Abrupt watercourse formation in a semiarid sedimentary landscape of central Argentina: the roles of forest clearing, rainfall variability and seismic activity

摘要: In a semiarid sedimentary catchment of central Argentina, we describe recent process landscape dissection, abrupt canyon and watercourse formation soil salinization. We link these adverse hydrological geomorphological transformations to three potentially important drivers: precipitation increase, seismic activity deforestation. Remote sensing imagery in the last 48 years showed an exponential increase length streams, with drainage density values tripling reach 0.22 km km2. During same period, forest area declined from 47% 10%, at expense agriculture expansion. A 3.4-fold expansion surface water bodies table level raise 0.15 m y−1 over 35 years was observed. Discharge new stream middle basin ranged between 0.25 0.45 m3 s−1 accompanied by large stable load salts (~0.7 g l−1). Nil recharge vadose accumulation dry forests stands contrasted rates ~16 mm salt-leached profiles under agriculture. Although dissection occurred during decades higher than average precipitation, extreme rainfall events were not exceptional that period. Results suggest replacement annual crops played more role, reducing evapotranspiration, triggering onset groundwater favouring subsurface through piping/sapping processes. The shows no signs stabilization present may only be ameliorated changes vegetation restore original non-flow condition forest. Copyright © 2012 John Wiley & Sons, Ltd.