The question is: what do you want to monitor without any hardware sensor

There is no way you can do that without a hardware sensor. There is no software that can do that. The purpose of hardware sensor is to interact with the physical environment and measure the required parameter(quantity) and then load to software to work on it. May be what you mean is that, you don't want physical contact or presence of hardware in the dam. If this is the case, you can get sensor (hardware) that can be placed far away from the dam ( no physical contact/presence) and measure required quantity, (though depending on application and what you want to monitor!)

if you don't want to buy any off-the-shelf hardware, you can build your own water level sensor

depending on your knowledge of making sensor (transducer) or you can do research about that, but I think you will still need to buy one component or the other

@Tomasz Zyska @Tajudeen O. Olasupo My question was in case if there is any " off-the-shelf sensors " hardware components you knows along with their simulating environment. For example there are MICAz built in sensor component in TOSSIM which i don't get any support to proceed with. My question is incase if any one knows about them.

You can put your own components together to build a monitoring system

and you will also find online support ( I can volunteer (at my free time) to assist if you questions or challenges). Options are

1. if you are familiar with C++, get Arduino, plus sensors (see link below) and build GUI with C# for simulation, and if you want to make it wireless, add XBee or LoRa (e.g Dragino) or other radio module. You can still monitor the system from Arduino IDE terminal/console because it might be difficult to integrate the C# GUI or you can integrate GUI monitoring in MATLAB which is easier

2.if you are familiar with python, get raspberry pi or beaglebone, plus sensors (see link below) and build GUI with tkinter for simulation, and if you want to make it wireless, add XBee or LoRa (e.g Dragino) or other radio module. You can still monitor the system for pi console

I am not sure if you can get any off-the-shelf system that is "plug and play" and serve your purpose directly, unless you contact a potential vendor for customized system and it will be very expensive!!!

Goodluck!

http://microcontrollerslab.com/water-level-sensor-interfacing-arduino/

https://www.google.com/search?q=arduino+water+level+sensor&tbm=isch&tbo=u&source=univ&sa=X&ved=2ahUKEwjG_NrhhcHeAhV-GDQIHVt1D30QsAR6BAgFEAE&biw=1366&bih=608

https://www.adafruit.com/product/464?gclid=EAIaIQobChMIq_3g4YXB3gIVBMZkCh1-nA3DEAQYAyABEgJKjfD_BwE

https://www.alliedelec.com/rs-pro-519232/70790346/?mkwid=sqzNCtQow&pcrid=30980760979&pkw=&pmt=&gclid=EAIaIQobChMIq_3g4YXB3gIVBMZkCh1-nA3DEAQYBSABEgKfrPD_BwE

https://www.digikey.com/product-detail/en/adafruit-industries-llc/997/1528-2003-ND/6827136&?gclid=EAIaIQobChMIq_3g4YXB3gIVBMZkCh1-nA3DEAQYASABEgLKMfD_BwE

https://www.alliedelec.com/rs-pro-519236/70790347/?mkwid=sqzNCtQow&pcrid=30980760979&pkw=&pmt=&gclid=EAIaIQobChMIq_3g4YXB3gIVBMZkCh1-nA3DEAQYAiABEgJFdfD_BwE

Oh @Tajudeen O. Olasupo big thanks for all your supports!

Thanks all!