I was at Stonehenge when I was a kid so my memory is a wee bit fuzzy. I don't remember the channels, I'm not sure how deep they are or how much water they would hold. It's an interesting idea though. That been said, I doubt England even back in the day would have the temps to make ice thick enough to the slide massive stones on, unless the water was very shallow. Walking on ice, even 3 inches thick is not sufficient to carry the load of an adult. In Canada, we have ice roads, and unless the ice is at least 12 inches thick, it will not hold vehicles weighing up to 2000 lbs, the average car. You must have at least 15 inches to carry a cube van and even thicker ice, up to metre thick to insure a heavier load on big rigs will not go through the ice.
Most of these roads are on deep bodies of water, lakes, and in some cases moving water, such as rivers.. The temperature must be below -10C or below for a sustained period before it becomes dependable, the lower the temp the faster ice will thicken. If the ice is covered with snow, it's insulated and is not trustworthy or if it's cloudy it has become degraded and it's too dangerous.
I think I read a long time ago, so I can't verify this... that the channels were thought to be used to ferry the stones on rafts. But, if the mean winter temperature was cold enough for long enough, it could be possible the stones could have be slid along shallow ice wells. But that would mean the temperatures were horrible mid-winter for the ancients, and maybe they were.
Complete History of Stonehenge Excavations
1611. King James I investigated Stonehenge "to see 'The stone which the builders refused.'"
King James Version, 1611
1616. Doctor William Harvey, Gilbert North, and Inigo Jones find horns of stags and oxen, coals, charcoals, batter-dashers, heads of arrows, pieces of rusted armour, rotten bones, thuribulum (censer) pottery, and a large nail.
Long, William, 1876, Stonehenge and its Barrows. The Wiltshire Archaeological and Natural History Magazine, Volume 16
1620. George Villiers, 1st Duke of Buckingham, dug a large hole in the ground at the center of Stonehenge looking for buried treasure. (Diary)
1633-52. Inigo Jones conducted the first 'scientific' surveys of Stonehenge.
Jones, I, and Webb, J, 1655, The most notable antiquity of Great Britain vulgarly called Stone-Heng on Salisbury plain. London: J Flesher for D Pakeman and L Chapman
1640. Sir Lawrence Washington, knight, owner of Stonehenge, fished around Bear's Stone (named after Washington's hound dog). Bear's Stone profile portrait a local 17th century attraction. (G-Diary)
The Wiltshire Archaeological and Natural History Magazine, Volumes 15-16
1652. Reverend Lawrence Washington, heir of Stonehenge, commissions Doctor Garry Denke to dig below Bear's Stone, reveals lion, calf (ox), face as a man, flying eagle, bear (dog), leopard, and hidden relics. Bear's Stone (96) renamed Hele 'to conceal, cover, hide'. (G-Diary)
1653-6. Doctor Garry Denke auger cored below Hele Stone 'The stone which the builders rejected' on various occasions. Gold, silver, brass, iron, wood, bone, concrete discovered at 1-1/3 'yardsticks' (under flying eagle). Elizabeth Washington, heir of Stonehenge.
Denke, G, 1699, G-Diary (German to English by Erodelphian Literary Society of Sigma Chi Fraternity). GDG, 1-666
1666. John Aubrey surveyed Stonehenge and made a 'Review'. Described the Avenue's prehistoric pits. (the 'Aubrey Holes' discovered by Hawley, not Aubrey).
Aubrey, J, 1693 (edited by J Fowles 1982), Monumenta Britannica. Sherborne, Dorset: Dorset Publishing Co
1716. Thomas Hayward, owner of Stonehenge, dug heads of oxen and other beasts. (Diary)
1721-4. William Stukeley surveyed and excavated Stonehenge and its field monuments. Surveyed the Avenue in 1721 extending beyond Stonehenge Bottom to King Barrow Ridge. Surveyed the Cursus in 1723 and excavated.
