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CONTENTS 3. Inga Adamonyte. INVESTIGATION ON THE impact of drainage parameters oN silting of drains 4. Arvydas Povilaitis. TRENDS IN STREAM LOADS OF NUTRIENTS AFTER FLOW NORMALIZATION 5. Daiva Matoniene, Vilma Sudoniene. THE SUBSTANTIATION OF FOREST PLANTING IN AGRICULTURAL LAND 7. Albertas Steponavicius. INVESTIGATIONS ON SLUDGE AS A FERTILIZER FROM DAIRY PROCESSING COMPANIES 13. Ceslovas Ramonas. SEEPAGE FLOW THROUGH THE SEALS IN JOINTS OF HYDROTECHNICAL RETAINING WALLS 17. Virgilijus Buozis. THE INVESTIGATIONS ON DRAINAGE MAINTENANCE ECONOMICAL EFFICIENCY 21. Saulius Guzys. MIGRATION OF SULPHUR IN LIMED SOILS OF WESTERN LITHUANIA 22. Romanas Lamsodis. PHOSPHORUS MIGRATION IN BEAVER-OBSTRUCTED DRAINAGE CHANNELS 23. Simanas Askinis, Stefanija Miseviciene. ECOLOGICAL ASPECTS OF SLURRY APPLICATION 26. Raimundas Baublys. THE ANALISIS OF REGULATED STREAM CHANNELS IN THE SESUPE RIVER BASIN
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 INVESTIGATIONS ON THE FILTRATION QUALITIES OF DRAINAGE TRENCH BACKFILL Valentinas Saulys*, Nijole BastienE Summary The paper analyzes filtration characteristics of drainage trench backfill and drainage functioning effectiveness, when drainage trench backfill was mixed with lime in clay soils and spacing of drains was increased 1.5 times. Study object contains light loam and clay soils with 17.6-60.6% of physical clay particles (<0.01 mm). Soil bulk density is 1.58 g/cm3, frame density is 2.63 g/cm3, soil porosity is 39.67%. Having analyzed drainage runoff of the period 1999-2003, a close relationship between drainage runoff and local meteorological conditions was observed. According to rainfall amounts, warm periods (April-October months) were determined to be dry (326 mm in 2000) to wet (510 mm in 2001). Even more significant differences were observed between monthly precipitation amounts (from 0 to 250% of monthly precipitation rate in August-October period, in 2002). Maximum values of weighted discharges of the drainage fluctuated from 1.539 (01 02 2002) to 0.395 ml/s·m (07 03 1999). In 1999-2003, dispersion analysis of weighted discharges of drainage was made according to Fishers criterion. As the results of the analysis show, there are obvious differences between average values of weighted discharges in the variant when drainage trench backfill is mixed up with active lime (0.6% of soil mass, drain spacing 16 and 24 m) and control variant (drain spacing 16 m). Average values of weighted discharges were 39-44% higher in variant where drainage trench backfill was mixed with active lime (0.6% of soil mass) and spacing of drains was 24m. Having analyzed average values of ground water levels in the zone between two adjacent drains in control variant and in variants where drainage trench backfill was mixed with active lime (0.6% of soil mass, drain spacing 16-24 m), certain differences were observed as well. In variant with mixed lime additives ground water level heads in the zone between drains were observed to be 16 cm lower on the average. The results of the investigations on filtration qualities of drainage trench backfill, topsoil layer and soil in the zone between drains have shown that the lowest filtration coefficients occur in soils of the zone between two adjacent drains and in topsoil layer, while the highest ones are observed in drainage trench backfill soil mixed with lime additives. Average value of filtration coefficient in topsoil layer is 0.95 m/d. With 95% reliability one can affirm that the filtration coefficient of topsoil layer is 0.90χ1.00 m/d. Filtration coefficient of drainage trench backfill with lime additives (0.6% of active lime for soil mass) is 3.22 m/d at a 50-cm deep soil layer. Filtration coefficient of the backfill of control drainage is 2.20 m/d at the same depth. Average values of filtration coefficient in the zone between two adjacent drains is 0.83 m/d at a 50-cm deep soil layer, which is only 13% less than the filtration coefficient of topsoil layer. Keywords: draining, trench permeability, filtration, weighted discharges of drainage, draining intensity.
*contact person Dr. Valentinas Saulys, senior researcher, Head of Drainage Maintenance, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, water filtration processes, drainage systems operation efficiency, water management policy. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 6 81 09. E-mail: valentinas@water.omnitel.net. Dr. Nijole Bastiene, senior researcher, Drainage Maintenance, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, drainage systems operation efficiency, drainage silting processes. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE INVESTIGATIONS ON HERBICIDE-EFFECTED HORSETAIL (Equisetum arvense) IN DRAINED LAND AREAS Nijole BASTIENE*, Valentinas SAULYS Summary This paper analyses the possibilities for chemical extermination of horsetail spread above drainage lines. The experience of foreign countries in chemical horsetail extermination is considered. Horsetail vegetation conditions including hydro-chemical characteristics of soil in the study object and meteorological data of the study period are analysed, too. The paper gives the results of the studies carried out using the herbicides banvel, glyfos, ariane, lontrel and roundap. The study results have determined the effect of the herbicides mentioned on horsetail vegetation and quantitative changes in above-ground and underground horsetail systems after sprinkling. The effect of herbicides mentioned is short-term (seasonal), as fresh horsetail sprouts were observed in all variants the following year. The paper also gives the data on the technical condition of drainage with lines overgrown with horsetail. Keywords: drainage, horsetail, herbicides.
