Precipitation Characteristics and Land Cover Control Wet Season Runoff Source and Rainfall Partitioning in Three Humid Tropical Catchments in Central Panama

Mechanisms of runoff generation in the humid tropics are poorly understood, particularly context land-use/land cover change. This study analyzed results 124 storm hydrographs from three tropical catchments markedly different vegetation and land-use history central Panama during 2017 wet season: actively grazed pasture, young secondary succession, near-mature forest. We used electrical conductivity to separate baseflow (old water) storm-event water (new-water). In all land covers, new-water dominated 44% sampled events, indicating dominance fast shallow flow paths landscape. Activation these was found depend on a combination maximum rainfall intensity total rainfall, which, turn, relates contrasting hydrograph separation among covers. Relationships between characteristics were nonlinear, producing threshold response with exceedance specific volumes and/or intensities. The pastoral catchment delivered order magnitude more events than two forested catchments. Although contributed minimally (<10%) season catchments, 43% pasture came five large where produced substantial increases new-runoff efficiency. Based our results, we propose conceptual model hydrologic systems that can explain previously observed disparities seasonal storage respect use/land cover.