The origin of the name Tjaden we must seek in the "Old Frisian" language. A language who was spoken in the north of the Netherlands and in Ostfriesland. In 1500/1600 the old Frisian language disappear gradual. In the north east of the Netherlands and Ostfriesland there came a Saxon language with Frisian influence. In the north of the Netherlands, there is a language we call "New Frisian".
In Saterland south of Leer, the people there speaks real Frisian. The "old Frisian" language was a family-language of the language who was spoken by the Anglo-Saxon in England about the year 1000.

The name Tjade or Tja means streaming water or little river. In the surrounding where i live, is a little river with the name Tjariet. Also the German Jade who is now large by inundation earlier, must be have earlier a little river, i think. The name Jade came from Tjade.

The name Tjade was earlier also writing as Tyade or Tiade.
The name Tjaden can be made in two manners:

1. In the old Frisian time the Tjade was as second or family name Tjadona. (Tjad)ona, the old Frisian word "mon" is the english word men. More men is in old Frisian "mona" - (Tjad)ona, ona came from mona. By Saxon influence Tjadona became Tjadena, O=e is a mute vowel (Hayen Tjadena, Pilsum about 1450), later also by the Saxon mute vowel Tjadena became Tjaden.
   
2. A other manner to come to the name Tjaden is in a later time. In Ostfriesland is now spoken Saxon "Plat Duuts" (The people in Ostfriesland call it Ostfriesisch). From the name Tjade you can make a second or family name Tjaden (Tjade Hayen, his son is named Hayo Tjaden).

Tjade / Tjaden we must look in streaming water or little river. Earlier, there were in the north of the Netherlands and Ostfriesland very much little rivers.

A other explanation for Tjaden.

A other word in the old language is thiad, it means people (in the meaning of own people, a example Frisian people). Maybe that Tjade came from Thiad(e). The type (th) from Thiad is the same type as the English "th". In Dutch or German it is "d". There was a time that earlier the "d" was write as "t". Thiad is an "old Germanic" word.

So there are two theories about the name Tjaden.
Personal i will give prefer to Tjade as streaming water / little river. This, because we had earlier much little rivers in Ostfriesland.

All the people with the name Tjaden come from Ostfriesland or from the neighborhood of Ostfriesland (Cleverns).
So Tjaden we can say as joke, you are a "quick waterman".

  —Evert Tjaden