Fig. 1. Flowchart for integrated risk assessment (plant level).
Integrated Approach to Risk Assessment in the Environmental Quality Control Within the Republic of Bashkortostan. V. E. Gvozdev, Ufa State Aircraft Technical University, Ufa, Bashkortostan, Russia; R. Z. Khamitov, Ministry of Emergencies and Environmental Safety, Ufa, Bashkortostan, Russia; and S. V. Pavlov and M. J. Polkanov, The Institute for Problems of Applied Ecology & Natural Resources Use, Ufa, Bashkortostan, Russia
The complicated environmental situation in the Republic of
Bashkortostan (Russia) is characterized by intensive
negative impact over the environment from technosphere. To assess
the rate of negative impact from entire industrial region and
from separate plants over the environment and population an
integrated approach is being applied in the framework of the
environmental safety system.
Integrated approach assumes the calculation of quantitative
hazard rate of impact over the environment from industrial
enterprises in standard functioning mode and in case of emergency
as well. Risk R is being used as hazard rate and in general it is
a function of two arguments - probability of undesirable event
occurrence p and losses caused by this event C:
Total risk value R1 (being applied to the
considered approach) consists of the risk value for the
industrial object standard functioning mode R1 and of
the risk value of the consequences of a possible accident at this
object R2, both of which, in their turn, are formed by
risk for population health and for the environment:
Standard functioning mode is characterized by lower level and longer duration of technogene impact upon the environment in comparison with short-term mass emission of contaminants during an accident. Risk value is determined as a dependence of pollutant composition, its volume and geographical location of pollution sources and their functioning parameters. In this case risk function can be written as:
where V - volume of certain contaminant in emission; N - number of people exposed to impact; S - area exposed to contamination; t - duration of impact.
Negative effect from impact to population is manifested in
calculation of probable increase of cancer disease relatively to
background and hazard quotient for carcinogens and toxicants
respectively; as for environment - it is calculated from
background and maximum concentrations when maximum permissible
concentration is exceeded and duration of this exceed.
In defining risk from consequences of possible accidents another component is added to above dependencies. This component takes into account the probability of equipment malfunctions and technological process violations that could lead to an emergency. Once probability component and a maximum volume of contaminant that could be released are taken into consideration risk value can be calculated for the second case. Appropriate risk functions are:
where p - probability of emergency; V - maximum volume of toxicant that could be released; N - number of people who could be in disaster area; S - possible disaster area; t - interval between the accident and the end of its consequences elimination.
The distinctions in calculating risk value for an emergency
case are as follows: duration of exposure will be considerably
lower, contaminated area will be determined according to a
different mathematical model of contaminants distribution.
Fig. 1 shows flowchart for integrated risk assessment for a plant level (appropriate scheme for a regional level is slightly different). At the first stage generalization of information concerning technological process peculiar to concrete enterprise is executed. This information contains data about location of industrial installations, type and quantity of matters employed in technological processes and stored within the plant, methods of matter transporting and storing, waste volume and ways of its storing, etc. Then the process of revealing all potential hazard begins. Type and volume of employed matters, topographical terrain data, population density, nature of objects located in the area with negative impact and meteorological information are the criteria for the hazard sources. Further on a separate analysis of negative impact upon the environment from standard functioning mode of industrial objects and for the case of possible accident is being carried out. Eventually risk value will be calculated and a decisionmaker makes a conclusion about its acceptability. Afterwards the above calculated risk value will be the initial point for risk management.
There are certain difficulties in calculating quantitative
indices in integrated risk assessment on the regional level. So
in this case qualitative characteristics are used. They are
derived from known methods of multidimensional statistics and
methods of reduction of analyzed variable space dimensionality.
As a result of these methods application objects are classified
depending on negative impact rate.
Fig. 2 presents the results of classifying cities of Bashkortostan by the degree of dependence on technogene loading of water objects. Information about volumes of water for industrial needs of enterprises situated in different cities, mass of contaminants emitted to water objects with plants waste waters, number of accidents that led to water objects contamination and released contaminants mass was used as initial data.
Integrated approach allows to obtain comparative risk
assessment of different territories and cities, arrange
industrial objects according to risk rate as well as to plan
measures directed towards diminishing the hazard first of all in
regard to the objects for which risk value is the highest. In
oral presentation there will be given an analysis of actual data
about accidents that took place and contamination of environment
with application of mathematical simulation methods combined with
geoinformational technique.