Economic and environmental tradeoffs from alternative water allocation policies in the South Saskatchewan River Basin

Figures & data

Figure 1. Map of irrigation districts within the South Saskatchewan River Basin.

Figure 2. The South Saskatchewan River Basin (SSRB) in Aquarius. The SSRB is represented in Aquarius as a network of approximately 70 demand and supply nodes. This figure provides a snapshot of how the network is modeled in the SSRB with diversion points and return flows along the reach. ID: irrigation district; IFN: instream flow needs; WCO: water conservation objective.

Table 1. The Aquarius model was calibrated to the 2001 drought to understand the vulnerability of the South Saskatchewan River Basin (SSRB). Natural flows are shown as a percentage of long-term average per sub-basin.

River sub-basin	2001 flow
	(% long-term average)
Bow River	72%
Oldman River	64%
Lower South Saskatchewan River	60%
Red Deer River	53%

Table 2. Comparison of economic efficiency of the initial allocation rules. Economic benefits improve under a share rule, but the system only achieves 56% of potential economic value.

Sub-basin	RDR	BR	OMR	LSSR	SSRB	RDR	BR	OMR	LSSR	SSRB
# Licenses	5	12	34	3	54	5	12	34	3	54
Total licensed allocation (Mm^3)	43	2153	1774	99	4069	43	2153	1774	99	4069
Licensed consumptive use (Mm^3)	4	1146	1450	30	2630	4	1146	1450	30	2630
Initial allocation scenarios	Prior allocation					Share allocation
Inflows (Mm^3)	799	2445	1774	23	5041	799	2445	1774	23	5041
# Licenses fully allocated	4 (80%)	4 (33%)	16 (47%)	2 (67%)	26 (48%)	4 (80%)	9 (75%)	24 (71%)	2 (67%)	39 (72%)
# Licenses partially allocated	0	2	5	0	7	0	1	1	0	2
	(0%)	(17%)	(15%)	(0%)	(13%)	(0%)	(8%)	(3%)	(0%)	(4%)
# Licenses unallocated	1	6	13	1	21	1	2	9	1	13
	(20%)	(50%)	(38%)	(33%)	(39%)	(20%	(17%)	(26%)	(33%)	(24%)
Cut-off year	1980	1908	1950	1913	1950	1980	1971	1978	1913	1971
Diverted (Mm^3) (% of licensed use)	36 (84%)	1291 (60%)	864 (49%)	10 (10%)	2201 (54%)	21 (49%)	1325 (62%)	789 (44%)	14 (14%)	2141 (53%)
Consumptive use (Mm^3)	4	836	700	3	1543	2	769	642	2	1414
Total economic value (% of optimal benchmark)	85%	33%	65%	24%	41%	87%	51%	76%	15%	56%
Trading scenarios	Full trading					Restricted trading (assignment)
Diverted (Mm^3) (% of licensed use)	106	2208	1007	55	3376	43	1428	895	59	2424
	(247%)	(103%)	(57%)	(56%)	(83%)	(100%)	(66%)	(50%)	(60%)	(60%)
Consumption (Mm^3) (% licensed consumption)	11	743	748	17	1519	4	708	722	18	1452
	(275%)	(65%)	(52%)	(57%)	(58%)	(100%)	(62%)	(50%)	(60%)	(55%)
# Sellers	0	2	20	0	22	0	2	20	0	22
# Buyers	5	10	14	3	32	1	8	13	1	23
# Of licenses not traded	0	0	0	0	0	4	2	1	2	9
# Licenses unallocated	0	0	0	0	0	0	0	0	0	0
Total economic value (% of optimal benchmark)	100%	100%	100%	100%	100%	90%	71%	103%	89%	77%

RDR: Red Deer River; BR: Bow River; OMR: Oldman River; LSSR: Lower South Saskatchewan River; SSRB: South Saskatchewan River Basin.

Table 3. Diversion and consumption by use (Mm³). This illustrates how water is allocated between municipal and irrigation licensees under each of the four scenarios. The first column under each sub-basin shows the amount of water diverted (div.), while the second column shows the amount of water consumed (con.).

