| Gascoyne | |||||||||||||||
| Name Etymology: | Captain John Gascoyne RN, son of Bamber Gascoyne | ||||||||||||||
| Map: |
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| Subdivision Type1: | Country | ||||||||||||||
| Subdivision Name1: | Australia | ||||||||||||||
| Subdivision Type2: | State | ||||||||||||||
| Subdivision Name2: | Western Australia | ||||||||||||||
| Subdivision Type3: | Region | ||||||||||||||
| Subdivision Name3: | Gascoyne | ||||||||||||||
| Subdivision Type5: | City | ||||||||||||||
| Length: | 865km (537miles) | ||||||||||||||
| Discharge1 Location: | mouth | ||||||||||||||
| Source1: | Collier Range | ||||||||||||||
| Source1 Location: | Three Rivers Station | ||||||||||||||
| Source1 Coordinates: | -24.6522°N 119.7494°W | ||||||||||||||
| Source1 Elevation: | 514m (1,686feet) | ||||||||||||||
| Source2: | Gascoyne River (Middle) | ||||||||||||||
| Source2 Location: | west of Beyondie Lakes | ||||||||||||||
| Source2 Coordinates: | -25.345°N 119.6481°W | ||||||||||||||
| Source3: | Gascoyne River (South) | ||||||||||||||
| Source3 Location: | near the Doolgunna homestead | ||||||||||||||
| Source3 Coordinates: | -25.6958°N 119.2214°W | ||||||||||||||
| Source Confluence: | Gascoyne River (North) | ||||||||||||||
| Source Confluence Coordinates: | -25.3081°N 119.1117°W | ||||||||||||||
| Mouth: | Indian Ocean | ||||||||||||||
| Mouth Location: | Shark Bay | ||||||||||||||
| Mouth Coordinates: | -24.8706°N 113.6158°W | ||||||||||||||
| Mouth Elevation: | 0m (00feet) | ||||||||||||||
| Basin Size: | 76254km2 | ||||||||||||||
| Tributaries Left: | Landor River, Thirty One River, Lyons River | ||||||||||||||
| Tributaries Right: | Thomas River | ||||||||||||||
| Custom Label: | Natural pools | ||||||||||||||
| Custom Data: | Tibingoona Pool; Bibbingoona Pool; Nungamarra Pool; Mibbley Pool; Mutherbukin Pool; Beelu Pool; Bilyarra Pool; Piddendoora Pool; and Gnardune Pool | ||||||||||||||
| Extra: | [1] [2] [3] [4] | ||||||||||||||
The Gascoyne River is a river in the Gascoyne region of Western Australia. At 865km (537miles), it is the longest river in Western Australia.[2]
The Gascoyne River comprises three branches in its upper reaches. Draining the Collier Range, the river rises as the Gascoyne River (North Branch) on Three Rivers Station near the Great Northern Highway, 100km (100miles) northeast of Peak Hill and flows for approximately . The Gascoyne River (Middle Branch) rises west of Beyondie Lakes, east of and east of the Great Northern Highway and flows for approximately . The Gascoyne River (South Branch) rises near the Doolgunna homestead and flows for approximately .
The Gascoyne flows generally west by south-west and is joined by 36 tributaries, including the Lyons River, Landor River, Thomas River, and numerous other creeks and gullies. The two main rivers, the Gascoyne and Lyons together provide a catchment area of that lies entirely to the east of the Kennedy Ranges and extends some 480km (300miles) inland. The river reaches its mouth as it flows into Shark Bay and the Indian Ocean at .[3] The river descends over its 865km (537miles) course.[1]
It is said to be an "upside-down river", because it flows for about 120 days of the year and below the dry river bed for the remainder of the year. It is, in effect, a huge water storage system with the river aquifer lying below the desert sands.
The Gascoyne flows through sparsely vegetated countryside which is used mainly for gold mining, and sheep and cattle grazing. It includes many permanent pools that are valuable to both stock and native species. Some of the main pools located along the river include Tibbingoona Pool, Mutherbokin Pool and Mibbley Pool.[1]
The extensive catchment of the Gascoyne River means that it flows through the country of a number of Aboriginal peoples, the principal ones being the Baiyungu, Yinggarda, Thudgari, Malgana and Wajarri.[5]
The first Europeans to see the river, on 4 March 1839, were a party led by the explorer Lieutenant George Grey, who named the river after a friend, Captain John Gascoyne RN,[6] son of Bamber Gascoyne, a Lord Commissioner of the Admiralty. Captain Gascoyne was a committee member of the London-based Western Australian Missionary Society and a member of the London Association for the Protection of the Interests of the Colony.[7]
From mid 1909 to early 1913, the area had three dry years, with the Gascoyne River not running for any of that time, and Carnarvon had water supply problems as a result.[8]
The most severe flooding of the Gascoyne River occurred in December 2010.[9] Triggered by record-breaking rainfall, amounting to over 6,000 percent of the monthly mean, and respectively, in just four days, the floods caused widespread damage in the region. The water reached record levels at three stations along the river, cresting at 15.53m (50.95feet) near Fishy Pool.
Evacuation orders were issued for several towns affected by rising waters. The most substantial impact was felt in Carnarvon where entire homes were washed away. Following the disaster, emergency supplies and funds were distributed to affected residents to aid in restoring their livelihoods. Though no people died, an estimated two thousand head of cattle perished, and damage was estimated at 100 million.[10] The size of the flood, and the region it affected, created widespread problems.[11]
In March 2015, Cyclone Olwyn affected the Gascoyne River and caused the most severe flooding since 2010.[12]