DEFORESTATION AND FLOODS IN NORTHERN CHINA 891 



could be found in the old bed. This is the case more or less with every river 

 running through the plain of China. 



"The only way to diminish this evil is to diminish the amount of soil brought 

 down from the mountains. And the reason for this enormous quantity of silt 

 coming down from the mountains is that those mountains are bare, so that during 

 a heavy rain nothing prevents the water from rushing downward practically 

 immediately after it has fallen, taking with it large quantities of soil, so that it 

 reaches the river down below more like torrents of mud than of water. Now if 

 those mountains were planted with trees not only then would the water be unable 

 to take away so much soil, but it would also reach the river gradually in a regular 

 flow divided over a longer period and not within a few hours in fierce torrents. 



"It is impossible, therefore, as I have said on several former occasions, but I 

 wish to repeat it again, to lay too much stress upon the enormous importance of 

 reafiforestation. The deterioration of the various rivers in China, and specially 

 of those in this province, would never have reached its present stage if deforesta- 

 tion had not taken place. I say specially the rivers in this province because they 

 all take their rise in the mountains west of the Peking-Hankow line, which for 

 a great part consist of loess, a soil which is easily carried away by the rain. 



"To build reservoirs in the hills in order to regulate the flow of the water, as 

 has sometimes been suggested, is not only far too expensive, hut, moreover, 

 wrong, as it does not do away with the problem of silt. Sooner or later these 

 reservoirs would become filled ; consequently new ones would have to be built, 

 a process which would have to be carried on into eternity. 



"Reafiforestation is most imperative, for without reafiforestation the improve- 

 ment of rivers can only be partly accomplished, but all these processes going 

 hand in hand, the improvement of the hydraulic conditions of the country will be 

 decisive." 



The foregoing .statements as to the importance of reforestation are 

 made by prominent engineers or men who have been closely identified 

 with the conservancy work in Chihli. These men are not foresters, but 

 the fact that they have- repeatedly emphasized forestry shows conclu- 

 sively how the problem of flood in Chihli — yes, in all China — can never 

 be permanently solved unless a systematic program of reforestation is 

 carried out together with the hydra tilic engineering works. As a 

 forester, I wish to show what lias already been written about the rela- 

 tion of forests to floods and tr) bring out how diflferent elements come 

 into play to tnake this relation so close. It is hoped that the informa- 

 tion thus set forth will help my readers to understand and appreciate 

 better the imi)ortance of tree-planting in the regulation of stream-flow 

 and in the control of destructive waters. 



h'or the sake of clearness we shall first discuss the efl'ect of forests 

 on floods under the following heads: 



1. Forests and stream-flow. 



2. Forests and soil erosion. 



3. Forests and floods. 