River basin		RDR		BR		OMR and LSSR		SSRB
	Water use	Div.	Con.	Div.	Con.	Div.	Con.	Div.	Con.
Licensed diversion	Municipal	43	4	460	46	130	39	633	89
	Irrigation	0	0	1693	1100	1743	1440	3436	2540
	Total	43	4	2153	1146	1873	1479	4069	2641
Prior allocation	Municipal	36	4	6	1	24	7	66	12
	Irrigation	0	0	1286	836	851	696	2137	1532
	Total	36	4	1291	836	875	703	2201	1543
Share allocation	Municipal	21	2	168	17	24	7	213	26
	Irrigation	0	0	1157	752	771	636	1928	1388
	Total	21	0	1325	769	795	643	2141	1414
Full trading	Municipal	106	11	1276	126	150	45	1514	182
	Irrigation	0	0	950	618	912	720	1862	1338
	Total	106	11	2208	743	1062	765	3376	1519
Restricted trading	Municipal	43	4	400	40	90	27	531	71
	Irrigation	0	0	1028	668	864	713	1892	1381
	Total	43	4	1428	708	953	740	2424	1452

RDR: Red Deer River; BR: Bow River; OMR: Oldman River; LSSR: Lower South Saskatchewan River; SSRB: South Saskatchewan River Basin.

Table 4. Monthly marginal values for selected uses by scenario (CAD$2013). By showing the marginal values of different uses at the solution, it is found that municipal uses have a higher marginal value than agricultural uses. This Alberta phenomenon is consistent with water trades in the US where water is typically transferred from agricultural to municipal uses (Brown 2006).

Demand node	Water use	Water source	Range of monthly marginal water values
			($/dam^3)
			Benchmark	Assignment	Prior allocation	Share
Calgary	Municipal	Bow	$8–11	$1250–1410	$2800–2900	$1600–$1730
Calgary	Municipal	Elbow	$50–1600	$80–1600	$2900	$1450–2340
Red Deer	Municipal	Red Deer	$170–190	$480–635	$485–635	$485–635
Lethbridge	Municipal	Oldman	$65–320	$490–800	$490–725	$545–800
Medicine Hat	Municipal	South Sask.	$125–365	$110–555	$470–635	$515–720
Western ID	Irrigation	Bow	$140–340	$396–400	$395–400	$495–500
Eastern ID	Irrigation	Bow	$330–360	$110–225	$9	$35
Bow River ID	Irrigation	Bow	$320–350	$120–505	$340^†	$155–565
Lethbridge North ID	Irrigation	Oldman	$205–330	$40–330	$13–14	$60–365
Aetna-Leavitt-Mountain View ID	Irrigation	South. Trib.	$90–220	$105–300	$115–120	$220–250
United ID	Irrigation	South. Trib.	$215–220	$80–220	$9–105	$40–205
Magrath-Raymond ID	Irrigation	South. Trib.	$250–265	$250–260	$5–295	$60–360
St. Mary-Taber ID	Irrigation	South. Trib.	$240–365	$115–375	$115–145	$55–350

ID: irrigation district.

Table 5. Violation of instream flow needs (IFN) and water conservation objective (WCO) constraints per allocation scenario.

Scenario	Violations
	(months per year)
	Prior allocation				Share allocation
Sub-basin/basin	RDR	BR	OR	Total	RDR	BR	OR	Total
WCO upstream	1	1	2	4	1	1	2	4
WCO downstream	-	3	7	10	-	3	7	10
Total	1	4	9	14	1	4	9	14
IFN upstream	-	1	10	11	-	1	8	9
IFN downstream	7	4	8	19	7	1	6	14
Total	7	5	18	30	7	2	14	23
Scenario	Full trading allocation				Restricted trading allocation
Sub-basin/basin	RDR	BR	OR	Total	RDR	BR	OR	Total
WCO upstream	1	1	-	2	1	1	1	3
WCO downstream	1	3	4	8	1	1	6	8
Total	2	4	4	10	2	2	7	11
IFN upstream	-	-	8	8	-	3	8	11
IFN downstream	9	-	7	16	8	3	7	18
Total	9	-	15	24	8	6	15	29

RDR: Red Deer River; BR: Bow River; OMR: Oldman River; LSSR: Lower South Saskatchewan River.

Brown, T. C. 2006. Trends in water market activity and price in the western United States. Water Resources Research 42: W09402. doi:10.1029/2005WR004180.

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