=Paper= {{Paper |id=None |storemode=property |title=Risk Assessment of Use of the Dnieper Cascade Hydropower Plants |pdfUrl=https://ceur-ws.org/Vol-1356/paper_105.pdf |volume=Vol-1356 |dblpUrl=https://dblp.org/rec/conf/icteri/SkrypnykH15 }} ==Risk Assessment of Use of the Dnieper Cascade Hydropower Plants== https://ceur-ws.org/Vol-1356/paper_105.pdf
        Risk Assessment of Use of the Dnieper Cascade
                    Hydropower Plants

                            Andriy Skrypnyk1, OlhaHoliachuk1
            1
                National University of Life and Environmental Sciences of Ukraine
                 avskripnik@ukr.net, olia_ailo34567@ukr.net



       Abstract. In this article we wish to evaluate efficiency of use of Dnieper cascade
       hydropower plants on the basis of common approaches to environmental
       management. We evaluate the efficiency of use the flooded areas of the
       hydropower station in agriculture. Assessment of the man-made risks includes
       evaluation of static (regular maintenance of dams) and stochastic (probability of
       artificial tsunami) components. According to the world statistics of disasters
       caused by dam reservoirs, the probability of man-made tsunami is estimated
       around 0.01%. Using this rate of probability we can state that expected losses van
       be 5% of the confidence level. Dnieper reservoirs ranking on the degree of energy
       risk (the possibility of man-made tsunami generation) was made.

       Keyword. risk assessment, hydropower plan, electricity, agriculture,
       environmental management.

       Key Terms. MathematicalModel, Data, Environment, Infrastructure,
       Development.


1    Introduction

   Before the era of nuclear power, contribution of hydropower in the energy balance
of the former Soviet Union was considered indisputable. Thus the negative effects
associated with the creation of reservoirs on the plains were not taken into account e.g.
flooding of large areas, destruction of towns and historic monuments, increase of the
risk of man-made disasters. But time passed and in 1970s in Ukraine were built several
nuclear power plants and as a result appeared the need to develop solar, wind and
bioenergy and it led to decrease of the share of electricity generation by hydropower
plants to 5-7%. Over the past decade, the agricultural sector of the Ukrainian economy
has become one of the major players in the global food market and agricultural export
of the country has become one of the landmarks of the national economic development.
That is why there is an urgent need to use territory of the cascade of Dnieper
reservoirsfor agricultural purpose. However, beside inappropriate use of land resources
[16] and deterioration of the quality of water resources there is a high risk of man-made
disasters which can be caused by the functioning of the Dnieper cascade hydropower
plants.
   A. Pigou [11], P.Samuelson [15], R. Coase [12] presented classical approaches to
exploration of the impact of externalities on economic performance (environmental
management). The main idea of this approach is that the price of products (in this
case electricity) does not respond the social price paid by people for violations of the
environment [13] and therefore assessment of economic growth should be calculated
taking into account the price of deterioration of the environment [1, 2] .
   English researchers proposed classical approach to the exploration of the causes of
destruction of dams, they assert the classical definition of the threats which are
connected with creation of artificial reservoirs [16]. In Great Britain all the artificial
reservoirs (more than 25 000 cubic meters of the size 100m * 100m * 2.5m) were under
the control of local authorities and then the responsibility to control artificial reservoirs
was transferred to National Environment Agency.
   For comparison, Kyiv reservoir has a volume of 3.73 billion cubic meters and it is
placed above the level of many districts of Kyiv [9]. Kurenevka tragedy which
happened in 1961 showed that even not significant in volume reservoirs (600 000 cubic
meters - 400m * 400m * 3,75m) can be extremely dangerous if they are placed above
the level of the nearby territories and can lead to generation of artificial tsunami [9].
During World War II in parts of the Dnieper River below the Dnieper dam the retreating
Soviet army tried to destroy the dam. The man-made disaster led to the flood victims
among whom were citizens of Zaporozhe and coastal villages and soldiers of the Soviet
Army (about 100 000 people ) [6].
   Researchers emphasize the negative effects of the creation and functioning of the
Dniper reservoirs, besides flooding of large territories the negative effects concern a
change of hydrological, hydro chemical and hydro biological regimes and slowing of
water circulation [3, 6, 7]. In general, there is a great number of scientific papers on
significant negative effects connected with creation of the Dnieper reservoirs for the
environment of Dnieper, in particular, and for the economy of Ukraine in general. But
the issue of quantitative estimation of possible losses caused by artificial tsunami has
got little attention among researchers.
   In this article we wish to explore a comprehensive risk assessment of further
functioning of Dnieper hydroelectric cascade considering alternative options of usage
of flooded areas and possible losses connected with future functioning of reservoirs and
to develop the methodology of losses assessment connected with destruction of dams
reservoirs.


