Question: The inhabitants of a small city carved into the side of a cliff are blind and use echolocation to navigate.
There is a lot of empty space, around a kilometer of between the cliff side where the village resides and the other cliff side, in other words a 1km valley.
Will echolocation still work effectively in this kind of situation?

Answer: 
Yes, in combination with other skills
=====================================

Your residents are going to use a combination of techniques to navigate. Echolocation is a way of avoiding obstacles, not of navigating over longer distances. In the Wikipedia image below, the bat can tell that there's a box ahead on its left, but the bat has no idea what's on the other side of that box.

[![Image describing echolocation in bats](https://i.stack.imgur.com/nU1UY.png)](https://i.stack.imgur.com/nU1UY.png)

If your villagers want to walk from the church to the blacksmith shop, for example, they'll have to have an idea of where both places are located and generally how to get between them. Here's a great overview of how blind people in the real world navigate from [Chicago Lighthouse](https://chicagolighthouse.org/sandys-view/getting-around/):

> 
> When in familiar places, visually impaired people generally know the
> layout and memorize where things are. Learning to travel in different
> or unfamiliar places is done by using orientation and mobility (O&M)
> skills. Orientation is the actual planning of how to get to and from
> places. Blind and visually impaired people use other senses – like
> sound, touch and smell – to orient ourselves to our surroundings. So,
> if I am walking outside and know there is a school nearby, then I can
> assume that it is near when I hear children playing and laughing.
> Likewise, the smell of freshly baked bread and cookies tells me I am
> near a bakery.
> 
> 
> 

By adding echolocation into the mix, you're giving your people a much better ability to avoid walking into objects. But they still won't be able to get around using that skill alone. They'll start hearing the hammering of the blacksmith and know that they're getting closer to the destination. As they approach, they'll be able to use echolocation to avoid running into the anvil.
The power level of the echolocation signal in bats is similar to that of the sounds the human voice can produce (order of 100 decibels). This allows the animals to perceive objects over distances never recorded to be further than 20 meters. <https://pubmed.ncbi.nlm.nih.gov/22978903/>

Regardless bats have also specially adapted receiving organ devices. The better human echolocator I've ever withnessed was that on Stan Lee's show "Superhumans". A blind man who could slowly drive a bike in a silent parking lot.