Principles of agrarian collapse in the Cordillera Negra, Peru

Abstract

The amount of land under cultivation on the arid north coast of Peru has decreased by 35-40% during the last 1,000 yr. Two physical processes are implicated in this agrarian collapse. The basic contributory process is uplift along the Peruvian continental margin, which causes ground slope changes. The 2nd process involves rare but recurrent rains caused by El Nino perturbations of the normal marine and meteorological conditions. Uplift leads to river entrenchment, and El Nino rains aggravate erosional downcutting. Downcutting strands canal intakes, forcing abandonment of irrigation systems in favor of newer, lower canals which irrigate less land.