http://weekly.ahram.org.eg/News/5677/21/Unknowns-about-the-Renaissance-Dam-.aspx
Unknowns about the Renaissance Dam
Leaks from the tripartite technical committee report on Ethiopia's
Renaissance Dam show glaring technical gaps in the plan that could lead to
disaster, writes *Maghawry Shehata*
Ethiopia's Renaissance Dam project had long been a subject of tension
between Cairo and Addis Ababa. The tensions began to flare on 2 April 2011
-- shortly after Egypt's 25 January Revolution -- when the latter announced
that it had laid the cornerstones to the dam and, subsequently, when it
began to divert the Blue Nile in order to construct the dam.
At that time, then Egyptian prime minister Essam Sharaf and his Ethiopian
counterpart Meles Zenawi agreed to create a tripartite technical committee
tasked with studying the designs, statistics and other information provided
by Ethiopia on that dam, the specifications for which were particularly
alarming to Egypt. Originally envisaged to have a reservoir capacity of 14
billion cubic metres, the designs for project steadily grew in their
ambitions and now provide for a 74 billion cubic metre reservoir capacity.
The technical committee set to work and completed its report in May 2013.
Although the three parties in this committee (Egypt, Sudan and Ethiopia)
agreed not to publicise the report, various agencies have disclosed its
most important substance. The following is some observations on that
substance.
A chief finding of the committee, after studying the facts and information
supplied by Ethiopia regarding the safety of the dam in light of the nature
of the soil on which it is to be constructed and the potential impact of
the heavy vertical and horizontal fracturing in the bedrock, was that
geophysical properties were not taken sufficiently into account in the
calculations for both the main dam (the Renaissance Dam), to be constructed
of reinforced concrete, and the saddle dam, to be constructed of stone and
rubble.
In addition, according to the summary of the information in the tripartite
technical committee's report, the planners had not studied the potential
effect of a dam of such a huge reservoir capacity (74 billion cubic metres)
as a source for generating a subterranean reservoir below the lakes area
and the potential impact of this on the properties of the sedimentary and
metamorphic rock beneath the dam. Such factors could lead to seepage
beneath the dams and heighten the likelihood of slippage and the consequent
partial or total collapse of a dam of such excessive specifications as the
Renaissance Dam.
It is also important to note that no studies, designs or data have been
made available on the saddle dam. Therefore, experts have no information on
which to base assessments regarding its ability to withstand the pressure
of the water that accumulates in its reservoir (63 billion cubic metres at
the rate of 500 cubic metres per second). It should also be borne in mind
that this water will be laden with sediments of various types and sizes and
there is little knowledge as to how the dam can tolerate the physical
impact of the rush and weight of the sediment-laden water during the
succession of rainy seasons that will pass during the projected life
expectancy of the dam.
Nor were studies conducted on the geo-chemical impacts on the bedrock as
the result of the development of a subterranean reserve beneath the dam's
reservoir area. That much of that rock is volcanic and, therefore, very
vulnerable to chemical reaction processes, increases the likelihood of
changes in the mechanical properties of the rocks and sediment both in the
reservoir area as well as beneath the dam itself, which could result in
fracturing or weakening its cohesion and, hence, possible ground sinkage.
There is not also sufficient information on the anticipated environmental
impact of the construction of the dam and reservoir. Nor has sufficient
study been accorded to the chemical properties of the water that will be
stored behind the dam or that will pass through its sluices, and the impact
of this chemical composition on river life.
In like manner, no study has been made of how the water that gushes from
the dam's turbines will effect the geo-morphological properties of the Blue
Nile in Sudan and of the impact of this on agricultural land and
facilities, the foundations of buildings and bridges, and the dams and
islands that the river traverses on its way to Khartoum.
To further underscore the huge gap or even total absence in geological and
geo-technical information related to Ethiopia's Renaissance Dam project,
whether due to the lack of studies or because relevant information has been
deliberately withheld from the tripartite technical committee, little or no
attention has been accorded to studying the seismological dimensions of the
geo-technological feasibility of the dam.
*The writer is former president of Menoufiya University and an expert on
water issues.*
Received on Fri Mar 14 2014 - 07:18:21 EDT