Mediterranean badlands: Their driving processes and climate change futures

Abstract

Badlands are landforms that occur all over the World. In the Mediterranean region, badlands are found in both dry (arid and semi‐arid) and wet (subhumid and humid) environments, and are characterized by complex hydro‐geomorphological dynamics, high intense erosion processes and extreme sediment yield. Understanding the impact of Global Change is key to predict the on‐site and off‐site effects on badland dynamics, particularly its consequences on bedrock weathering, on sediment yield and delivery and on plant colonization. Here, conducting a systematic literature review, we analyzed an extensive database and identified the main climate‐drivers affecting the hydro‐geomorphological dynamics in Mediterranean badlands (based on non‐metric multidimensional scaling and structural equation modeling analysis). Later, we examined the main impacts expected from climate change forecasting in the near future, and we explored the interactions between badlands response to climate variation. In Mediterranean badlands, weathering processes are mainly related to wetting–drying cycles and freeze–thaw cycles in dry and wet badlands, respectively. In both environments, rainfall amount appears as the main driver for runoff response, and rainfall amount and rainfall intensity for erosion dynamics. Future climate scenarios forecast a decrease in annual rainfall, number of rainfall events and frost days, and in soil moisture, and an increase in rainfall intensity. These changes will have direct hydro‐geomorphological implications with direct and indirect effects on badland dynamics. This may result in a decrease in annual runoff in dry badlands, but the occurrence of more frequent extreme events would increase soil erosion and could negatively affect biological soil crust. In wet badlands, weathering and erosion processes may decrease, and a stabilization of the slopes, with consequently improved vegetation growth, may be expected. In addition, the forecasted changes must be taken into account, especially considering the possible off‐site effects of these extreme environments.

Sediment export in marly badland catchments modulated by frost-cracking intensity, Draix–Bléone Critical Zone Observatory, SE France

“…However, the impact of climate (change) on regolith production and ensuing landscape ero-sion remains difficult to quantify. In a context of rapid global climate change, how will sediment production be affected (e.g., Nearing et al, 2004;Hirschberg et al, 2021;Nadal-Romero et al, 2021)? How will dominant erosion processes evolve according to lithologies and climatic variations?…”

Introduction to the Women in Geomorphology special issue

“…Papers addressing process and form in coastal environments include examinations of dune morphodynamics and evolution (Hovenga et al, 2021; Konlechner & Hilton, 2022; Kooijman et al, 2022); the influence of sorting and bedforms on the magnitude of coastal eolian transport (Uphues et al, 2022); coastal changes in response to an extreme storm (Spiske et al, 2022); estuarine mangrove dynamics (Glover et al, 2022) and the morphology of estuarine bedforms (Lefebvre et al, 2022); geotechnical properties of salt marsh soils (Brooks et al, 2022) and tidal wetland development (McKeon et al, 2022); seasonal morphodynamics of intertidal bars (Biausque et al, 2022); and wave impacts and cliff erosion (Thompson et al, 2022). Papers addressing hillslopes and mass movements include interactions between raindrop impacts and particle settling velocities in sheet flow (Bako et al, 2022); a review and synthesis of soil piping (Bernatek‐Jakiel & Nadal‐Romero, 2023); a review of erosion plot studies in the Brazilian Cerrado (Souza Fonseca et al, 2022); seasonal variations in gully erosion (Agostini et al, 2022); influences on Mediterranean badlands formation (Nadal‐Romero et al, 2022); numerical models of landslide effects on the cosmogenic isotope signal of fluvial sediment (Schide et al, 2022); surface slip on strike‐slip faults (Reitman et al, 2022); post‐fire patterns of rock weathering (Mol & Grenfell, 2022); precursory indicators of alpine rockfall (Hendrickx et al, 2022); grain‐size distributions of mass movement deposits (Harvey et al, 2022); influences on landslide initiation based on field observations and numerical modelling (Patton et al, 2022); physical experiments on debris‐flow erosion (Roelofs et al, 2022); and comparison of digital elevation models built from different data sources (Atwood & West, 2022). Glacial geomorphic studies are represented by papers examining topographic controls on ice flow and glacier front recession (Davies et al, 2022); moraine dynamics in the context of climate change (Rowan et al, 2022); and streamlined sub‐glacial bedforms (McKenzie et al, 2022).…”

Sediment export in marly badland catchments modulated by frost-cracking intensity, Draix-Bléone Critical Zone Observatory, SE France

“…Based on a review of multiple badland areas in the Mediterranean region, Nadal-Romero et al (2021) have recently investigated the impact of climate change on these particular landscapes, taking into account different climate-drivers (rainfall amount, rainfall intensity, wetting-drying cycles, freeze-thaw cycles, soil moisture content, etc.). Their analysis predicts that for wet badlands such as Draix-Bleone, the expected increase in rainfall intensity should increase erosion capacity on one hand, but that the expected increase in temperature should lower the number of freeze-thaw cycles, thereby reducing the efficacy of frost-weathering processes and decreasing sediment availability on the other hand.…”

“…and ensuing landscape erosion remains difficult to quantify. In a context of rapid global climate change, how will sediment production be influenced by climate change (e.g., Nearing et al, 2004;Hirschberg et al, 2021;Nadal-Romero et al, 2021)?…”