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CONTENTS
ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 5–15 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture MINERAL NITROGEN CYCLES IN AGROECOSYSTEM UNDER THE INFLUENCE OF DIFFERENT INTENSITY CROPPING SYSTEMS Saulius Gužys*, Zita Pertrokienė The investigations were carried out in the LAU, WM institute land plots in the Endocalcari Endohypogleyic Cambisol (CMg-n-w-can)The basis of the experiment is 3 variants (3 drainage systems) field trial. Every variants characterizes of individual cropping system with typical on one complex of agricultural means. Organic cropping system was applied in variant I. In this system applied manure. Don’t applied mineral fertilizers in this variant. II variant is sparing cropping system. In this cropping system used manure and mineral fertilizers as well as pesticides. III variant is intensive cropping system. In this system don’t use manure while used mineral fertilizers and pesticides. Organic cropping system was distinguished by smaller soil nitrogeness while the smaller total field crop productivity was characterizes intensive cropping system. However this cropping system distinguished by higher energetic efficiency (CET – 13). Cropping systems has little influence on nitrogen accumulation in plants. Only in perennial grass and spring wheat (grain) accumulated amount of nitrogen was smallest in organic cropping system, comparing with sparing and intensive ones. By highest nitrogen removal with plant production was in sparing cropping system. By highest drainage runoff was distinguished by organic cropping system. Smaller N-NO3- concentration in drainage water was in the conditions of intensive cropping system. In the conditions of sparing and organic cropping system this concentration increase by 11 % to 21,8 mg l-1. While smaller N-NH4+ concentration in the drainage water was in the conditions of organic cropping system. The leaching of all elements was determined drainage runoff. The organic cropping system with smaller drainage runoff was distinguished and larger leaching of elements by drainage. Cumulative nitrogen balance in all cases was negative. The smaller deficit of one was characterizes by organic cropping system. Keywords: balance, concentration, cropping systems, leaching, nitrogen, yield, yield quality.
*contact person Dr. Saulius Gužys, senior researcher, Water protection department, Water Management Institute of Lithuanian University of Agriculture. Research interests – agrochemistry, agroecology, agricultural hydrology. Address: Parko 6, LT-58102, Vilainiai, Kėdainiai district, Lithuania. Phone: +370 671 06124. E-mail: s.guzys@water.omnitel.net. Zita Petrokienė, junior researcher, Water protection department, Water Management Institute of Lithuanian University of Agriculture. Research interests – investigations on plant nutrient migration and balance, water protection. Received 06 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 16–25 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture IMPACT OF REDUCED LAND TILLAGE ON SOIL CAPILLARY POTENTIAL AND REDISTRIBUTION OF MOISTURE Giedrius Baigys*, Kazimieras Gaigalis, Ginutis Kutra The article deals with the materials related with the research on forces determining water movement, possessing scientific and practical value in substantiating agrotechnical and reclamation measures to regulate water regime and reduce leaching of nutrients into ground and surface water bodies. The research was carried out in Pikeliai object trial fields (area – 0.76–1.36 ha) drained by separate drainage systems and in the fields of exact experiments in Dotnuva object, Kėdainiai D. The soils of the trial fields are light and medium loams. The content of clay (<0,002 mm) and dust (0,05–0,002 mm) particles, having the greatest impact on the formation of aggregates and ψm, in the arable (0–20 cm) soil layer accounted for 14.3 and 34.8 % in Pikeliai object and 14.0 and 30.4 % in Dotnuva object respectively. The laboratory analysis results of soil in both objects show that it is possible to retain more productive moisture and plants can absorb more of it when applying reduced or zero-tillage systems. By capillary potential investigations carried out outside it was established that water moves from arable (10–20 cm) layer to deeper (30–60 cm) layers in all investigation variants in Pikeliai experimental object in spring and autumn. The exception in spring was only the variant of traditional tillage. In the variant of traditional tillage in Dotnuva object the soil moisture from deeper layers moved towards the soil surface in spring and autumn and only in the end of May there was a streak formed at a depth of 30–40 cm, the moisture from which moved both upwards and downwards. In the variants of reduced tillage and direct drilling the streak formed at a depth of 20–30 cm, from which moisture moved both towards the soil surface and to deeper soil layers during spring soil tillage and sowing periods. The formed transitional water movement zone closer to the soil surface (compared with traditional tillage) has positive influence in providing plants with moisture and improving the absorption of nutrients from surface layers. In autumn, when ground water level increased in all variants the water movement direction was from deeper layers to the surface ones. Environmentally it is relevant as nutrients come to the surface together with water; they are absorbed by perennial grasses, winter crops or catch crops cultivated after harvesting annual plants. Keywords: capillary potential, land tillage, tensometer, water supplies.