*contact person Dr. Nijole Bastiene, senior researcher, Drainage Maintenance Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, drainage systems operation efficiency, drainage silting processes. Address: Parko 6, Vilainiai, 5030 Kedainiai district. Phone +370 347 6 81 09. E-mail: vegelyte@delfi.lt Dr. Valentinas Saulys, senior researcher, Head of Drainage Maintenance Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, water filtration processes, drainage systems operation efficiency, water management policy. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 INVESTIGATION ON THE impact of drainage parameters oN silting of drains Inga AdamonytE Summary The requirementS for the reconstruction of drainage systems originate from the damage or natural abrasion of one or several components of drainage systems. The damages of drainage systems often occur due to the silting of drains, choking with soil and growing up with plant roots. The damages are caused by absorbed soil particles. It is especially relevant in suffosic soils. The damages of drainage outlet could be easily noticed and eliminated by a land owner. Mechanical silting with soil particles causes about 38 % of all defects. The influence of technical parameters of drainage systems on mechanical silting of drains is analysed in the article. The impact of the diameter of sublateral and collector drains on the silting of drains as well as the influence of the depth of sublaterals and collectors from the land surface on drain silting are discussed. On the basis of the studied methodology, statistical analysis of the data and generalised calculations are presented. Keywords: silting, drainage failures, diameter of drainage pipes, draining depth.
Inga Adamonyte, doctorate student, Water Management Department, Lithuanian University of Agriculture. Research interests environmental engineering and landscape management. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Lithuania. Phone: +370 37 75 23 37. E-mail: adinga@one.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 TRENDS IN STREAM LOADS OF NUTRIENTS AFTER FLOW NORMALIZATION Arvydas POVILAITIS Summary Detection of long-term trends in time series of water quality data is one of the major objectives of water quality monitoring program in Lithuania. In the present study, investigation was carried out to determine how time series of nutrient delivery data can be decomposed into two components: a random component that picks up the impact of natual fluctuations in a stream flow and a hydrologically normalized component that may be regarded as an estimate of human impact on water quality. The data on inorganic nitrogen and phosphate-phosphorus concentrations as well as calculated stream load values from the rivers Merkys, Sventoji and Levuo at 3 sampling sites within the period from 1990 to 2002 was analysed. The rivers Merkys and Sventoji have been regarded as influenced by both point and non-point sources of pollution above the sampling sites. The river Sventoji has been attributed to the rivers affected by non-point source pollution. The results have indicated that flow normalization technique was able to remove a substantial fraction (from 15.2 to 52.8%) of the intermonthly variations in Ninorg and PO4-P deliveries. A large part of the variance in concentrations and stream loads was a result of the variation in the associated streamflow. Therefore, the removal of this source of variance from the data made trend-testing procedure more powerful and reliable. The investigation has also revealed that the use of nutrient concentrations and/or transported loads instead of transported loads after flow normalization can lead to the substantial sophistication of the results in detecting trends in nutrient data. Keywords: inorganic nitrogen, phosphate-phosphorus, streamloads, flow normalization.
Dr. Arvydas Povilaitis, associate professor, Land Reclamation & Improvement Department, Lithuanian University of Agriculture. Research interests hydrology, water quality, mathematical modelling and GIS. Address: Universiteto 11, LT-4324 Kaunas-Akademija, Lithuania. Phone: +370 37 75 23 80. E-mail: arvis@hidro.lzuu.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE SUBSTANTIATION OF FOREST PLANTING IN AGRICULTURAL LAND Daiva MATONIENE*, Vilma SUDONIENE Summary Agriculture should be highly cost-effective under the conditions of market economy. Otherwise, the agriculture will not be able to compete with the agriculture of EU. Cost-effective agriculture is possible to be developed only in soils of good quality. The usage of land depends on agrarian, ecological, environmental and economical policy of the state. In land areas less favourable for farming the cost-effectiveness of agricultural production in possible only with state support. Currently, the state support is not sufficient to ensure profitabile farming. In most countries of the world forests are being planted in less favoured areas, as it is useful from ecological, economical and environmental points of view. The article analyses functional purposes of forests, factors determining forestation, possibilities of forest planting in areas less favourable for farming, juridical substantiation of forestation, and discusses the soils recommended for forests. Keywords: agricultural land, forests, less favourable land, agricultural land use productivity point.
*contact person Dr. Daiva Matoniene, lecturer, Land Management Department, Lithuanian University of Agriculture. Research intrerests agricultural land planning in land areas less favourable for farming, formation of land tenure. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Kaunas district, Lithuania. Phone: +370 37 75 23 72. E-mail: Daivamat@delfi.lt. Dr. Vilma Sudoniene, lecturer, Land Management Department, Lithuanian University of Agriculture. Research intrerests economical and ecological grounding of the formation of land tenure. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 LEGAL AND ORGANIZATIONAL PRECONDITIONS FOR THE LAND MARKET IN LITHUANIA Pranas ALEKNAVICIUS, Vidmantas GURKLYS, Antanas MAZILIAUSKAS* Summary The restrictions on land transactions will be abolished in the nearest future in Lithuania. This means that a new land policy regarding land markets should be developed. The analysis related to the current land market situation, legal acts, and restrictions on land purchase in Lithuania was carried out by the authors. The basic provisions of Lithuanian legislation influencing land market activity were identified and macroeconomic impact of the restriction on land trade was assessed. The expenditures in terms of time and money for the land transactions were established. The suggestions for the amendments of legal acts facilitating land purchase and allowing implementing the adequate land policy were formulated. Keywords: land market, land transaction, obstacles, legal acts.
*contact person Dr. assoc. prof. Pranas Aleknavicius, advisor of the Minister of Agriculture. Research interests: land law, land reform. Dr. assoc. prof. Vidmantas Gurklys, assoc. prof., Land Management Department, Lithuanian University of Agriculture. Research interests: land reform, geographic information systems. Dr. assoc. prof. Antanas Maziliauskas, dean of Water and Land Management Faculty, Lithuanian University of Agriculture. Research interests: environmental engineering. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Lithuania. Phone: +370 7 75 23 50. E-mail: Antanas.Maziliauskas@nora.lzua.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 INVESTIGATIONS ON SLUDGE AS A FERTILIZER FROM DAIRY PROCESSING COMPANIES Albertas STEPONAVICIUS Summary In our country dairy processing companies accumulate large amounts of heavily polluted wastewater and liquid wastes that are treated in municipal treatment facilities, used for soil fertilization or released into ponds. Having evaluated the pollution load of wastewater and price of its treatment in municipal treatment facilities, recently autonomous treatment facilities have been constructed at dairy processing companies for the treatment of the above-mentioned wastewater and wastes. The paper gives a thourough analysis of the treatment process of wastewater and liquid wastes in treatment facilities, analyzes the amounts of accumulated sewerage sludge, discusses the composition of sludge, amounts of heavy metals contained in it and its fertilization value. The possibility for accumulated sludge to be used as a soil fertilizer is also discussed in the paper. Considering the studies performed and the normative documents of the environment protection, recommended rates and regime of fertilization with sludge from dairy industry are presented. The agro-technical and qualitative indices of sludge spreaders made at the Institute have been specified on the basis of the environment protection requirements. Keywords: wastewater, treatment efficiency, sludge, pollution load, spreaders, fertilization.
