Impact of land degradation from mining activities on the sediment fluxes in two large rivers of French Guiana

2018

Article référencé dans le Web of Science WOS:000465580100009

Gallay M., Martinez Jean-Michel, Allo S., Mora A., Cochonneau Gérard, Gardel A., Doudou Jean-Claude, Sarrazin Max, Chow-Toun F., Laraque Alain

Land Degradation and Development, 2018, 29 (12), p. 4323-4336 ISSN 1085-3278

We analyzed two contrasting catchments located among the world's largest unspoiled tropical rainforests impacted by mining in the northeastern coastlands of South America. We used the following: (a) mining, agricultural, and urbanized areas to compare the land use evolution with suspended sediments and sediment yields; (b) field monthly river suspended sediments in the two catchments (2004-2015: n = 154); (c) MODIS remote sensing water color technique in the Maroni basin to complete (n = 387) and extend field suspended sediment sampling from 2000 to 2015; (d) hydroclimatic statistical analysis conditions and sediment concentrations to identify the long-term trends, the abrupt changes in time series and to analyze if the environmental and anthropogenic factors control sediment yield regional variations. No significant long-term changes were observed in precipitation or water discharge with the Mann-Kendall test. However, the mean suspended sediment concentration has increased significantly (239%) in the Maroni River with a breakpoint in 2009 and decreased (33%) in the Oyapock River (breakpoint in 2008). These differences are explained by the larger percentage of deforestation because of mining activities in the Maroni (0.37%) than in the Oyapock (0.06%) catchment. In the Maroni River, the increasing sediment yield trend (2000-2015) coincide significantly (r2 = 0.97; p < 0.0001) with the increase of 400% of mining areas, whereas no significant relationship with the runoff was found. In the Oyapock River, the runoff explains the sediment yield decreasing trend (r2 = 0.82; p < 0.0001) and no relationship with the land use change was found.

Sciences du milieu [021] ; Pollution [038] ; Hydrologie [062] ; Géologie et formations superficielles [064] ; Télédétection [126]

GUYANE FRANCAISE ; MARONI COURS D'EAU ; OYAPOCK COURS D'EAU

Fonds IRD [F B010075627]

fdi:010075627