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VOLUME 10(32)Content
ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 621.22 EVALUATING ECONOMIC AND ENVIRONMENTAL CRITERIA FOR LARGE SCALE HYDROPOWER SCHEMESJ. BURNEIKIS, Lithuanian Energy Institute, P. PUNYS, Lithuanian University of AgricultureSummaryAt present there is excess in power production in Lithuania. This is due to still going on economic downturn since soviet times. For this reason there is no urgent need to build new power plants in the meantime. However the recent political decision related to shutting down the first block of Ignalina nuclear power plant in 2004 and the second one in the foreseeable future might change the above mentioned consideration. In this light we have to be prepared for the forthcoming shortfall between demand and supply of electricity by covering it with new power plants, especially promoting renewable energy - hydropower. The harnessing large scale hydropower resources - two largest Lithuania's rivers, representing 80 % of technical potential, could give about 2.2 TWh/year. However hydropower will not substitute power generated by nuclear power plant or existing thermal plants. Hydro contribution could reach 15 to 20 percent of total electricity demand. Hydropower planning, especially large one, is becoming increasingly complex, with strong competition in power production market, and growing environmental constraints. One of the real facts that could favour hydro in competing position with other types of power supplies is to take into account the external costs. In practice widely applied the least cost method is known up date to make judgment about each electricity generation source. To compare hydro and its main competitor thermo-electric installation project in a fair way, all costs and benefits directly and indirectly associated with their development and operation should be accounted for, as much as possible in monetary terms. It has to be noted that this study has not considered the reservoir environmental impact. Taking into account the fuel cost needed for thermal plant operation the hydro plant is commercially viable. This is very important since 95% of all the electricity is generated using imported fuels in Lithuania. However the pay back period is not very much attractive (up to 10 years). If the costs of thermal plant emissions, so-called externalities, are taken into consideration, then hydropower project can easy compete with fossil fuel-fired unit. Actually in Lithuania the taxes in force are not applied for the abatement green house gas emissions which is a global problem. Considering even the low tax rate (US$2/tone) the CO2 applied to emissions from thermal plants the amount would reach around US$38 million every year. These damages to environment can be avoided if large scale hydro plants on Nemunas and Neris rivers were developed. To sum up, the development of large scale hydro in Lithuania is a long term assignment. Nevertheless, considering steady growing fuel prices for power generation and environmental taxes resulting from the atmospheric emissions, planned large hydroplants on above rivers should justify. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 532.626 EVALUATION OF DRAINAGE TECHNICAL CONDITIONL. KATKEVICIUS, L. KINCIUS, J. SALTAUSKAS, Lithuanian University of AgricultureSummaryThe evaluation of land reclamation structures technical condition is a constituent inherent part from their maintenance. The data of evaluation of drainage technical condition is a base of planning exploitation works and means, preparing supervision and reconstruction targets, creating the cadastre of land reclamation structures and technical passports. While executing drainage maintenance, supervision and reconstruction works it is important to estimate its technical condition correctly. In order to estimate the technical conditions the exact and uniform methodic is needed. In the article a new methodic for evaluation of drainage technical condition is proposed. Evaluation of drainage systems is suggested according to degree of wearing in % and badly drained area in % from total drainage land. It is evaluated by points, which determine the level of maintenance, supervision or drainage reconstruction works. The uniform methodic of land reclamation structures technical condition will help in establishing the need of means and agricultural strategy in land reclamation. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 626.8 EVALUATION OF THE INFLUENCE OF TILE DRAINAGE ON NITROGEN LOSSES - NUMERICAL EXPERIMENT APPROACHArvydas POVILAITIS, Lithuanian University of AgricultureSummaryThe USDA - Erosion/Productivity Impact Calculator (EPIC) model has been adapted to simulate the influence of tile drainage on nitrogen leaching out of the soil. The methods used are both analyses of water quality data as well as numerical simulations from selected pilot area in Lithuania. The results indicate that the direct effect of drainage is an increase in the quantities of nitrogen leached from agricultural land. However, it was also shown that the choice of land management practice was extremely important for the leaching process.
