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Tadeusz Liziński Problemy zarządzania ryzykiem w kształtowaniu Risk management problems S u m m a r y Summarizing polder areas issues one should first consider polderization processes as being finished, at least in a larger scale. This is a result of the decreasing role of croplands in food production. Because of specific hydrographic conditions in polder areas it is possible to create the so-called territorial productive systems there. The cost of maintaining polder infrastructure (and thus the managed area) is affected by the number and length of facilities in relation to the total area. Analysis of the long term costs positively verify the hypothesis adopted here of their stable character and dependence on natural conditions and spatial organization of areas and polder appliances. It has been also confirmed that such analysis should precede a decision on renaturisation of chosen polder areas or their modernization by consolidation of pump stations and polders or by the isolation of sub-polder and construction of secondary pump stations. For that purpose it seems reasonable to apply methodical approach contained in the Cost-Benefit Analysis and the method of Net Present Value. Evaluation of polder areas and appliances is connected with the assessment of non-commercial goods and services. This applies to such goods as: the sense of security of people living in these areas constantly threatened by floods or environmental goods and services associated and often dependent on polder appliances. Valorization of natural and technical resources of Elbląg Canal confirmed the usefulness of the Travel Cost Method applied in environmental economy to assess natural resources in tourism and recreation to this aim. The Contingent Valuation Methods and the Hedonic Price Method might be useful in economic assessment of flood control investments aimed at increasing the sense of security. Polder areas have some amenities which make them attractive for many activities but which also bring some risk. It means that some unfavourable situations and losses might occur. In the risk management one may distinguish main elements including those most often mentioned: risk identification, risk classification, risk measurement and response to risk. Based on long-term studies performed by Żuławski Research Centre in Elbląg of the Institute of Land Reclamation and Grassland Farming and other studies in the Vistula delta the following components of polder risk were identified:
Considering identified polder risk components in the Vistula delta, four levels of the risk could be distinguished: The first risk level has regional range which means that it includes the whole delta with the source located in the Vistula channel. The second risk level has sub-regional character and pertains separately to Gdańsk Żuławy, Great Żuławy and Elbląg Żuławy. Vistula Lagoon, Lake Druzno , rivers and canals of the polder systems and gravitationally drained areas are the source of threat. The third risk level concerns polders and polder sections and has a character of in-polder flood which doesn't pose a threat to people's life or real estates but can cause losses in production, especially in agricultural production. The fourth risk level is connected with agricultural productive space and results from the response of Żuławy alluvial soils to excessive precipitations. Losses are caused by crop reduction, difficult labour conditions and increased production costs. Verification of adopted hypothesis and assumptions and realization of the study aims enable to formulate the following methodical and practical general conclusions:
Within the improvement of theoretical basis of polder risk management, particularly at its highest level, it seems reasonable to broaden the existing principles of measuring flood risk and its acceptability. Foundation of this measurement on the probability of base and control flows for various classes of hydrotechnical constructions should be supplemented with socio-economic evaluation. The strategy of regional development in polder areas should always be based on precise flood control strategy which is a prerequisite for the existence of polder areas. Despite expected changes, the agricultural functions in polder areas will remain important. Large number of farms on one polder or polder section and diverse land use structure will always generate conflicts in local water management. These conflicts won't be reduced by basic reclamation network which should provide certain standard availability of agricultural productive space. Working schedule of pump stations and maintenance of basic network should be adapted to the dominating means of polder arrangement with the consideration of soil environment protection. Solutions concerning detailed reclamation network and cropping risk should be the problem of a user. These problems could be solved in the instruction of polder water management.
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