Models simulate nitrate dynamics in Garonne, Southwest France

Jan 05, 2009

The over-enrichment of fresh, transitional, and marine waters with nitrogen (N) can lead to problems associated with eutrophication, such as a change in species composition of aquatic plants and nuisance algal blooms. In this context, dynamic models of flow and water quality are required to aid the implementation of the Water Framework Directive and to understand the impacts of environmental change.

Scientists from CNRS in Toulouse (France) and the University of Reading (U.K.) described the spatially and temporally complex flow and N dynamics of a major European watershed, the Garonne (62,700 km2) located in southwest France, using multivariate analysis before applying the linked rainfall-runoff HBV and the Integrated Catchment Model of Nitrogen (INCA-N) models to simulate daily flow and N dynamics.

This is the first application of the linked HBV and INCA-N models to a major European river system commensurate with the largest basins to be managed under the Water Framework Directive. Results from the study were published in the November-December 2008 issue of the Journal of Environmental Quality.

The spatial and temporal dynamics in the stream water NO3-N concentrations in the Garonne watershed were first described and related to variations in climate, land management, and effluent point-sources using multivariate statistics (PCA, RDA).

Building on this, INCA-N simulations were in accordance with expected flow and seasonal N patterns. In the low and mid reaches of the Garonne, the NO3-N concentrations exhibited a clear seasonal pattern with a peak concentration coinciding with fertilizer applications; that is, results highlighted that 75% of the NO3-N river load in the lowlands came from arable farming. In the upper reaches, climate controls on flow were the most important in determining the NO3-N concentrations which exhibited dilution patterns during high spring flows.

This study reinforces the interest of using semi-distributed models that represent key hydrological pathways, the spatial variations in inputs to land cover types, and a representation of the terrestrial and aquatic biochemical cycles. Thus, semi-distributed models can be used successfully to simulate the seasonal and decadal flow and water quality dynamics from mountainous headwaters to the lowlands in the largest European catchments, at large spatial (>300 km2) and temporal (≥ monthly) scales using available national datasets.

View the abstract of this study at jeq.scijournals.org/cgi/content/abstract/37/6/2155 .

Source: American Society of Agronomy

Explore further: Australians rally for climate, including at G20 talks

add to favorites email to friend print save as pdf

Related Stories

How Paramecium protozoa claw their way to the top

Sep 19, 2014

The ability to swim upwards – towards the sun and food supplies – is vital for many aquatic microorganisms. Exactly how they are able to differentiate between above and below in often murky waters is ...

Crowdsourcing could lead to better water in rural India

Sep 18, 2014

With more than 10 million service points, India's rural drinking water system provides a real monitoring headache for public health officials. To help address the challenge, a three-continent research consortium ...

Protecting infrastructure with smarter CPS

Sep 16, 2014

Security of IT networks is continually being improved to protect against malicious hackers. Yet when IT networks interface with infrastructures such as water and electric systems to provide monitoring and control capabilities, ...

Recommended for you

Tens of thousands join London climate march

26 minutes ago

Tens of thousands of people in London joined a global day of protest Sunday to demand action on climate change, among them British actress Emma Thompson who said the challenge to save the planet was like ...

UN summit to test commitment to climate fund

29 minutes ago

A global fund created to spearhead climate change financing faces a key test at a UN summit this week when it looks to the leaders of the industrialised world to stump up billions of dollars to fill its underflowing ...

Green dream: Can UN summit revive climate issue?

Sep 20, 2014

Five years ago, the environment movement was in its heyday as politicians, actors, rock stars and protestors demanded a looming UN summit brake the juggernaut of climate change.

User comments : 0