Dr. Albertas Steponavicius, researcher, Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests manure handling processes, their effect on the environment, investigations on wastewater treatment and landfill leachate. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 6 80 20. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 TERRITORIAL ARRANGEMENT AND COUNTRY TOURISM PERSPECTIVES IN THE VISTYTIS REGIONAL PARK Vilma SINKEVICIUTE Summary Functional zones and territorial arrangement of the Vistytis regional park as well as establishment aims and tasks are analysed in the article. Investigation on recreation and tourism organisation is carried out along with country tourism expansion possibilities. The Vistytis regional park was founded in 1992, for survival of Suvalkai mountain chain landscape, its ecosystem and cultural heritage. The park area covers 10,1 thousand ha. Questionnaires on the country tourism business were delivered among country people. The questionnaires included the following items: country tourism evaluation, possibilities to run country tourism business, possibilities to rearrange a farmstead for visitors. In order to achieve optimal results in the Vistytis regional park, it is necessary to accomplish strategic targets and recomendations, conduct educational and cultural activities, popularize natural and cultural heritage and its protection, propagate park-related ideas among the population, take care of publishing material dealing with park issues. About 50 % of elderly people live in the Vistytis regional park. They have no good enough living conditions, they do not trust strangers these are the main reasons for their refusal to run the country tourism business. In the majority of farmsteads there is enough space, but most farmsteads cannot be used for country tourism because of low technical conditions of buildings. Keywords: environment protection, country tourism, recreation.
Master Vilma Sinkeviciute, student for doctors degree, Landscape Management Departmentat, Lithuanian University of Agriculture. Research interests environment design, land use. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Lithuania. Phone: +370 37 75 23 72; fax: +370 37 75 23 92. E-mail: visin@one.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE DEPENDENCE OF MINERAL NITROGEN METABOLISM ON AGROECOSYSTEM PRODUCTIVITY AND RELATED FACTORS Ramute AKSOMAITIENE*, Saulius GUZYS, Zita PETROKIENE Summary The paper gives summarised results of the studies on mineral nitrogen migration under the conditions of agroecosystems of different biological productivity. The investigations were carried out in a study object of Water Management Institute of LUA, situated at Lipliunai village (Kedainiai district) in the Middle Lowland of Lithuania in 1997-2002. Soils prevailing in the study object are Endocalcari Endohypogleyic sandy loam cambisols (CMg-n-w-can). Row crop rotation was of the highest productivity. Mineral nitrogen content in soil was distinguished by a rather large variation in space and time and was predetermined by most natural and anthropogenic factors. No relation between drainage runoff and the intensity of agricultural activity was determined. However, the drainage runoff mostly depended on meteorological and as soil hydrological conditions. Mineral nitrogen concentration in drainage water and its leaching due to crop biological productivity and applied nitrogen fertilizers were changing in y=a-bx+cx2 regularities. The least losses of mineral nitrogen were observed when N balance was negative or neutral. Keywords: mineral nitrogen, crop rotations, drainage, runoff, concentration, leaching, balance.
*contact person Dr. Ramute Aksomaitiene, senior researcher, Head of Chemical Analysis Laboratory, Water Managemant Institute of Lithuanian University of Agriculture. Research interests investigations on plant nutrient migration and balance in basins of streams and drainage systems, water protection. Address: Parko 6, LT-5048, Vilainiai, Kedainiai district, Lithuania. Phone: +370 347 6 80 00. E-mail: chal@water.omnitel.net. Dr. Saulius Guzys, senior researcher, Chemical Analysis Laboratory, Water Managemant Institute of Lithuanian University of Agriculture. Research interests agrochemistry, agroecology, agricultural hydrlogy. Zita Petrokiene, junior researcher, Chemical Analysis Laboratory, Water Managemant Institute of Lithuanian University of Agriculture. Research interests investigations on plant nutrient migration and balance, water protection. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 NITROGEN REMOVAL EFFICIENCY IN CONSTRUCTED WETLANDS OF HORIZONTAL SUBSURFACE FLOW Valerijus GASIUNAS Summary Constructed wetlands (CW) of horizontal subsurface flow have been arranged in Lithuania recently. They ensure the efficient removal of nutrients as well as organic matter. The paper analyzes N-removal efficiency considering the load of filters. Higher initial N concentrations contained in wastewater predetermine better average total N removal efficiency in constructed wetlands of horizontal subsurface flow. When initial total N concentration increases from 20 to 60 mg/l, wastewater treatment efficiency changes from 35.1 to 45.3 %. In filter-treated wastewater total N amount contains 65-75% of mineral N, 0.1% of nitrite N and 3.0% of nitrate N. Higher total N concentrations contained in water effluent predetermine higher ammonia N amounts, too. When total N concentration changes from 10 to 40 mg/l in water effluent, ammonia N concentration increases from 51.5 to 81.0%. Wastewater treatment efficiency much depends on N load for one unit of filter area. To achieve total N amount of 15 mg/l in treated wastewater (requirements for wastewater treatment facilities with the output of >10000 PE), the calculated total N load of filters of horizontal flow should not exceed 0.75 g/m2/day. Keywords: wastewater treatment, constructed wetlands, nitrogen.