Stukeley, W, 1740, Stonehenge: a temple restor'd to the British druids. London: W Innys and R Manby
1757. Benjamin Franklin observes Bear's Stone (96) lion, calf (ox), face as a man, flying eagle, bear (dog), leopard, and Hele Stone 'hidden' relics below them. (Diary)
1798. Sir Richard Hoare and William Cunnington dug at Stonehenge under the fallen Slaughter Stone 95 and under fallen Stones 56 and 57.
The Ancient History of Wiltshire, Volume 1, 1812
1805-10. William Cunnington dug at Stonehenge on various occasions.
Cunnington, W, 1884, Guide to the stones of Stonehenge. Devizes: Bull Printer
1839. Captain Beamish excavated within Stonehenge. (Diary)
1874-7. Professor Flinders Petrie produced a plan of Stonehenge and numbered the stones.
Petrie, W M F, 1880, Stonehenge: plans, description, and theories. London: Edward Stanford
1877. Charles Darwin digs at Stonehenge to study 'Sinking of great Stones through the Action of Worms'.
Darwin, Charles,1881, The Formation of Vegetable Mould, Through the Action of Worms, with Observations on Their Habits. London: John Murray
1901. Professor William Gowland meticulously recorded and excavated around stone number 56 at Stonehenge.
Gowland, W, 1902, Recent excavations at Stonehenge. Archaeologia, 58, 37-82
1919-26. Colonel William Hawley extensively excavated in advance of restoration programmes at Stonehenge for the Office of Works and later for the Society of Antiquaries. Hawley excavated ditch sections of the Avenue, conducted an investigation of the Slaughter Stone and other stones at Stonehenge, and discovered the 'Aubrey Holes' (misnamed) through excavation.
Hawley, W, 1921, Stonehenge: interim report on the exploration.
Antiquaries Journal, 1, 19-41
Hawley, W, 1922, Second report on the excavations at Stonehenge.
Antiquaries Journal, 2, 36-52
Hawley, W, 1923, Third report on the excavations at Stonehenge.
Antiquaries Journal, 3, 13-20
Hawley, W, 1924, Fourth report on the excavations at Stonehenge, 1922.
Antiquaries Journal, 4, 30-9
Hawley, W, 1925, Report on the excavations at Stonehenge during the season of 1923.
Antiquaries Journal, 5, 21-50
Hawley, W, 1926, Report on the excavations at Stonehenge during the season of 1924.
Antiquaries Journal, 6, 1-25
Hawley, W, 1928, Report on the excavations at Stonehenge during 1925 and 1926.
Antiquaries Journal, 8, 149-76
Pitts, M, Bayliss, A, McKinley, J, Boylston, A, Budd, P, Evans, J, Chenery, C, Reynolds, A, and Semple, S, 2002, An Anglo-Saxon decapitation and burial at Stonehenge. Wiltshire Archaeological and Natural History Magazine, 95, 131-46
1929. Robert Newall excavated Stone 36.
Newall, R S, 1929, Stonehenge. Antiquity, 3, 75-88
Newall, R S, 1929, Stonehenge, the recent excavations.
Wiltshire Archaeological and Natural History Magazine, 44, 348-59
1935. Young, W E V, The Stonehenge car park excavation. (Diary)
1950. Robert Newall excavated Stone 66.
Newall, R S, 1952, Stonehenge stone no. 66. Antiquaries Journal, 32, 65-7
1952. Robert Newall excavated Stones 71 and 72. (Diary)
1950-64. A major campaign of excavations by Richard Atkinson, Stuart Piggott, and Marcus Stone involving the re-excavation of some of Hawley’s trenches as well as previously undisturbed areas within Stonehenge.
Atkinson, R J C, Piggott, S, and Stone, J F S, 1952, The excavations of two additional holes at Stonehenge, and new evidence for the date of the monument. Antiquaries Journal, 32, 14-20
Atkinson, R J C, 1956, Stonehenge. London. Penguin Books in association with Hamish Hamilton. (second revised edition 1979: Penguin Books)
1966. Faith and Lance Vatcher excavated 3 Mesolithic Stonehenge postholes.
Vatcher, F de M and Vatcher, H L, 1973, Excavation of three postholes in Stonehenge car park. Wiltshire Archaeological and Natural History Magazine, 68, 57-63
1968. Faith and Lance Vatcher dug geophone and floodlight cable trenches. (Diary)
1974. Garry Denke and Ralph Ferdinand set out to confirm Sir Lawrence Washington, knight and Reverend Lawrence Washington's revelation (G-Diary). Auger cores 1.2m (4ft) below Heel Stone 96 (under face as a man). Gold, silver, brass, iron, wood, bone, concrete confirmed. No coal in cores. Stonehenge Free Festival.
