Why are concrete masonry dams often built in narrow mountain gorges?

Concrete masonry dams are frequently constructed in narrow mountain gorges primarily due to economic and structural efficiency. In such confined settings, the total volume of material required to build a high barrier is significantly limited compared to the massive structures needed to span broad, wide valleys.1

The choice of design in these locations often favors arch dams, which are specifically engineered to take advantage of the narrow topography. These dams feature a curved profile that directs the horizontal thrust of the water against the sound rock of the valley sides or into concrete abutments. This configuration allows the water pressure itself to help keep the masonry joints closed, enhancing the structural integrity of the dam. Because their strength is entirely dependent on effective support from the gorge walls, these dams require sites with favorable, solid rock foundations.23

While gravity dams can also be built in narrow gorges, their design relies on their own weight to resist water pressure, making them distinct from the shell-like, load-transferring mechanism of arch dams.42