Dr. Valerijus Gasiunas, senior researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests natural methods of wastewater treatment. Address: Parko 6, Vilainiai, LT-5048 Kedainiai, Lithuania. Phone: +370 347 6 80 21. E-mail v.gasiunas@water.omnitel.net. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE INVESTIGATIONS ON THE STATE OF NaturalizED DRAINAGE CHANNELS Ana Dolgopoloviene, Narimantas Titas ZDANKUS* Summary Due to the peculiarities of climate, hydro-geologic and topographic conditions, the largest part of Lithuanian territory suffers from excess water. This factor induced the draining of agricultural lands which was started in Lithuania hundred years ago and is still going on. Currently, there are 65 thousand km of channels, the largest part of which (about 60%) is damaged by naturalization. The process is going on with increasing intensity due to the limited financial support for service and maintenance of land reclamation systems. We have carried out questionnaire on land reclamation service departments, which resulted in the collection of data about typical damages of the channels. As the questionnaire results show, the abnormal growth of grass is observed in 20% to 35% of channels (see Fig.1), the depth of channels reduced due to the sedimentation is determined in 10% to 30% of channels (see Fig.2), bushes appear in 10% to 25% of channels (see Fig.3), washout of slopes and toe is observed in 5% to 20% of channels (see Fig.4), bottom damages caused by scour are observed in 5% to 25% of channels (see Fig.5). The data was used to make up a map of isolines of index K determining channel state (see Fig.6), which was calculated from the above mentioned typical damages (in percent). The collected information allows us to state that naturalization processes occur in about 60% of channels. A decision should be made about the necessity to stop the naturalization processes and to repair the channels. Keywords: channel, naturalization, deformation.
*contact person Ana Dolgopoloviene, doctorate student, Vilnius Gediminas Technical University. Research interests environmental enginering and landscape management. Habil dr. Narimantas Titas Zdankus, professor of Liquids Mechanics Department, Vilnius Gediminas Technical University. Research interests mechanics of liquids, dynamics of open riverbeds and ground water. Address: Sauletekio 11, Vilnius, Lithuania. Phone: +370 5 2 74 47 15. E-mail: hk@ap.vtu.lt. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 EFFECTS OF THE CONTROL DRAINAGE ON SOIL WATER REGIME AND NUTRIENT LEACHINNG Edmundas RAMOSKA*, Vytautas MORKUNAS Summary In this paper possibilities for the regulation of drainage runoff are analysed trying to make the most efficient use of water resources and to reduce pollution of the environment. The aim of the researches was to establish the efficiency of affluent applied in drainage systems, at the same time solving the problems of relief, soil properties and moisture regime regulation. The investigations were carried out in control and conventional drainage systems arranged in Endocalcari-Endohypogleyic Cambisols and Hapli-Epihypogleyic Luvisols in sandy-loam and loam soils in the Middle Lowland of Lithuania. On the basis of the data obtained within a 3-year study period it was determined that at the beginning of plant vegetation the retained runoff accumulates in drainpipes through which it penetrates into the soil and makes up a water irrigation fringe. Having dammed up the drainage in spring, water was retained there for the period of 30-50 days. Factors predetermining the water head include microrelief. At the beginning of spring the affluent is predetermined by the position of soil water level in between drains as well as by land use and climatic conditions. The damming process may start a month earlier in the areas where winter crops are grown to compare with the areas covered with summer crops. In spring, when the highest water level had abated down to a 70-cm depth, the drainage head made no influence on water level between two adjacent drains. Early long-term drainage head in spring resulted in a higher water level between drains. At the period of plant vegetation, having ponded the drainage during drought, water reserves of the soil increased by 16 mm on the average. Runoff modelling limits the leaching of nutrients by drains. The retained amounts of nutrients in 1 ha within a 6-9-month period were as follows: carbonates 26 kg, bicarbonates 160 kg, potassium 0.5 kg, nitrate nitrogen and total nitrogen 2.8-4.0 kg. The concentration of nutrients in drainage water of studied variants was not successive; higher N-NH4 concentration was observed in water of control drainage. Keywords: control drainage, head, run-off, leaching of nutrients.
*contact person Dr. Edmundas Ramoska, senior researcher, Hydromelioration Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, water regime regulation in mineral soils. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone +370 347 6 80 08. E-mail: e.ramoska@takas.lt. Dr. Vytautas Morkunas, Deputy Director for Science, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, land draining. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 SEEPAGE FLOW THROUGH THE SEALS IN JOINTS OF HYDROTECHNICAL RETAINING WALLS Ceslovas Ramonas Summary In hydrotechnical retaining walls the sealed temperature, deformation or temperature-deformation joints are provided at distances of 20-30 m. The characteristics of sealing material such as elasticity and others decrease in the course of time. Fissures may appear due to different deformations of individual sections of a retaining wall; leakage may start and a specific seepage flow may form up in the soil around the fissure. The paper deals with the theoretical and experimental analysis of the above-mentioned seepage. Possibilities and procedures of numerical mathematical modelling of such seepage are described. Modelling of 23 variants of the seepage assessing the leakage rate of the fissure, the height of the wall and its distance to levee drainage line was carried out. Modelling results show the maximum heights of seepage water level at the fissure, the seepage flow widths and lengths in the levee body. Keywords: seepage flow, retaining wall, mathematical modeling of seepage.
Dr. habil. Ceslovas Ramonas, professor, Department of Building Constructions, Lithuanian University of Agriculture. Research interests hydraulic engineering, planned and profile seepage. Address: Universiteto 10, Akademija, LT-4324 Kaunas district, Lithuania. Phone: +370 37 75 23 22. E-mail: sk@nora.lzua.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 APPLICATION OF GIS FOR THE DETECTION OF AREAS SUSCEPTIBLE TO AGRICULTURAL ACTIVITY Giedrius BALEVICIUS Summary The article describes the development of digital maps used for the detection of areas susceptible to agricultural activity. The maps were created on the basis of Lithuanian satellite image data base (1:50000), land cadastre map (1:50000) and Lithuanian ecogeological map (1:20000). The model was created using GIS modeling tools and ArcView software. This methodology is helpful when detecting territories susceptible to human activity. Special land management activities are to be developed in those areas in order to decrease land use intensity and susceptibility to antropogenical effects. Keywords: susceptible areas, GIS, digital maps, ArcView, modeling.
