FORESTS AND STREAMFLOW 405 



of forest under the control of the Forest Department today stands at 241,774 

 square miles, and the question may well be put whether India would be 

 getting more or less the same rainfall now as it did 50 years ago if the 

 destruction of the forests had not been checked in time. 



''This question has received much attention in Europe. In the forest of 

 Haye near Nancy, for example, a series of observations were kept up for 33 

 years with the result that, taking the rainfall in the center of the forest 

 as 100 centimetres, the rainfall at the edge was 93.9 and that outside was 

 76.7 or a decrease of 23.3 per cent. These proportions were ascertained to 

 be independent of the wind direction and the influence of the forests is also 

 independent of the seasons. 



"The most authoritative work on climatology is perhaps the Handbuch 

 der KUmatologie by Dr. J. Hann. In Volume 1, pages 186-193, 1908, will be 

 found a full summary of the results of European and American observations 

 on the influence of forests upon air temperature, ground temperature, humidity, 

 rainfall and the run-off. As regards rainfall he finds that the amount falling 

 inside the forests in Germany is about three per cent larger than that outside. 

 In the tropics there is reason to believe that, as shown by the example of 

 the Central Provinces referred to above, the difference may be considerably 

 greater than this. 



''At the same time it may at once be admitted that the influence of forests 

 on the total rainfall is in the case of India uncertain, and on the Continent, 

 although divergent views are held, it is generally held not to be of any great 

 importance. 



"In India no doubt the total rainfall depends on the monsoon currents 

 which are affected by the conditions which obtain in the Indian Ocean and 

 sub-equatorial regions. Nevertheless, there is good reason to believe that the 

 rainfall is heavier by perhaps nine per cent over well wooded districts than 

 it is over similar adjoining districts which have been deprived of their forests." 



The Forester then reviews briefly the contributions to the discussion by 

 John H. Finney, Professors Glenn, Roth and Swain, and Barrington Moore 

 in American Forestry and then adds the following statement in regard to 

 various districts of India: 



"In India reliable data as to severity of floods in main rivers fed from 

 catchment areas under forest conservation as compared with those in rivers 

 fed from catchment areas which have suffered from deforestation are in the 

 nature of the case practically nil, and it seems that nothing short of a series 

 of observations carried out on a river fed from a well wooded catchment area 

 and again on the same river after all the catchment area had been denuded 

 of its forests, could absolutely prove the effect of forests on the severity of 

 floods in the main rivers. The enquiry lately carried out shows on the whole 

 that there is no increase in the severity or duration of floods in most of 

 our main rivers, and here again it may well be asked what would have been 

 the state of affairs had not the Government of India pursued a consistent 

 forest policy for the past fifty years? It is owing to this policy that a 

 considerable proportion at least of the catchment area of most of our great 

 rivers is well wooded and that the evils following deforestation have been 

 minimized. 



"If evidence regarding the influence of forests on floods in the main 

 rivers is wanting, or circumstantial only, it is otherwise concerning the floods 

 which occur locally in the catchment areas, and the damage and erosion of 

 the hillsides which surely follow disforestation. It is here that the pro- 

 tective effects of forests and the injuries caused by their removal is most 

 marked and reports from numerous sources show that in India as elsewhere 

 disastrous effects have closely followed disforestation. 



"Mr. McKenna, the Director-General of Agriculture in Burma, writes: 



