Morfometría del Barranco de Santiago, Gomera (Islas Canarias)

Abstract

The Barranco de Santiago is a river basin of the south of the island Gomera (Canary Islands). To this basin belongs the Garajonay peak (1.487 m). This river basin has somewhat more than 10 km of length, and its waters arrive to the Atlantic Ocean. The rocks on those which flows are all volcanic, and in them can be differentiated three principal types. This river net has been digitized taking the coordinates (x, y, z) of the points origin and final of the greater possible number of lines in which they have been divided its course. To scale 1:25.000 have been able to differentiate a total of 489 such right lines, that be at the point the order 4, upon applying the hierarchic order according to the Strhaler's criterion. Said river net is formed by two basins smaller, that correspond to that of the Guarimar and Benchijigua ravines. Both present structural features (forms dentritic and linear respectively) that permit to assign to each one of them a different evolution: more maturity for the case of Benchijigua and an origin most recent in for the Barranco de Guarimar. Though it is a basin with reduced dimensions (area of 23,63 km²), through the structure that presents the drainage net three structural zones have been differentiate, that coincide mainly, with the different groups of volcanic rocks. Two steps in the longitudinal profile of the Barranco de Santiago, one to 500 m and the other to 70-80 m of altitude above the sea level, make to deduce the raising existence, at least of this magnitude, of this part of the island during the Quaternary. The existence of others two steps to greater altitude permit to suppose that, after the analysis in all the ravines of Gomera it will be able to confirm or to reject in the future, the action in addition to other dynamic of greater importance.