Giedrius Balevicius, engineer, doctorate student, Land Reclamation Departament, Lithuanian University of Agriculture. Research interests planning of agricultural territories, the polyfunctional use of agrolandscape. Address: Universiteto 10, LT-4324 Akademija, Kaunas district, Lithuania. Phone: +370 37 73 23 72. E-mail: balevicius@mail.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 ESTIMATION OF THE POSSIBILITIES OF GROUNDWATER SEEPAGE MODELING SOFTWARE IN LITHUANIA Zydrunas VYCIUS Summary This article aims to introduce software for groundwater seepage modeling, to explore its potential and applicability in Lithuania. It also examines specifications required for the formation of the digital model, calculation process and representation of the results. Programs developed in foreign countries were analysed using their description, demo versions as well as comments of developers. Presented programs are powerful and widely applicable. Groundwater seepage around, under or through structures and systems is one of the most important natural occurrences that influences their durability and operational conditions. A contemporary approach to the calculations of groundwater seepage requires utilization of digital computing methods that represents mathematical characteristics used to explain the system or phenomenon of a research. Computer-aided calculations of groundwater seepage are based on the derivation methods of digital differential equations that describe mathematic model of groundwater movement. These methods can be divided into two groups: finite elements and finite differences. The majority of computing programs (MIKE SHE, MODFLOW, PLAFI) use finite difference method which is simplier to apply. Finite element method is used by such programs as FEFLOW and GEO-SLOPE. This method is more complicated, however it is considered to be more precise. The article concludes that PLAFI groundwater seepage modeling program is most acceptable to be used under the conditions of Lithuania (the program was developed in Lithuania). Keywords: groundwater seepage, digital model, digital software.
Zydrunas Vycius, doctorate student, Building Constructions Department, Lithuanian University of Agrculture. Research interests development and optimization of groundwater seepage mathematical modeling process. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Kaunas district, Lithuania. Phone: +370 37 39 77 22. E-mail: vzydrius@bamba.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE INVESTIGATIONS ON THE EFFECTS OF GRASS COVER ON THE HYDRAULIC CONDUCTIVITY OF DRAINAGE CHANNELS Vaclovas POSKUS Summary The studies were carried out in two control profiles of the excavated Graisupis ditch, situated at the of 2.4 and 4.8 km from the outlet in the land of intensive farming in Kedainiai district. The study object contained mineral loam/sandy-loam soils on the flat relief. The areas of catchments in control profiles were 12.1 and 5.9 km2, the largest discharges of spring floods were 3.4 and 1.6 m3/s. Cross-sectional parameters, grass characteristics and flow parameters were measured under the conditions of different discharges (6 replications in each control profile during the vegetation period and 4 replications in spring when the channel bed is clean). As the study results show, roughness coefficient of the grass-covered channel bed increased up to 21 time, water tables were observed to be 20-40 cm higher, the outlets of the drainage were flooded up. Considering the average grass indices determined in control profiles, grass hydraulic resistance was calculated according to 4 formulas based on the scheme when grass cover resistance is estimated as the total resistance of separate obstructions. The difference of 27.3 % between calculated results and natural measurements was determined. The formula estimating grass cover parameters as well as flow regime was determined to be most suitable. Keywords: bed, overgrowth, roughness, coefficient of hydraulic resistance, average velocity.
Vaclovas Poskus, junior researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests natural processes in drainage channels. Adress: Parko 6, Vilainiai, LT-5030 Kedainiai, Lithuania. Phone: +370 347 6 81 09. E-mail: pvaclovas@delfi.lt. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE INVESTIGATIONS ON DRAINAGE MAINTENANCE ECONOMICAL EFFICIENCY Virgilijus BUOZIS Summary Currently, the amount of drainage maintenance works is increasing in Lithuania, however the financing of the repair works is decreasing. Therefore scarce funds allocated for drainage repair works are to be used efficiently and their usage should have an economical background in each object. In EU countries, the funds for drainage maintenance works are approved considering the profit of drainage operation expenses on farms. To determine the economical efficiency (profit) of drainage maintenance works, the studies were carried out under the conditions of Middle Lithuania. Drainage maintenance economical efficiency was determined on the basis of economical efficiency coefficient of expenses on repair works, i.e. the relationship between the profit and expenses of repair works. The article gives the results of the studies carried out in districts of Middle Lithuania (Kedainiai, Joniskis, Siauliai, Sakiai, Marijampole) in 1999-2001. The studies included the evaluation of economical efficiency of drainage repair works. On the basis of the study results, average values of drainage maintenance efficiency indices were determined: profit of land users gained from drainage maintenance works, expenses on drainage repair works and their economical efficiency on crop-cultivating farms. In the Middle Lithuania the profit from maintenance works makes up from 491 to 1124 Lt/ha (the average 770 Lt/ha), expenses on repair works make up 1490 to 3909 Lt/ha (the average 1565 Lt/ha), efficiency coefficient of expenses on repair works is 0.23 to 0.38 Lt/ha (the average 0.31 Lt/ha). The efficiency coefficient of the expenses on drainage maintenance works shows the economical profit of drainage maintenance project to a user of drained land and contributes to the determination of the succession of drainage repair works. The analysis of the data of natural studies carried out on crop-cultivating farms in Kedainiai district shows that the principle factors affecting the economical efficiency of drainage maintenance works include the area of drainage maintenance works, the productivity of cultivated crops in the area and the amount of total expenses on drainage repair works. A significant connection was determined among those indices. On the basis of the dependences determined, a graph was made up. The graph helps to determine the economical efficiency of expenses on drainage repair works in a separate object considering the productivity of cultivated crops and expenses on repair works. Keywords: drainage maintenance, economical efficiency, drainage operation conditions.
