Home - Themes - Diagnose physical alterations in rivers - Hydromorphological monitoring for a truly unique database worldwide


    -Frédéric Gob \ University of Paris I
    "Thanks to the standardised data collected from over 1 000 monitoring points via Carhyce, it is now possible for the first time to undertake a reliable, small-scale analysis of the physical parameters determining river morphologies..."

    -Dominique Monti \ University of the Caribbean and Guiana
    "On the islands of Réunion, Guadeloupe and Martinique, hydrology has an enormous impact on the biodiversity of aquatic communities. Rivers are shallow, turbulent and not rich in vegetation..."

Hydromorphological monitoring for a truly unique database worldwide

With over 1 000 monitoring points now registered, the input of hydromorphological data accelerated in 2012. The Carhyce protocol was extended to large rivers and now includes a new method to assess substrate silting/clogging.

Over 1 000 monitoring points throughout continental France now collect data on river width, depth, slope, sediment grain size, bank type and structure, etc. That is the result of a data-collection effort launched in 2009 at the same time as the Carhyce protocol developed by a group of experts (Onema, Water agencies, Irstea, CNRS and several universities) to comply with the requirements of the Water framework directive. At the end of 2012, most of the monitoring points in the surveillance-monitoring network (RCS) that are accessible on foot had been visited by Onema personnel. At each point, the data are collected along 15 transects (lines across the river bed), a procedure requiring four people for a full half day. Data collection is also carried out on operational monitoring points by engineering firms trained to do so.

Large rivers as well

Carhyce tested successfully in 2012 for the Caribbean. At the same time, the protocol was adapted to large rivers, using echo-sounding equipment to measure depths, lasers for widths and high-resolution video to analyse grain sizes, etc. These modifications will make it possible to complete the RCS monitoring network by 2015. The hydromorphological-monitoring system also includes the ICE protocol (information on ecological continuity). Finally, a standardised method developed by Onema and Irstea is now available to assess silting/ clogging of river beds. The quantity of fine sediment along the bottom (a factor affecting ecological balances) will be measured by hydraulic conductivity. Taken as a whole, all this information centralised by Onema constitutes a hydromorphological database that is particularly rich and rare among the countries of the world. It opens unprecedented opportunities to study the relationships between the physical degradation of habitats and life forms.

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