Close Range Stereophotogrammetry and Video Imagery Analyses in Soil Ecohydrology Modelling

Ecohydrology is an emerging discipline in the environmental sciences. Soil micro-relief is of relevance to various ecohydrological processes such as rainwater redistribution, seed displacement through water runoff, water erosion and plant competition for water. Mechanicaloptical methods to characterise the soil surface and its incidence in these processes are time consuming and can produce modifications of soil relief. This research explores a methodology combining non-contact techniques (close range stereophotogrammetry and geostatistical modelling) for microtopographic description with video imagery analysis to formulate quantitative determination of surface water movement and infiltration in undisturbed field plots. The numerical quality of the results obtained was tested with ad hoc laboratory models representing various elementary landforms (basin, hill and ridge), as well as with infiltration runoff experiments in undisturbed field plots. The requirements to define a minimum set of properly oriented digital images to attain target precision thresholds in modelling soil microtopography for ecohydrological applications are shown as well as the conditions and experimental arrangement to obtain adequate video imagery of water movement on the soil surface. The use of geostatistical algorithms to analyse ecohydrological processes occurring at the soil surface is illustrated with results obtained from field plots. The methodology presented serves to characterise and quantify water-related ecological processes occurring at the soil surface while preserving undisturbed soil conditions. Potential applications are in ecohydrology, soil erosion science and environmental material transport studies.