Moreover, agricultural development along the banks of the river caused soil erosion and led to landslides, depositing large amounts of silt and rocks in the reservoirs. The authorities responded by building up sand retention dams. The river increasingly came to resemble a blocked digestive system. Over the years, soil and rocks have accumulated around the sand retention dams, making the river shallower and slowing the current.
而沿岸農業開發，破壞水土，造成崩塌，大量沙石被帶至水庫，水庫管理單位四處築起攔砂壩，整個大甲溪如同消化不良，攔砂壩往往三、五年就淤滿砂石，失去攔砂功能，造成溪床變淺、水流變緩。