Work

Local- and global-scale hydrological and sediment connectivity over grassland and shrubland hillslopes

Year: 2025

Type: article

Abstract: Quantifying connectivity patterns in dryland ecosystems is crucial for understanding how water and sediments flow across the landscape, crucial for mitigating the impacts of climate change and land use modifications. This study quantifies the multi-scale water-mediated connectivity within grassland and shrubland hillslopes using a weighted, directed network model. By integrating high-resolution elevation, vegetation data, and modeled event-based hydrologic and sediment transport, we quantify both structural (topology) and functional (dynamical) connectivity under varying rainfall and soil moisture conditions. Our findings reveal a marked increase in local connectivity metrics in shrublands compared to grasslands, with metrics such as betweenness centrality and the weighted length of connected pathways increasing up to tenfold. Despite these substantial local changes, global properties like link density and global efficiency show less drastic variations, suggesting a robust network topology that sustains geomorphic functionality across different vegetation states. This indicates that although local connectivity is highly sensitive to vegetation changes, the overall structure and functional connectivity of water and sediment at the global scale remain relatively stable. Functional connectivity is more strongly correlated with structural connectivity for sediment than for water. This difference is particularly pronounced under high rainfall conditions, yet shows little sensitivity to variations in antecedent soil moisture, highlighting the critical role of event-driven processes in shaping connectivity patterns. The study advances our quantitative understanding of how structural changes affect functional processes in dryland ecosystems. It offers a comprehensive framework for analyzing connectivity at multiple scales, which can inform targeted management strategies aimed at enhancing ecosystem resilience.

Source: Journal of Hydrology

DOI: 10.1016/j.jhydrol.2025.132896

Authors: Shubham Tiwari, Laura Turnbull, John Wainwright

Institution: Durham University

Language: English

Topic: Soil erosion and sediment transport

Subfield: Soil Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDGs: Life on land, Climate action

Open Access status: hybrid

Estimated APC paid: $4,030