*contact person Giedrius Baigys, Junior Researcher, Water Resources Sector, Water Management Institute of the Lithuanian University of Agriculture. Research interests – water protection, variation and improvement measures of soil water regime and hydrophysical characteristics. Address: Mituvos 9, LT-50134 Kaunas, Lithuania. Phone: +370 37 311263, fax: +370 37 331270, e-mail: giebai@kaunas.init.lt. Dr. Kazimieras Gaigalis, the head of Water Resources Sector, Water Management Institute of the Lithuanian University of Agriculture. Research interests – hydrology, monitoring and evaluation of water runoff of small streams. Ginutis Kutra, Senior Researcher, Water Resources Sector, Water Management Institute of Lithuanian University of Agriculture. Research interests – soil and water protection, sustainable agriculture, hydrotechnical constructions of soil protection. Received 06 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 26–31 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture PECULIARITIES OF WATER REGIME REGULATION IN POLDERS IN 1998–2008 Arvydas Povilas MALIŠAUSKAS The article deals with the aspects of the variation water level, in pumped water amount and ground water level in typical polders of the lower reaches of the Nemunas and the Nevėžis basin in 1998–2008. The established indicators are compared with the data of regulating polder water regime during previous (1970–1984 and 1991–1997) periods. Since 1991 the intensity of pump-house activities in polders has decreased compared with the previous period, however, from 1997–1998 on the variation of pumped out water amount has illustrated the tendencies of stability. In winter polders up to 1.5 times of water is pumped out and in summer polders – up to 3–5 times less. During plant vegetation period (May–October) a share of pumped out water amount made 15–23 and 82–86 % of the annual amount respectively. Therefore, the duration of flooding of meadows lower than the average ground surface in summer polders was 3–4 months. In winter polders the ground water level was 0.5–1.4 m during the vegetation period, in summer polders it is rarely lower than 0.5–0.7 m and the arable layer of low-lying meadows most often has moisture surplus. The amount of good grasses is decreasing in the mineral soils of such meadow swards. They are replaced with tall grasses of lower value. Keywords: fluctuation, polder, variation, water level.
Dr. Arvydas Povilas Mališauskas, senior researcher, Water Protection Departament, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, hydraulic engineering and hydrology. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai district, Lithuania. Phone: +370 612 82 980. E-mail: a.malisauskas@water.omnitel.net Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 32–41 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture INFLUENCE OF FERTILIZATION WITH LIQUID MANURE ON POTASSIUM CONCENTRATION IN CAMBISOLS AND LEACHING Stefanija MISEVIČIENĖ The article discusses the results of the research carried out in Juodkiškiai trial field of WMI LUA in 1999–2003. Modernization of large-scale animal husbandry enterprises results in the accumulation of huge amounts of liquid manure and fields are fertilized with this fertilizer while limiting the amount of nutrients in terms of nitrogen. Due to this fact every year different amounts of potassium enter crop rotation fields together with liquid manure depending on its composition. The research was targeted at establishing potassium accumulation and leaching from crop rotation fields fertilized with liquid manure as well as the rates of this element that do not impoverish soil and do not pollute the natural environment as systematic fertilization with manure has influence on potassium regime in soil (increases the amount of soluble and metathesis potassium). Therefore, the influence of fertilization and other indicators on the variation of potassium in soil, the balance of this element and leaching into drains during crop rotation was investigated. To calculate the balance the potassium amounts present in plant residues and drainage water and passed in with precipitation, seeds, fertilizers and taken out with yield (secondary and primary production) were established. When fertilizing with liquid manure potassium balance was negative while growing perennial grasses as much potassium was needed to mature their yield. The investigations established that potassium concentration in drainage water and its leaching was increased by precipitation during the research period and it was reduced by the amount of this element taken out with yield. Soil geochemical environment had influence on the increase of potassium supply in soil. It was established that long-term fertilization with liquid manure increased potassium supply in soil. Environmentally potassium leaching did not cause problems as potassium concentrations in all variants did not exceed MAC. Keywords: leaching, liquid, manure, potassium balance.
