RIVER PROBLEMS IN CHINA ll 



These questions of national politics cannot, however, 

 be considered at great length on this occasion, and we may 

 proceed to discuss how the engineer proceeds to study a river 

 problem. There is one binding rule, viz. : The river must 

 be considered as an organic whole. 



First of all the whole of the area from which the river 

 receivers water must be surveyed so that the area served by 

 the various branches and gradients in the valleys may be 

 known. 



Secondly, rainfall observations for a number of years 

 at many evenly distributed points over the whole area are 

 required. 



Thirdly, accurate plan and soundings of the main chan- 

 nel and levels of the immediately adjacent country must be 

 prepared. In the case of flat country these levels should 

 extend over the whole surface. Thus in the case of the 

 Yellow Eiver it is urgently necessary to know the levels all 

 over the Great Plain. 



Fourth : Measurements of current velocity and in the 

 lower parts of tides and tidal currents must be made. 



With these particulars it can be estimated without 

 great inaccuracy that sectional area is required and if im- 

 provements can be made by deepening the bed. From a 

 judicious consideration of all the facts certain lines are then 

 laid down to which the river can reasonably be expected to 

 conform and works are designed which will develop 

 tendencies towards these lines. Speaking generally sharp 

 curves and abrupt changes of width or section should be 

 removed and the width should be regulated to diminish at a 

 uniform rate as the river is ascended, projections and hollows 

 being eliminated. By means of long jetties the channel can 

 be kept narrow out into deep water and in this way bars can 

 be removed or reduced and by projecting spurs or hard 

 facing the cutting away of a convex can be stopped. 



In China speaking generally the dyke question is the 

 most serious and the points to be decided are as follows : — 



(1) How high and broad the dykes should be. 



(2) How far they should be placed from the main 

 channel. 



(3) "Where overflow weirs and other connections should 

 be made. 



(4) What system is employed for maintenance. 



In addition there is the question of training works to 

 prevent loops from reaching the dykes and in cases such as 

 the Yellow River the provision of silt settling areas. 



Questions of dredging in conjunction with dykes are also 

 important. In those cases where a stream has several 



