Structural differences in hydrological models & their implications for NbS
New research from PiNC Lab’s Petra Holden and colleagues, published in the journal, Ecological Modelling, examines how structural differences across hydrological models can affect the certainty of predictions of the benefits of nature-based solutions (NbS).
“Structural differences in hydrological models create uncertainty in predicting the benefits of nature-based solutions - including the supply of clean water and drought and flood risk reduction. It is critical to actively consider this uncertainty for water security planning and decisions,” says Holden.
According to the study, which was led by Alanna Rebelo, quantifying uncertainty in hydrological modelling has critical implications for informing decisions around land-use and land-cover trade-offs, and management. However, different hydrological modelling tools commonly used in water resource management are known to produce diverse results.
However, this uncertainty is frequently overlooked in both research and applied cases. Indeed, the influence of structural differences in terms of water balance partitioning in different models (known as model fidelity) has particularly been neglected.
This new study aims to quantify the uncertainty resulting from hydrological model structural differences for a specific nature-based solution scenario: clearing of invasive alien trees from mountain catchments in a water scarce region of South Africa.
Highlights from the research include:
Comparison of five hydrological modelling tools used to guide decision making.
Mean annual streamflow estimates ranged from 126.7 to 142.8 Mm3 (12 % of streamflow).
Clearing of alien trees as a scenario produced ranges of 121.4 to 141.1 Mm3 (15 %).
Reduced evapotranspiration is the driver, however the pathway differed among models.
Pathways included changes in canopy interception, soil and groundwater controls.
Article citation:
Alanna J. Rebelo, Julia Glenday, Petra B. Holden, Shaeden Gokool, David Gwapedza, Peni Metho, Jane Tanner, Structural differences across hydrological models affect certainty of predictions of nature-based solution benefits, Ecological Modelling, Volume 501, 2025, 110940, ISSN 0304-3800, https://doi.org/10.1016/j.ecolmodel.2024.110940