The contribution of shrinkage cracks to bypass flow during simulated and natural rainfall experiments in northeastern Mexico

Abstract

Understanding the spatial and temporal dynamics of desiccation cracks and related hydro-geomorphologic processes is a key component for the sustainable management of water resources in Vertisols. The contribution of shrinkage cracks to infiltration of runoff and sediments was studied during natural and simulated rainfall experiments in Vertisols of the semi-arid plains of northeastern Mexico during the summer of 1998. Surface runoff amounted to 10.7% of the total applied rainfall, but it increased from 2.3 t o 18.3% during the first and last applied rainfall. Soil cracks partially filled with transported sediments in surface runoff, but never sealed by swelling or by sedimentation during the sprinkling of 180 mm of rainfall applied in three installments during 1 wk. However, cracks observed in 1999 closed during natural rainfalls with a total depth of 450 mm, distributed in 10 storms during 3 mo. The development of soil cracks and their contribution to promote short-circuit flow are highly variable processes in time and space. Key Words: Dynamics of shrinkage cracks, irregular wetting fronts