2     Characteristics of Flooded Areas and Options of Alternative
       Exploitation

   As we already mentioned, in twenty-first century the hydroelectric power generation
ceased to be a decisive factor in the energy balance. The GDP growth in 2000-2007
was not connected with an increase in production of electricity. During this period was
an increase in production of cereals for which the usage of electricity was minimal. It
is difficult to estimate the total social costs of flooded areas, and overall benefits from
the functioning of large reservoirs of water. In addition, it is difficult to assess losses
connected with deterioration of water quality due to the lack of flow. There are a lot of
other aspects that do not prove the necessity and efficiency of the functioning of
reservoirs. However, we will focus on two main aspects: 1) alternative usage of
reservoir areas in agricultural production; 2) level of risk connected with further
exploitation of reservoirs (dams of the Dnieper reservoirs). Dnieper cascade
hydroelectric station was built during the period of planned economy, the first dam was
built on Dnieper in 1927 (Zaporozhe) and the last in 1976 (Kanev). General
characteristics of reservoirs and power plants are presented in Table 1. The total area
of Dnieper reservoirs is 6.9 thousand sq. km, 1.1% of the territory of Ukraine (Table
1). But if we take into account that the territory near rivers area was always the most
fertile for agricultural sector, it is necessary to assess the share of reservoirs in the
volume of agricultural land, which is 1,7%. Not all agricultural lands are fertile that is
why the factual area which is used in agricultural sectoris about 27 million hectares
(270 thousand sq. km) with a standard deviation 0.8 million hectares [4]. In this case,
the share of the Dnieper reservoirs increases up to 2.6% of the area used for agriculture.

                      Table 1.Structure of Land Resources of Ukraine

                                                      Total area
 The main types of land and economic activity
                                                      Thousand sq.
                                                                   % of total area
                                                      km
 Agricultural land                                    415          68.8
 Forests                                              106          17.6
 Built-up areas                                       38           6.3

 Territories covered by surface water (Dnieper 24(6.9)                 4.0(1.1)
 reservoirs)
 Unsuitable land for agricultural production   21                      3.3
 Total (territory of Ukraine)                  604                     100.0
       Source:[4]
   Compare the coast of total volume of products available through agricultural
production from flooded areas after the creation reservoirs, and the cost of electricity
generated by hydroelectric Dnieper cascade. General characteristics of reservoirs and
their electricity generation capacity is presented in Table 2. From the total area of
reservoirs we extracted the natural are of water surface using natural characteristics of
the Dnieper and obtained the size of flooded areas which potentially could be used in
agricultural sector.
   The area of flooded territory is 6 thousand. sq. km. Dnieper cascade which consists
of six hydroelectric power plant produce 10 billion kw * hr. per year, (40% are produced
by Dnieper, 15% by Kremenchuk and15% by Kakhovska, 13% by Dniprodzerzhynsk,
10% by Kaniv, 7% by Kyiv. Dnieper hydropower station (HPS) has the best ratio of
natural areas to the area of the reservoir - 38% and the worst ration has Kyiv HPS - 5%.
                                                   Table 2. Main Features of Reservoirs




                                                                                                    man-made tsunami, J
                                                                                                    The potential energy of




