estuary zones

• river head (zone 1): large sediments at the bottom (grave), freshwater, no tidal action felt. The water here has a high velocity and is still able to carry smaller sediments without dropping them.
• upper reach (zone 2): smaller sediments at the bottom, silt/sand, low salinity
• middle reach (zone 3): muddy sediments at the bottom, medium salinity water, some tidal action felt. Small sediments are suspended in the water. Heavy saline water wedges underneath the lighter fresh water. The water here has a low velocity.
• lower reach (zone 4): sandy / muddy sediments at ht bottom, high salinity water
• mouth (zone 5): sand and seashells make up the sediment here, fully saline water, full tidal action of the ocean. The water here has a high velocity and is able to carry smaller sediments without dropping them.