Virgilijus Buozis, junior researcher, Drainage Maintenance Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests operation of drainage systems, drainage functioning reliability and its economical efficiency. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 651 7 59 51. E-mail: pupii@one.lt. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE CHANGE IN NITRATE NITROGEN LEACHING OF SOILS IN THE KARST ZONE OF MIDDLE LITHUANIA Stefanija Miseviciene*, Aurelija Rudzianskaite Summary The paper specifies the data on drainage runoff and nitrate nitrogen leaching in light loam and sandy loam soils (Birzai district in Northern Lithuania and Kedainiai district in Central Lithuania, respectively). The studies were carried out in the period of 1999-2001. The study included the evaluation of the extent and peculiarities of nitrate nitrogen leaching by drainage in agricultural land areas under different agro-climatic conditions. As the study results show, larger precipitation amount and lower air temperatures were determined in Northern Lithuania, which resulted in a 16-17% higher runoff here (in studied soils) compared to Central Lithuania. As it was determined, in soils under investigation nitrate nitrogen concentrations decreased due to cultivated crops: perennial grass predetermined 2.5-3.5 times less nitrate nitrogen concentrations compared to those contained in arable land. Due to similar texture of soils the differences of nitrate nitrogen leaching in the study areas were insignificant: in Pakamponys object (Birzai district) 5.3 kg/ha of nitrate nitrogen were leached from land area where perennial grass was grown, 20 kg/ha of the element were leached from arable land; in Juodkiskis object (Kedainiai district) leached nitrate nitrogen amounts were 9 and 18 kg/ha respectively. Keywords: drainage runoff, nitrate nitrogen concentration, leaching.
*contact person Dr. Stefanija Miseviciene, researcher, Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests ecology and environmental engineering, the impact of the handling and usage of slurry on the environment, researches on the transformation processes of pollutants. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 68021. E-mail: s.miseviciene@takas.lt. Dr. Aurelija Rudzianskaite, researcher, Hydromelioration Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, researches on drainage and ground water regime and pollution. Received 10 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 PECULIARITIES OF THE RUNOFF OF STREAMS IN THE REGION OF DRAINED KARST SOILS Povilas SUKYS*, Alvyda SAULIENE Summary The paper analyses the formation and seasonal distribution of runoff of two small streams the sources of which are located in drained karst soils of different genetic origin. As the study results show, the size of the stream watershed area to its source is affected by soil characteristics and surface gradient. The source of the streams under investigation is a drainage runoff from 100 ha of glacial-lacustrive clay soils (average surface gradient 0.2-0.3%) and 30 ha of moraine and sandy loam soils (average surface gradient 0.5-1.5%). Fluctuations of drainage runoff (the source of the stream) affected the runoff of the streams in about 85% of glacial-lacustrive soils (water measurement post located at the distance of 0.5 km below the effluent) and in about 75% of moraine soils (water measurement post located at the distance of 1.8 km below the effluent). Keywords: watershed of stream effluent, drainage runoff, stream runoff.
*contact person Dr. Povilas Sukys, head of Hydromelioration Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, interrelations between soil moisture, ground water regime and the pollution. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 6 80 08. E-mail: lygis@water.omnitel.net. Alvyda Sauliene, junior researcher, Hydromelioration Laboratory Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, drainage runoff in karst soils. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 P-REMOVAL FROM WASTEWATER IN A LABORATORY MODEL BASED ON THE FILTRATION THROUGH MINERAL MEDIA Zenonas STRUSEVICIUS*, Sigita Marija STRUSEVICIENE Summary In the process of biological wastewater treatment P-removal is efficient enough when the concentration of organic pollutants (according to BOD5) is no higher than 190 mg/l and its ratio with phosphorus does not exceed 20. Having studied the composition of wastewater from dairy farms, wastewater pollution load according to BOD5 was determined to be 800 to 900, the ratio BOD5 / Ptotal was 30-36. After the biological treatment of wastewater from dairy farms with high initial pollution and insufficient ratio of BOD5 / Ptotal, phosphorus concentration in pre-treated wastewater reached 12.6 mg/l (Strusevicius, Struseviciene, 2003). Currently, a large variety of natural and artificial dry mineral substances are being imported in Lithuania. Considering the composition of the substances, they might be used as filter media for P-absorption. The article gives the results of the tests on P-removal from wastewater carried out in a laboratory model. During the investigations wastewater was flowing via mineral filters (filtralite-P (FLP), zeolite (CE), shulgite (SG)). Total amount of Ca, Fe and Al oxides contained in those filters were 23.0, 16.1 and 7.9% respectively. The rates of P-removal from wastewater in the filters were as follows: 88.5% (FLP), 45.5% (CE) and 96.3 (SG). Considering different hydraulic load, P-mass balance was calculated. The calculation results showed the following P adsorption amounts: FLP 5.08 g/day, CE 1.76 g/day, SG 3.91 g/day (calculated for 1 m3 of each filter). Wastewater filtration through mineral media resulted in the removal of other pollutants, too: organic pollutants removal (according to BOD5) was 30.8 to 72.5%, the removal of nitrogen compounds (more than 90% of which were in the form of ammonium salts) was even 93.2% in CE filter. Nitrogen removal in filters with other mineral media was not significant. Keywords: phosphorus, wastewater, adsorption, filters.
