downward bias造句

• It was specially pointed out that , when the tail water is constant maximum tide , the computed flood surface is higher than that of nonsteady current , so there is some safety superelevation . underestimation of the roughness will make downward bias to compute along - river surface and bring hidden trouble for flood control . to improve the section can decrease the water level or offset the water rise for increase of floodplains " roughness , but it need much engineering works
  特别提出，按照恒定流计算出来的设计水位比非恒定水位具有一定的安全储备；而对于滩地糙率的低估又会造成设计水位的偏低，给防洪工作带来隐患；如果利用改进断面形式来降低水位或弥补糙率增加带来的水位抬高，需要较大的工程量，所以平时应注意滩面的减糙管理工作。