Last Modified: 2023-03-03 14:47:11.309

Software Version

HEC-WAT Version 1.1.0 was used to create this example. You can open the example WAT study with HEC-WAT Version 1.1.0 or a newer version.

Download Initial Project File: Hydrologic_Sampler.7z

Purpose

In this workshop we will create a new Hydrologic Sampler (HS) alternative for a Russian River HEC-WAT study. Then we will update the existing FRA simulation in the study to use the new HS alternative, which will require us to also update the Model Linking, Output Variables and Skip Flags to use the new HS alternative. Finally, we will perform a compute of the updated FRA simulation and review the results.

For the Hydrologic Sampler alternative, we’ll be entering the information for generating basin-wide precipitation events in the Russian River basin, based on the Basin-Average frequency curve method.  We’ll need four elements:

  1. A distribution that describes the flood season, capturing when events happen.
  2. A frequency curve for 8-day basin-average precipitation depths.
  3. A list of HMS sub-basins and their drainage areas.
  4. Shape sets of hyetographs shapes, one for each of the HMS sub-basins.

Hourly precipitation data for 1950 through 2010 is available from a USGS gage in the Russian River basin.  A drainage area weighted basin average time series has been generated, as shown in the figure below.

Period of Record of average precipitation depth in the Russian River Basin

It was determined that an 8-day period is critical for generating the events that challenge the flood protections in the watershed.  The figure below shows the annual maximums of 8-day accumulated precipitation depths.  From this data set of annual maximums, we have determined when the flood events occur, and estimated the precipitation frequency curve.

Workshop Overview

Work through all four parts of the Hydrologic Sampler workshop.