rain water storage

As there were/are no rivers in Jaffna/Kokuvil our ancestors built reservoirs(kulam)in kokuvil too but now many of them may have disappeared or depleted. In 1950s I remember there were two in nanthavil farmland and one in nariyankundu near parameswara college junction. There might have been one in thalayali and another on eastern side of kulapiddy junction as during rainy season water was getting collected there and in the nights frogs make a lot of noises. If we don't store surface rain water-floodwater-our wells might become drier day by day.Our local bodies and NPC should take care of this.