Environmental Engineering Reference
In-Depth Information
The highest land in the Minnesota portion of the Red River basin is located in
Clearwater County in the Wild Rice River watershed at an elevation of 2,010 feet
above sea level. The lowest land, located in Kittson County along the Red River near
the Canadian border, is 750 feet above sea level.
The most flood-prone areas generally are those with the least slope and those
downstream from areas of steep slopes.
The gradient of the Red River ranges from a little over 1.0 foot per mile north of
Breckenridge, to about 0.5 foot per mile in the vicinity of Grand Forks, to about 0.2
foot per mile at the Canadian border. Profiles of the Red River from Wahpeton to the
Canadian border are shown on Figure 9.1.
RUNOFF TRAVEL TIME
Another way to help understand the hydrology and delivery of water to restorations
in large riverine basins is to identify early, middle, and late tributary areas relative
to the river main stem. Computed runoff travel times (Figure 9.3) based on topogra-
phy and land use show the relative travel time of runoff (the darker the shading, the
longer the travel time).
The map only depicts time in transit. Therefore, the detention effect of wetlands,
lakes, and other storage is not shown.
DEFINITION OF EARLY, MIDDLE, AND LATE AREAS
RELATIVE TO THE RED RIVER MAIN STEM
Figure 9.4 identifies early-, middle-, and late-runoff areas within the Red River basin
relative to the main stem. This generalized map was based on the evaluations of
historical flood hydrographs, knowledge of more recent floods, and computed runoff
travel times. The design of hydrological restoration in Iraq's Mesopotamian marshes
will require data on seasonal water flow and the timing of flood flows.
The Red River of the North is one of only a few major rivers in North America
that flow north. This increases its spring flood potential, because snow in the south-
ern headwaters of the basin often melts before snow in the northern areas, causing
peak flows from downstream tributaries to coincide with the flood crest on the Red
River. The northward flow of the river also results in more ice jam problems than
most southern-flowing rivers experience. In addition, the Red River is located within
the broad, flat bottom of glacial Lake Agassiz, which has only a slight northward
slope. As a result, the main stem and tributary rivers in the glacial lake plain area of
the basin frequently overflow onto broad floodplains. A significant body of knowl-
edge and data on the hydrology and flood hydraulics relationship is available for the
Red River basin (see references). However, hydrological relationships with biological
diversity or productivity remained unexplored. A series of studies were designed and
implemented to test and understand these relationships and to provide an applied
basis for the design and implementation of wetland restorations in the Red River
basin. The following summarizes some of the general findings from these investiga-
tions (Table 9.1).
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