*contact person Dr. Zenonas Strusevicius, head of Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests ecology and landscape studies, handling of wastes, wastewater and manure, the effect of the process on the environment, investigations on pollutants transformation processes. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 68020. E-mail: zenonas@water.omnitel.net. Dr. Sigita Marija Struseviciene, researcher, Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests ecology and landscape studies, handling of wastes, wastewater and manure, the effect of the process on the environment. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 MIGRATION OF SULPHUR IN LIMED SOILS OF WESTERN LITHUANIA Saulius GUZYS Summary This paper presents the summarised results of investigations on sulphur migration and balance investigations carried out in the Minija-Skinija basin in Western Lithuania. The study object contained Bathihypogleyi-Albic Luvisols (LVa-gld-w) sandy loam, which has formed on loam soils under the conditions of organic and intensive cropping systems. The studies were performed in the period of 1994-1998. Soil liming as a means of chemical soil melioration neutralizes soil acidity and changes sulphureous regime in soil. The amount of mobile sulphur in soil is reduced even 7-8 times. This process is more evident under the conditions of intensive cropping system. Cropping intensity had no influence on the concentration of Ca2+ and total mineral content in drainage and ground water. The concentration of sulphates in soil water depends on soil acidity, sulphureous and microbiological activities of soil as well as cropping intensity. Drainage water is more susceptible to natural and anthropogenic changes in the functions of the ecosystem in comparison with ground water. The amount of SO42- leached by drainage water is mostly predetermined by drainage runoff and concentrations of those compounds in water. Smaller amounts of sulphates (18%) were leached under the conditions of intensive cropping system in comparison with the organic one. Neither organic nor intensive cropping system ensured the positive sulphur balance. In order to avoid S deficiency as a factor limiting crop productivity and to ensure the positive balance of sulphur in agroecosystems, additional usage of sulphur fertilizers is a necessary condition for rational farming. Keywords: sulphur, organic cropping system, intensive cropping system, soil, liming, drainage water, ground water, leaching, balance.
Dr. Saulius Guzys, senior researcher, Chemical Analysis Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests agrochemistry, agroecology, agricultural hydrology. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 6 80 00, e-mail: chal@water.omnitel.net. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 PHOSPHORUS MIGRATION IN BEAVER-OBSTRUCTED DRAINAGE CHANNELS Romanas LAMSODIS Summary The study was conducted to quantify the changes in phosphorus migration when water flows via the beaver impounded stretches of drainage channels in Lithuania in 1999-2003. To detect the changes, phosphorus concentrations were observed in the following cross-sections (spots) of channels: in a channel upstream the beaver-site (I); in a downstream beaver-site pond near the dam (II); in a channel downstream the beaver-site (III). To characterize the geo-chemical conditions of the migration, pH index, dissolved oxygen and BOD7 in the same channel cross-sections were determined (Table 2, Fig. 2). The study results were as follows: beaver impoundments were considered as geo-chemical barriers to stop the phosphorus migration (Fig. 3 and 6, Table 3); the plausible decrease in PO4-P run-off from beaver-obstructed catchments might range within 16-38 kg km-2 yr-1 (calculated in accordance with data of Tables 1 and 3); due to organic matter accumulation in beaver-sites, a slight increase in Porg concentrations in the ponds (Fig. 5, Table 3) and in Porg run-off downstream (c. 1-3 kg km-2 yr-1) was observed. Keywords: drainage chanel, beaver, phosphorus, concentrations, phosphorus run-off.
Dr. Romanas Lamsodis, senior researcher, Drainage Maintenance Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests function ability of drainage channels; channel and the environment; biodiversity in agrolandscape. Address: Parko 6, Vilainiai, LT-5048 Kėdainiai district, Lithuania. Phone: +370 347 6 81 09. E-mail: lammor@delfi.lt. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 ECOLOGICAL ASPECTS OF SLURRY APPLICATION Simanas ASKINIS*, Stefanija MISEVICIENE Summary The paper analyses the process of slurry application from ecological point of view. Under the conditions of intensive farming large rates of fertilizers are applied seeking to obtain the highest possible crop productivity. This contributes much to the pollution of drainage water, ground water and ambient air. It is impossible to avoid completely the pollution of the environment, however it is to be reduced by al possible means. Once slurry is spread on the ground, it should be immediately ploughed up in order to avoid undesirable nitrogen evaporation (during a 1-hour period between slurry application and soil tillage evaporated N amount is 1%, during a 12-hour period evaporated N amount makes up even 13%). To reduce nutrient leaching into the environment and to ensure a better nutrient usage, the studies performed with the aim to determine an optimal time for slurry application. The analysis of nutrient leaching was made considering the time of the year when slurry was applied. As the study results show, leached NPK amounts were less in the variant where slurry was applied in spring to compare with the variant where slurry was applied in autumn. In fields with drain spacing of 20 m and slurry applied in autumn the leached amounts of nitrogen, phosphorus and potassium were 11.8%, 0.4% and 1.1% respectively from total input of those elements. In fields where slurry was applied in spring leached NPK amounts were 9.9%, 0.2% and 1.1% respectively. In variant where slurry was applied in autumn and spring (0.5 rate in both seasons) leached nitrogen amount was 9.1% less than in variant 1 and 10% larger than in variant 2; leached phosphorus amount was 0.25% from total P input, i.e. 30% less than in variant where slurry was applied in autumn and 12% more than in variant where slurry was applied in spring. The differences of leached potassium amounts were insignificant among variants. NPK concentrations in drainage water of all test variants differed insignificantly, however the lowest NPK concentrations were observed in the variant where slurry was applied in spring. The application of slurry rarely predetermines higher nutrient amounts contained in ground water than their maximum allowable rates. However nutrient concentrations are tend to increase. Ammonia nitrogen (N-NH4+) concentration was fluctuating within the range of 0.2 to 1.1 mg/l during the study period, subject to fertilization rate, though background values seldom exceeded 0.2 mg/l. Ammonia nitrogen amount contained in ground water was mostly influenced by mineralization and ammonification processes occurring in ploughed up vegetative residues, when organic N was changed into mineral N and further leached into deeper soil layers by intensive rainfall. Maximum nitrate nitrogen concentration in drainage water was 5.6 mg/l. Phosphate (P-PO4) amounts contained in ground water were insignificant and did not exceed 0.18 mg/l. Potassium (K+) concentration in ground water was fluctuating within the range of 1.5 to 4.6 mg/l and reached its peak at the beginning of summer every year. As the study results show, a more intensive ground water pollution is observed in dry periods of the year when ground water level is lower. During the study period samples of ground water were taken in a borehole arranged in the experimental field. The ground water quality was good and corresponded to the sanitary regulations for potable water (in 84% of all samples the quality of water was very good, in 3% of samples it was satisfactory). Keywords: slurry, pollution of the environment, ground water, drainage water.
