Manitoba's Water Protection Handbook - Government of Manitoba

Did You Know?Many ProcessesContribute to WeatherThe water cycle is just one of the climatic processesthat contribute to our weather. Other processesinclude water currents, air movements andvolcanoes. Over the course of time, long-termweather patterns have created extremes - fromice covered continents to vast deserts. Climaticfluctuations lasting days, months, or a few years canresult in local droughts and floods.Distribution of theEarth’s Water SupplySupply/Source Volume Percent(in thousands of Totalcubic kilometres)Oceans 1,310,302 97.3Ice 29,492 2.2Groundwater 6,733 0.5Inland Lakes 242 0.02Soil Moisture 740 .005Atmospheric Water Vapour 140 .001Rivers 1.30 .0001Source: Environment Canada• Only 2.7 per cent of the earth’s water is freshwater- 2.2 per cent is locked up in glaciers and polarice caps. This leaves about 0.5 per cent distributedas groundwater, soil moisture, atmospheric watervapour, lakes and rivers.• Average annual precipitation in the province rangesfrom 400 millimetres in northern Manitoba to 600millimetres in the southeastern corner.• Two-thirds of Manitoba’s precipitation fallsbetween May and October.• Manitoba’s average snowfall ranges from 1,200millimetres in the south to 1,700 millimetres inthe north.• Each year, an average of 300 to 350 millimetresof water is evaporated in the north while 450 to500 millimetres evaporates in the warmer southernhalf of the province.• Manitoba’s large lakes have a moderating effecton climate - they act as heat sinks making the falland early winter milder and the summer cooler.• Winter snowfall serves as water in storage. Whenthe snow melts in the spring, Manitoba’s riversand streams carry large amounts of water andmany serve as important spawning groundsfor fish.• All life depends on water. Two-thirds of the humanbody is composed of water. In fact, water is soimportant to our bodies that we can only survivefor a few days without it, but more than 30 dayswithout food.• Heavy rains result in more runoff while light steadyrains generally soak into the soil.3