Old subject
"I would like to connect it upto somekind of sensor and gsm module to read the current water level of the river and send the information back to a database.
The question I have is how to read the water levels? Can a ultrasonic range finder work? as it would need to be atleast a couple of meters (min 5 meters up to 6-7 meters) away from the surface due to differences floods etc."
I want to put the sensor on top of the roof to take the mesure at a certain point of the ravine (Section). (The ravine will be in a mountain area inside a slum area in Haiti).
I am working with a local OpenStreetMap community as an OSM contributor myself (we are using Drone as well, http://umap.openstreetmap.fr/fr/map/geo ... 7/-72.0717 ). Drone is to do pre mapping with a Near Infra Read camera ( to extract land cover and the height of the building like of 3d mapping).
And then if we success with this local community to build this hydro station, we will collect important information and can run a 2d hydrological model.
And then collect information after a flood, to help the community to get more involve in some risk reduction project and get the best map and data available.
All the project are coming with open source license.
I have already tested some basic ultrasonic, but upto 2 meters is not working and we need to write a lot of code to extract correct information.
Do you have any idea which material I need to use for this test.
frmoine:
The question I have is how to read the water levels? Can a ultrasonic range finder work?
While there are ultrasonic water level sensors which work in the range of up to 10 meters, they are mostly used in water standing still, like in a water tank or in a well shaft. A 10 meters range make them relatively expensive, too.
For general usage it seems to me that submersable hydrostatic pressure sensors are more common: For mounting you lower the hydrostatic pressure sensor to the lowest expected water level (below water surface), and then you don't measure the air distance above the water surface, but you measure the water pressure of the water above the sensor: The more water is above the sensor, the higher is the hydrostatic pressure you can measure. 10 meters of water = 1 bar.
Such submersible hydrostatic level sensors are available for different measuring ranges and different applications. As the cable has to be connected absolutely watertight to the sensor as it is operated below the water surface, you always have to order the sensor in the desired range mounted with a cable of the desired lenght directly at the manufacturer. Unfortunately a single sensor including a watertight cable will cost several hundreds of Euros.
But the price for water resistant ultrasonic sensors for measuring the water level in a dwell shaft up to 10 meters is roughly the same amount, I suppose.
There are many types of devices.
Ultrasonic - noise can be a problem and debris can be a factor.
Hydro-static pressure is a good bet but rushing current can effect your reading.
Guided Radar using a rod probe up to 4 meters or a rope probe up to 12 meters is available.
Guided Radar is what I used in level measurements in a turbulent environment with sand and other elements and it worked well unless it got buildup on it and it had to be cleaned but the stuff we were measuring is not nearly as clean as flooding rivers.
If you don't have much of a budget you might use just a series of wires with a Vcc via a small resistor being in the water and using multiple analog inputs at your spaced wires with pull down resistors so you don't measure static. This would be a rather crude way but if very low resolution is acceptable the it could work.
Laser might be another way to go.
There are ways to use hydro-static working like a manometer without have to put the sensor in the water by measuring the vacume pressure but then you might have an issue of getting entrained gasses causing the reading to be off after a period of time.
The Arduino Mega has 16 analog inputs and there is a way that using resistors in series with multiple contact areas at increasing height per channel could give you better resolution than just "is it touching the water".