Day 4

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Paper title Inclusion of animal burrowing activity into remote sensing based numerical models – a study revealing the potential and importance of modelling feedbacks between pedo-, hydro- and biosphere
  1. Paulina Grigusova University of Marburg, Germany Speaker
  2. Annegret Larsen
  3. Diana Kraus
  4. Roland Brandl
  5. Nina Farwig
  6. Jörg Bendix Department of Geography, Philipps-University Marburg
Form of presentation Poster
  • A7. Hydrology and Water Cycle
    • A7.01 Inland Water Storage and Runoff: Modeling, In Situ Data and Remote Sensing
Abstract text One of the less understood feedbacks is the role of burrowing animals on the soil hydrology. Burrowing animals were shown to increase soil macroporosity and affect vegetation distribution, both of which have huge impacts on infiltration, preferential flow, surface runoff, water storage and field capacity. However, the specific role of burrowing animals on these variables is to date poorly understood, the presence of burrowing animals has largely not been included in the erosion models. A suitable approach which enables studying their impacts on the catchment scale and compare them across several climate zones is missing but needed to fully understand the feedbacks between the pedo- and biosphere.

To close this research gap, we combined in-situ measurements of soil properties and burrow distribution, high resolution remote sensing data and machine-learning methods with numerical modelling.

For this, we first conducted field surveys on the presence and absence of animal burrows along a predefined track with 8 the hillside. We extracted 160 soil samples along the catena of study hillsides, as well as 316 soil samples from animal burrow areas and control areas without an animal burrow. We analysed them on several physical and chemical properties needed for model parametrisation and as well estimated the difference between samples extracted from burrow area and control area. We studied the daily surface processes at the burrow scale and measured the volume of excavated sediment by the animals and the sediment redistribution processes within the burrow area during rainfall events using laser scanners for a period of 7 months.

Then, we combined the in-situ measured soil properties and the burrow distribution with remote sensing and machine learning and upscaled the soil properties and the presence of animal burrows to each catchment at a resolution of 0.5 m. We conducted a land cover classification to estimate the vegetation cover and combined LiDAR data with the DGM to estimate the vegetation height.

We implemented the upscaled soil properties, burrow locations and vegetation parameters into Morgan-Morgan-Finney model and parametrised one model per catchment. For this, we adjusted the input parameters at the burrow locations according to the measured soil properties, vegetation cover and height, estimated microtopography changes, burrowing behaviour and sediment excavation and redistribution within the burrow area. We validated the model using the in-situ installed sediment traps.

To estimate the impacts of burrowing animals, we ran the model with included and not included animal burrows. We estimated the daily and yearly impacts of the presence of the burrows on soil erosion, infiltration, preferential flow, surface runoff, water storage and field capacity.

We present a parametrised model, which includes the presence of animal burrows in its calculation and the modelled impacts of burrowing animals on soil erosion, infiltration, preferential flow, surface runoff, water storage and field capacity on the catchment scale at a 0.5 m resolution. We compare the short-term and long-term impacts on the soil hydrological properties at the burrow and catchment scale along the climate gradient.

The numerical model achieved an accuracy of R2 = 0.70. The presence of burrows had a positive impact on sediment erosion, infiltration and water storage and negative impact on surface runoff and field capacity. These effects were on the daily and burrow scale most pronounced in the semi-arid and mediterranean climate zone. In the semi-arid climate zone, the burrows heavily affected already sparse vegetation which then affected the surface infiltration and runoff. In the mediterranean climate zone, the burrow size and entrance diameter especially had an impact on the preferential flow. At the catchment and yearly scale, the effects were most pronounced in the humid zone. Although the density of burrows was here low, due to regularly occurred rainfall events the burrowing animals here cumulatively contributed the most to all hydrological processes. In the arid zone, the impact of burrowing animals was detectable during sporadically occurring heavy rains.

Our study thus shows the potential of inclusion of burrowing animals into numerical models as well as the importance to do so, as our results show heavy impacts of the presence of the burrows on hydrological processes in all climate zones at various temporal and spatial scales.