Sand mining further erodes the coast, and ground water drainage to sustain human populations triggers land subsidence even as the sea level rises by around 5mm a year.

Subsurface pipe drainage in drought-prone region is superior to surface drainage in draining off water and salt, controlling ground water-level, and increasing crop output, etc.

And municipal water supply and drainage pipe is erected on the ground, if there are problems, will give the city the normal production and life bring serious effect.