Some rivers have been dammed under the guise of flood control. what might be an unintended consequence of using this approach?

Reduced fertility of downstream land due to reduced silt deposits

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]