Why to use waterproofing in water which flows continuous? is it correct or any other used?

If i got your question right, you mean why to waterproof concrete that is submerged all the time in water?

well, some waterproofing experts say that if the concrete is totally and continously submerged in water "no dry wet cycle" , there is no reason to waterproof it at all " in hot climate areas only, if in cold areas , the water may turn to ice and other concrete deficiencies may take place" , the reason for that is the water will prevent the oxygen from reaching the steel reinforcement which will prevent electrical cell to be created so there will be no corrosion in steel reinforcement & the concrete will stay intact.

Some other waterproofing experts say that this is a wrong approach " I personally go with this opinion" , the concrete subjected to water or submerged under water MUST be waterproofed anyway because there are chances for a Dry-Wet cycle to happen "water table can change due to artificial or natural causes even after years of construction" which may cause deterioration of concrete & steel corrosion, also the splash zone "the area of concrete just above water level" will definetely develope detrioration of concrete and corrosion in steel reinforcement.....also, there are chances for a change in the PH value of the water to happen in case of acidic chemicals gets to the water and lower its PH value "more Acidic" less than the value that concrete can retain.

so, as a conclusion....it's always better and more economical in the long run to waterproof your concrete....either subjected to water or not at the time of construction....i have seen lots of basements that gets water table raised after years of construction due to several reasons....so, investing a little more money in a proper waterproofing system at time of construction would save lots of money wasted on later repairs.

i hope this was informative enough.