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Reference : UMR5245-JEAPRO-005
Workplace : CASTANET TOLOSAN
Date of publication : Thursday, March 25, 2021
Type of Contract : FTC Scientist
Contract Period : 13 months
Expected date of employment : 15 May 2021
Proportion of work : Full time
Remuneration : 2648 euros gross monthly for less than 2-year experience
Desired level of education : PhD
Experience required : 1 to 4 years
The postdoc position aims to investigate weathering and erosion processes of the CZ in two nested catchments: Aurade, a small agricultural carbonated experimental catchment (328 ha) and the Save, a regional basin (1100 km2), both representative of the Gascogne territory (SW of France).
The Aurade catchment is one the observatory site of the French Research Infrastucture (RI) OZCAR (Critical Zone Observatories: Applications and Research) and the Save river basin is one of the study-sites of the LTSER Zone Atelier Pyrenees-Garonne which belongs to the French RI RZA (Zone Atelier Network). OZCAR and RZA represent together the French contribution to the European RI eLTER (Long-Term Ecosystem Research in Europe).
These sites undergo high physical and chemical weathering processes due to their environmental landscape and to the occurrence of intense flood events. The main objectives are to estimate the physical erosion processes at both small catchment (Aurade) and large river basin (Save) scales using the data collected on suspended matters (weekly) and turbidity (continuously) since several years. In addition, three new equipments have been acquired recently on the Aurade catchment to collect the sediment transported during the flood events and to separate the different granulometric fractions of the bottom sediments transported. All these data will be integrate at the Aurade catchment scale to complete the 30 years survey database and the study of physical erosion processes.
The postdoc work will consist of 5 steps:
- to calibrate for each catchment the relationship between the TSS concentration measured weekly and hourly during the flood events and the turbidity measured continuously using a multiparameter probe.
- to study the relationships between TSS concentrations and water discharges, particularly during the flood events to better understand the erosion-transport-sedimentation processes at both catchment scales.
- to quantify the sediment transported during the flood events both in the water column and in the stream bottom of the Auradé catchment
- to estimate for each catchment, the mass balance of the TSS exported using different methods of calculation and to calculate the uncertainties.
- to estimate the physical erosion rates for each catchment using the TSS transport and the soil density and compare these values with the chemical weathering rates, already calculated on the long term.
- to treat the existing data on TSS concentrations and turbidity for both catchments
- to install and to calibrate on the Aurade catchment the new equipments for high turbidity measurement and bottom sediment transports.
- to collect and analyse the suspended matters and the bottom sediments in Aurade and Save catchments
- to participate to the different scientific meetings and to exchange with the researchers, postdoctorates and PhD working in the same scientific areas, particularly within the OZCAR and RZA scientific communities
- to communicate the results obtained during the meetings and to prepare peer-reviewed scientific publications and presentations for scientific conferences.
- Hydrology and biogeochemistry of catchments,
- Hydrology of river sediment transport
- Physical/chemical erosion processes at catchment scales
- Data treatment
- Field survey experiments and sample collection of surface waters and sediments.
- Licence (B) to drive a vehicule to go in the field regularly
- Ability to collaborate within a multidisciplinary team and potentially with external socio-economic partners
- Strong english working knowledge and practice
The postdoc will be based at Laboratory of Functional Ecology and Environment, is a joint research unit between CNRS- UPS Toulouse 3 and Toulouse INP. The work is located in the Campus ENSAT of the Laboratory at Auzeville-Tolosane. He will be a member of the ECOBIZ team, which manages two other observatories from the OZCAR RI and the LTSER ZA PYGAR. The researches in the field will concern the Aurade and the Save catchments and the surrounding areas, located 40 km from Toulouse.
Constraints and risks
The postdoc must be responsive and available to go to the field if necessary during floods, even on weekends.
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