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1. Large urban centers have begun to worry about the sustainability of their water supplies Watershed management has become an important issue. http://www.catskillaccommodations.com/maps/images/ny100b.gif

2. The water supply for the Toronto and surrounding suburbs all comes from the Oak Ridges moraine which is at under heavy pressure from developers.

3. The watershed concept Quantitative analysis of stream flow The water balance equation Alberta watersheds The runoff coefficient, and runoff maps Measuring the area of watersheds on a topographical map and calculating stream discharge & velocity The temporal variability of stream flow Stream order within a watershed

4. The Hubbard Brook Watershed in the Appalachian mountains (New Hampshire) supports a rich Maple/Beech regrowth forest Experimental Watersheds where effects of various harvest regimes and methods on nutrient cycling are being studied Mirror Lake alongside Highway 93 A watershed is the entire drainage basin of a stream or river, from which all surface runoff and groundwater leaves at a single point.

5. Experimental studies on watersheds shaded area—after clear-cut • After clear-cutting & shrub removal the watershed cannot retain nutrients • levels of NO3-, K+, and Ca++ in streamwater draining experimental areas after clearcutting and shrub removal

8. A Watershed is like a semi-funnel P= precipitation (Vol /DA) /t Units L/t P x DA = R Units L/t * L2=L3/t R=runoff Vol/t

9. The hydrological balance equation EA PA To allow for both precipitation and evapotranspiration from the watershed we have (P-E)DA = R Where P an E have the same units (L/t). When multiplied by DA (L2) gives Runoff (Volume/t or L3/t)

10. Almost immediately after it stops raining on the funnel, water stops pouring out the spout. Imagine if that the surface of the funnel is lined with a sponge. Water would tend to seep to the bottom of the sponge and trickle out the spout for some time even after it stopped raining. Hydrologists refer to the water in the “sponge” as storage (S—units volume (L3). We can now write the equation as (P-E)DA - DS = R This equation indicates that there need not be an instantaneous runoff response to changes in P-E because the storage capacity of the watershed can change. The units of each term including DS are L3/t.

11. What watershed processes contribute to storage? The volume bound up in the various pools of the watershed Snow, glaciers, wetlands, lakes, streams rivers, groundwater, soil and plants Each of these pools gain water from precipitation and give up water to surface runoff The flows in and out of these pools are measured in Volume/t, as a changes in the volume of each pool. The hydrological balance equation Runoff(r*DA)= (Precipitation – Evapotranspiration) *DA – D Storage

12. Location:Alberta Government>Environment>Water> Alberta River Basins Alberta River Basins 1.Hay River 2.Peace/Slave 3.Athabasca 4.Beaver 5.North Saskatchewan 6.Red Deer 7.Bow 8.Oldman 9.South Saskatchewan 10.Milk The watershed/Drainage basin is the key management unit http://www3.gov.ab.ca/env/water/basins/BasinForm.cfm

13. x The Watershed/Drainage basin Smaller watersheds are nested subunits of larger watersheds

14. Watershed of High River Reservoir The Watershed of the Oldman River Little Bow River watershed

15. Runoff (R ) from different sized watersheds within the Oldman R watershed Slope = r—the runoff coefficient =0.030 m3/s per km2 =0.95 m3/m2/yr =0.95 m/yr [3.16 x 107 s/yr] 30 Castle River (Beaver Mines) * * Oldman R at Waldrons 20 * Runoff (R ) m3/s Waterton R (park gate) * 10 Castle River (Ranger stn) Gold Cr. * 600 800 200 400 Watershed Area (km2)

16. Map of mean annual runoff (r) for Western Canada (mm) Averaged over the last 30 yr. 1000mm=1m3/m2 of watershed each year or 1000 mm = 0.032 m3/s per km2 of watershed area