De or het watererosie?

The correct Dutch article is:

de watererosie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use watererosie

the watererosiede watererosie
this watererosiedeze watererosie
that watererosiedie watererosie
our watererosieonze watererosie
your watererosiejouw watererosie
every watererosieelke watererosie
which watererosie?welke watererosie?
a big watererosie / the big watererosieeen grote watererosie, de grote watererosie