WET News

february 2015 WET NEWS 17 a restoration project helps the river Nar meet the requirements of the Water framework Directive. The challenge: Overcoming exces- sive nutrient levels R ising in chalk hills to the east of the village of Tit- tleshall, the Nar river flows South for 2.5km until it reaches Mileham, then predom- inately west for 39.5km through Litcham, Castle Acre, West Acre and Narborough until it reaches the tidal Ouse at King's Lynn. The river rises on chalk and in its course to Narborough flows over chalk formations. In its lower course the underlying ge- ology is more complex and con- sists of a progression from Nar- borough downstream through a series of clays and greensands, making it one of only a few re- maining fenland chalk streams. In line with the requirements of the Water Framework Direc- tive (WFD), the project is designed to ensure that the Nar maintains good ecological sta- tus by 2015 and in doing so it aims to improve the habitat for wildlife and promote biodiver- sity. The river monitoring sta- tion incorporates an Adcon GPRS telemetry unit from OTT Hydrometry, which automati- cally collects data and feeds a website, providing easy access for the project team. Agricultural runoff is a par- ticular problem in the Anglian region because of the light sandy soils which are easily eroded during times of heavy rainfall. Fertilisers can add to the problem because they can be washed from the field and end up in water courses. As a result, many Norfolk Rivers con- tain high levels of nitrate and phosphate. Excessive levels of these nutrients can lead to eutrophication, symptoms of this can include vigorous growth of blanket weed; this change in water quality lowers dissolved oxygen levels in the streams and rivers, and harms wildlife. In the past, the Nar channel has been made straighter, wider and deeper; initially to improve navigation, and later to improve • T hE coNcEpT • a Hydrolab Minisonde water quality monitor and an adcon a755 remote Telemetry unit (rTu) were used along with a bed-mounted Doppler flow meter • an adcon a755 rTu communicates via GPrS NEEd To kNoW 1 agricultural runoff is a particular problem in the anglian region because of the light sandy soils 2 Many Norfolk rivers contain high levels of nitrate and phosphate 3 The project ensures that the Nar maintains good ecological status by 2015 as part of the WfD "To be able to judge the success of the project it is essential that we are able to compare water quality data from the old river channel to the new river channel... to improve the biodiversity" INSIGHT a remote river monitoring station keeps tabs on the condition of the river Nar. The collected flow and water chemistry data is then stored and transmitted every hour via the rTu to an online server hosted by OTT Hydrometry ThE VERdIcT "To be able to judge the success of the project it is essential that we are able to compare water quality data from the old river channel to the new river channel, because we need to improve water quality in order to improve the biodiversity of the river" Helen Mandley A solution: Tracking quality and flow T he Norfolk Rivers Trust installed a remote river monitoring station to track water quality and flow before and a›er river restoration work at an area of ecological importance on the River Nar. In order to establish a continuous monitoring station for water quality and flow, OTT Hydrometry provided a Hydrolab Minisonde water quality monitor and an Adcon A755 Remote Telemetry Unit (RTU). In combination with a bed mounted Doppler flow meter, the station can provide a continuous record of the river's condition. The Hydrolab Minisonde 5 takes measurements for turbidity, flow, conductivity, temperature and luminescent dissolved oxygen (LDO) every 15 minutes. The collected flow and water chemistry data is then stored and transmitted every hour via the RTU to an online server hosted by OTT Hydrometry. This allows information to be downloaded and analysed in the trust's office without the need for regular site visits. Data can be accessed at anytime from anywhere using the Adcon app. Operating on extremely low power, and designed specifically for the collection and transmission of remote monitoring data, Adcon RTUs utilise a variety of communication methods depending on site conditions. For example, radio represents a low-cost alternative in areas with poor GSM coverage and where line of sight is possible, with repeaters if necessary. The monitoring site on the Nar has some GSM coverage, but the signal is poor, so an Adcon A755 RTU communicates via GPRS. The A755 RTU was developed specifically for areas with low signal, because it stores all monitoring data when signal strength is too low for transmission, and then sends the information when signal coverage improves, sending the backed up data first. Project officer Helen Mandley says: "To be able to judge the success of the project it is essential that we are able to compare water quality data from the old river channel to the new river channel, because we need to improve water quality in order to improve the biodiversity of the river." A series of 'restoration units' have been identified by The River Nar Steering group that includes the Norfolk Rivers Trust, each applying restorative work to a specific section of the river. These units extend to 2027 but will be reliant on the availability of future funding. drainage. However, this has had a detrimental effect on wildlife. The River Nar also suffers from sediment deposition aris- ing from point sources such as land drains, and from diffuse sources such as run-off resulting from cultivation in wet periods. Assisted by funds from WWF- UK, the Coca-Cola Partnership and the Catchment Restoration Fund, the Norfolk Rivers Trust has established a £609k river and flood plain restoration pro- ject to reduce pollution in the River Nar and improve the habi- tat for wildlife. The project included the cre- ation of reed beds and other in- ditch options to trap sediment before it enters the Nar.

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