The defender arrives in a free transfer from Athletic Bilbao.
Alemany said: "A year ago we were aware that we would have to wait a year to reinforce our defence. We set ourselves the challenge of looking for a player to replace Gerard Piqué. We took into account that the economic reality of the club is what we all know, so we had to adjust to the situation.
"I think it is a feal that Athletic will find understandable. The player was free, although, from the first moment, we perceived the player's total willingness. He has the characteristics that we all value, he can help the team. He is a player with that we have a great advantage in that he can adapt immediately, and he knows the Spanish La Liga which we value.
"He is fast, has good ball control, characteristics that will help us a lot in our style of play. He also has a great character and we value this."