Articles | Volume 19, issue 1
https://doi.org/10.5194/hess-19-453-2015
https://doi.org/10.5194/hess-19-453-2015
Research article
 | 
26 Jan 2015
Research article |  | 26 Jan 2015

Using high-resolution phosphorus data to investigate mitigation measures in headwater river catchments

J. M. Campbell, P. Jordan, and J. Arnscheidt

Abstract. This study reports the use of high-resolution water quality monitoring to assess the influence of changes in land use management on total phosphorus (TP) transfers in two 5 km2 agricultural sub-catchments. Specifically, the work investigates the issue of agricultural soil P management and subsequent diffuse transfers at high river flows over a 5-year timescale. The work also investigates the phenomenon of low flow P pollution from septic tank systems (STSs) and mitigation efforts – a key concern for catchment management. Results showed an inconsistent response to soil P management over 5 years with one catchment showing a convergence to optimum P concentrations and the other an overall increase. Both catchments indicated an overall increase in P concentration in defined high flow ranges. Low flow P concentration showed little change or higher P concentrations in defined low flow ranges despite replacement of defective systems and this is possibly due to a number of confounding reasons including increased housing densities due to new-builds. The work indicates fractured responses to catchment management advice and mitigation and that the short to medium term may be an insufficient time to expect the full implementation of policies (here defined as convergence to optimum soil P concentration and mitigation of STSs) and also to gauge their effectiveness.

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Short summary
High-resolution phosphorus and flow data were used to gauge the effects of diffuse (soil P) and point source (septic tank system) mitigation measures in two flashy headwater river catchments. Over 4 years the data indicated an overall increase in P concentration in defined high flow ranges and low flow P concentration showed little change. The work indicates fractured responses to catchment management advice and mitigation which were also affected by variations in seasonal hydrometeorology.