Niborski et al. (2026) The Elusive Runoff Generation: Understanding Thresholds and Pathways in a Dry Sedimentary Plain

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Hydrological Processes
• Year: 2026
• Date: 2026-01-01
• Authors: Marcos J. Niborski, Francisco Murray, Estéban G. Jobbágy, Roberto J. Fernández, Marcelo D. Nosetto, Ricardo A. Páez, María V. Petit, Patricio N. Magliano
• DOI: 10.1002/hyp.70399

Research Groups

Researchers from Dry Chaco rangelands, Argentina. Specific institutional affiliations are not provided in the abstract.

Short Summary

This study quantified the spatial and temporal variability of runoff in flat drylands of the Dry Chaco rangelands, revealing its highly stochastic nature driven by rainfall thresholds rather than watershed or piosphere area, and highlighting its ephemeral flash-flood characteristics.

Objective

• To quantify the annual runoff and its relation with watershed and piosphere (high cattle impact) areas.
• To quantify the uneven contribution of the largest rainfall and runoff events to their respective yearly totals at different temporal scales.
• To evaluate the runoff responses to rainfall characteristics (event size and intensity).
• To quantify the lag time between rainfall and runoff peaks and its relation to the maximum length of the watershed.

Study Configuration

• Spatial Scale: Six watersheds in Dry Chaco rangelands, Argentina, ranging in size from 200,000 square meters to 20,000,000 square meters.
• Temporal Scale: Three consecutive years of measurements, with a 15-minute resolution.

Methodology and Data

• Models used: Not specified in the abstract.
• Data sources: High-resolution field measurements combined with remote-sensing analyses.

Main Results

• Runoff was not explained by watershed or piosphere area.
• Runoff exhibited greater variability than rainfall; the 10 wettest days accounted for 100% of annual runoff and 60% of annual rainfall.
• Only 15% of rainfall events generated runoff.
• Runoff generation required, on average, a rainfall event size of 20.3 ± 1.6 millimeters and a rainfall intensity of 3.39 ± 0.61 × 10⁻⁶ meters per second (equivalent to 12.2 ± 2.2 millimeters per hour).
• Above these thresholds, the response between rainfall and runoff was linear (coefficient of determination R² > 0.66 for event size and R² > 0.62 for intensity).
• The mean lag time between rainfall and runoff peaks was 2580 ± 1620 seconds (43 ± 27 minutes), indicating the ephemeral flash-flood nature of runoff.
• A linear relationship (correlation coefficient r = 0.87) was observed between the mean lag time and the watershed's maximum length.
• The study highlights the stochastic nature of runoff in Dry Chaco rangelands, modulated by subtle watershed physical elements and microtopography.

Contributions

• Challenges the traditional concept of a fixed runoff generation area, proposing a more flexible, idiosyncratic concept based on interactions between terrain features and rainfall event characteristics.
• Provides high-resolution field measurements and remote-sensing analyses for flat drylands, a poorly assessed environment for runoff quantification.
• Quantifies the stochastic nature of runoff in space and time for Dry Chaco rangelands, emphasizing the critical role of rainfall thresholds and event characteristics.

Funding

Funding information is not provided in the abstract.

Citation

@article{Niborski2026Elusive,
  author = {Niborski, Marcos J. and Murray, Francisco and Jobbágy, Estéban G. and Fernández, Roberto J. and Nosetto, Marcelo D. and Páez, Ricardo A. and Petit, María V. and Magliano, Patricio N.},
  title = {The Elusive Runoff Generation: Understanding Thresholds and Pathways in a Dry Sedimentary Plain},
  journal = {Hydrological Processes},
  year = {2026},
  doi = {10.1002/hyp.70399},
  url = {https://doi.org/10.1002/hyp.70399}
}