Received in February, 2000; accepted in April, 2000. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10(32) UDK 626.8 RESEARCH OF SEDIMENTATION IN THE UPPER BASIN OF KRUONIS PSHP BY SUSPENDED LOAD IN THE REVERSIVE CANALC. RAMONAS, B. RUPLYS, A. VAITIEKUNAS, Lithuanian University of AgricultureSummarySedimentation causes a change of many characteristics of any reservoirs, among them - decreases the intensity of seepage, because fine particles of sediments colmate a bottom and slopes of reservoirs. In the paper a research of the volume of sediments deposited in the upper basin (UB) from suspended load is described. The volume was calculated from the difference of the suspended load concentrations in the water pumped into UB and in the water let back from UB through turbines. Concentrations were determined from the water samples taken at the reversive canal profile fixed by a steel rope. In 1997-1999 eight successive concentration measurements (both in pump and in turbine regime of the PSHP) were carried out: 5 when one of PSHP units was in operation, 2 - when two and 1 - when three units were in operation. The obtained results show that the research method, logical in principle, is uneffective because 1) operation regime of PSHP is very unfavourable (turbine regime starts immediately after the pump regime, so there is too little time for sedimentation) and 2) sediments in the UB from time to time are resuspensed by the waves generated by stronger winds (sometimes the water let through the turbines from UB is more turbid then the water pumped into UB). In general, sedimentation in the UB is statistically reliable and it is a result of suspended particles settling: concentrations of particles are low (~18mg/l), therefore the calculated predicted layer of sediments is ~0,7 mm/year for one PSHP unit; for the research of the sedimentation in the UB of the Kruonis PSHP the use of direct research methods should be more acceptable. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 627.13 THE USE OF GIS DATABASES FOR NUMERICAL MODELING OF HYDRODYNAMICS OF THE LOWER NEMUNASA. SIKSNYS, Lithuanian University of AgricultureSummaryThe possibilities of the use of GIS databases for numerical modeling of hydrodynamic processes in large sectors of flow of the lower Nemunas are described in this paper. The article dwells on the created computer programs for transforming and ordering of databases of model. The results of test calculations obtained by modeling of flow in the Nemunas bed and flooding part of valley in the sector between Rambynas hill and Panemun? settlement are presented in the article as well. More than 100 thousand cells were used in numerical 2-dimensional hydrodynamic model, therefore large numerical massifs describing geometrical and hydraulic characteristics of each cell were created. Special computer programs for preparing, controlling and ordering of these databases were created. Using the mentioned programs GIS data were transformed into formats suitable for model, graphical tools were used for data controlling, correcting and adding, changing the number of cells in the model, rotating and zooming of model, etc. 2-dimensional hydrodynamic model were modernized and adapted for large number of cells. The addition computer programs for results control, analysis and ordering were created. The test calculations indicated the new wide possibilities of the use of GIS data in numerical modeling of hydrodynamic and sediment transport processes. That may be of great use and benefit while solving practical problems of the lower Nemunas, as well as estimating effectiveness of various technical solutions and investments. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 556.5: 574 NUTRITION INFLUENCE ON THE BIOTA OF MIDDLE-SIZED LITHUANIAN RIVERSR. TUMAS, Lithuanian University of Agriculture, Vytautas Magnus UniversitySummaryThe generalisation of river water quality observations (1991-1998) of 17 rivers in Lithuania have been carried out to determine the influence of agriculture on water quality. River water quality in this study is analysed recognising river basin as geosystem, while the runoff polystructure represents its main constancy and mobility characteristics. Western and Middle Lithuania stands for lithological foundation, where internal structure of water balance factors is governed by soils of heavy mechanical constitutions and by specific features of the landscape. Natural geosystems of East part of the country constitute another mode of transformation in soils of medium texture, conglomerates of gravel and clay. There exists an essential difference between two systems. Due to this, polystructure of the