OOps! I overlooked the full context of your question :( "jaloplabon" and "bonna" are more or less same in meaning. In fact we commonly use "bonna". "jaloplabon" is used in literature ... I mean in novels, short stories etc. Basically, "plabon" means flood, same as "bonna".....and "jol" is water..... However "jolochash" is little different....it's more like a tsunami .... a huge wave of water rushing in to submerge everything. Hope it helps!

"bonya" bala hoy .... "bonya" means flood. It's really surprising that you are learning Bengali...it really sounds great ^^. Please keep it up. BTW, in Bengali, they often mix English words in a sentence. Like you wrote "Rane Seasone....". It's actually "Rainy Season - e(in)". Since you are also learning English you may find it very interesting... Good Luck ^^