for the Keokuk Municipal Water Works water plant in Keokuk, IA. Using Sub-Centimeter Real Time Kinematic (RTK) GPS equipment over 15 points were collected at critical locations around the plant. These points have both the elevation in ft, and the gauge level. This database can be referenced at any given time to know exactly what features will be compromised at a given river level. In addition, 3 or 4 permanent markers will be placed at the top critical locations such as entryways. These markers will be 2” x 36” aluminum markers that will be anchored in the entryways. They will
display the base elevation & gauge level (at the base of the door) and three 1’ increments to the top of the marker.

The presentation will also cover using the same Sub-Centimeter Real Time Kinematic (RTK) GPS equipment to accurately measure the elevation of the levees as they are pushed up and sandbags are added. Having access to accurate measurements on the levee can help avoid unknown low spots as well as unnecessary additions in locations that already have adequate height.

Mid-West GIS will be conducting this seminar at the following location:

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