Flows and Transport in Rivers - Hydro-Environmental Analysis: Freshwater Environments - page 84

Depth

Width

FIGURE 4.1 Characterization of low. (From FISRWG, Stream Corridor Restoration: Principles, Processes,
and Practices , Federal Interagency Stream Restoration Working Group, 1998.)

1997). The estimation of the low components requires the availability of historical data and often
some assumptions related to the underlying statistical distribution of the lows.
This chapter introduces the methods for the measurement and analysis of lows. First, the meth-
ods for the measurement of lows are presented, followed by the methods for analysis.

4.2 WATERSHED IMPACTS
The hydrology of a watershed is one of the primary factors inluencing the physical and biological
characteristics of rivers and streams. The impacts vary with the watershed's geology, including its
topography, land use, and land cover. The magnitude and the duration of rainfall also have a profound
impact, as illustrated by the typical rainfall runoff hydrograph illustrated in Figure 4.2. During periods

Lag time

Rainfall (mm)

Storm

Surface runoff

Channel precipitation
Interflow

Groundwater flow = base flow

Time

FIGURE 4.2 Stream hydrograph. (From Hebert, P.D. (ed.), Canada's Aquatic Environments, [Internet]
CyberNatural Software, University of Guelph, 2002. Available at http://www.aquatic.uoguelph.ca/. With
permission from the Biodiversity Institute of Ontario.)