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Chapter 1: Introduction

1.3: Sequential Air Photos of the Assiniboine River West of Brandon

Figure 1.3a: 1945 photo

The Assiniboine River 1 flows from west to east with a large meander loop 2 to the north. Below the meander the river is remarkably straight, hugging the south bank of the Assiniboine Spillway the south side of which is more heavily wooded 3 than the north side 4. This is a result of a wetter microclimate on steep north-facing slopes. The photo was taken in the early winter after a light snowfall. Snow—very light-toned—has accumulated more in some places than in others; for example, it is more obvious on a rough field surface in the northwest 5 than over the fields just to the south 6. At this early stage of winter, the Assiniboine is not frozen and appears as a characteristic light tone due to high-suspended sediment content.

Figure 1.3b: 1968 photo

The area shown in figure 1.3a is in the northwest corner of this smaller scale photo. Twenty-two years after 1.3a was taken, the meander loop has been cut across 1. Given the width of the meander neck, it would seem that the river was artificially straightened. A small causeway across the north end of the meander 2 hints at the reason for the straightening. Land within the loop is now cropped 3 while it was not on figure 1.3a. To gain access to the area it was possible for the farmer to build a causeway across the static water of the cutoff whereas this could not be done with a flowing river. Note also the contrast between the light tone of the sediment-laden Assiniboine River 4 and the dark tone of the sediment-free cutoff 5. The Little Saskatchewan River can be seen in the northeast 6 following much the same route as it did in figure 1.1b.

Figure 1.3.a: 1945 Photo

Figure 1.3.a: 1945 Photo

Figure 1.3a

Vertical air photo: A7566-5

Flight height: 12,400 feet a.s.l.; lens focal length: 209.55 mm

Scale: 1:13,900 (approx.)

Date: April 13, 1945

Location: Township 10, Range 20 WI

Map sheets: 1:250,000: 62F Virden

1:50,000: 62F/16 Alexander

Figure 1.3.b: 1968 Photo

Figure 1.3.b: 1968 Photo

Figure 1.3b

Vertical air photo: A20470-66

Flight height: 21,950 feet a.s.l.; lens focal length: 152.73 mm

Scale: 1:39,000 (approx.)

Date: May 21, 1968

Location: Township 10, Ranges 20 and 21 WI

Map sheets: 1:250,000 62F Virden

1:50,000 62F/16 Alexander