An information sheet on the water quality of the Newby catchment in water year 2012 is now available. You can download the pdf or read more:

Newby Catchment Water Quality:

Hydrological Year 2012

This information sheet describes the water quality of the Newby Catchment, drained by Newby Beck, in the 2012 hydrological year (1st October 2011-30th September 2012).

Annual and Seasonal Pollutant Transfer

• Over 30 rainfall events in the Newby catchment (Figure 1) generated streamflow responses which transferred sediment, phosphorus and nitrate (Figure 2).
• More than 90% of sediment and 75% of phosphorus in the stream were transferred in highflows (Table 1). See below for more information on highflow events.
• The majority of nitrate was transferred in lower flows, with highflows accounting for less than 50% (Table 1).
• The 2012 hydrological year was abnormal, with a relatively dry winter followed by a wet spring and summer, so pollutant transfers were low in winter but high in spring and summer (Figure 3).

Figure 2. Hourly data for the Newby catchment outlet for the hydrological year 2012, showing flow and pollutant responses to rainfall.

Table 1. Comparison of rainfall, flow and pollutants transferred through the Newby catchment outlet in 2012 at different flow types.

Total  Value	Time	% Annual Load
Rainfall	Discharge	Sediment	Phosphorus	Nitrate
Lowflow	10	5	2	0.1	0.4	1.9
Midflow	80	60	54	7.0	20.2	52.7
Highflow	10	35	44	92.9	79.4	45.4

Figure 3. Seasonal comparisons of rainfall, flow and pollutants transferred through the Newby catchment outlet in 2012.

Event Pollutant Transfers

• Over 90% of sediment and 75% of phosphorus was transferred through the Newby Beck stream outlet during highflows, which consisted of around 30 rainfall events.
• More than 80% of sediment was transferred in just half of these events, though these occurred throughout the year.
• In two separate events in December 2011 and September 2012, over 65 tonnes (over 10%) of sediment was transferred through the stream network.
• Over 30% phosphorus was transferred in four events occurring in October 2011, May 2012 and September 2012.

Figure 5. A typical autumn/winter event in the Newby catchment.

In a typical autumn/winter event (Figure 5):

• Discharge and suspended sediment rise in response to    rainfall, and phosphorus increases in line with sediment.
• Sediment and phosphorus peak rapidly either with or just before discharge as runoff transports pollutants to the stream.
• Nitrate initially falls due to dilution, but increases later as slower flow pathways reach the stream.

Figure 6. A typical spring/summer event in the Newby catchment.

In a typical spring/summer event (Figure 6):

• Discharge, sediment and phosphorus behave similarly to autumn/winter events.
• Nitrate initially falls slightly due to dilution, but then peaks sharply.

Turbid highflow at Newby Beck stream outlet, June 2012.

Key Messages

• Rainfall events throughout the year generated streamflow responses which transferred sediment and phosphorus through Newby Beck.
• Farmland soils and farm practices in the Newby catchment may therefore be of concern for sediment and phosphorus transfer throughout the year.
• A number of large events represented the majority of sediment loss in 2012, but many smaller events were      responsible for the majority of phosphorus loss.
• Nitrate was mainly transferred in lower flows, but event transfers in the spring and summer were also important.

Surface runoff into a ditch and bank erosion and turbid streamflow in the Newby catchment, June 2012.

 
Further Information: The EdenDTC project is a collaborative research project funded by the UK Department for Environment, Food and Rural Affairs (Defra). To find out more, or if you have comments or queries, please view our website: www.edendtc.org.uk, or email us at [email protected].

EdenDTC InfoSheet: 19/03/13