© 2014 The International Institute for Sustainable Development
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3.0 Results
3.1 Hydrology and Water Balance
Nutrient mass load transported to the lake by stream lows, and the other contributing sources, was calculated by multiplying the volume of water inlows by nutrient concentrations. For stream nutrient concentrations, all
loads were derived from relationships established between sampled stream water nutrient concentrations and simultaneous discharge. The modelled water balance for each potentially contributing input to the lake streams,
diverted inlow, precipitation and groundwater and then output from the lake evaporation, diverted outlow and groundwater was used to calculate loading mass is illustrated in Table 4.
Table 4. Pelican Lake modelled water balance million m
3
presented by stream flows, diverted inflow, groundwater, precipitation, evaporation and diverted outflow over the eight-month research period
Month Input
Output GW
Δ volume Stream flows
Diverted inflow PL08-Inlet
Precipitation Evaporation Outflow
PL08-Outlet
March 0.757
4.97 0.222
1.17 0.0
-2.35 2.43
April 0.489
1.54 1.43
2.12 0.0
0.94 2.24
May 2.194
0.11 1.10
3.09 0.0
3.72 3.90
June 8.263
2.16 5.82
2.47 0.731
-15.8 -3.28
July 2.352
0.0 5.73
1.25 6.23
1.14 1.41
August 0.004
0.0 1.16
0.37 0.0
-1.39 -0.582
September 0.256
0.0 2.21
0.62 0.0
-2.43 -0.562
October 0.165
0.0 0.84
0.68 0.148
-0.502 -0.310
Note: GW = groundwater; Δ volume = changes in lake volume.
Diverted inlow PL08A-Inlet and diverted outlow PL08C-Outlet is the volume of water entering or leaving the lake through a regulated dam at the south end of Pelican Lake. The dam’s inlet, allowing water from the Pembina
River into Pelican Lake, was opened for 18 days March 10–14 and 19–20, April 18–22 and May 31–June 5. The dam’s outlet was opened for three days at the end of June 28–30 June and then for 29 days during July July 1–29;
Tables 4 and 11.
The water budget for Pelican Lake indicated that in the month of June, a signiicant amount of water left the lake, the change in lake volume was -3.28 million m
3
, and transferred to surrounding aquifers, -15.8 million m
3
. This month also corresponds to the highest lake level recorded during the study period.
3.2 Phosphorus Budget: Load transported to and from the lake
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