The proliferation of new underground rivers in the province of San Luis responds to a phenomenon called ‘sapping’. They are giant galleries 50 meters wide by 25 deep.
The scientific documentary ‘New River'reflects the studies being carried out by scientists from the Environmental Studies Group of the National Council for Scientific and Technical Research (CONICET) and the National University of San Luis (UNSL), who began to investigate in 2008 the proliferation of new underground rivers in the province of San Luis. The culprits would be corn and soy plantations without crop rotation.
This phenomenon is called sapping. It is an erosive process generated by underground water, which causes collapses and canyons. The water does not dig from the top down but from the bottom up. Through this process, for example, some branches of the Grand Canyon of the Colorado were formed thousands of years ago. Ythe surface of Mars is also believed to have been shaped by sapping. “It took us a long time,” says Jobbágy, to realize that what we had in front of us was sapping. The rarity of the local process is its phenomenal scale in space: the new rivers of San Luis are giant galleries 50 meters wide by 25 deep ”.
“The New River is the most spectacular of the six new rivers that were formed so far, because it is the one with the deepest ditches, up to 25 meters. We do not know how far the deepening can go, the only physical barrier is in the hard rock of the basement ”, expressed Esteban Jobbágy, leader of the team of agronomists, biologists and technicians.
What most worries the researcher is not the deepening butthe ability of this watercourse to move mud, which could put the periphery of Villa Mercedes at risk and cut routes 7 and 8. “If these two routes are cut at the same time, the movement of merchandise in the country will be complicated: it will be a problem of national and almost regional magnitude, because Chile and Brazil exchange on those routes. The losses could be millions ”.
Before this panorama, The researchers recently signed an agreement with the province of San Luis to be in charge of projecting how the problem will continue, monitor it and propose possible works to stop it, “because nobody really knows what works to do. Our job will be to guide that. There is the practical problem, and the difficulty of explaining it with the state of the art of Hydraulic Engineering and Hydrogeology: that is where we come in to try to find explanations and then find solutions ”. The studies will be carried out through hydrological and geomorphological computational simulation models.
From the exhibition of the documentary, the researchers received calls from residents of San Luis and even Córdoba who state that they are seeing similar phenomena in their cities. And in addition, there have already been two concrete actions motivated by the government of the province itself: land use plans were established inspired by the legislation of Uruguay, a pioneer in this regard - “the owners of the land, from now on, are those responsible for presenting a plan that ensures crop rotation for five years ”, explains Jobbágy-, and plans for reforestation of the area.