Dr. Stefanija Misevičienė, senior scientific researcher, Water Treatment Laboratory, Water Management Institute of Lithuanian University of Agriculture. Research interests – ecology and environmental engineering, effect of slurry handling and usage on the environment, studies of pollutants transformation processes. Address: Parko 6, Vilainiai LT-58102, Kėdainiai district, Lithuania. Phone: +370 347 68021. E-mail: s.miseviciene@takas.lt Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 42–51 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture CHANGES IN RIVER WATER QUALITY DOWNSTREAM FROM THE PIG COMPLEX Zenonas STRUSEVIČIUS, Jurgita KAZAKEVIČIENĖ*, Laimutė Elzė BERANKIENĖ The researches were carried out from 2002–2007 in the upper reaches of the Šušvė River, a Nevėžis tributary, at the JSC Litpirma pig complex near the township of Šiaulėnai. The complex has been operating since 1978 and produces 25 thousand fattening pigs per year, along with an associated 56 thousand m3 organic fertilizers (liquid manure, slurry and solid manure), which are spread on surrounding agricultural fields. Some of these fertilizers find their way into the Šušvė. This article presents the impact of a large pig breeding company on river water quality and quantifies the leaching of nitrogen, phosphorus and potassium (NPK). It is based on water quality research data collected from an 11.6 km section of the Šušvė River, both upstream and downstream of Šiaulėnai, regarding drainage water outflow from the fertilized fields and from Šiaulėnai domestic wastewater. According to its water quality, the Šušvė around Šiaulėnai belongs to a class of little polluted rivers, with the exception of the amount of total nitrogen. The average annual concentration of total nitrogen exceeds the norm by 2.3 times, especially during the cold season (6.66 mg l –1). The highest concentration reaches 11 mg l-1. During the warm season, when nutrients are used for plant growth, the average concentration decreases almost to the norm (2.94 mg l-1). The wastewater from the Šiaulėnai treatment plant, together with 2.16 tons of nitrogen and 0.03 tons of phosphorus, flows into the section of the river under investigation. Drainage water from 728 ha of fields that have been fertilized with organic fertilizers carry an average of 11.4 tons of nitrogen, 0.073 tons of phosphorus and 5.53 tons of potassium. There are two tributaries into this section of the Šušvė which cause the average river discharge to increases by an average 0.55 m3 s-1, affecting substance concentration. According to the data averaged over the 2002–2007 period, the NPK concentration in the Šušvė, 11.6 km downstream from Šiaulėnai, changes insignificantly when compared with the Š1, and, according to the pollution classification, the river remains in the same class as upstream from Šiaulėnai. The average annual concentration of total nitrogen and potassium increases by 0.1–0.2 mg l-1, phosphorus by 0.003 mg l-1, while ammonium nitrogen decreases by 0.01 mg l-1. Changes in NPK quantities carried by this section of the Šušvė were calculated as: total nitrogen increased by an average of 83 tons yr–1 (58 %), potassium by 51 tons yr-1 (54 %) and the smallest increase, for total phosphorus, by 1.2 tons yr-1 (48 %). All of these pollutants leached into the river during the cold season (to 60 % total phosphorus and to 88 % total nitrogen) when there was no vegetative growth. A wet year affects the quantities of leached NPK. There is a dependency between river discharge and the leached NPK quantities, which can be suitably represented by a polynomial equation. Keywords: concentration, fertilization rate, manure, NPK, runoff.
