The flooding of Port Meadow, an historical perspective
An e-mail on this subject by Keith Dancey taken from OxonBirds:
I have live in Wolvercote for well over thirty years, and in that time I have found it rare for the Meadow to hold flood water around the Aristotle Lane entrance beyond the winter months. It normally floods once (maybe, twice) a year during winter, and the low-lying fingers of Meadow opposite Medley trap the river water and fish. These fingers do not drain back into the main course of the river because of higher ground between them and the river. Hence, the "floods" ability to persist beyond the river being in spate. These fingers of low-lying ground do not form any significant catchment area, however, so it is even rarer for them to "pool" significantly from mere heavy or persistent rain. I have known several years when the river has never burst it banks, not even in winter, and the Meadow has not held any significant standing water at all in those periods. Up until recently, the "normal" course of events is for a varying degree of flooding to occur, usually but not always, in winter, and for that flooding to disappear by summer. Also, up until recently, those winter floods regularly froze, allowing local people to ice skate on the Meadow. Not every flood reaches Wolvercote Common, in the north, however. That is fairly rare. Up until recently, then, the Meadow is normally bone dry in summer, including even the "seasonal pools" alongside Godstow Road. I can remember when these pools always dried out in summer.
In the summer of 1976 I walked across the Thames at Godstow Bridge, barely getting the soles of my sandals damp. The River was just one or two feet wide and easily jumped. In those days - before the Law insisted on manned supervision - there was a thriving river bathing place, complete with changing huts, below the bridge (all gone now, along with Longbridge, Tumbling Bay, Parson's Pleasure...) In that
summer, all the canal locks were sealed shut.
I think, if you inspect the vegetation, you will not find a great deal of the typical wetland grasses of semi-permanent wetland, testifying to the seasonal nature of the Meadow's past flooding. However, our climate is changing, and the pattern of flooding on the Meadow has recently changed dramatically. I would say that since the "Great Flood" of 2007, the Godstow Road pools have never dried out, and the fingers of low-lying Meadow remained completely flooded, for the first time ever, for more than two full years. Since then, wetland grasses have started to appear. But will they last? It is interesting to note that the "Great Flood" was a July event; not a typical winter flood. Climatalogically speaking, July is unique in that, over recorded history, it holds the thirty-year average for both the driest and wettest month! However, those changes in climate were not being driven by the same forces which are beginning to play havoc now. In the last three years, local birders have "benefitted" from the Port Meadow floods, but it remains to be seen whether these will continue on quite the same scale. Wetland birds, and birders, may be disappointed.
Keith Dancey
I have live in Wolvercote for well over thirty years, and in that time I have found it rare for the Meadow to hold flood water around the Aristotle Lane entrance beyond the winter months. It normally floods once (maybe, twice) a year during winter, and the low-lying fingers of Meadow opposite Medley trap the river water and fish. These fingers do not drain back into the main course of the river because of higher ground between them and the river. Hence, the "floods" ability to persist beyond the river being in spate. These fingers of low-lying ground do not form any significant catchment area, however, so it is even rarer for them to "pool" significantly from mere heavy or persistent rain. I have known several years when the river has never burst it banks, not even in winter, and the Meadow has not held any significant standing water at all in those periods. Up until recently, the "normal" course of events is for a varying degree of flooding to occur, usually but not always, in winter, and for that flooding to disappear by summer. Also, up until recently, those winter floods regularly froze, allowing local people to ice skate on the Meadow. Not every flood reaches Wolvercote Common, in the north, however. That is fairly rare. Up until recently, then, the Meadow is normally bone dry in summer, including even the "seasonal pools" alongside Godstow Road. I can remember when these pools always dried out in summer.
In the summer of 1976 I walked across the Thames at Godstow Bridge, barely getting the soles of my sandals damp. The River was just one or two feet wide and easily jumped. In those days - before the Law insisted on manned supervision - there was a thriving river bathing place, complete with changing huts, below the bridge (all gone now, along with Longbridge, Tumbling Bay, Parson's Pleasure...) In that
summer, all the canal locks were sealed shut.
I think, if you inspect the vegetation, you will not find a great deal of the typical wetland grasses of semi-permanent wetland, testifying to the seasonal nature of the Meadow's past flooding. However, our climate is changing, and the pattern of flooding on the Meadow has recently changed dramatically. I would say that since the "Great Flood" of 2007, the Godstow Road pools have never dried out, and the fingers of low-lying Meadow remained completely flooded, for the first time ever, for more than two full years. Since then, wetland grasses have started to appear. But will they last? It is interesting to note that the "Great Flood" was a July event; not a typical winter flood. Climatalogically speaking, July is unique in that, over recorded history, it holds the thirty-year average for both the driest and wettest month! However, those changes in climate were not being driven by the same forces which are beginning to play havoc now. In the last three years, local birders have "benefitted" from the Port Meadow floods, but it remains to be seen whether these will continue on quite the same scale. Wetland birds, and birders, may be disappointed.
Keith Dancey