Findings of hydrologic studies create sound basis for Amaila hydropower potential

A multiplicity of comprehensive and extensive evaluations of the hydrological conditions of the Amaila Falls Hydroelectric Project site has been carried out by a number of international engineering firms.

Accordingly, the Government of Guyana is pleased to release the hydrologic studies completed as part of the feasibility analysis of the Project.

The main hydrological study was done in 2001 by Montgomery Watson Harza (MWH) Engineers, one of the world’s leading engineering firms. The hydrology analysis used historical rainfall and river flow measurements from several locations in the region of the Project as well as over 40 years of monthly stream flow data (from 1950 to 1990) to calculate inflows and determine the potential energy that the Project might generate. To estimate flows in the Kuribrong River, where the Project is located, available data from a nearby river basin (the Potaro River) were multiplied by a “transposition factor”- a coefficient used to allow meteorological estimations, to effectively arrive at the hydrologic estimated flows for the river system entering the Project reservoir.

In 2008, an update review of the hydrological study done by MWH was completed to assess the validity of the monthly flow estimations for the project site. The 41- year historical flow estimates were incorporated into an energy model developed by MWH for the Project.

The previous hydrologic studies completed over the years that evaluate the hydrographic conditions of the Project site and which form the basis for the site selection are:

1) Amaila Falls Hydroelectric Project Feasibility Study Report, Kaehne Consulting Ltd. June 2002;

2) Amaila Falls Hydroelectric Project Guyana Feasibility Study Report Hydrology, MWH, December 2001; and

3) Hydroelectric Power Survey of Guyana Final Report, Montreal Engineering Company Limited, April 1976

Since 2001, a review of the hydrological study done by MWH was completed in 2008, to assess the validity of the monthly flow estimations for the project site and then in 2011 a second hydrological review was completed by Halcrow Group limited.

The findings of the reviews have all been positive, inferring a low hydrology risk to the Project. Specifically the Halcrow review validated the transposition factor used by the initial study citing it as “representative of the project site”. Additionally, even when varying this transposition factor by an acceptable range, energy yields still remained good, moving by 1% to 8% of the average annual yield. The specific energy estimates based on the 41 years of flows have also been affirmative. The review estimated:

Average annual energy yield at the generator terminals to be 1141 Gwh, with maximum and minimum yields being 884 Gwh and 1343 Gwh respectively.

Average annual energy output from the power plant at 1090 Gwh (at the transformer terminals taking account of machine outages and transformer loss)

Average annual power available at the distribution point in Linden and Georgetown at 1017 Gwh and 1047Gwh taking into account transmission line losses.

For a dry year, the annual energy yield at 994.8 Gwh and 952.8 Gwh for monthly and daily flows respectively.

All the findings above create a sound basis for the hydropower potential of the Project and reaffirms the Project’s acceptable hydrology risk to the Government of Guyana, thus, setting the stage for the outlook of reliable, stable and a dependable energy source for the people of Guyana.