When planning the construction of a dam, the topography of the valley is a crucial factor in determining the most suitable type of dam. The question specifically asks about a narrow 'V' shaped valley.

Dam Types Suitable for Narrow V-Shaped Valleys

Different types of dams are designed to suit varying geological and topographical conditions. Let's consider the options provided and how they relate to a narrow 'V' shaped valley:

• Barrage: A barrage is typically a low-height structure built across a wide river to divert water or raise its level. It is primarily a diversion structure and not designed to hold back a large reservoir in a deep valley. Barrages are not suitable for narrow, deep 'V' shaped valleys.
• Arch Dam: An arch dam is a concrete dam that curves upstream. Its strength comes from transferring the hydrostatic pressure (force of the water) horizontally to the abutments (the sides of the valley or canyon). This design is highly efficient in narrow canyons or 'V' shaped valleys where the rock sides are strong enough to resist the thrust of the arch. The 'V' shape provides natural support for the arch action.
• Earth Fill Dam: An earth fill dam is constructed using compacted earth material. It relies on its sheer weight to resist the water pressure. Earth fill dams require a wide base and are generally more suited for wider valleys with flatter foundations. The narrow base of a 'V' shaped valley is less ideal for the large footprint required by an earth fill dam.
• Overflow Dam: An overflow dam, also known as a spillway dam, is designed to allow water to flow over its crest. This is often a feature incorporated into other types of dams (like gravity dams or arch dams) rather than a standalone dam type primarily defined by valley topography. While a dam in a 'V' valley might incorporate an overflow section, "overflow dam" itself doesn't specify the structural type best suited for the 'V' shape.

Considering the characteristics of each dam type and the specific topography of a narrow 'V' shaped valley, the Arch dam is the most suitable choice. Its arched structure efficiently transfers the water load to the strong, close-set valley walls inherent in a 'V' shape, making it economically and structurally advantageous for such locations.