| The state of Nuevo Leon, in northeastern Mexico, is situated in a semiarid region. The Sierra Madre Oriental (SMO) is a mountain range that traverses the state and plays an important role in its hydrological regime. All the rivers in the state originate within the SMO and run through the plains where the water is used for agriculture and urban consumption. However, very little is known about the dynamics of water on the slopes of the SMO. The objectives of this study were: (i) to define water pathways and fluxes within the soils of some typical sites of the SMO; (ii) to identify the factors that control water motion; and (iii) to assess the influence that vegetation type has on water pathways. Five representative sites (plots) were selected based on slope aspect, soil characteristics, and vegetation type. On each plot throughfall, overland flow, subsurface flow, and soil water content change were measured. Two approaches were used: natural rainfall and irrigation. Additional geological, soil, and vegetation variables were measured. There are no statistically significant differences in throughfall percentage among plots. Overland flow only occurred in plot 1 located on a south-facing slope; no overland flow was observed at the slope scale at this site. Subsurface flow was absent or small in the forested plots (north-facing slopes). The dominant process on these slopes is water infiltration which, coupled with a rapid percolation of water through macropores into a highly fractured bedrock, assured a rapid transmission of water to the bedrock. |
