WATER DEFICIT AS A CLIMATIC DISCRIMINANT 



15 



JFMAMJJASOND 



Fig. 2. The monthly distribution of potential water deficit and surplus at five stations 

 in Scotland in i960. The black line indicates the generalised limit of areas with no 

 potential water deficit. 



across north-west Europe, outside Scotland. A map has been compiled on 

 lines somewhat similar to those discussed in this paper, by Mohrmann 

 (1958) and this shows that the areas of negligible PWD can be found in 

 Ireland, Wales, north-west England, and in Norway, with an outher in the 

 Alps. But Mohrmann based his map on computed values of PE and he does 

 not work on PWD by wet and dry periods - i.e. he does not take into account 

 the distribution of rainfall. If he had done so, it is unhkely that nearly so many 

 areas would be included. Much of Wales, north-west England, and Norway 