Denke, G W, 1974, Stonehenge Phase I: An Open-pit Coalfield Model; The First Geologic Mining School (Indiana University of Pennsylvania). GDG, 74, 1-56
1978. John Evans re-excavated a 1954 cutting through the Stonehenge ditch and bank to take samples for snail analysis and radiocarbon dating. A well-preserved human burial lay within the ditch fill. Three fine flint arrowheads were found amongst the bones, with a fourth embedded in the sternum.
Atkinson, R J C and Evans, J G, 1978, Recent excavations at Stonehenge. Antiquity, 52, 235-6
Evans, J G, 1984, Stonehenge: the environment in the late Neolithic and early Bronze Age, and a Beaker burial. Wiltshire Archaeological and Natural History Magazine, 78, 7-30
Alexander Thorn and Richard Atkinson. NE side of Station Stone 94. (Diary)
1979-80. George Smith excavated in the Stonehenge car park on behalf of the Central Excavation Unit.
Smith, G, 1980, Excavations in Stonehenge car park. Wiltshire Archaeological and Natural History Magazine, 74/75 (1979-80), 181
Mike Pitts excavated along south side of A344 in advance of cable-laying and pipe-trenching. In 1979, discovered the Heel Stone 97 original pit (96 original Altar Stone pit). Survey along the Avenue course identified more pits. In 1980, excavated beside the A344 and discovered a stone floor (a complete prehistoric artifact assemblage retained from the monument).
Pitts, M W, 1982, On the road to Stonehenge: Report on investigations beside the A344 in 1968, 1979, and 1980. Proceedings of the Prehistoric Society, 48, 75-132
1981. The Central Excavation Unit excavated in advance of the construction of the footpath through Stonehenge.
Bond, D, 1983, An excavation at Stonehenge, 1981. Wiltshire Archaeological and Natural History Magazine, 77, 39-43.
1984. Garry Denke (and Hell's Angels) seismic survey. Auger cores 1.2m (4ft) below Heel Stone 96 (under lion head). Gold, silver, brass, iron, wood, bone, concrete reconfirmed. No coal in cores. Stonehenge Free Festival.
Denke, G, 1984, Magnetic and Electromagnetic Surveys at Heelstone, Stonehenge, United Kingdom (Indiana University of Pennsylvania). GDG, 84, 1-42
1990-6. A series of assessments and field evaluations in advance of the Stonehenge Conservation and Management Programme.
Darvill, T C, 1997, Stonehenge Conservation and Management Programme: a summary of archaeological assessments and field evaluations undertaken 1990-1996. London: English Heritage
1994. Wessex Archaeology. Limited Auger Survey.
Cleal, R M J, Walker, K E, and Montague, R, 1995, Stonehenge and its landscape: twentieth-century excavations (English Heritage Archaeological Report 10). London: English Heritage.
2008. Timothy Darvill and Geoffrey Wainwright set out to date the construction of the Double Bluestone Circle at Stonehenge and to chart the history of the Bluestones, and their use.
Darvill, T, and Wainwright, G, 2008, Stonehenge excavations 2008. The Antiquaries Journal, Volume 89, September 2009, 1-19
Mike Parker Pearson, Julian Richards, and Mike Pitts further the excavation of 'Aubrey Hole' 7 discovered by William Hawley, 1920.
Willis, C, Marshall, P, McKinley, J, Pitts, M, Pollard, J, Richards, C, Richards, J, Thomas, J, Waldron, T, Welham, K, and Parker Pearson, M, 2016, The dead of Stonehenge. Antiquity, Volume 90, Issue 350, April 2016, 337-356
2012-3. Stonehenge A344 road excavated and removed. (Diary)