Author(s): H. Walter Cazenave; Argentina
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Keywords: Casa de Piedra dam; Colorado River; Suspended material; Watering channels; Freatic layers
Abstract: Casa de Piedra dam, in the Colorado River valley, Northpatagonia, Argentina, was mainly built for flow regulation purposes. The lake (4.000 hm 3) formed behind the dam, promotes particles sedimentation and rather clean released water with a huge load capacity. The released water has a higher velocity and erosive capacity than one at pre dam period. It has altered the river channel geography through hydroform creation and modification. Increased erosion has also resulted in the alteration of river course within the valley. This is compounded by minimal lime being transported by the river, which naturally impermeabilized water channels. Strong channels infiltration in the cultivated zones has also caused freatic layers elevation. This problem is less significant in the oldest zone, although it also manifests when there is water channel cleaning. This trouble emphasizes the need to rethink new impermeabilization tecniques to assist with watershed management. “Clean waters” brought sea-weeds, which had to be attacked by means of biological and chemical methods, as foreign fish introduction, like “Carpa of Amur”. Through maps and satellite comparisson obtained with regular intervals, it was possible to quantify hydrographical changes, like new meanders appearence in relationship to time. It happened faster than the previous phase, that is to say, the dam construction.
Year: 2004