[Acoustics] Fw: River Discharge Measurements

[Pedro Moreira]

Sometimes when making discharge measurements at amazon basin rivers with high sediments concentrations and mooving bottom we have to replace ADCP bottom tracking with accurate DGPS´s for boating positioning purpose.
When making traditional discharge measurements with current meter at smaller sites where one cannot install a steel cable across the rivers I wonder if any one of you have replaced the old sextants by one more up-to-date equipment like distanceometer or even DGPS itself. At large amazon basin rivers because of its large width (up to 4 km) we have to use thedolites.
For those who continue to use sextants please I would like to receive evaluation of  the following products or others and its dealers and internet sites: 
Low Cost 
Chinese ASTRA IIIB (~ US$ 500.00)
DAVIS Mark 15 (~ US 200.00)
DAVIS Deluxe Mark 25 - Plastic (~ US$ 300.00)
High Cost
German Cassen & Plath Horizon Ultra (~ US$ 1,700.00)
German Cassen & Plath Navistar Professional (~ US 1,500.00)
German Cassen & Plath Navistar Tradicional (~ US 2,600.00)

Any suggestions will be helpful. Thank you in advance.

Pedro Moreira
Hydrology Engineer
System Analyst
CPRM - Brazilian Geological Service
Rio de Janeiro - RJ
Brazil
55 21 2546-0352
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