This paper uses high-frequency bankside measurements from three catchments selected as part of the UK government-funded Demonstration Test Catchments (DTC) project. We compare the hydrological and hydrochemical patterns during the water year 2011–2012 from the Wylye tributary of the River Avon with mixed land use, the Blackwater tributary of the River Wensum with arable land use and the Newby Beck tributary of the River Eden with grassland land use. The beginning of the hydrological year was unusually dry and all three catchments were in states of drought. A sudden change to a wet summer occurred in April 2012 when a heavy rainfall event affected all three catchments. The year-long time series and the individual storm responses captured by in situ nutrient measurements of nitrate and phosphorus (total phosphorus and total reactive phosphorus) concentrations at each site reveal different pollutant sources and pathways operating in each catchment. Large storm-induced nutrient transfers of nitrogen and or phosphorus to each stream were recorded at all three sites during the late April rainfall event. Hysteresis loops suggested transport-limited delivery of nitrate in the Blackwater and of total phosphorus in the Wylye and Newby Beck, which was thought to be exacerbated by the dry antecedent conditions prior to the storm. The high rate of nutrient transport in each system highlights the scale of the challenges faced by environmental managers when designing mitigation measures to reduce the flux of nutrients to rivers from diffuse agricultural sources. It also highlights the scale of the challenge in adapting to future extreme weather events under a changing climate

. (2015) 'Dominant mechanisms for the delivery of ne sediment and phosphorus to uvial networks draining grassland dominated headwater catchments.', Science of the total environment., 523 . pp. 178-190. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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The water quality of our rivers and lakes is a reflection of the landscape over and through which it travels. The UK government, along with all European Union member states, are obliged under the Water Framework Directive (WFD) to aim for good ecological status of fresh water bodies by 2015. In order to evaluate the effectiveness of potential mitigation measures in reducing diffuse water pollution from agriculture at the catchment scale, the Demonstration Test Catchment (DTC) project was developed. The project is jointly funded by Defra, the Environment Agency (EA) and the Welsh Assembly Government (WAG). There are three DTCs across the country: the Eden catchment, Cumbria; the Wensum catchment, Norfolk and the Hampshire Avon catchment. The Eden DTC has established three~10 km 2 focus catchments, chosen to reflect different farming practices, geologies, elevations and hydrological characteristics. Within each focus catchment, two sub-catchments have been selected, one control and one mitigated, in which numerous existing and novel mitigation measures will be tested. It is hoped that the mitigation features will be multi-purpose, having positive effects on pollutant retention, flooding, carbon sequestration, habitat creation and biodiversity. The effectiveness of these measures is assessed through networks of hydro-meteorological and water-quality instrumentation, most of which will provide data in near real time, with sub-hourly time steps.

Hydrological catchments today are largely the product of human activity. They have been engineered. The negative impacts of some of this engineering such as deforestation and agriculture intensification need to be addressed but the solution is not simply a matter of doing the opposite, for example through afforestation or moving to less-intensive farming. We propose a catchment systems engineering (CSE) approach that utilizes and expands on existing catchment-based approaches, combining interventions that work with or mimic natural processes with traditional "hard" engineering to provide a practical route to improved catchment function. The approach is predicated on the need to take an holistic view of catchments and to make proactive interventions that provide and enhance multiple ecosystem services. CSE seeks to address problems that are international in scope, recognizing the need to understand better how hydrological processes have changed due to human activity and how those changes influence frequency, duration, and severity of environmental problems such as floods, droughts, and poor water quality. The emphasis is placed on how we can act to engineer catchment systems to a safer functionally appropriate level utilizing measures such as nature-based solutions alongside traditional engineering structures. CSE is the means to provide multiple ecosystem services while recognizing trade-offs between reducing flood and drought risk directly, improving water quality and creating healthy habitats for wildlife. By targeting local hydrological flow pathways in defined spatial and temporal windows (e.g., during rainfall events at key locations such as riparian zones), CSE can deliver holistic water resource management now.