The theoretical and analytical content of this PhD thesis generates the critical knowledge necessary to affirm that free spaces (or open spaces) are the elements capable of restructuring the contemporary city. Amongst them, what we have defined as "water lands" play a prominent structuring role. On the other hand, to take advantage of its potential, water lands must be approached in all its complexity, based on an interpretation of the territory and design and management strategies. At all times, it is necessary to aspire to inter scalar and interdisciplinary work that ensures good management of water resources. These two statements frame the two hypotheses formulated in this research, which are collected in the first part of the thesis and which arise from the readings of both the Barcelona school (Enric Batlle, Raquel H. Tardin) and the Anglo-Saxon school ( Ian McHarg, Wenched E. Dramstad, James D. Olson, and Richard TT Forman, James Corner, Charles Waldheim, and Michael Hough). The first hypothesis, which affirms that the land of the water must be in the focus of attention of the project of the contemporary city on a territorial and urban scale, which together with the other free spaces can come to structure it with the construction of an ecological matrix, is verified in the second part of the thesis from the analysis of what we call a case study, the conurbations of Sabadell and Terrassa. In the study carried out, the territory is analysed on a territorial scale and later in a detailed scale. Drawing is the main tool used in this thesis, that allows a reading of the territory from its collective imagination, from urban history, from water, from its landscape, from ecology and from urban planning. From this analysis it is verified, on the one hand, that the axes of the Besos and Llobregat basins have become their own functional and economic structures, demonstrating the permanence of the identity of the territory defined by water. On the other hand, that the river axes appear to us as powerful structural ...