*contact person Dr. Zenonas Strusevičius, the head of Water Treatment Department, Water Management Institute of Lithuanian University of Agriculture. Research interests: ecology and landscape management, the impact of the handling of wastewater and manure on the environment, pollutant transformation processes. Jurgita Kazakevičienė, scientific researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests: ecology and landscape management, the impact of the handling of manure, urine and wastewater on the environment. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai district, Lithuania. E-mail: jkazakeviciene@zebra.lt Dr. Laima Berankienė, senior researcher, Water Protection Department, Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and land management, hydrology and river pollution. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 52–61 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture TECHNICAL STATE OF DRAINAGE SYSTEM AND LAND SUITABILITY FOR INTENSIVE FARMING: CASE STUDY OF THE BRUKŠVOS POLDER Nijolė BASTIENĖ*, Valentinas ŠAULYS, Vaclovas Poškus The article presents the results of a case study “Evaluation of technical state of Brukšvos polder in Klaipėda district and preparation of recommendations regarding suitability of polder for agricultural production development”. The data on the state of Brukšvos polder hydro-system (pump station, dikes, ditches, subsurface drainage, local roads) is being analysed. The suitability of Brukšvos polder for the development of intensive agriculture was assessed on the basis of meteorological conditions, characteristics of soil and the state of land reclamation structures. It was established that the polder is suitable in all respects to be used for the development of potato seed breeding; however, technical state of drainage system is not sufficient in terms of reliable cultivation. On the basis of the research material collected certain actions were envisaged in order to turn the polder into a modern drainage system with automatic water regime control. Keywords: farming activities, land reclamation structures, polders, state.
*contact person Dr. Nijolė Bastienė, senior researcher, Hydromelioration Department, Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and landscape management, drainage system reliability and maintenance efficiency. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai distr., Lithuania. Phone: +370 6 81 09. E-mail: vegelyte@delfi.lt Dr. Valentinas Šaulys, professor of Hydraulics Department, Vilnius Gediminas Technical University. Research interests – environmental engineering and landscape management, investigation of the usage and maintenance of land reclamation equipment. Vaclovas Poškus, junior researcher, Hydromelioration Department, Water Management Institute of the Lithuanian University of Agriculture. Research interests – environmental engineering and natural processes in drainage channels. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 62–66 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture PERMEABILITY OF HORIZONTAL FLOW FILTERS DEPENDING ON WASTEWATER LOAD Valerijus GASIŪNAS To ensure that filters of horizontal flow work with appropriate accuracy calculations not only for pollution but also for hydraulic load should be made. Our research was carried out in the wastewater treatment facilities predominantly operating by maximum hydraulic load. The hydraulic design of filters is usually based on Darcy equation. However, the measurements in the beginning of filters’ operation indicated that calculated permeability according to Darcy equation did not match the estimated; i.e. the equation is not suitable for hydraulic calculations of the filters. Measurements revealed that maximum permeability of filters after the beginning of operation by maximum hydraulic load was gradually decreasing and after a year proved to be 4–5 times lower. However, when the regime of filters’ operation was modified to resting beds, i.e. when one filter is being fully operated for one week another out of use for the same time, its permeability recovered by 50–60 % from the initial. After six years biological preparation ‘Septic Gobbler’ and the resting period of one month was put into use to initiate filters’ hydraulic permeability recovery. After the procedure maximum permeability was recovered by 80 % in comparison with the initial. When additional filter was arranged and the operation regime altered to resting beds (namely, when every filter is fully loaded for two weeks and in the recovery phase for another two) the recovered permeability remained permanent in the further use. In wastewater facilities with the output of more than 5 m3 d-1 filters are being constructed in the way that a periodical functioning (min 2 filters or separate parts of a filter) is ensured. Half of the time filters are operating, half of the time they are standing still. Permeability of all filters should be twice as high as calculated wastewater discharge. If recovery cycles of filters operation are applied the processes of pollutants’ removal improve. Keywords: constructed wetlands, horizontal flow, permeability.
Dr. Valerijus Gasiūnas, senior researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests – natural wastewater treatment methods. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai district, Lithuania. E-mail: v.gasiunas@water.omnitel.net. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 67–74 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture MODELING OF SEDIMENT DEPOSITON IN THE LOWER SECTION OF NEMUNAS DELTA Alfonsas RIMKUS Flooded meadows in Nemunas delta are very important for ecology, as they entrap sediments and sediment-bound nitrogen or heavy metals. This process has been investigated in the upper part of delta, existing higher the mouth of Gėgė river. The valley in this part is bright; therefore the main part of the brought sediments is deposited here. The lower part is narrower, but it is flooded more frequently, therefore the significant part of sediments can be deposited there as well. Consequently it was decided to investigate this part also. It was estimated by mathematical-hydraulic modeling that sedimentation here contain about 60 % of its amount in the upper part. Summary sedimentation of both parts reaches about 40 % of all sediments brought to the delta. It was estimated by calculation of sediment deposition in the riverbed, that the large amount of sediments is being deposited in the upper part of delta below the strip, where flood water overflows from the riverbed into the valley, where the water discharge becomes less. The deposited here sediments are washed down. However they cannot be quite brought through all lower part, consequently they are slowly but continually accumulated there. Keywords: mathematical modeling, riverbed process, sediment deposition.
