Welsh Journals

NATURE IN WALES VOL. 2, No. 3. AUTUMN 1956 THE WATER BUDGET IN WALES G. MELVYN HOWE Department of Geography and Anthropology, University College of Wales, Aberystwyth It is sometimes assumed by naturalists, farmers and others that a knowledge of the average monthly rainfall in an area is sufficient to determine its vegetational characteristics or its agricultural potentialities. This unfortunately is not true for, apart from the soil factor, it neglects the important fact that a large proportion of the rainfall is lost again through evaporation from open water and soil Figure i surfaces, and transpiration from grass, crops, shrubs and trees. There is, in addition, surface and sub-surface run-off (Fig. I).