By Anton Pijl, Teun Vogel, and Paolo Tarolli
Hillslope viticulture is a valuable practice across Mediterranean Europe and beyond, not just in economic terms but also for its historical tradition and cultural heritage. Yet, soil degradation such as erosion or slope failure is a growing challenge for cultivators and is threatening the preservation of these landscapes. Future climate projections show a trend of extreme rainfall events, and already nowadays we can witness its impact on soil degradation. In this work, we illustrate how soil and water conservation in vineyards is facilitated by the support of remote sensing technologies such as low-cost drone surveys. Remote sensing allows high-precision mapping of the vineyard ground surface through 3D reconstruction. This can be used to detect, understand or even predict soil degradation, for example by simulating the flow of water and sediments across a vineyard. Such a workflow enables efficient scenario analyses of new vineyard interventions or climatic conditions. Soil protection works can be guided by this workflow for a rapid and low-cost evaluation of new designs. As such, landscape planners are encouraged to utilise this potential to help safeguarding the sustainability of vineyard landscapes.
The actual threat of a changing climate to soil resources
In the summer of 2020, the north Italian traditional vineyard landscape of Soave was struck by a devastating downburst, as described in detail in a recent blog of the Natural Hazards Division of the European Geosciences Union (EGU) (https://blogs.egu.eu/divisions/nh/2020/12/21/climate-change-is-viticulture-under-threat/). Such extreme weather events are able to destroy entire vineyards in a matter of hours, both the vine plants and underlying soils, by the forces of wind and water. Climate trends show higher frequency and intensity of rainstorms interspersed by drought (Gao et al., 2006; IPCC, 2014; Nasta et al., 2020). Growing rainfall aggressiveness and seasonality are challenging the sustainability of existing soil protection measures, such as terraces (Figure 1). As such, the urgency of soil and water conservation in vineyards is clearer than ever, in order to preserve these valuable but fragile landscapes (Tarolli and Straffelini, 2020).
Remote sensing and soil & water conservation
Water flow across the vineyard surface is a primary driver of soil erosion, while surface water flow is mostly driven by topography. Any topographic detail – i.e. the terrain shape of roads, terraces or drainage systems – determines the direction and velocity of water flow. Even small-scale terrain elements such as wheel tracks or earth ridges under vine plants can affect surface flow, and therefore erosion patterns. The impact of terrain shapes on the movement of water and sediment can be studied using remote sensing (Figure 2). Modern techniques, such as drone surveys (a.k.a. RPAS or Remotely Piloted Aircraft Systems) and laser scanning surveys can be used to capture the terrain morphology in 3D Digital Elevation Models (DEMs), achieving a reconstruction precision in the order of centimetres (Eltner et al., 2016).
While precise DEMs may be particularly fascinating for geomorphologists, they are also highly relevant for any practitioner or scientist in the field of land planning or agriculture (Colomina and Molina, 2014), due to several reasons. Firstly, remote sensing data can be used to recognise soil degradation by its imprint on the terrain, which is detectable in a precise DTM. Automatic detection, in particular, offers a powerful tool in rapid inventorying and monitoring of soil degradation at landscape scale. Secondly, remote sensing data can help understanding why degradation occurs in specific locations (e.g. Figure 2, yellow exclamation mark). Model simulations are invaluable tools in this process, e.g. by physical erosion modelling based on high-resolution remote sensing data (Pijl et al., 2020).
Lastly, a remote sensing workflow as illustrated in Figure 2 can be used for testing new vineyard designs in terms of soil and water conservation impacts. This offers a rapid and low-cost alternative to pilot tests in the field, and allows diverse scenario analysis of designed interventions or climatic conditions. An example is provided in the video below, summarising a scientific study where different terrace configurations were compared in terms of soil and water conservation impacts (Pijl et al., 2020).
Integrating remote sensing data in sustainable landscape planning
There are growing opportunities of integrating remote sensing analysis in the planning and management of vineyard landscapes. Thanks to rapid technological developments and expansion, an increasing amount of remote sensing data (e.g. high-resolution DEMs) from governments or private sources are freely available (e.g. see opentopography.org or earthengine.google.com). Combining these increasingly accurate data with the skillset of an experienced spatial analyst enables more effective and efficient landscape planning. For instance, workflows as illustrated above can help identifying and prioritising landscape zones at risk (Tarolli and Straffelini, 2020), and facilitates suitable designing of soil protection solutions in those areas. In northern Italy, a good example of such integration is the Soilution System project (soilutionsystem.com), as part of an EU rural development programme (Programma di Sviluppo Rurale per il Veneto 2014-2020) under the scientific coordination of the University of Padova (Italy). In a time when the sustainability of vineyard landscapes is threatened by climate change, remote sensing can become an effective tool for optimising soil and water conservation practices.
Anton Pijl – Postdoctoral Researcher at University of Padova, Italy (email@example.com). Anton obtained his PhD degree in the field of soil & water conservation in steep-slope agricultural landscapes. During his doctoral programme he conducted and published several scientific studies on the challenge of soil erosion in vineyards, and the role of GIS and remote sensing in improving sustainable management practices. In his current postdoctoral position, he continues the analysis of vineyard soil degradation by combining plot monitoring data and physical erosion modelling. In his work, there is a special focus on the opportunities of state-of-the-art technologies and tools for 3D spatial analysis and visualisation of surface processes.
Teun Vogel – Environmental Consultant at Cambisol, The Netherlands (www.cambisol.com)
Teun has a background as scientist at Wageningen University (The Netherlands), but has found his passion in consultancy and social entrepreneurship as a parallel perspective. He has started the environmental consultancy firm Cambisol focusing on the general vision of transforming degraded lands into green and lush places. He gained international expertise in mapping and design, growing experience to execute projects from A to Z: from being a RPAS pilot in the first surveys to being responsible for the final design and implementation of soil and water conservation measures.
Paolo Tarolli – Professor at University of Padova, Italy (firstname.lastname@example.org) Paolo is Professor in Integrated Watershed Management and Water Resources Management at the University of Padova. He is Principal Investigator of Earth Surface Processes and Society research group (linkedin.com/in/earthsurfs). He is Deputy President of the EGU Natural Hazards division and Executive Editor of Natural Hazards and Earth System Sciences (NHESS) journal. His fields of expertise include digital terrain analysis, earth surface processes analysis, natural hazards, geomorphology, LiDAR, structure-from-motion photogrammetry, topographic signatures and impact of human activities, and future water scarcity in agricultural systems.
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