Even in the far-from-finished state in which I saw the site of Liverpool's International Garden Festival, its main features were impressive. A 500 -meter-long man-made river dominates, with water traveling from a hillside spring into two tarns, on to feed a main lake, then crossing a canyon on an aqueduct, plunging over a waterfall, and churning into white-water rapids through a gorge. And that is only the first part of its journey. The stream terminates in a serpentine-type of river ending up in a final pool by the Festival Hall.
It is hard to believe that the site was originally flat and featureless. Now hardly any of it is level, a world of hollows and bunds, hillocks designed to protect the gardens from the fierce wind that can blow off the Mersey River.
By the Mersey itself - surprisingly wide and beautiful - a new esplanade with sunken gardens has been built. This is to be permanent. It has a bandstand and nautical features rendered decorative: anchors and funnels and bollards.
Nearby is an area of cascades and dramatically high geysers with promised rainbow effects and bubbling, swirling pools of water. Thirty-two pieces of specially made sculpture will be placed here - among them works by Elizabeth Frink, John Kemp (a flock of crows), Barry Flanagan, and Kate Blacker (corrugated, painted fish under water).
There will be a Gardeners' Bazaar - stalls in a kind of outdoor market. There will be a Learning Garden for children - a microcosm of the whole site. The Nature in the City area will also be educational: Its various sections will look at ways in which natural habitats can be created on reclaimed urban land and at man's present and possible future uses of plant life.
A miniaturized model forest - the work of Britain's Forestry Commission - will use seedling trees. The West German garden will show newly introduced hybrid rhododendrons not seen in Britain before. The Canadian Garden will boast an Indian artist carving a 12-foot totem pole. Florida has a prime setting inside the Festival Hall for its tropical garden. Other features include a British Rose Garden (two in one, in fact), a Victorian Garden (loosely based on the theories of Gertrude Jekyll and William Robinson, heroes of English garden history), an Alpine Garden, and a Scottish Garden (which promises to be as good as a visit to the Highlands and Lowlands, minus, one hopes, the gnats).
An unquestionably popular garden will be one designed by a 14-year-old boy from Cambridge. Theodore Gayer Anderson won a competition set up BBC's ''Blue Peter'' TV program.His design of a spectacular red dragon was given first prize out of 19,940 entries.
Perhaps one of the strangest, but also appropriate, gardens will be the Garden of Hope. This has been designed by Vince Nevin, based on an idea suggested by the Merseyside Churches Ecumenical Council. It will have two aspects: The first represents inner city dereliction, with black clinker and cinders, broken railings, and an avenue of dead trees. The second (not visible from the first until the last minute) is the Garden of Delight. A flood of brilliant color, progressing from red through yellow to white, it will have a fountain in its center. It is meant as a place of rest and contemplation. Its theme, of course, is revitalization of the city, a theme that can hardly be avoided at the 1984 Liverpool International Garden Festival.