They also make long-term studies and measurements of how much silt a dam will hold back and what the results will be in terms of coastal erosion, in order to take preventive action such as adding supplementary silt downstream. Only in this way can one avoid the double loss caused by reservoirs becoming choked with silt and land being swept away.
也對水庫會攔下多少泥沙，海岸因此會有多少侵蝕，進行長期觀測、記錄，進而進行補沙等保護措施，唯有如此，才不致淤了水庫、丟了土地，兩敗俱傷。