                                                                                                                                                                                                                       production, mln kW • h
                                                                            Volume, million cubic




                                                                                                                                                                             Flooded area, square




                                                                                                                                                                                                                                       annual
                                               The height of the dam,




                                                                                                                                                        area,
                        The average depth, m




                                                                                                                                  Area, square km




                                                                                                                                                                                                        Capacity, MW
                                                                                                                                                               natural
                                                                                                                                                        square km




                                                                                                                                                                                                                       Average
                                                                                                    *1014



                                                                                                                                                        The




                                                                                                                                                                             km
                                               m


                      1                        2                        3   m                       4                         5                     6                    7                          8                  9
Kyiv                  4.0 11.5                                          3730                        3.4                       922                   44                   878                        408.5 683
Kaniv                 4.3 10.5                                          2500                        2.04                      581                   110.7                470.3                      444                972
Kremenchuk            6.0 17                                            13520                       19.8                      2252 166.5                                 2085.5                     632.9 1506
Dniprodzerginsk       4.3 12.6                                          2460                        2.5                       567                   102.6                464.4                      352                1328
Dnipro                8.1 35.4                                          3320                        10.2                      410                   154.8                255.2                      1569 4008
Kakhovske             8.4 16                                            18180                       21.04                     2155 276                                   1879                       351                1489
                                                                                                                              6887                                       6032                                          9986
           Source: [3;10]
   We will explore the possibilities of obtaining agricultural production in flooded
areas, we will start from evaluation of the efficiency of agricultural areas during last
four years. Due to the high risk of the agricultural sector we use averaged indicator of
efficiency during four last the years (Table 3).We obtained the indicator of efficiency
of the usage of 1 thousand square kilometer of flooded areas which is equal o 0.89
billion UAH (prices of 2012), with a standard error of 0.03 billion. This means that we
can get agricultural products at total value of 5.4 billion UAH (with a standard error of
0.2 billion) from flooded territories which are under Dnieper cascade

        Table 3. General characteristics of the agricultural sector for the period 2010-2013
                                                        2010                           2011                       2012                              2013
                                                                                                                                                                             x( ( x))
    Volume           of                                 194.9                          233.7                      223.2                             252.9                    226.2(10.3)
    production (billion
    UAH)*
    Area (sq. km)                                       246.4                          247.1                      261.3                             262.0                    254.2(3.7)

    Agriculture       return                            21.1                           27.0                       20.5                              11.2                     20.0(2.8)
    (%)
        * prices of 2012
Source: AgriculturalUkraine 2013 / Kyiv.-2014-p.187-200.
   The value of electricity produced during a year and financial value of potential
agricultural products are presented inTable 4.
   We introduce the concept of efficiency of areas of separated reservoirs as the ratio
of the value of the annual volume of electricity produced to the potential value of
agricultural products that can be grown on flooded areas.

               Table 4. The effeciency of the flooded areas in monetary terms



                                    Output      of
                                                     Price       of
                      Flooded       agricultural
                                                     electricity        The efficiency of
                      area,         products on
Name of reservoir                                    produced, bln.     the flooded areas,
                      square        the flooded
                                                     USD. (VAT          %
                      km.           areas, bln.
                                                     included)
                                    USD.


Kyiv                  878           0.78             0.22               28.2
Kaniv                 470.3         0.42             0.31               74.8

Kremenchuk            2085.5
                                    1.86             0.49               26.1

Dniprodzerginsk       464.4
                                    0.41             0.43               103.5
Dnipro                255.2         0.23             1.29               568.6
Kakhovske             1879          1.67             0.48               28.7
Total                6032        5.37                3.22               60
             Source: own calculations
   The total amount of the value of electricity produced is significantly less than the
potential value of agricultural products that can be grown on the flooded areas, the value
of electricity is only 60% of the potential value of grown agricultural products relative
to the average indicator of Ukraine agricultural productivity. Graphical representation
of efficiency for certain reservoirs is shown in Figure 1.
              2,0


              1,5
                                                                   Output of agricultural
    bln.UAH




                                                                   products on the flooded
              1,0                                                  areas, bln. USD.


