water surface slope meaning in English

水面坡度
水面坡降

Test results show that the water surface slope , velocity and ratio of water depth to draft are the main influencing factors of ships ascending rapids
试验结果表明，滩段的水面比降、水流速度及船舶水深吃水比是船舶上滩的主要影响因素。
Considering the joint operation of the three gorges and gezhouba hydropower stations , influences of the daily regulation planning of the hydropower stations on the water surface slope of the downstream reach of the three gorges reservoir are studied
?结合三峡和葛洲坝两电站联合运行的实际情况，研究了调节方案对三峡水库下游河道水面比降的影响。