*contact person Dr. Simanas Askinis, senior scientific worker of Water Treatment Laboratory at the Water Management Institute of Lituanian University of Agriculture. Research interesest ecology and environmental studies, handling of wastewater and manure and the effect of the process on the environment, investigations on pollutants transformation processes. Addess: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 347 6 80 20. E-mail: s.askinis@delfi.lt. Dr. Stefanija Miseviciene, scientific worker of Water Treatment Laboratory at the Water Management Institute of Lituanian University of Agriculture. Research interesest ecology and environmental studies, handling of manure and the effect of the process on the environment, investigations on pollutants transformation processes. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 ADAPTATION OF annAGNPS model for the modelling of runoff charakteristics UNDER the conditions OF middle lihuania Henrikas PAULIUKEVICIUS Summary In Lithuania AGNPS model is applied for the modelling of nutrient runoff and concentrations. Currently, a new version of the model AnnAGNPS for annual runoff modelling is being developed. The accuracy of the modelling of nutrient regime depends on the accuracy of runoff evaluation. The paper analyses the results of the modelling of runoff of two small basins situated in the Middle Lithuania. Models of the Viksrupis (the Susve, the Nevezis, basin area 30,4 km2) and the Kraujupis (the Nevezis, basin area 1,75 km2) have been created. On the basis of the data of the Kraujupis basin, the analysis of runoff susceptibility to data parameters has been carried out. The runoff is mostly affected by the index of runoff curve numbers and soil moisture. When collecting and processing the data on modelled basins most attention should be focused on the analysis of land use and soil characteristics. The modelling of runoff characteristics of the period 1998-1999 has been performed. Determination coefficient of the connection between measured and modelled peak discharges was 0.4-0.65. Modelled peak discharges 1.3-1.6 times exceeded the measured ones. In 1998, modelled annual runoff exceeded the measured one, while in 1999 it was lower than the measured runoff. Keywords: modelling, runoff, peak discharge.
Dr. Henrikas Pauliukevicius, senior researcher, Modeling and Informatics Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, hydrology, geography, water pollution. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. Phone: +370 615 3 05 49. E-mail: henpaul@delfi.lt. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 ANNUAL CHANGE IN AMMONIUM NITROGEN CONCENTRATIONS IN THE RIVER SUSVE Laima BERANKIENE*, Albertas NARVIDAS Summary The paper analyses annual change in ammonium nitrogen concentrations in the lower reaches of the river Susve in 1992-2002. According to the pollution level, the river is clean here: ammonium nitrogen concentration exceeded maximum allowable concentration (MAC) only in 7 cases out of 132. The highest ammonium nitrogen concentration was measured to be 0.80 mgN/l. Its annual change was affected neither by the season of the year nor meteorological conditions and water discharge in the river. Considering the pollution level, two periods of pollution were distinguished: intensive (1992-1997) and non-intensive (1998-2002). In the first period the average annual concentration of ammonium nitrogen reached 0.294 mgN/l; in the second period it was 0.052 mgN/l. In the study period (1992-2002) the average leached amounts of ammonium nitrogen were 32.7 t/year or 2.8 t/month in the Susve basin. The largest amounts of nitrogen were leached in 1994 (82.5 t/year), the smallest amounts were leached in 2000 (2.6 t/year). When comparing the periods of intensive and non-intensive pollution, the second period showed 3.4 times less ammonium nitrogen load. Ammonium nitrogen load is strongly influenced by the season of the year: larger nitrogen amounts are leached in March and April (41.8%), smaller amounts are leached in July, August and September (4.3% of total annual amount). Annual changes in ammonium nitrogen amount in the river water are observed in dry years as well as in years abundant in water. The dependence of ammonium nitrogen load on the river discharge was obtained as follows: in the period of intensive pollution R2 = 0.81, in the period of non-intensive pollution R2 = 0.68. Keywords: ammonium nitrogen, concentration, load, annual change.
*contact person Dr. Laima Berankiene, senior researcher, Modelling and Informatics Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering and landscape management, hydrology, pollution of rivers. Address: Parko 6, Vilainiai, LT-5048 Kedainiai district, Lithuania. E-mail: berankiene@freemail.lt. Albertas Narvidas, junior researcher, Modelling and Informatics Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests environmental engineering. Received 11 2003.
ISSN 1392-2335 Transactions of Lithuanian University of Agriculture and Water Management Institute of Lithuanian University of Agriculture, 23(43)-24(44), 2003 THE ANALISIS OF REGULATED STREAM CHANNELS IN THE SESUPE RIVER BASIN Raimundas BAUBLYS Summary Changes in the length of streams and their basin areas in the Sesupe basin induced by the period of intensive land reclamation were estimatated on the basis of the analysis of hydrographic network of the basin. Stream network changes were studied having compared new data about countrys hydrography with the data of Lithuanian Rivers Cadastre of 1959. The relation between total and regulated length of the streams and its reliability was evaluated on the basis of mathematical statistical methods. Stream channels of the Sesupe basin were grouped on the basis of regulation results. The streams of the Sesupe basin got shorter by 5.4 km (10.8%) on the average. The areas of their basins changed by 3.75 km2 (1.2%). Regulated channels of streams comprise on the average 69.3% of total length of streams in the Sesupe basin. The biggest part of stream network in the Sesupe basin comprises streams with a regulated interval shorter than 3 km. The paper discusses the possibilities to use the obtained study results for the renaturalization of regulated streams and the analysis of ecological, environment protection and landscape management problems. Keywords: stream network, regulated streams, renaturalization.
Raimundas Baublys, doctorate student, Lithuanian University of Agriculture. Research interests environmental engineering. Address: Universiteto 10, LT-4324 Kaunas-Akademija, Lithuania. Phone: +370 37 39 77 07. E-mail: raimisba@yahoo.com. Received 11 2003. |
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