Dr. habil. Alfonsas Rimkus, freelance researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests – hydraulics of hydro structures, riverbed processes. Address: Parko 6, LT-58102 Vilainiai, Kėdainiai district, Lithuania. E-mail: alfonsas.rimkus@hidro.lzuu.lt Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 75–81 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture INFLUNCE OF DEFECTS ON RELIABILITY OF REINFORCED CONCRETE HYDRAULIC STRUCTURES Rytis SKOMINAS When building hydraulic structures in Lithuania, reinforced concrete (which is already 30–50 years old) was used for the construction of main structures. Presently, the technical maintenance and running repairs of CC2 and CC3 consequence class hydraulic structures are carried out only periodically; however, the majority of the CC1 consequence class structures are derelict. The CC1 consequence class hydraulic structures are important for the functioning of various systems and hydro schemes. Therefore, it is important for them to remain secure and reliable. For the achievement of this aim, it is important to determine the variation of construction under the influence of various defects occurring because of the impact of the environment. According literature the most objective state of structure can be estimated by probabilistic method. Depending on this method the random statistical dispersal of material and impact is estimated same as consequence class of structure. In order to evaluate the influence of these defects (concrete deterioration impacted by frost while forming of potholes as well as due to the attrition of the mechanical affect; concrete and steel corrosion) of reinforced concrete constructions upon the safety of structures, two variants of thin-wall, angle retaining wall were chosen for the research. Keywords: defects, reinforced concrete structures, reliability.
Doc. Rytis Skominas, Lecturer, Building Construction Department, Lithuanian University of Agriculture. Research interests – hydroengineering, building materials and constructions. Address: Universiteto 10, LT-53361 Akademija, Kaunas district, Lithuania. Phone:+370 37 75 23 22, e-mail: rytis.skominas@lzuu.lt. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 82–88 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture THE CHANGE OF ORGANIC matter CONCENTRATION IN THE UPPER REACHES OF NEVĖŽIS Aurelija RudzianskaitĖ The pollution of the river water with organic substances deteriorates the chemical, biological and microbiological quality of the water and has a negative effect upon the biological variety of the water environment. The article analyzes the change of organic matter in the upper reaches of the river Nevėžis. The greatest amount of organic substances (according to COD and BOD) got into the river under the influence of concentrated pollution, the fewer amount – under the influence of agricultural pollution and in the course of natural processes. The concentration of organic substances in the river water had a seasonal character: rivers with a better ecological state (the Juosta and the Skroblus) were more polluted with organic matter in spring, and rivers with a worse ecological state (the Nevėžis upstream and lower Panevėžys) – in summer. The water temperature 0.1 to 1.8 °C in rivers researched was higher in the period from 1996 to 2000 than from 1986 to 1989. The temperature arose especially in January, February, March and December. The water temperature arose mostly below the town. The concentration of organic matter (according to COD) was higher when the water temperature was above 10 °C. Keywords: bichromate oxidation, biochemical oxygen demand, organic matter, permanganate oxidation.
Dr. Aurelija Rudzianskaitė, senior researcher of Water Protection Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering, relations between the regime and pollution of surface and subsurface water. Address: Parko 6, Vilainiai LT-58102, Kėdainiai district, Lithuania. E-mail: aurelija@water.omnitel.net. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 89–94 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture THE INFLUENCE OF IRRIGATION REGIME TO SPRUCE (Picea abies (L.)Karst) SEEDLINGS QUALITY INDICATORS Vilda GRYBAUSKIENĖ The exchange of the country’s economic situation and development of the forestry sector has become important for the spruce seedlings irrigation regime, and hence its influence on seedling quality indicators. During its investigation in 2003 spruce seedlings were assessed quality indicators: height, stem diameter and underground mass. At the 2003 growing season precipitation was 302 mm – 64 % probability, the temperature was 1.1 °C higher than the LA. Summary of observations shows that at the optimum moisture conditions during the 1st half of May seedlings increase of height was 1.4 cm, at the late May – 2.7 cm in June – 6 cm, July–August – 6.2 cm in September growth rate is fixed to – 5.5 cm. In the field of natural moisture conditions seedlings increase in the height –3 cm in May, June–August – 5 cm, and in September – 5.2 cm. At the non-irrigated field’s seedling mass was 20 % lower than plants mass growing in optimal moisture conditions. The study found that the correlation between spruce seedling height of the stem and stem diameter is very strong R = 0.803 for optimal moisture field, the natural moisture conditions, this relationship strong R = 0.725. Keywords: irrigation, quality indicators, stem height, stem diameter.