runoff is different. The response of different landscape to similar human activities differs as well. The agricultural impact on the watercourse quality is related to both production and practice, but not so much: mostly river water pollution depends on landscape peculiarities and climatic conditions. The total inorganic nitrogen (NO3-N+NO2-N+NH4-N) concentrations (average for 1991-1997) found in Middle Lithuania rivers are the biggest 1.9-3.7 mg/l (phosphorus - 0.04-0.13 mg/l), less in West part of the country - 1.0-1.7 (phosphorus - 0.03-0.05) and the least in East part - 0.4-1.3 (phosphorus - 0.02-0.07). Major river basins in East Lithuania have large groundwater aquifers in which substantial amount of nutrients are retained. In small Lithuanian rivers after an unprecedented decrease in the application of mineral fertilisers (fivefold) and manure since 1991 (in connection to the economical situation in Lithuania) the nutrient load-decreasing phase started, but due to substantial inertia of terrestrial and aquatic ecosystems there was no unequivocal evidence that this change in the agricultural practices had influenced the riverine loads of nutrients (fig. 1). The nutrient results in growth of phytoplankton biomass and subsequent physical, chemical and biological changes in running water. The saprobity index reflecting abundance of phytoplankton, zooplankton and periphyton in polluted rivers, for all analysed rivers vary in narrow range (1.6-2.0). No similarity to the nutrients: concentrations of mineral nitrogen in the running water of East and Middle part of the country differ several times. Yearly average concentration of phytoplankton - 1.5 -1.88 mg/l. The diatom algae and blue-greens prevail (fig. 2). According to hydrobiological evaluation, pollution of small Lithuanian rivers corresponds middle class (fig.3). Structural composition of the fish communities in the Lithuanian rivers is determined by following factors (in descending order of importance): 1) river size, 2) heat budget, 3) stream flow control level, 4) biotope diversity, 5) level of human generated eutrophication, 6) pollution level. The total number of fish species in the river increases from river head (1-4 species) toward outlet (40-50). Species from warm streams (t>18°C) belong to plane boreal and arctic fauna complexes. The main body of the river fish communities depending on river length, heat budget and flow regulation level consists of 3-4 species. The Sirvinta river recognised as a warm stream. Along this river relations between zooplankton and fish biomass have been noticed. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2000 vol. 10 (32) UDK 626.43 INVESTIGATION OF EARTH DAMS' STATE IN KAUNAS DISTRICTJ. VYCIUS, Lithuanian University of AgricultureSummaryAccording to the data of Hydrographical Network Service of Environment Ministry, exploiting institutions and Hydraulic Engineering Department of Agricultural University of Lithuania (AUL) in Kaunas district there are 56 earth dams which reservoir areas are larger than 0,5 ha. From them 13 dams where area of reservoirs are larger than 5 ha. All these dams were constructed in soviet period (1960-1989) for irrigation, recreation, fishery, river flow control and other purposes. 28 dams are qualified as potentially dangerous hydraulic structures. According to the Environment Ministry instruction potentially dangerous hydraulic structures are such objects which can provoke risk for human life and environment due to stored water resources in reservoirs. At present when leasing and privatization processes of agricultural and other constructions are going on in Lithuania it is important to determine technical state and value of hydraulic structures which are objects for leasing and privatization. Investigations of earth dams' state in Kaunas district (mostly visual observations) were carried out since dams erection. These works were more intensive in 1984-1985 and especially they became more active in 1997-1999 when Ministry of Agriculture odered in Hydraulic Engineering Department of AUL to elaborate the system of technical state determination of earth dams. Creating this method, based on scientific field observation of hydraulic structures, earth dam complex was analysed as the whole of constructive and functional elements choosing principal dam stability determining and secondary less imporant ones. 33 earth dams were investigated in Kaunas administrative district and their technical state was determined according to quantitive indices - scale of defectiveness. The technical state of earth dams in Kaunas district are analysed in this paper.
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