Biological macropores effect on runoff and infiltration: a combined experimental and modelling approach

The influence of the large macropores made by the soil macrofauna on water infiltration has been well studied for about two decades. However, the results depend on the measurement methods, the variability is very high, and we do not yet really understand all the processes and their consequences. A more detailed description of the key processes should allow more formalisation through modelling and a comparison between the various experimental results. We present here an example of such an approach, that goes from field study to modelling, about the influence of termites on infiltration. The effect of termites on runoff was studied during 4 years, under natural rainfall, in Niger. A spatialised model was developed to simulate the interception of runoff by the macropores. The results of the field experiment underline the great and durable impact of termites on infiltration, and allow to better understand the processes responsible of this effect at various time or space scales. Simulations provide a deeper insight on the observed processes and reinforce our interpretations.