The 3rd Northern Forum FWG Meeting:
To Learn the Process of Formation and Destruction of the Ice Blockage on the Rivers of Yakutia, We Need a Testing Area

By Konstantin I. Kusatov,
Head of the Yakut UGMS Hydrology

Our knowledge about the ice blockage on the rivers is based on the basic theoretical discussions of the Sen-Venan Equation or on the mathematic or analogue models. At the present time the hydrologic stationary stations of the hydro meteorological service measure only the water level but not the parameters of an ice-blockage.

Such information is not enough for further investigation of ice-blockages. In order to get acquainted with a phenomenon one should systematically measure its parameters. The first attempts to measure the parameters of ice blockages were made in the 1970s in the USSR . During this period in the science and technology state committee the following theme was worked out: “The study of quantitative and qualitative characteristics of ice blockages”.

For studying the ice-blockage parameters the nature observations were made from Moldavia and Latvia to the Lena River . The specialists from Saint Petersburg visited Yakutsk in May after making observations of the river Yuzhny Bug in February. The theme “The quantitative and qualitative characteristics of ice blockages” meant the design of an ice thickness measuring device.

In the State Hydrologic institute together with the Rizhsky institute of the civil aviation a radio measurer of the ice thickness called “Metel” was designed. During the designing of a device the researchers found out that a similar device was made in Rybinsk city in Saratov , it was called “Radioledomer – 1” . This device measures only the thickness of a monolithic ice but not the in the water ice. That is why the device was not used for measuring the blockage ice thickness.

In Yakutsk a device “Georadiolocator” is being tested from 2003. The device must be upgraded to make it possible to measure the blockage ice thickness.

Now in February 2006 the device measures the thickness of a monolithic, in the water ice and displays the position data, there are possibilities to measure the stream depth.

The next stage of an upgrade can be the possibility to make photos of the ice and to measure the stream speed under the water. The latter is a very serious one.

Thus such a device is being worked out that in future will be able to give the quantitative characteristics of ice blockages. D.I.Mendeleev said that the science starts from measurements. Apparently after we get some quantitative parameters of ice blockages we can hope on a significant progress in its studying.

An ice blockage has not only the dynamic parameters there are also the geometric parameters of the river bed and ice. The ice thickness, its flat dimensions, which vary from the hearth of the blockage till the tail both in the length of the river and the time. The blockages are formed in different places that's why it is hard to take proper account of the influence of morph metric characteristics of the river bed during the formation of the ice blockages.

Depending on the place of the ice blockage formation and the granulometric composition of the river bed a deformation of the river bed occurs. This phenomenon influences the formation and destruction of an ice blockage.

Thus if we want to know the time dynamics of a blockage, to measure its parameters we need to choose a simple section of the river with one channel with a hardly eroded bed. Besides the section must be close to the communication centers.

Such section of the river in our opinion is situated upper Lensk city near the Polovinny Island . The Polovinny Island is situated up the fairway in 17 km from Lensk. In this section the bottom and the river banks are covered with cobblestones and boulders (one from three dimensions is 10cm).

The morph metric characteristics were taken in 1971-74 during the period of working out the theme “The quantitative and qualitative characteristics of ice blockages”. Making an ice-blockage testing area has two aims:

1) If the ice blockage above Lensk preserves the ice cover is broken naturally without blockages. According to the long term observations the ice under a large blockage breaks easily in low temperatures. As long as the blockage remains the section under it won't be blocked. Therefore the first aim of making an artificial blockage is to prevent the disastrous ice blockage under Lensk.

The experience of making artificial ice blockages can be used for protecting other settlements, in particular a town Srednekolymsk. In 1999 an ice blockage was formed above Srednekolymsk and remained for about three days which allowed the broken ice to move far under the town. In such a condition even the water of the river was full an ice-breaker passed easily.

2) In an artificial ice blockage area it is possible to mount many water level measuring sensors like GRK-1 and to receive the data both about the ice blockage length and time parameters.

With the help of a radio locator in an artificially made ice blockage we can observe the changes in the ice thickness by the length of the blockage and by the time characteristics.

In figures 1-3 there is a scheme of an ice blockage in slit and draft in different stages of its formation. In figure 1 there is a slit of a blockage where it is possible to analyse the thickness of ice and the water level with the help of sensors of GRK-1 device. Figure 2 shows the stuffing of ice, here we can make the correlations of the blockage ice thickness judging from the kind of stuffing. Figure 3 shows the scheme of destruction of ice. The cross cracks in the ice witness the start of destruction of ice.

During the process of observations of the ice blockage forming it is necessary to measure the pressing force distantly as shown in the figure 2 and also to define when the process of pressing turns into the process of breaking.

Presently there isn't a remote definer of compression between the particles of ice when the ice blockage is formed. While planning the experiment we should find it out.

The experiment of making an artificial blockage means the monitoring of the ice thickness. Consequently it is necessary to frequently measure the ice thickness by one and the same rout. So the problem of reduction of prices of getting this information arises.

For reducing the risk of flooding the settlements during the spring floating of ice from 2001 the Emergency Control Ministry takes preventive measures of reducing the ice cover solidity by the following means:

- sawing the ice cover in the most dangerous areas;

- blackening the surface of the ice cover by atomization of ashes, dusty coal from a plane AN-2 or dispersion of sand from cars;

- boring the ice cover for laying explosives.

The experience of sawing the ice along the river made in 2001 was considered unsuccessful and from 2002 they started to make diamond shape sawing. This kind of sawing was considered the most successful till 2005 because it reduced the solidity of ice and it seemingly broke by the saw cuts. But in 2005 during the first floating of ice the ice broke not by the saw cuts so the efficiency if this kind of sawing was considered doubtful.

The blackening of the surface of the ice by atomization is considered as the most effective one which is made by various means.

At the same time these three preventive measures are not scientifically defined. The effectiveness of these measures is determined by those who implemented them practically so the estimation is rather rough. That is why it is absolutely necessary to scientifically base the preventive measures. That is why an ice blockage testing area above Lensk near the Polovinny island is required. It is essential to start beforehand by finding the executors, in particular:

•  To formulate a technical assignment of making a project of the hearth of the ice blockage;

•  On the basis of a technical assignment to make a project of works and a scientific account.

The executors are:

•  the technical assignment are able and agree to prepare the specialists from the Institute of Physical-Technical Problems of the North and GU of the Yakut UGMS;

•  the project can be made by ‘Sibgiprorechtrans', they say that the chief engineer of the project Mashcovskaya agrees to do such a job.

•  the nature observations of the ice blockage formation and destruction can be made by the specialists from IFTPS, GU YaUGMS, the Northern Mining, LBU, the Russian Emergency Situations Ministry in the Republic of Sakha Yakutia , Vsryvstroy and others.

The next task of the experiment is destroying the ice blockage during which many situations can occur:

•  during the destruction of the hearth of the ice blockage the whole body of the ice blockage can be destroyed or some part of it can remain untouched.

•  ‘above' the remaining blockage the supporting forces can also remain.

In these cases it is necessary to destroy the remaining blockage too.

By measuring the thickness of the ice lengthways it is possible to define the place of the remaining blockage before the destruction.

Many variants of studying the blockage parameters in this testing area have been made.

It is necessary to plan a research effort of making an ice blockage on the Lena river, studying its parameters and the technology of its destruction by the year 2007.

From the experience of destructing the ice blockages on the rivers Lena, Aldan in 1997, 2000, 2001 we see that the blockage destroys not that quickly as we wish.

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