Vilda Grybauskienė, assist.,
Land Reclamation Department, Lithuanian University of Agriculture; lect.,
Geotechnical Engineering Department, Kaunas University of Technology. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 95–102 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture REGRESSION MODEL TO CALCULATE SPRING FLOOD CHARACTERISTICS Henrikas PAULIUKEVIČIUS Runoff characteristics such as average perennial runoff, occasional floods, the smallest runoff, are widely used in planning and management. In the lack of measurement data regression equations are used most often. The article analyses possibilities to calculate the characteristics of the largest runoff (the average peak flow, modulus of flow and 1 % probability discharge) in the ungaged rivers. According to the regression equations, which are made of water gauging stations, data links with basin physical, geographical and climatic characteristics. To make regression equations there was used the data for 25 river basins up to gauging stations and their accuracy was checked according to the data of 12 river basins. Determination coefficients of the regression equations with 9 independent variables are from 0.80 to 0.94. The determination coefficient of the average biggest modulus is the biggest whereas the errors are smallest. The size of relative errors is similar to the research data in the USA. The accuracy of the regression equations, which are used to calculate 1 % probability discharge, is a bit higher than the regional formulas offered to apply in Lithuania at present. Keywords: basin, regression equation, runoff.
Dr. Henrikas Pauliukevičius, senior researcher, Water Protection Department, Water Management Institute of Lithuanian University of Agriculture. Research interests – environmental engineering and land management, geography and hydrology. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai, Lithuania. E-mail: h.pauliukevicius@takas.lt. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 103–109 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture The investigation of HPP turbines switch impact in river lower reaches Saulius VAIKASAS*, Vaclovas POŠKUS The investigation of a hydropower plant (HPP) operating on the environment, first at all in downstream reaches is analysed in the paper. The impact on habitat quality changes can be estimated by the ecohydraulic parameters such as velocity, water depth, Froude Number (Fr), turbulence and vorticity regimes fluctuations. Analysis of literature and experiment results from Virvytė and Šušvė HPP turbines operation regimes suggest, that dams and reservoirs may impart change in the environment though facility operations over a sustained period. In pounded reaches nearby above HPP dams of Virvytė River low Fr number habitats (0.04>Fr> 0.0007) were created and negative dam impact was observed. A large disturbance experiment when a positive wave front resulting from an increase of initial sanitary flow rate Qs = 0.4m3 s-1 till total flow rate Qtot =10.4 m3 s-1 moving downstream after the switch on turbines was made. The maximal water level increase speed Dh /Dt = 0.18 m min-1 (10.8 m h-1) was fixed on the second minute from the beginning. As a positive surge can travel over very long distance without losing much energy because it is self – perpetuating damaging of downstream biota, it is evident that in practice rapid operation of HPP turbines switch must be avoided. The preliminary estimation of pressure fluctuation due the turbine switch on is proposed. Keywords: downstream, environment, fluctuation, HPP, impact, pressure, surge, turbine.
