A section plane is made on the SDD image of the year 2000 to study the spatial changes of water clarity along Qiantang River.The results show that the water clarity declined from west to east.

• 用对2000年SDD图像划剖面的方法，来研究水体的空间变化特点，结果表明，从西到东，水体透明度大体上呈下降趋势。