              0,5
                                                                   Price of electricity
                                                                   produced, bln. USD. (VAT
              0,0                                                  included)




    Fig.1.Comparison of possible income from agricultural production and power generation

                    Source: own calculations on base table 4

   Data in Table 4 show that the efficiency of the flooded areas is significantly different
for different reservoirs. The most effective reservoir is Dnieper HPS, because it was
built in the place where the flow of Dnieper is rather fast (significant differences in
levels). Further construction of power hydro stations led to the flooding of large areas
that would have greater value if they were used in agricultural sector.


3         Risks Evaluation of Further Dnieper Cascade Functioning

   All possible losses connected with functioning of reservoirs are not limited to the
wastage of flooded areas. The general scheme of the risks evaluation of further
functioning of reservoirs is presented in Figure 2. They can be divided into three
groups: economic, technological and environmental.
   We made an attempt to assess the expected total annual losses L which consist of
economical - Lеk ; ecological - Lekol ; and technological - Lt :

                                      L  Lеk  Lekol  Lt                                  (1)
    In the first approximation economic losses are equal to the difference between the
price of potential agricultural products Vap and the value of producing electric energy

Ve :
                                      Lek  Vap  Ve                                        (2)
                                          Risks



        Economic                                                      Man-made
                                   Environmental




                            Thetotalannual expectedloss

             Fig. 2.Model of possible risks of functioning of Dnieper reservoirs

   Environmental risk in a first approximation must be evaluated on the basis of cost
of measures aimed to bring the mass of water in the reservoir (with absence of flow)
to state of the river water.
   The most difficult to evaluate are technological (man-made) risks, which present
both static (regular repair of dams, measures aimed to support state reservoirs) and
stochastic components. The latter is relevant to the possibility of artificial tsunami due
to partial or complete destruction of the dam. Taking into account the global statistics
the probability of the destruction of the dam is evaluated around 0.01% [14]. At first
glance it is a small probability and it seems that is can be ignored, but the evaluation of
the probability of depressurization of the reactor of Chernobyl type was considered
lower for two orders of magnitude (0.0001%), which did not prevent this to happen.
We evaluate the risk of man-made reservoir functioning for each reservoir. The
potential energy that depends of the height of the dam and of the volume of reservoir
after the destruction of the dam creates an artificial tsunami (Table 2). We wish to
explore the least effective case (Table 4) and the most dangerous in terms of potential
losses– Kyiv reservoir.
   The approximate evaluation of the power of the artificial tsunami in case of
destruction of the dam of Kyiv HPS can be calculated on the basis of the potential
energy of water masses and sludge. The volume of the Kyiv reservoir is 3730 million
ton. (Table 2) to which we add 90 million tons of radioactive sludge [8]. The average
depth of reservoir is 4m and the average height of dam is 11.5m, dam reservoir center
of gravity is situated at a height of 9.5 m according to the water level of the Dnieper
River after the dam. That is why the potential energy of artificial tsunami that threatens
Kyiv is:
              Eц  m  h  g  3730  10 9  9.81  11.5  4.2  1014 J
              m  (3.73  0.09)  1012 kg;
                                                                                         (3)
              h  11.5 м  2 м  9.5m;
              g  9.81m / s 2

   According to the energetic characteristics the potential tsunami that threatens Kyiv
is equal to five nuclear charges dropped during the Second World War on Hiroshima
(15-20 kt. TNT) [15]. Of course, the shock effect of nuclear explosion and artificial
tsunamis is difficult to compare because the shock wave in the first case expands at
speed exceeding the speed of sound and artificial tsunami speed is determined by the
depth of the Dnieper, and taking into consideration the depth of Dniper the speed will
not exceed 30 km / h.).
   The situation is complicated by the presence of 90 million tons of radioactive sludge
at the bottom of the reservoir, the presence of which can contribute significantly to
strengthening of the effects of artificial tsunami and the risk of radioactive
contamination of the Dnieper and coastal areas to Kanev reservoir. In the case of this
scenario, 10% of Kyiv may be contaminated [9].
   Similar characteristics are calculated for each of the reservoirs (Table 2).
Kremenchuk and Kakhovka reservoirs have the highest level of risk connected with
emergance of artificial tsunami, it can be explained by volume of the accumulated
water.
   Losses caused by artificial tsunami in certain time t due to the violation of the
integrity of the dam are proportional to the product of the tsunami energy ( E ts ) and

