We often forget how different the Rio Grande Valley is now compared to when the first Spaniards entered the region. Some of this, of course, is obvious—the buildings, roads, fields of cotton and chile. Other changes, though tend to be more subtle. The river used to meander back and forth across the floodplain and, in flood, cover the valley floor from edge to edge. No more! Dams upstream have reined in the flooding. Furthermore, the river has been canalized to save water, since a straight stream has much less surface area for evaporation than a wandering, natural river.
ln another effort to conserve water for
irrigation, much of the earlier vegetation has been eliminated.
Trees growing on the floodplain were mostly phreatophytes, a
fancy word denoting plants dependent on the water table rather
than precipitation. Such plants transpire enormous amounts of
water into the atmosphere, water lost to irrigation—the
river bottom bosques had to go. And so they did! And now we may
never be able to picture, even in mind's eye, the wild Rio
Grande of the past.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.