People construct dams across rivers for many reasons: to protect their land from floods, to store water, to generate power, to redirect river channels, to create artificial lakes (reservoirs), and to keep water levels high so that boats can travel without running aground. All dams, no matter why they are built, must be strong enough to contain huge volumes of water without leaking or breaking. Investigate the scene through your transit to discover how dams are built and some effects of dam construction.