The short version
What "riverside" is actually being sold
River-facing is the most common premium claim in Corbett and the least consistently delivered. The term covers everything from a property whose lawn ends at the Kosi to one where a corner of water is visible from the third floor if the trees co-operate. Both will be described the same way in a listing, and the price difference between them is often smaller than the experience difference.
The Kosi runs alongside the Ramnagar–Ranikhet road, which is why the Dhikuli and Garjiya belts carry nearly all the genuine riverside inventory. Properties there sit between the road and the water, and the good ones use the frontage properly: seating at the water, a lawn that runs down to it, and rooms oriented across rather than along the river.
The view is worth having. Corbett mornings after a dawn safari are among the better hours of the trip, and a riverbank is a considerably nicer place to spend them than an internal courtyard. Birds work the banks, the light is good, and the sound of moving water does more for the sense of being somewhere wild than any amount of decor.
What the view should not do is override the gate. The Kosi belt serves the northern gates well and the southern gates poorly. If your permit is at Jhirna or Dhela, a river-facing room means a pre-dawn drive across the whole reserve frontage, and you will resent the balcony by the second morning. Get the gate right first; then get the best river frontage available on that side.
Verifying the claim before you pay
Ask for a photograph taken from the room, not from the property. Marketing images are frequently shot from the best point on the grounds, which may be nowhere near your room category.
Ask what sits between the room and the water. A lawn is good. A parking area, a boundary wall or a second row of cottages means you have bought a view of them.
Ask which room categories actually face the river. Very often only a minority do, and the rest are sold as "river view" on the strength of the property's address.
Check the season. The Kosi is a wide, strong river after the monsoon and a much thinner braided channel across stony bed in late spring. Both are attractive; they are not the same photograph.
Check what the frontage is used for. Seating, lighting and access to the water are what make frontage worth paying for. A river you can see but not reach is a picture, not a feature.
