Cavitation,
Bearing failure
motor over heating

Why?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Dear Little inch
I am in a situation now where i have to run 2-3 submersible pump in such a situation. i plan to install a float switch to solve this issue .

Some pumps can survive dry running or low flow and simple low power units can be pretty robust.

But it really isn't a good idea if they weren't designed for it.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Two issues come to mind:
Vortexing due to low water level, so it will start to suck air and could stop pumping
Motor overheating. Most submersibles are designed so that the water keeps the motor cool. Some are designed with internal recirculation systems so that the pumped water cools the motor, many are not.

What flow and head are required, this makes a big difference to the pump size / selection and the cooling requirements.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

Dear Artisi

15-meter head and approximately 27 LPS flow

Hi,
What says the manual? Did you check with vendor?
Probably not the best idea!
My 2 cents
Pierre

bearing, seals, shaft, etc... all must be due to overheat based on what you explained.

R.Efendy