Towards an Optimal Method for Assessing the Spatial and Temporal Hydrological Dynamics of a Keyline System

Climate change will heavily impact agriculture through alterations of precipitation dynamics which leads to more frequent agroecological droughts and intense precipitation events. Strategies to adapt to these changes are necessary to maintain food safety and sustain livelihoods in the agricultural sector. One method for farmers to mitigate the impacts from climate change is the Keylines design which can be described as open ditches parallel to the elevation line. These are designed to retain runoff, reduce erosion and increase infiltration which should lead to a higher amount of water available to plants during dry periods (e.g., Ponce-Rodríguez et al. 2021). However, scientific research and corresponding data regarding Keyline systems and their influence on field hydrological dynamics is sparse.

To quantify the hydrological impact of Keyline systems, a comprehensive field experiment has been set up combining Keyline systems with agroforest on two agricultural fields, one of which is located in the eastern Jura-range and one outside of Zurich. The goal of this study is to assess the optimal integration of tools to investigate how the soil moisture patterns are altered by Keyline systems and quantify the timing and amount of water retained. The work presented here shows the first results of a comparison between different soil moisture analysis methods applied to agricultural fields, including (a) soil hydrological modelling, (b) electric resistivity tomography, (c) UAV-based L-band radiometry, (d) in-situ soil matrix potential and volumetric water content measurements and (e) destructive gravimetric water content measurements. Several of these methods currently undergo rapid developments due to the technological advancements made in recent years, leading to an increased accessibility for a broader range of users (e.g. Du 2020; Zhou et al. 2025). This highlights the need to assess the tools regularly to showcase possible applications and directions for further development. The results presented here demonstrate the capabilities as well as the limitations of the individual methods and shows how the different systems can be used complementary with each other to obtain a complete assessment of the soil hydrological dynamics. This will help researchers investigating soil moisture dynamics to make informed choices regarding their research tools for the assessment of nature-based solutions to adapt to climate change impacts within but also beyond agriculture.

Literature:

Du, C. (2020). Comparison of the performance of 22 models describing soil water retention curves from saturation to oven dryness. Vadose Zone Journal, 19(1), e20072. https://doi.org/10.1002/vzj2.20072.

Ponce-Rodríguez, M. D. C., Carrete-Carreón, F. O., Núñez-Fernández, G. A., Muñoz-Ramos, J. de J., & Pérez-López, M. E. (2021): Keyline in bean crop (Phaseolus vulgaris l.) for soil and water conservation. Sustainability, 13(17), 9982. https://doi.org/10.3390/su13179982.

Zhou, Y., Schwank, M., Boutin, J., Richaume, P., Mialon, A., Holmberg, M., Kalescke, L. Zeiger, P., Leduc-Leballeur, M., ... , Kerr, Y. (2025, in review): Setellite Microwave Radiometry at L-band for Monitoring Earth’s Essential Climate Variables. IEEE Geoscience and Remote Sensing Magazine.