Chapman River is a river in the

Mid West The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four Census Bureau Region, census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of ...

region of

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

Course

The river arises on the Victoria Plateau east of

Northampton Northampton () is a market town and civil parish in the East Midlands of England, on the River Nene, north-west of London and south-east of Birmingham. The county town of Northamptonshire, Northampton is one of the largest towns in England; ...

. It flows in a southerly direction, passing through the town of Nabawa in the

Shire of Chapman Valley The Shire of Chapman Valley is a local government area located in the Mid West region of Western Australia, immediately northeast of the City of Geraldton and about north of Perth, the state capital. The Shire covers an area of and its seat o ...

, and continuing south to about the latitude of

Geraldton Geraldton (Wajarri: ''Jambinu'', Wilunyu: ''Jambinbirri'') is a coastal city in the Mid West region of the Australian state of Western Australia, north of the state capital, Perth. At June 2018, Geraldton had an urban population of 37,648. ...

. It then descends to the coastal plain, turning to the west-north-west and disgorging into the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

at Bluff Point in

Champion Bay Champion Bay is a coastal feature north of Geraldton, Western Australia, facing the port and city between Point Moore and Bluff Point. Champion Bay was named by Lieutenant John Lort Stokes of , who surveyed the area in April 1840. He named ...

Tributaries A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

of the river include Chapman River East, Skelton Gully, Una Brook and Rushy Gully.

Hydrology

Most of the Chapman River's 1,160 km² catchment consists of cleared agricultural land. This land is heavily fertilised and subject to

soil erosion Soil erosion is the denudation or wearing away of the upper layer of soil. It is a form of soil degradation. This natural process is caused by the dynamic activity of erosive agents, that is, water, ice (glaciers), snow, air (wind), plants, and ...

, so the river carries high concentrations of

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

and chlorophyll a. This, together with the encroachment of urban areas into the river's

riparian zone A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...

, has resulted in a degraded river system with

eutrophic Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytoplank ...

lower reaches. The river generally does not flow in summer, but always flows in winter. From the mouth to about 1.5 km upriver, the river is

estuarine An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

. This stretch always contains some water. The mouth itself is usually closed by a

sandbar In oceanography, geomorphology, and Earth science, geoscience, a shoal is a natural submerged ridge, bank (geography), bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body o ...

, but this opens at the onset of heavy flow, and closes after flow has receded. When the sandbar is open, sea water enters the estuary, mildly affecting its salinity. During periods of very high rainfall, soils are washed into the river and carried out to sea. Following heavy rains in June and July 1986, it is estimated that: the Chapman River washed 39,000 tons of suspended sediment into the ocean; that at peak flow a ton of sediment entered the ocean every seven seconds; and that this loss of sediment represented the loss of some A$73,000 of soil nitrogen.

Conservation

The Chapman River's riparian zone is managed as part of the Chapman Regional Wildlife Corridor Project, and much of it is afforded some protection by the declaration of regional parks within the zone, such as Spalding Park.

History

The Chapman River was named on 7 April 1839 by the explorer

George Grey Sir George Grey, KCB (14 April 1812 – 19 September 1898) was a British soldier, explorer, colonial administrator and writer. He served in a succession of governing positions: Governor of South Australia, twice Governor of New Zealand, Go ...

while on his second disastrous expedition along the Western Australian coast, and was probably named after John Chapman, later a British Conservative

Member of Parliament A member of parliament (MP) is the representative in parliament of the people who live in their electoral district. In many countries with bicameral parliaments, this term refers only to members of the lower house since upper house members of ...

(MP) but then deputy chairman of the Western Australian Company. Chapman was a business partner of Grey's friend Sir William Hutt (Chairman of the Western Australian Company and brother of

John Hutt John Hutt (24 July 1795 – 9 April 1880) was Governor of Western Australia from 1839 to 1846. Life Born in London on 24 July 1795, John Hutt was the fourth of 13 children of Richard Hutt of Appley Towers, Ryde, Isle of Wight. He was educate ...

, second

Governor of Western Australia The governor of Western Australia is the representative in Western Australia of the monarch of Australia, currently King Charles III. As with the other governors of the Australian states, the governor of Western Australia performs constitutional ...

), after whom Grey had named the nearby Hutt River, two days previously.

References

{{Rivers of Western Australia Rivers of the Mid West region