Paraná River Project - Background: Methodology 2

Living with the river Downstream view of the Paraná River

Field survey to establish braid-bar alluvial architecture for contemporary and abandoned channels

  1. GPR Background: The alluvial architecture of km-scale braid-bars both within-channel and adjacent to the contemporary braidplain will be quantified using GPR. Using the new Pulse EkkoPro and ‘Smart Cart’, it is now possible to collect over 10km of GPR line in one day. We will use 100 MHz and 50MHz antennae which should give penetration depths of 12-14m.
  2. GPR Survey Programme: GPR surveys will be completed during each low flow season in 2008-2010 with two GPR systems. Recent (1-3 yrs), established (10+ yrs) and older (1000+ yrs) braid-bars will be identified for survey. Channel bars will be located in areas with both low and high suspended sediment loads. A grid with 100m spacing will be used on each bar. A limited number of vibracores and suction cores will be taken at the intersections of GPR lines to facilitate ground-truthing of radar facies, permit grain size sampling and collect organic material for dating.
  3. GPR Data Analysis: All survey lines will be post-processed in Seismic Unix with additional analysis using Petrel software.
  4. ERT: The GPR surveys and cores will be supplemented by one Electrical Resistivity Tomography (ERT) survey. We will use a resistivity array with 50 electrodes spaced 2m apart, that will produce a 20m deep profile with 1m resolution. Data will be processed using RES2DINV software to generate resistivity profiles