Scientists and Managers Meet to Evaluate the Ecological Status of Temporary Rivers

The European LIFE TRivers project is being led by the UB.
The European LIFE TRivers project is being led by the UB.
Research
(03/02/2016)

Temporary rivers are those that show recurring interruptions to their flow, and they may even go completely dry during certain periods of the year. Although temporary rivers are very common in the Mediterranean basin and have great value in terms of biodiversity conservation, it is very difficult to establish the ecological status of rivers of this type because most analysis tools are designed for use with permanent rivers. The European LIFE TRivers project, funded by the European Community, is being led by the UB with the participation of the Environmental Diagnostics and Water Studies Institute (Instituto de Diagnóstico Ambiental y Estudios del Agua or IDAEA-CSIC), the Catalan Water Agency (Agencia Catalana del Agua or ACA) and the Júcar Hydrography Confederation (Confederación Hidrográfica del Júcar or CHJ). The projectʼs aim is to provide tools that can be used to properly diagnose the ecological status of temporary rivers and improve their management, in agreement with the European Unionʼs Water Framework Directive (WFD). In pursuit of this goal, new software known as TREHS (Temporary Rivers Ecological and Hydrological Status) has been developed. During the second meeting held for the project, which took place at the offices of the Segura Hydrography Confederation (CHS) in Murcia, managers and experts involved in fluvial management were able to test this tool for the first time.

The European LIFE TRivers project is being led by the UB.
The European LIFE TRivers project is being led by the UB.
Research
03/02/2016

Temporary rivers are those that show recurring interruptions to their flow, and they may even go completely dry during certain periods of the year. Although temporary rivers are very common in the Mediterranean basin and have great value in terms of biodiversity conservation, it is very difficult to establish the ecological status of rivers of this type because most analysis tools are designed for use with permanent rivers. The European LIFE TRivers project, funded by the European Community, is being led by the UB with the participation of the Environmental Diagnostics and Water Studies Institute (Instituto de Diagnóstico Ambiental y Estudios del Agua or IDAEA-CSIC), the Catalan Water Agency (Agencia Catalana del Agua or ACA) and the Júcar Hydrography Confederation (Confederación Hidrográfica del Júcar or CHJ). The projectʼs aim is to provide tools that can be used to properly diagnose the ecological status of temporary rivers and improve their management, in agreement with the European Unionʼs Water Framework Directive (WFD). In pursuit of this goal, new software known as TREHS (Temporary Rivers Ecological and Hydrological Status) has been developed. During the second meeting held for the project, which took place at the offices of the Segura Hydrography Confederation (CHS) in Murcia, managers and experts involved in fluvial management were able to test this tool for the first time.

Determining whether a river is naturally temporary

Temporary rivers pass through multiple stages, with abundant flow in the springtime later becoming a series of disconnected pools or even drying up completely. This variability makes it very difficult to use the standard methods to characterise their ecological status. “One of the most significant problems is knowing when to take samples, since the water flow is intermittent and can depend upon the time of year, the meteorology and the effects of human action”, explains Narcís Prat, a professor from the UB Department of Ecology and coordinator of the TRivers project.

In order to help characterise the evolution of each riverʼs hydrological characteristics over time, and thereby determine the probability of the river being dry at various times during the year, the TREHS software incorporates the available historical data for each riverʼs flow, as well as simulations based on surface run-off models. The tool also allows information to be obtained or complemented by interviews with local residents. “These statistics allow us to determine the hydrological status of the river, to know whether or not it is naturally temporary. This in turn helps us select the sampling schedule that best fits the temporary regime and also assists with interpreting the biological samples”, explains Francesc Gallart, an IDAEA-CSIC researcher.

Results from field sampling work that took place during 2015 were also presented at the meeting, including both hydrological data and preliminary results from the biological data. “The data show a clear decrease in biological quality from the moment at which the river stops flowing and only pools remain”, explains Núria Cid, a post-doctoral researcher from the UB Department of Ecology.

Also during the workshop, Teodoro Estrela, head of the CHJʼs Hydrological Planning Office, presented an approach used to evaluate the status of ephemeral temporary rivers (watercourses that are without water for most of the year).

Workshop and field visit
Representatives from the Segura Hydrography Confederation, the Júcar Hydrography Confederation, the Catalan Water Agency, the University of Murcia, the New Culture of Water Foundation (Fundación Nueva Cultura del Agua), and the Portuguese Environmental Agency, among other institutions, all participated in a very practical workshop. The participants were able to use the latest version of the TREHS tool to analyse their own data related to temporary rivers and clear up any questions about how to use it. On the previous day the participants also visited one of the temporary water flows in the province of Murcia: the Chícamo River. This river is affected by loss of water diverted for irrigation, which causes it to go dry along the its course. It was recently declared as a fluvial reserve.

According to the participants, the workshop was very satisfying and helped to shed light on the problems that managers encounter when trying to define environmental goals and evaluate the ecological status of temporary rivers. “They still donʼt receive much recognition, but because of the role they play in the ecosystem they really should be valued more, protected and properly managed”, Núria Cid concludes.