Field manual for identifying and preserving high-water mark data

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environmentvisit https://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. AbstractThis field manual provides general guidance for identifying and collecting high-water marks and is meant to be used by field personnel as a quick reference. The field manual describes purposes for collecting and documenting high-water marks along with the most common types of high-water marks. The manual provides a list of suggested field equipment, describes rules of thumb and best practices for finding high-water marks, and describes the importance of evaluating each high-water mark and assigning a numeric uncertainty value as part of the flagging process. The manual also includes an appendix of photographs of a variety of high-water marks obtained from various U.S. Geological Survey field investigations along with general comments about the logic for the assigned uncertainty values.

Preliminary peak stage and streamflow data for selected U.S. Geological Survey streamgaging stations in North and South Carolina for flooding following Hurricane Florence, September 2018

“…In other cases, high-water marks are documented for the purpose of recording the depth of the flood waters ( fig. 9; Koenig and others, 2016;Feaster and Koenig, 2017).…”

Total water level data from the January and March 2018 nor’easters for coastal areas of New England

“…5) during a riverine or coastal flood is known as a HWM (Benson and Dalrymple, 1967). The highest water level is often documented by deposits of natural and manmade pieces of debris (seeds, grasses, tree needles or leaves, woody material, sediment, trash, or ice) that are transported by floodwaters or waves, and deposited on the sides of buildings, fences, mailboxes, telephone poles, and trees (Koenig and others, 2016;Feaster and Koenig, 2017). These types of deposits are common during flooding and are used as evidence in identifying the highest water level ( fig.…”

“…Using procedures described by Benson and Dalrymple (1967), Koenig and others (2016), and Feaster and Koenig (2017), HWMs were identified, flagged, and documented for the peak total water level elevations from the January and March 2018 nor'easters. Information on the approximate horizontal location, the type and general accuracy of the HWM, and approximate elevation above the land surface were documented so they could be found by surveyors later.…”

Flood-inundation maps for the lower Pawcatuck River in Westerly, Rhode Island, and Stonington and North Stonington, Connecticut

“…Absolute differences were less than 0.5 ft for 6 of the 10 HWMs, between 0.5 to 1.0 ft for 2 of the 10 HWMs, and greater than 1 ft for 2 of the 10 HWMs. Field crews can sometimes collect a HWM that is lower than the peak water-surface elevation of a flood, as more than one line of marks can be left by debris, seeds, and mud as floodwaters recede (Feaster and Koenig, 2017). This is likely the case with USGS-100, as it has a simulated water-surface elevation 2.10 ft higher than the surveyed HWM elevations, and as the model is well calibrated to another nearby HWM (USGS-99).…”