Кастлерех өзені: Жаңа Оңтүстік Уэльс су жүйесі

River in New South Wales

The Castlereagh River is located in the central–western district of New South Wales, Australia. It is part of the Macquarie Castlereagh catchment within the Murray–Darling basin and is an unregulated river, meaning no dams or storage have been built on it to control flows. On a map of NSW, the Castlereagh has a distinctive appearance among the north western rivers for its fish hook like shape: from upstream in the north at its confluence with the Macquarie River it extends southwards to a hook shape, flattened out at the base, which curves to the right (east and northwards) through to the tip of the hook in the Warrumbungle Mountains at the river's source. The Castlereagh rises 20 km west of Coonabarabran in the heart of the Warrumbungle mountains From its commencement upstream in the mountains the river initially flows east through the town of Coonabarabran. It then arcs round south and southwesterly to the village of Ulamambri, then south to Binnaway, and SSW to the small town of Mendooran which lies at the eastern side of the river's hook shape. From here the Castlereagh flows in a westerly direction at the flattened bottom of the hook and then turns north westerly towards the town of Gilgandra. From Gilgandra it continues to run northwesterly across the plains through Gulargambone and Coonamble, then continuing across expansive plains, with no urban centres, where elevations are less than 200m, until it joins the Macquarie River at its uppermost reaches beyond the Macquarie Marshes. Its confluence with the Macquarie is about 65 km SW of Walgett. Groundwater is found in the alluvial sediments on the plains in the lower Castlereagh catchment and is generally associated with the ancient channel of the river. The Castlereagh has a very sandy bed throughout its course, with especially wide outer banks on the plains. Charles Sturt, after travelling along the Castlereagh in 1828 from Coonamble to its junction with the Macquarie, noted that there was not one pebble or stone to be picked up in its bed, which was dry for the whole length he travelled. Further upstream, the Castlereagh, Macquarie and Bogan rivers run "more or less parallel as they cross the plains, where creeks and streams break away from the main rivers, making connections between the Macquarie and the Bogan, the Macquarie and the Barwon, and the Castlereagh and the Barwon. As the waterways approach the Barwon River the interconnected streams, as well as lagoons and channels, support extensive flood dependent woodlands and grasslands". Estimates of the length of the course of the Castlereagh River from its commencement to its mouth vary from ,

(ii) Claim as an underground flowing river. In more recent times, it has also been called an "upside down river".

The gradients of the upper reaches of the Castlereagh River and its tributaries are steep, located in the Warrumbungle Mountains and its foothills. In flood events, velocities can be dangerously high a speed of 3 metres per second has been recorded at Coonabarabran. Additionally, the catchment area of the upper Castlereagh is criss crossed with many streams and creeks flowing off the foothills, whose floodwater rushes with high velocity into the main river. Flow times downstream can vary greatly depending on the severity of flood. Flood peaks travelling between Coonabarabran and Gilgandra have been recorded taking as little as nine hours to travel the distance, and up to 47 hours. Usually in peak floods, the greater the water volume, the faster the travel times of the peak.

It is not correct that the Castlereagh River is an underground river (subterranean river) or an 'upside down' river. However, water that once was in the river bed on the surface does flow through the extensive sands under the riverbed. This water is therefore part of the underground soil, and is not separate from it as a truly underground river is separate from the soil. The fact of water existing under the riverbed was known by Europeans at least in the early part of the last quarter of the 1800s, if not before, as evidenced in statements given to the Water Conservation Commission Inquiry at Dubbo in 1885. The below ground sedimentary deposits in the area of the Great Artesian Basin are particularly good water stores (aquifers), and the highly permeable sediments below NSW's western flowing rivers create excellent aquifers. A theory of an extensive sub artesian store of water was proposed by Mr James Samuels and published in the "Empire" of 27 and 28 August 1868, including a view that dry inland rivers would have water under the bed. Some pastoralists in western NSW paid attention and began to sink wells, often near rivers. This may have contributed to the idea of an underground flowing river in the largely empty above ground Castlereagh. The river contains wide alluvial sandbeds. Because the pore space between sand particles is large, water can easily move through the soil layer (i. e. the sand layer). This means the river's sandbeds can be described as highly permeable. (Permeability is measured by calculating the discharge rate at which water will be transported through the pore spaces of the material; the discharge rate being controlled by the hydraulic conductivity of the saturated material). The Castlereagh River and the ground water of the Great Artesian Basin are highly connected. The water is not flowing as a separate and distinguishable underground river flow, but is moving initially through the permeable alluvial sandbeds and then through paleochannels to deeper groundwater aquifers. The Castlereagh's alluvial sandbeds make up what is called the "hyperheic zone". This is the region of saturated sediment below, or adjacent to, a river where surface water and groundwater are actively mixing and exchanged. The movement of the groundwater in the Castlereagh through its alluvial sands is said to be a hyporheic process. In the Castlereagh, the further transit of surface water to the aquifers of the Great Artesian Basin is then enabled through the ancient paleochannels underlying the Castlereagh, and this water movement is a large scale hyporheic process. (Hutchinson and Webster 1998).

The Castlereagh sits over the Great Artesian Basin (GAB) and within a re charge area for the waters of the GAB (where the GAB waters are replenished from above ground). Areas of re charge are divided into zones, called 'sources' and the Castlereagh River is within the Southern Recharge Groundwater Source. This source, together with the Eastern Recharge Groundwater Source, is characterised by better quality groundwater than other zones.

