Using Surfer and Grapher for Stream Flow Visualization

Introduction

Richard Koehler, a visiting scientist with the Cooperative Program for Operational Meteorology, Education and Training (COMET^®), uses Surfer and Grapher to display river flow rates and climatic data sets. His displays make it easier to recognize short- and long-term fluctuations that disrupt the natural processes of a river. Recognizing and identifying artificial fluctuations and disturbances is critical to understanding river systems and developing management efforts to achieve more natural flow regimes. In addition, climatic data for many drainage basins can be displayed in a more effective method for easier comparison between basins.

Working with Large USGS Datasets

Visualizing river records covering 100 years of daily data values can be a problem. Typical methods include line graphs, monthly averages, daily average with extremes, or plotting a small part of the entire record. Grapher does a great job of plotting the data and displaying obvious features and trends.

Line graph of stream flows of the Colorado River at Lees Ferry, AZ.
Water Year 1921 through 2001.
 
A = high flow during snowmelt.
B = low flow when Glen Canyon dam closes.
C = 1983 El Nino wet weather cycle.
D = high flow during 1996 artificial Grand Canyon flood.

Raster Visualization of Stream Flow Data

Rick uses Surfer to plot the data using a raster method that he presented in his doctoral thesis at the University of Arizona. He assigns the day of the year to the X axis, the year value to the Y axis, and the log(flow) value to the Z axis. By displaying flow rates with color, and stacking the yearly graphs vertically, similarities between years and anomalous events become more apparent.

Raster graph of stream flows of the Colorado River at Lees Ferry, AZ.
Water Year 1921 through 2001.
 
A = high flow during snowmelt.
B = low flow when Glen Canyon dam closes.
C = 1983 El Nino wet weather cycle.
D = high flow during 1996 artificial Grand Canyon flood.
 
1 = low flow during Christmas due to lower demand for power generated by Glen Canyon dam.
2 = repeated low flows during weekend power downturn (Sundays).

COMET is a program of the University Corporation for Atmospheric Research (UCAR) in Boulder, Colorado.