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National Water Account 2018

Perth: Statement of Water Flows

The volume of water in the region's storages increased during the 2017–18 year for the second year in a row.
This increase represents the change in water volume in the region's aquifers and surface water reservoirs.

The Statement of Water Flows is provided below and presents the actual water flows associated with the region's water stores during the year, including flows corresponding to the accrual transactions shown in the Statement of Changes in Water Assets and Water Liabilities.

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	2018 ML	2017 ML	2016 ML	2015 ML	2014 ML	2013 ML
Water inflows
Surface water inflows	1,374,944	1,782,956	778,502	937,289	1,154,779	602,345
Precipitation	55,877	37,453	16,824	21,238	25,009	17,978
Runoff	749,192	840,406	352,148	549,983	787,143	359,858
Delivery: inter-region	0	0	**0	**0	**0	**0
Inter-region inflow	132,914	444,083	69,756	–	–	–
Flood return	10,674	19,919	–	–	–	–
Groundwater discharge*	339,369	339,166	256,534	291,896	283,158	179,752
Discharge: urban supply*	84,496	99,858	**81,104	**72,130	**56,936	**43,378
Riparian release: urban supply*	2,422	2,071	**2,136	**2,042	**2,533	**1,379

Groundwater inflows	1,780,134	1,637,715	1,236,022	1,372,693	2,013,987	1,266,864
Inter-region inflow	45,775	45,724	47,475	45,218	52,788	48,940
Inter-region coastal inflow	0	0	0	0	0	0
Recharge: landscape	1,701,602	1,567,101	1,165,106	1,304,530	1,937,932	1,194,424
Leakage: urban system*	24,270	23,431	21,873	21,155	21,005	20,583
Managed aquifer recharge*	8,487	1,459	1,568	**1,790	**2,262	**2,917

Urban water system inflows	509,463	523,067	517,538	503,927	487,054	463,576
Wastewater collected	141,185	140,439	138,858	140,771	141,024	136,938
Supply system delivery: inter-region	1,795	1,832	1,953	1,922	2,121	1,939
Delivery: desalinated water	148,904	149,872	138,645	119,457	113,060	95,770
Allocated diversions: surface water*	85,631	91,326	101,204	119,649	105,998	89,853
Allocated extractions: groundwater*	131,948	139,598	136,878	122,128	124,851	139,622

Irrigation scheme inflows	72,969	59,277	69,094	66,060	73,851	56,458
Allocated diversion: surface water*	72,969	59,277	69,094	66,060	73,851	56,458
Total water inflows	3,737,510	4,003,015	2,601,156	2,879,969	3,729,671	2,389,243
Water outflows
Surface water outflows	1,618,782	1,750,059	434,482	651,497	802,896	411,966
Evaporation	57,417	48,591	28,912	46,052	33,600	28,719
Outflow	1,185,613	1,221,652	196,413	380,925	555,390	205,977
Leakage: landscape	150	150	150	150	196	142
River losses	114,471	238,759	–	–	–	–
Overbank flow	64,368	51,454	–	–	–	–
Allocated diversion: urban system*	85,631	91,326	101,204	119,649	105,998	89,853
Allocated diversion: irrigation scheme*	72,969	59,277	69,094	66,060	73,851	56,458
Allocation diversion: individual users	38,163	38,850	38,709	38,661	33,861	30,817

Groundwater outflows	1,585,031	1,521,160	1,361,781	1,473,885	1,767,928	1,447,206
Inter-region outflow	19,523	19,350	21,863	23,439	30,164	27,056
Inter-region coastal outflow	290,714	261,169	**233,290	**261,245	**352,251	306,260
Discharge: landscape	422,166	389,247	332,617	378,114	622,737	447,397
Discharge: surface water*	339,369	339,166	256,534	291,896	283,158	179,752
Non-allocated extraction: individual users	81,791	81,256	80,845	79,610	73,249	72,573
Allocated extraction: urban system*	131,948	139,568	136,878	122,128	124,851	139,622
Allocation extraction: individual users	299,520	291,374	299,754	281,453	281,518	274,546

Urban water system outflows	501,755	514,501	517,992	503,488	487,088	463,620
Supply system delivery: urban users	227,634	224,799	263,200	232,537	234,774	232,315
Recycled water delivery: urban users	4,698	8,622	9,095	8,035	8,203	0
Discharge: sea	118,202	119,190	123,163	125,025	124,900	120,293
Discharge: landscape	4,465	5,734	6,145	5,962	5,673	5,338
Supply system transfer: inter-region	18,563	20,883	27,923	24,796	20,797	29,010
Other supply system decreases	8,518	8,454	8,785	10,016	10,005	8,407
Leakage: groundwater*	24,270	23,431	21,873	21,155	21,005	20,583
Supply system discharge: reservoirs*	84,496	99,858	**81,104	**72,130	**56,936	**43,378
Supply system discharge: riparian release*	2,422	2,071	**2,136	**2,042	**2,533	**1,379
Managed aquifer recharge*	8,487	1,459	1,568	**1,790	**2,262	**2,917

Irrigation scheme outflows	74,297	59,377	70,657	64,529	73,007	57,167
Delivery	54,059	43,456	**53,456	**52,397	**56,310	**41,808
Leakage: landscape	20,238	15,921	**17,201	**12,131	**16,697	**13,359

Total water outflows	3,779,865	3,845,097	2,384,912	2,657,399	3,130,919	2,379,959

Unaccounted-for difference	342,004	**(8,818)	**(381,211)	**(280,035)	**(224,255)	**(186,048)


Water storage
Surface water storage	390,226	297,520	262,516	334,828	345,109	256,428
Opening surface water storage	297,520	262,516	334,828	345,109	256,428	294,271
Change in surface water storage	92,706	35,004	(72,312)	(10,281)	88,681	(37,843)
Closing surface water storage	390,226	297,520	262,516	334,828	345,109	256,428

Groundwater storage	–	–	–	–	–	–
Opening groundwater storage	–	–	–	–	–	–
Change in groundwater storage	206,943	**114,096	**(92,655)	**(47,183)	**285,846	**(138,921)
Closing groundwater storage	–	–	–	–	–	–
Total closing water storage	390,226	297,520	262,516	334,828	345,109	256,428

* between-store flows

** different to published volume in historical accounts (see Governance section for more information)

National Water Account 2018

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Perth: Statement of Water Flows

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