According to the colonial surveyor Thomas Mitchell in 1846, the original inhabitants called the river the Barr. The British imposed the name "Castlereagh" (through explorer Oxley) only two hundred years ago in 1818. River systems are fundamentally important to Aboriginal Australian people. As Professor Marcia Langton has described, the Aboriginal people's holistic view of the world creates connection to waterscapes as spiritual, social and jural spaces just as much as physical domains just like the same principles that connect people to landscape. Established laws that come from the sacred ancestral past "allocate rights and interests among particular people, to water sources". These are "rights and responsibilities, according to religious principles." The Castlereagh River passes through hundreds of miles of country and several different nations of the Aboriginal people. Therefore, the rights regarding the Castlereagh may have been complex. The source area of the river, from the Warrumbungles through to its down slopes area, encompassed the western edge of Kamilaroi /Gamilaraay country. The river's upper reaches around Mendooran and Gilgandra flow through the northern end of Wiradjuri country. Once past Gilgandra, the river flows into the area of the Wailwan people, across the plains and through to its lower reaches. Along the Castlereagh to around Coonamble, there was clearly overlap of these three groupings Kamilaroi, Wiradjuri and Wailwan. Europeans observed that, at Gilgandra near the long waterhole that existed on the Castlereagh, "the 'Coonabarabran' tribe (European given name) of the Gamilaraay people camped on the eastern side of the river, and the Mole tribe of the Wiradjuri on the western side". Evidence of Aboriginal culture was to be found all along the Castlereagh. Some caves in the Warrumbungle Ranges contain hand stencils, marked rocks and engravings. Rocks at Willow Vale in the Castlereagh River near the centre of Coonabarabran have grinding grooves on them.

The first European record of Aboriginal people along the Castlereagh came through the John Oxley exploration party of 1818. Waiting for waters in the Castlereagh near present day Coonamble to recede, Oxley wrote on 27 July 1818 that "Natives appear to be numerous; their guniahs (or bark huts) are in every direction, and by their fire places several muscle shells of the same kind as those found on the Lachlan and Macquarie Rivers were seen. Game (kangaroos and emus), frequenting the dry banks of the river, were procured in abundance." At the time, Oxley's party was camped at the banks of the Castlereagh River, and the spot is today marked with a memorial stone 2 km north of the town. After finally crossing the river on 3 August and heading easterly towards the Warrumbungle mountains, Oxley wrote the next day: "The natives appear pretty numerous: one was very daring, maintaining his ground at a distance armed with a formidable jagged spear and club, which he kept beating against each other, making the most singular gestures and noises that can be imagined: he followed us upwards of a mile, when he left us, joining several companions to the right of us. Emus and kangaroos abound, and there is a great diversity of birds, some of which have the most delightful notes, particularly the thrush." Charles Sturt was leading a European exploring party in 1828 when he travelled along the Castlereagh from a point just near Coonamble all the way downstream to its junction with the Macquarie River, and thence to the Darling River. His record of his journey refers to several friendly encounters with different Aboriginal groups who gave his party assistance on these lower reaches. He found that they were generally in severe want because of drought, and considered that they were perishing from famine. The exploratory journey of Oxley brought the area of the Castlereagh to the attention of pastoralists. The rich soils along the upper Castlereagh from Mendooran to Coonamble appealed to pastoralists for cattle raising and from the early 1830s Aboriginal people encountered Europeans moving into their country. Europeans were clearly present as early as 1832 at least (see "European history" below). So commenced a struggle for Aboriginal people to access resources as they once had, and to survive in their traditional way.

A devastating flood in January 1874 killed thousands of head of livestock, and damaged many buildings in Binnaway, Mendooran, Gilgandra and Coonamble. There had been incessant rain in the area of the Upper Castlereagh for three weeks (most of January) leading up to the day the river broke its banks. Over the same few days severe floods also occurred on other river systems: flooding on the Talbragar River at Dubbo was the worst experienced to that time, the town of Singleton was completely flooded, Maitland was flooded, as was Cassilis. On Saturday, 24 January, the Castlereagh River commenced rising rapidly, with rain falling heavily all day. During Sunday, 25 January the river continued rising and at Gilgandra on Monday 26th at 5 p. m. it had attained its full height. It was reported from Binnaway that the Castlereagh rose 28 feet in seven hours from 5am till twelve, and a great many sheep were lost in the area. At Coonamble, houses, stores, hotels and the public school were flooded. There was a "terrific current" in the flood waters and "it rushes by with a noise resembling the surging of the sea at a distance." People considered in any danger were rescued by boat or horseback. On the day of the flood, many settlers from the Coonamble area were in the town for land Appraisement Court hearings and the flood meant many of them could not leave for up to a week. At Gilgandra the flood broke the banks in the middle of the night and it was reported that, while it was "hard to tell the immense amount of damage done on the whole river, but what has occurred here is sufficiently disastrous". All those at the inn got out as the waters were rising in the building, heading some distance to the police paddock located on a rise to the north of the village. The Johnstone family, newly arrived one week, were camped in their tents to take up the 'Castlereagh' run located on flats on the western side of the river immediately to the north of the small village of Gilgandra. At Ulomogo (then a very small village located between Gilgandra and Gulargambone) Mrs Goodal and her family, of the Ulomogo hotel, narrowly escaped but her manager, (surname said to be Newland) was drowned while returning to the hotel to collect items.

The 1955 flood, in February, was the most severe in European history. This flood was due to extreme cyclonic weather conditions in northern Australia.