cost values (urban infrastructure) located in the area of artificial tsunami( S ots ):
                       Lt  k  Ets  S ots                                              (4)

where, k – coefficient of dimension J-1, which can be determined only empirically.

  The expected losses:
                          L t  p  Lt                                                   (5)
  Variance:
               2  p  L2t  (1  p)  p  L2t    Lt p                               (6)

  Losses in confidence level α - L ( p( L  L )   ) [13]:
              L  L t  x  Lt    p  Lt ( p  x     p ),
                                                                                         (7)


where x -quantile of the normal distribution.
   We make an assessment of potential losses of Kyiv which can be caused by the
potential of artificial tsunami concentrated in the Kiev reservoir.
   Up to 10% of the houses located in Kyiv according to the evaluation of hydrologists
are under the tsunami risk. The volume of living area in houses in Kyiv is 62.2 million
square meters [5]. The cost of 10% of Kiev buildings, at an average price of 0.5
thousand dollars per sq. m, is 3.1 billion USD. Hence, the expected losses for a given
probability of violating the integrity of the dam is 3·105 dollars. Losses in confidence
level α:
                     L  L t  x  Lt p  Lt ( p  x p ) 
                    3.1 10 9 (10  4  1.65  10  4 )                              (8)
                    3.1 10  0.0166  5.1 10
                             9                     7


   This means that the annual potential losses from the use of the Kiev reservoir taking
into account the risk of man-made tsunami are near 51 million USD.
   After analyzing potential threats and possible damage, which can be caused by
artificial tsunami in Kyiv we cannot propose the immediate dismantling of all the dams
on the river Dnieper. The data in Table 2 on artificial potential energy of the tsunami
should be supplemented by information connected with potential losses according
expression (8). There must be made a forecast of losses caused by the destruction of
the reservoirs. After all the calculations, we can evaluate the hazard rank of every
reservoir and thus offer the procedure of their disassembling in order to restore the
natural state of the Dnieper.


4    Conclusions

   New information technologies and development of the theory of environmental
management leads to a revision of the main concepts of the planned economy. Thus it
leads to the change of our view on necessity and efficiency of functioning of
hydropower stations. We analyzed the energetic efficiency of certain reservoirs on the
basis of an alternative use of the flooded territory in agriculture. Energy efficiency of
different reservoirs is rather different. A significant share of electricity is produced by
Dnieper hydropower station, thus there is an opportunity of gradual transition to use
of updating energy sources that do not threaten energy security. Therefore, the final
decision about dismantling of hydropower stations should be made on the basis of
comprehensive assessment of economic-ecological efficiency and evaluation of losses
which can be caused by man-made tsunami.
   We propose a complex approach to risk assessment of use of the Dnieper cascade
hydropower station. We use a stochastic method of assessment of potential losses
connected with the use of Dnieper reservoirs in order to assess the losses, which can be
caused by violation of the integrity of the dam. We evaluated the potential losses of
man-made tsunami for Kyiv reservoir. In the research was made evaluation of the
potential hazards of each of the Dnieper reservoirs which can be caused by man-made
tsunami. On the basis of the achieved results we ranked the reservoirs according to the
degree of economic insecurity.
   Transformation of the of the key symbol of the Ukrainian state of rapid flow into the
system of stagnated reservoirs has no economic reasons taking into account that
hydropower stations produce only 5% of the electricity of the total amount and the
flooded areas can be used more efficiently. are more effectively use the flooded areas.


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