surface gradient

例句：

1. 1.The surface gradient of the soil is an important factor influencing plant growth.
   土壤的表面梯度是影响植物生长的一个重要因素。
2. 2.The surface gradient of the river changes rapidly with the seasons.
   河流的表面梯度随着季节的变化而迅速变化。
3. 3. The surface gradient of the ocean is responsible for the movement of water and the distribution of nutrients.
   海洋的表面梯度负责水的运动和营养物质的分布。