Student projects

Context. Accurate modeling of plant-soil water relations is crucial for optimizing agricultural production, particularly in light of predicted climate changes (e.g., Tramontini et al., 2013; Martínez-Lüscher et al., 2016). This is particularly relevant in viticulture, where accurate knowledge of terroir effects on the plant response is crucial (van Leeuwen et al., 2020), especially in light of their impacts on grapevine most valuable final product (i.e., wine). Grapevine production in the Valais is a topical example. Here, the unique climatic conditions have made the region the most productive in Switzerland for viticulture. However, predicted hydroclimatic changes (most notably expected increases in temperature and in drought frequency and intensity) will altogether alter such a delicate equilibrium and cause notable challenges associated soil-plant water relations and resulting crop yield and quality.

Objectives. This thesis aims at calibrating and validating a state-of-the-art ecohydrological model against data collected at the Experimental Station for Viticulture and Oenology in Leytron, Canton of Valais (managed by Agroscope). You will use the Tethys and Chloris (T&C) ecohydrological model (Fatichi et al., 2012), adapt it for the description of grapevine dynamics, and use it to quantify soil-plant water dynamics under different management and climatic conditions. The student is expected to actively work on a literature review of the topic (10%), perform numerical simulations using T&C (60%), and critically assess the results (30%). The thesis will be conducted in collaboration with Agroscope.

If you are interested, please contact Sara Bonetti ([email protected]).

 

Vignes de la vallée du Rhône, coteaux d’Ardon, canton du Valais, Switzerland (from flickr.com).

Context. Landscape topography and its time evolution play a crucial role in a variety of ecohydrological and geomorphological processes. For example, the spatial distribution of energy (e.g., radiation) and water (e.g., soil moisture) variables, which are the main drivers of vegetation and nutrients distribution, is highly dependent on the topographic features of a landscape (e.g., elevation, slope, aspect, curvature, drainage area) (Florinsky and Kuryakova, 1996). The amount of solar radiation intercepted by a surface is affected by local slope and aspect (Essery and Marks, 2007), while surface and subsurface water redistribution are strongly influenced by microtopographic attributes such as landscape connectivity, curvature, and slope, thus regulating the local soil moisture available to plants (Dymond et al., 2017). Conversely, vegetation cover influences landscape evolution in many ways, such as providing physical resistance to soil erosion and enhancing soil cohesion (Meng et al., 2022). Despite the significant progress in the past decades, the understanding of potential feedback mechanisms between vegetation and landforms, as mediated by local environmental and climatic conditions, is still limited.

Objectives. This thesis contributes to answering the question “how do vegetation and topography co-evolve”? The student will couple a state-of-the-art spatially distributed ecohydrological model (Tethys-​ Chloris, Fatichi et al., 2012) and a landscape evolution model (CAESAR-Lisflood, Coulthard et al., 2013) to quantify how landscape evolution impacts the spatial distribution of vegetation and, conversely, how vegetation distribution affects the landscape evolution dynamics. The student is expected to actively work on a literature review of the topic (10%), perform numerical simulations (70%) and critically assess the results (20%).

If you are interested, please contact Sara Bonetti ([email protected]) and Taiqi Lian ([email protected]).

Example of lavaka in the Hauts-Plateaux, central Madagascar (Image credit: Trent Marwick, distributed via imaggeo.egu.eu). The cascading vegetation mirrors the cycles of erosion and stabilization typical of dynamic landscape features.

Context. The increasing global demand for agricultural products is placing a growing pressure on surface and subsurface water resources (D’Odorico et al. 2019). The combination of such a pressing need to ensure food security with the water scarcity of many world’s regions represents a major challenge for the sustainable management of water resources. Various water use and water sustainability indicators (e.g., virtual water content, water debt repayment time) have been developed and used to quantify the linkage between food and water resources as a function of climate, soil, and agricultural practices and assess their local sustainability (e.g., Mekonnen and Hoekstra 2011, Tuninetti et al. 2019).

Objectives. This thesis aims at characterizing crop-specific water sustainability at the global scale. Specifically, you will map the spatial distribution of source- and crop-specific water uses and assess their local sustainability in terms of water debt repayment time (Tuninetti et al. 2019; Bonetti et al. 2020). The student is expected to actively work on a literature review of the topic (10%), perform data analyses (20%) and numerical simulations (50%), and critically assess the results (20%).

If you are interested, please contact Sara Bonetti ([email protected]) and Francesca Bassani ([email protected]).

Projected changes (with respect to the year 2013) in crop water footprint for the production of 14 major crops (blue/red indicates expected increase/decrease in water requirements for crop productions). Results account for 14 crops (cotton, potato, sunflower, rapeseed, millet, soy, groundnut, barley, cassava, maize, rye, sorghum, wheat, rice).