## Term Assignment

Introduction

The amount (tonnes) and concentration (mg per litre of water) of suspended sediments transported by streams is a good indication of sediment production in the watershed by erosion and mass wasting and the availability of suspendible materials.

Objective

To examine the spatial and temporal variations in the suspended sediment load of four Canadian rivers.

The Hydrometric Stations

River Station Name Station Number
FRASER Mission, BC 08MH024
ANNAPOLIS Wilmot, NS 01DC005
NORTH SASKATCHEWAN Prince Albert, SK 05GG001
MACKENIZE Arctic Red River, NWT 10LC014

Instructions

Analyze and explain the variations in suspended sediment load and concentration over time and between stations. Make extensive use of graphs and tables. Start with the following analyses:

• Calculate two measures of basin denudation rate, in tonnes/km2, for each watershed by dividing the total annual suspended sediment load (tonnes) by the gross basin area (km2) and by the effective drainage basin area (the area that consistently generates runoff and sediment, if it is available), if available.
• On one graph for each river, plot mean stream discharge (m3/sec) and mean suspended sediment load (tonnes) on a monthly basis, that is the monthly average for a number of years.
• Plot the mean monthly suspended sediment concentrations (mg/L) for all five rivers on one graph, clearly distinguishing between the four curves.
• Plot daily sediment load (tonnes) and concentration (mg/L) during storms or snowmelt events, that is, when there are significant changes in streamflow.

Compare sediment load and concentration among the four rivers, and discuss any differences and similarities and what they imply about the geology, geomorphology, land cover and climate of these watersheds.  This discussion must focus on the data, graphs, tables and on any information that you collect about the watersheds from the library, map library and Internet .

Here are some Web sites:

Environment Canada Home Page
http://www.doe.ca/envhome.html
Environment Canada, water and climate page
http://www.cmc.ec.gc.ca/climate/
National Atlas of Canada, schoolnet page
http://www-nais.ccm.emr.ca/schoolnet/maps/Home.html
Geological Survey of Canada, surficial geology map of Canada
http://sts.gsc.nrcan.gc.ca/page1/sgm/maps.htm
Canada Centre for Remote Sensing, images of Canada
http://www.ccrs.nrcan.gc.ca/ccrs/imgserv/tour/toure.html
Saskatchewan Water Corporation
http://www.saskwater.com/
US National Geophysical Data Centre (global databases)
http://www.ngdc.noaa.gov/

The data are stored in text (ASCII) files. The file name is the station number. The file extension refers to the sediment or stream flow parameter:

 .fsm ——> summary of flow data, mean monthly values for the period of record .fdy ——> the daily discharge data .fex ——> extreme discharges .fmn ——> mean flows, mean monthly values for each year .ssm ——> summary of sediment data .cdy ——> the daily sediment concentration data .ldy ——> the daily sediment load data

For example, the file 08MH024.cdy contains the daily sediment concentrations for the Fraser River measured at Mission, B.C.. The data are in tables (i.e., space delimited), so you should be able to load them directly into a spreadsheet.

Click here to download 323tp99.exe which contains all the data for the four rivers. In My Computer (Windows 95) or File Manager (Windows 3.x) double click on this file to extract all 28 data files (seven for each river).