Greenough River facts for kids

The Greenough River is an important river in the Mid West area of Western Australia. It flows for about 340 kilometers (211 miles) before reaching the Indian Ocean.

The River's Journey

The Greenough River starts its journey near the Woojalong Hills on the Yilgarn Plateau. This is where its headwaters are, meaning the very beginning of the river.

The river flows southwest through deep valleys. It passes through the Waterloo Ranges before reaching the flat coastal plain. Near the ocean, sand dunes block its path. This makes the river turn northwest. It then flows alongside the coast for about 35 kilometers (22 miles).

Finally, the Greenough River empties into the Indian Ocean at Cape Burney. This spot is about 9 kilometers (6 miles) south of Geraldton.

River Branches and Mouth

The Greenough River has ten smaller streams, called tributaries, that flow into it. These include Woojalong Brook, Woolbarka Brook, and Urawa River.

The part of the river closest to the sea is an estuary. An estuary is where fresh river water mixes with salty ocean water. The exact point where the estuary ends is not fully known. It probably extends about 7 kilometers (4 miles) upstream.

A sandbar usually blocks the river mouth from the ocean. This sandbar is a ridge of sand built up by waves and currents. It only breaks open when the river flows very strongly, usually after heavy rains. Once it opens, it often stays open for several months. People have reinforced the sandbar with brushwood on one side. This helps it open only on the southern side, where the nearby sand dune is more stable.

How the River Changed Over Time

Scientists believe the Greenough River's path has changed over thousands of years. Long ago, it might have flowed further inland before turning northwest. It may have followed a path similar to the Geraldton–Dongara railway line.

Eventually, the river cut its own path through a limestone ridge. This created the course we see today.

Moving Sand Dunes

The area around Greenough is known for strong winds. These winds create large, moving sand dunes. These dunes are slowly shifting northwards. Experts think that the southern dune might reach the river mouth around the year 2045. If this happens, the Greenough River could flood more often. It might even be forced to change its course again.

River Water and Floods

Most of the time, the Greenough River is dry. However, it does have some permanent pools of water, like Bootenal Spring.

Flooding History

The entire river basin can experience very severe floods. These floods have caused a lot of damage to local farms and communities over the years.

The worst flood on record happened in 1888. Over 50 square kilometers (19 square miles) were flooded. The water was more than 5 meters (16 feet) deep in some areas south of Greenough. Four people sadly drowned, and many families lost everything. Because of this, the town of Greenough was eventually abandoned.

Another big flood occurred in 1953. The river was reported to be much wider than during the 1883 floods. An 8-foot (2.4-meter) wall of water rushed down the river. It then steadily rose to 20 feet (6 meters) high, completely covering the bridge near Walkaway, Western Australia. The 1953 flood was the largest in 30 years.

Water Quality

The river water is often eutrophic. This means it has too many nutrients, usually from pollution. It is also often full of sediment, which is tiny bits of rock, sand, or soil carried by the water.

There is evidence that this has affected the local environment. For example, many migratory wading birds no longer visit the floodplain as much as they used to.

River's Name

The Greenough River was named on April 8, 1839. It was named by the explorer George Grey. He was on his second expedition along the Western Australian coast.

Grey named the river after George Bellas Greenough. Mr. Greenough was the President of the Royal Geographical Society in 1837. This was when Grey's expedition was being prepared.