13 FEBRUARY 1904, Page 11

REAPPEARING RIVERS.

AWRITER in the County Gentleman notes that the first evidences of the restoration of the normal stores of water to the hidden cisterns of the hills must not be

sought in the floods which now cover the flat meadows of the valleys. The floods are only rain-water going to waste, hurrying as fast as it can to the sea, and leaving no store behind to last for years to come. It is the great reservoirs formed in the chalk downs, the oolite of the Cotswolds, or

in the Mendips that keep the rivers fed from year's end to year's end; and even after the deluge of that summer some time elapsed before the head waters of many of our streams reappeared in their dry channels. The first sign that the balance of waters was once more " liquid " in the hills was the outflow of the curious intermittent springs known in most of Wessex and Kent as " winterbournes." They are found in Hampshire, Berkshire, the Cotswolds, and in most chalk or oolite districts, and are among the minor natural phenomena which seem always to have arrested the attention of the country people. The term " Winterbourne " is found as place-name, as the name of the intermittent spring, and as a family name in most districts where these springs exist. It is possible that in the last case it may have been originally bestowed, in the "underground" argot of the rustic population, which no one but themselves understands, on families of gipsies, or others of their more adventurous acquaintance, who moved about the country in summer, and only settled permanently in the village in the late autumn and winter, when the " bournes " were running. Many of the gipsy families do this still, coming into houses for the cold months and living in their carts in the spring and summer. For many years the " winterbournea " have failed to flow, in summer and winter alike. Their hollows and the short bed of the overflow stream have been converted into gardens or enclosures, and it was assumed that the goddess of the spring had ceased to be the genius loci for ever. But this year the winterbournes all burst out with a double flow, and in some cases at a far earlier data than in the days when they received their name. The flow was often almost instantaneous. The shepherds were the first to bring the news that the "bourne was out." The water was bubbling and spouting up from the unnoticed passages below, like the overflow from a burst main in a London street, washing out and detaching all the growth of land plants and shrubs which had taken the place of the water plants that first sprang up on the moist bed exposed to the sun. In many of the channels of these bournes cottage gardens had been laid out, and sheds and chicken-pens had been built, and in others crops were flourishing when the miniature deluge came. Some twenty- eight years ago, after a. long cycle of drought, the owner of one of these boumes, which rose near his stately gardens, so missed the beauty of the little pool that he caused the bottom to be covered with concrete, and the pool to be filled artificially with water. All went well till the wet cycle began, when the water burst up with a leap, cracked and divided the concrete floor, and then washed the fragments down the channel like pebbles in a brook.

For the last four years the country has been marked not only by dead springs, but by "dying rivers." In many cases the head-waters for miles vanished, and left nothing but an empty bed, or a chain of pools, such as the Australians call "water holes," and which are the normal form of the rivers on that continent The upper waters of the Pang, perhaps the prettiest trout-stream feeder of the Lower Thames, suffered in this way, as also did the upper waters of the Lambourn, parts of the river Cray, in Kent, and many unnamed parents of rivers in Barks and Bucks and Wiltshire, together with some of the ancient and disused canals. The stoppage of the waters lasted so long as to make a complete change for the time in the flora and fauna of the streams, or rather of their beds. As the waters shrank all the aquatic creatures, from trout to water shrimps, gathered in the deepest pools, and as these gradually dried up the bottoms were left covered with their bones, or shells, or carapaces. The rats and birds carried off the fish, and nothing but dry husks of what were myriads of living creatures remained of the humbler denizens of the waters. At first the mints, and cresses, and water plantains, and other semi-aquatic plants flourished exceedingly on the dry beds. But as summer after summer went by, with the river still unfed, grass and thistles, and buttercups and docks, with nettles and brambles, and even poppies, grew up in the stream-bed. Instead of water snails, and mussels, and river cockles, and the ancient shell-covered creatures known as planorbis and succinea and physa, which fed on the plants that have grown in fresh water from immemorial ages, the land molluscs invaded the river-bed to feed on the land plants, and in due course their empty shells fell down and lay among those of their dead predecessors of the watery king- dom. We have no equivalent to the term " drowned "to describe the death of water creatures when killed by immer- sion in air. But their annihilation was complete in this destruction of their element by sun and drought.

The river Lambourn, which falls into the Kennet at New- bury, has always been an intermittent stream in the first mile of its course. But for some seasons the period of drought became longer and extended further down what was the bed of the stream, until it looked like a jungle of tall weeds and grasses growing between willow-bordered banks. The fish retired with the waters, moving down the river, until the springs rose again and filled the upper reaches. The stream, as its name implies, is a typical" bourne " ; while as it runs through a land of sheep the amateur etymologist is tempted to derive the first part of its name from the early lambs that played upon its banks. It must not be supposed that the trout streams which lay dry, or nearly dry, in parts of the course will be any the less full of fish in years to come. Exposure to the air creates a double growth of plants, first, as has been said, of the class of rank vegetation that normally grows upon the banks where land and water meet, and in the shallow mud and water, and, later, of land plants, the seeds of which germinate perhaps two seasons later, and also flourish in great luxuriance on the elements in the soil which the water plants may possibly have left unexhausted. From the death and decay, as well as from these double contributions of earth and water, the river-bed is so stocked with potential food for fish that their growth is astonishingly rapid when the waters once more flow. The trout hurry up to their rich feeding grounds, and the abundant food supply soon restores their numbers, while increasing the size of the fish.

It is said that chalk will absorb, and hold without parting with its store, one-third of its weight of water. The result is that though the rivers which rise in chalk springs are the most permanent and the most even in volume of any in the country, their source of supply, when it does cease, cannot be restored immediately. The rolling chalk downs must first absorb their share of the lost moisture before parting with a single drop of their superfluous store to feed the springs and little brooks, or to fill the big pools like those of Alresford, or the natural tank at Ewelme. The sand parts with the waters which fall from above rather more readily, and in due course the pools and meres are refilled somewhat rapidly. In the clay countries, where none of the rivers and brooks are as a rule fed by springs, but only by the surface drainage from rainfall, the rivers, ponds, pools, and moats have for some years been steadily shrinking. But when the rain did come, as, for example, in the sixty hours' downfall which descended upon Essex in June last, the clay soil, being impervious, retained all the surplus water in the ponds and artificial lakes, which were at once filled to their normal level or beyond it ; while on the Norfolk light soils the result of an almost equal downfall was scarcely seen at the time, owing to the great quantity absorbed in the sandy earth. It should be added that very many of the fountainq now flowing once more in districts of stone and rock are "syphon springs," which had ceased to flow because the waters in the cavity from which the natural syphon pipe runs had sunk too low for it to "work." These springs are the outlets of hollows in the earth or rock, from which the pipe rises like the spout of a teapot, but the summit and vaulted roof of which rise much higher than the level of the " spout " or mouth of the pipe. When the water fills the cavity to a level above this orifice, it rises up the pipe and flows over the top. But when a deficiency of water causes that in the cavity to sink below the level of the syphon outlet, the spring ceases to flow.