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Chapter 4: Climate

Only a few aspects of an area’s climate show up on remotely sensed images, for example, the distribution of snowfall. However, air photos do show several of the effects of, and responses to, climate such as the construction of shelterbelts to protect against the wind.

4.1: Winter Landscape South of Rivers

Most air photographs are taken during the summer half of the year, but this early winter photo illustrates the usefulness of photos taken when there is snow on the ground. The photo shows the Little Saskatchewan River in the north 1, very dark-toned because it is not yet frozen. The Rivers Dam 2 can be seen near the top of the photo, with frozen Lake Wahtopanah behind it 3. A spillway bypasses the dam on the south 4.

Agricultural land is snow-covered and appears very light-toned, with hummocks in the underlying land producing a bumpy appearance 5. In places harvesting patterns can be seen 6. In contrast, wooded land is dark-toned 7. The deciduous trees, without leaves at this time of year, throw long shadows easily picked out on the snow-covered fields 8. Route ways on the photo include PTH 25 in the north 9 with a dark-toned bare surface because of traffic use. In contrast a less used north/south secondary road 10 is snow-covered. The CN railway line 11 roughly parallels PTH 25. A gravel pit is located in the northeast 12.

[[fig. 4.1]]

4.2: The Assiniboine River and Valley Near Fort Ellice in Late Winter

This late winter photograph illustrates the usefulness of a light snow cover in picking out minor relief features. The Assiniboine River 1 meanders southwards across the area. It has left behind meander scars, particularly noticeable where woodland has been removed 2, and also a series of abandoned channels 3, 4, 5, 6 which tend to collect snow. The river flows in a steep-sided, flat-floored spillway, the east side of which is dissected by gullies that collect snow 7, 8, 9, 10, 11. A small stream with a steep-sided valley 12 flows southeast to join the Assiniboine off the photo. More snow has accumulated and remains on the colder, north-facing slope 13 than on the south-facing side. On the Assiniboine valley floor one field in particular has retained snow 14, possibly because stubble has been left standing. The snow cover emphasizes minor drainage channels 15.

The linear feature on the east side of the Assiniboine Valley 16 is the CN railway line built just above the flood plain.

[[fig.4.2]]

4.3: Light Dusting of Snow in Palaeochannel Area North of Portage la Prairie

This early winter photo shows two abandoned river channels 1, 2 meandering across a flat plain. A light dusting of snow picks out some of the meander scrolls 3, 4. It also emphasizes the harvesting pattern in several fields 5 including an unusual arrangement in one of them 6. Farm buildings on this open plain have tree shelterbelts on the north side at least 7. The trees throw long shadows that indicate that they are deciduous 8—without leaves at this time of year. Rather surprisingly snow drifts near shelterbelts 9 indicate that recently wind was from the southeast. Section lines 10 and quarter section lines 11 are obvious. As usual farms 12 are located along section lines.

[[fig. 4.3]]

4.4: The Souris Valley West of Lauder in Autumn and Spring

The two photographs show the same stretch of the Souris River in autumn (figure 4.4a), and in spring (figure 4.4b). In the former the course of the northeast flowing Souris River 1 can be seen, meandering at first, followed by a straight stretch. A weir is located 2 where the river changes from meandering to straight. Scars indicating former river positions can be seen 3 but only one stretch 4 is occupied by water. In the spring photo (figure 4.4b) all the abandoned channels are filled with water 5; water also occupies the lowland between meander scrolls 6. This comparison illustrates the usefulness of interpreting photos taken at different seasons.

Also the photo in figure 4.4b was taken several years before photo in figure 4.4a so changes in the landscape can be observed:

1)  a drainage ditch 7 has been constructed on figure 4.4a.

2)  several dugouts 8 have been constructed on figure 4.4a.

3)  gravel roads have been constructed 9 or improved 10 on figure 4.4a.

Note also, the orientation of the photo in 4.4a is unusual in that the sides are not east/west and north/south. It is part of a sequence of photos taken along the course of the Souris River resulting in photo sides which trend at an angle to the cardinal points.

[[fig.4.4.a]]
[[fig.4.4.b]]

4.5: Field Shelterbelts North of Lyleton

During the 1930’s drought, soil erosion was severe in this dry flat area in the extreme southwest of Manitoba. Thin soils that had developed on hummocky ground moraine were easily blown away. The mottled appearance of several fields 1 results from the removal of dark-coloured soil constituents from slightly elevated areas.

From the earliest days of agriculture in the area, shelterbelts were built around farm buildings 2. A new strategy in response to the drought was the planting of field shelterbelts in north/south 3 or east/west 4 lines with trees brought from the tree farm at Indian Head in Saskatchewan. Farmers were also given grants for small-scale water projects such as the construction of dugouts 5 and small dams 6 to capture spring runoff. Gainsborough Creek 7, that flows west to join the Souris River (off the photo), is intermittent in this area and more a series of ponds 8—probably dam-created for water supply—rather than a continuous river. As is usual, roads follow section lines 9, and in two cases they are relatively newly constructed 10.

