Phosphorus and Suspended Sediment Loads in Base-Flow and Runoff Events: A Case Study of a Small Stream in NW Spain

Abstract

This study focuses on the role of runoff events in influencing concentrations and export of suspended sediments and phosphorus in a headwater stream draining an agroforestry catchment in northwestern Spain. Large differences exist between suspended sediment and phosphorus (P) concentrations measured during base-flow conditions and runoff events, with a higher delivery during runoff events. Suspended sediment and phosphorus exports were 29.44 and 0.08 kg ha⁻¹ y⁻¹ respectively, with more than 50% delivered during runoff events (12% of the year). The relative contributions of phosphorus forms to the total annual export were 75% and 25% as particulate and dissolved phosphorus, respectively. Soil erosion is the main source of suspended sediment and phosphorus in the stream.

Keywords:

• Agroforestry catchment
• phosphorus
• runoff events
• suspended sediments

Acknowledgments

This research is part of a project funded by the Spanish Ministry of Education and Science (REN2003–08143) and by Xunta of Galicia (PGIDIT05RAG10303PR). The first author was awarded a research contract/grant (Angeles Alvariño Programme) funded by the Xunta of Galicia.