# Calculating the Total Annual Depth of Streamflow

Initial Publication Date: September 8, 2015

#### Introduction

The objective of this step is to calculate the total annual depth of streamflow from a given streamflow time series . We have used the historical instantaneous streamflow data of the Hall Creek in Indiana (USGS gage 0337580) for the period 01/01/2000 - 12/31/2000 to demonstrate the step.

## Conceptual Outcomes

- Students demonstrate the understanding of the concept of expressing total streamflow volume as equivalent depth (volume/area) units.

- Students demonstrate their ability to obtain total volume from streamflow time series records.

## Practical Outcomes

- Students learn to calculate total runoff volume from a streamflow time series in MS excel.

- Students learn to express the total streamflow volume in equivalent depth units.

30 minutes

## Computing/Data Inputs

• Numerical data: Streamflow time series (15-minute intervals) file for Hall Creek in Indiana: Streamflow time series (Excel 2007 (.xlsx) 1.5MB Sep7 15)
• Numerical data: Area of Hall Creek Watershed = 21.8 square miles

## Computing/Data Outputs

• Numerical Value: Total annual streamflow depth at the watershed outlet

MS Excel

## Instructions

The first step is to find the total volume of streamflow. To do this, add all the streamflow values, and multiply the sum by the time interval (in seconds) of the series as shown below. Next, divide this total streamflow volume by the watershed area to get the equivalent total annual streamflow depth, using consistent units in the process.

Now, you know how to calculate the equivalent streamflow depth from a given streamflow time series at the watershed outlet.