[[fig. 4.5]]

4.6: Responses to Climate in the Souris Valley West of Souris

The Souris River 1 flows west to east through the area that is flat and windswept. A standard response is to plant trees around farm buildings 2. In one location trees 3 protect both the CP railway line 4 and a farm to the south 5. Another row of trees protects the line further west 6, just west of a railway junction at Schwitzer 7.

All the land apart from the wooded banks of the Souris 8 has been cleared for agriculture. On this late September photo, harvesting has been completed leaving behind characteristic patterns 9. Two dugouts are located in this area 10, and a weir exists on the Souris 11, probably to raise the water level for agricultural supply.

[[fig. 4.6]]

4.7: The Little Saskatchewan River and Its Valley North of Elphinstone in Late Winter

The photo shows the upper reaches of the Little Saskatchewan River 1 flowing south from Riding Mountain and cutting through an area of hummocky ground moraine. The river is meandering on a flood plain 2 up to 1,200 feet (366 m) across, with numerous cutoffs 3. On this late winter photo, water covers much of the floodplain resulting in a very dark tone 4. Numerous lakes occupy hollows in the ground moraine. All the winter snow cover has melted from the land, but ice still exists on several lakes usually producing a light tone 5, but in two cases the ice is dark-toned 6.

Some of the land has been cleared for agriculture, but because of the hummocky terrain and thin soils woodland remains 7. On the agricultural land harvesting patterns from the previous year can be seen 8, and several fallow fields exhibit the characteristic light-toned crests 9. The route ways in the area are gravel roads often influenced by the terrain to digress from the DLS grid 10. One road crosses the Little Saskatchewan River 11, and in the north a path traverses the river 12, but it is flooded at this time.

[[fig. 4.7]]

4.8: Frozen Lakes and Snow Distribution in Early Winter in Central Manitoba

This early winter Landsat 1 image shows clearly the distribution of snow and ice over parts of central Manitoba. Wooded areas are easily picked out because of their dark tone, for example, Riding Mountain 1, Duck Mountain 2, and the Porcupine Hills 3. In both Riding Mountain 4 and Duck Mountain 5 scars left by forest fires are obvious; woodland has only partly regenerated in these areas resulting in a lighter tone than the surrounds. By this date all the lakes are frozen and have a snow cover producing a light-toned, even-textured surface, for example, Clear Lake 6 and Whitewater Lake 7 in Riding Mountain, Dauphin Lake 8, the north end of Lake Manitoba 9, Lake Winnipegosis 10, Waterhen Lake 11, and Swan Lake 12 in the north. The Assiniboine River has been dammed at Shellmouth 13 creating Lake of the Prairies 14—light-toned and even textured. The image was obtained close to the winter solstice when the sun angle was low resulting in long shadows, especially where valleys trend east/west, for example, those of Boggy Creek 15, the Shell River 16, Birdtail Creek 17, and parts of the Assiniboine 18 Despite the fact that they are frozen and snow-covered, some river courses appear dark-toned because they are fringed by woodland, for example, Swan River 19 leading to Swan Lake and Wilson River 20 flowing to Dauphin Lake.

[[fig. 4.8]]

4.9: Frozen Lakes in Early Winter Near the Northern Settlement of Lynn Lake

This October photo of an area near the mining settlement of Lynn Lake 1 shows how early lakes are frozen over in northern Manitoba. At this time some lakes, for example, Lynn Lake 2 and West Eric Lake 3, are ice covered, the ice surface appearing in medium grey tone with a stippled texture. Route ways on the ice show as light-toned lines 4, several of which converge on a jetty 5 on the west side of Lynn Lake. Other lakes are still partly open, for example, Eric Lake 6 in the north and West Lynn Lake 7 in the south. Open water is very dark-toned with a smooth texture 8. In the case of West Lynn Lake open water occurs where a stream enters 9. Little snow had fallen by the date of the photo but some—very light-toned—can be seen in clearings in woodland 10 and in the town site 11. Winds from the north have created small drifts on West Eric Lake 12.

This area lies within the coniferous forest vegetation zone.[i] Long pointed shadows are thrown from coniferous trees on to the ice in several locations 13. The directions of the shadows—almost due north—indicate that the photo was taken near noon. Within Lynn Lake are two large buildings 14 and numerous barrack-like buildings 15 to house miners. The town’s airfield 16 is located to the northwest.

4.10: Ice Distribution on Lakes of Central and Southern Manitoba in Late Spring

In this late spring image, ice has melted from the lakes of southern Manitoba. Lake Manitoba 1, Dauphin Lake 2, and the south ends of lakes Winnipeg 3 and Winnipegosis 4 are ice-free and appear a khaki green/muddy brown. However, the north ends of lakes Winnipeg 5 and Winnipegosis 6, as well as Cedar Lake 7, South Moose Lake 8, North Moose Lake 9, and all the lakes further north are still iced over with a snow cover; they are therefore imaged as white. In the south some lakes—clear of ice—appear almost black, for example, Pelican Lake 10, Clear Lake 11, and Lake of the Prairies 12. Numerous prairie fires, imaged as red, were burning at the time in southern Manitoba 13, southern Saskatchewan 14, and North Dakota 15.

[[fig. 4.10]]

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