Like yesterday's post on Yardley, Yarden is extremely similar in every way - nature name, place name, rare, but it seems to work as a boy's name just a tiny bit more than Yardley thanks to it's trending -n ending. However, the similarity in sound to "garden" makes it seem a bit whimsical-meets-tomboy for a girl. The perfect unisex name.
The statistics say Yarden is for girls, though. While Yardley was given to 9 girls in 2014 and none in 2015, and not given to boys at all, the name Yarden was given to 7 girls in 2014, then 5 in 2011 and none between those dates. Yarden previously had a run between 2002 and 2008, missing some years between, and not given more than 11 times in a year. It started being used on girls in 1984 with 6 births (probably five and less than five births for any number of years beforehand) and started being used on boys in 1990 with 5 births. Interestingly, Yarden seems to switch sides: given to boys in the years it's not used on girls and vice versa, but not strictly so. For example, Yarden was used on both genders in the early 90's, but more so on girls. Then between 1996 and 2001 it was more used on boys - in fact only once on girls in 2000, but then after 2002 it wasn't used on boys again until 2009.
Yarden is a Hebrew name, unlike Yardley which is English. It means "to flow down, to descend" in reference to the movement of a river - specifically the Jordan river. Indeed, this was the original word/name that Jordan derived from (like most European names, j and y are frequently switched and/or misspoken by English speakers). Yarden is considered unisex but sometimes Yardena is given to girls. Given that Jordan and Yarden have the same meaning, this could make an excellent alternative to parents that like Jordan but fear it's popularity or think it might be dated.
A couple of famous namesakes include Yarden Gerbi, judoka world champion from Israel and Olympic bronze medalist, and Yarden Cohen, an Israeli footballer.