OCR Text |
Show 5811 3811 258 the bed. By Mr. Blackmar: Q In Connection with this matter of silt and sediment, the expression " scour and fill" is used. What do you mean by that? A The terms " scour" and " fill" are applied to changes in the level of the river bed. As we have made these observa-tion, it has usually been in one particularly place in the cross section, and if we have a table or a bridge across themselves stream., and we notice that, in taking samples, our weight hits bottom at one depth on one occasion and another depth on another occasion. When the depth is greater for a given gage height, we say the bottom is secured out. If the depth is less for a gage height, we say a fill has taken place -- the material has been taken away from this place or brought in by the river. Q Well, do I understand from that that the place which is secured out is at a subsequent time filled up? A Probably it is, yes, sir. Q A Kind of continuous process, always changing. Q Considering the amount of silt that is carried in |