*contact person Habil. dr. Saulius Vaikasas, senior researcher, Water Management Institute of Lithuanian University of Agriculture. Research interests – investigations and modeling of flood currents and riverbed processes, environmental engineering and landscape management. Address: Parko 6, Vilainiai, LT-58102 Kėdainiai district, Lithuania. Phone: +370 347 6 81 09. E-mail: s.vaikasas@delfi.lt. Vaclovas Poškus, Junior Researcher, Water Management Institute of the Lithuanian University of Agriculture. Research interests – riverbed processes in small regulated rivers. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 110–116 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture The classification of cracks according their riskiness for structures of reinforced concrete wing walls on Stilling Basin of hydroschemes Raimondas ŠADZEVIČIUS*, Algimantas PATAŠIUS, Feliksas MIKUCKIS The state of 155 reinforced concrete shaft and overflow spillways structures of hydroschemes was evaluated during the scientific expedition in the period 1998–2009. During expedition it was paid attention to retaining walls structures used to construct wing walls. Retaining walls are under the influence of climatic conditions, water, soil pressure and other types of loads as well as technological factors. Cracks appear because of both the aggressive enviroment and the load influence. Cracks are classified according to their geometrical and statistical parameters, a characteristic stages of creeping when increasing the external load and etc. But these classifications lack of information on evaluation of the technical state of reinforced concrete wing walls on hydroschemes of pods. The aim of this paper is to present a more detailed classification of reinforced concrete wing walls cracks according their riskiness for structures. It was noticed that 90 % of the analyzed constructions had cracks. There are known three types of cracks according their riskiness for structures: 1) secure cracks, 2) dangerous cracks, 3) medium risk cracks. Developed detailed classification of reinforced concrete wing walls cracks according to the most common reasons of the emerging cracks and their riskiness for structures. This classification helps to determine the necessity of repairing or reconstruction. Keywords: cracks, reinforced concrete wing walls.
*contact person Raimondas Šadzevičius, Lecturer, doctor of technical sciences. Lithuanian University of Agriculture, Engineering Construction Department. Research interests – evaluation of technical state of reinforced concrete constructions on hydraulic structures. Address: Universiteto 10, LT–53361 Akademija, Kaunas distr., Lithuania. Phone: + 370 37 75 23 22; fax: + 370 37 75 22 27, e–mail: raimondas.sadzevicius@lzuu.lt. Algimantas Patašius, Associated professor, doctor of technical sciences. Lithuanian University of Agriculture, Engineering Construction Department. Research interests – evaluation of technical state of reinforced concrete constructions on hydraulic structures. Feliksas Mikuckis, Associated professor, doctor of technical sciences. Lithuanian University of Agriculture, Engineering Construction Department. Research interests – evaluation of technical state of reinforced concrete constructions on hydraulic structures. Received 10 2009. ISSN 1392–2335 Water Management Engineering, 35 (55), 2009, 117–123 © Lithuanian University of Agriculture © Water Management Institute of Lithuanian University of Agriculture EVALUATION OF TECHNICAL STATE OF THE GROUND MATERIAL DAMS IN LITHUANIA Vitas DAMULEVIČIUS, Algimantas PATAŠIUS, Raimondas ŠADZEVIČIUS, Juozapas VYČIUS* In the period of 1950–1990 a number of small and middle size dams were constructed in Lithuania for the purpose of hydropower, irrigation, recreation, fishing, antierosion, flood control etc. Dams wear out as all constructions do, and inaccuracies in the time of field survey, designing and construction, as well as defects of building materials quality appear. Some dams were built without appropriate technical projects and in hydro-geologically unsuitable sites. Technology of building used to be broken frequently due to the haste of planned economy during the Soviet period. At present there are more than 1100 hydroschemes with the reservoirs of different area (mostly from 3 to 6350 hectares). Of this number 414 reservoirs have area larger than 5 hectares and there are 165 ponded lakes with hydroschemes of various destinations. There are 617 reservoirs that are attributed to the category of potentially dangerous hydroschemes according to the water head (more than 3 m) and ponded reservoir surface (5 ha or more). It is a paradox that lower dams (to 15 metres height) are more wrecking as less attention is paid to investigation, designing, construction and maintenance of small and medium size dams. After restoring the Independence of Lithuania lots of reservoirs and dams lost their former destination and became less necessary and some of them without owners. During last two decades in the transitional period from planned-command to market economy the amount of means allotted for maintenance of dams and reservoirs decreased. At present the state of hydroschemes raise preoccupation. The article presents the investigation of methods to establish technical state of Lithuanian hydroschemes, and the general prospect of technical conditions of Lithuanian hydroschemes, estimated according to these methods. Keywords: field investigations, ground material dams, technical state.
*contact person Vitas Damulevičius, Lecturer, Lithuanian University of Agriculture, Hydraulic Engineering Department.
Research interests –
evaluation of technical state of hydraulic structures, protection of water
resources.
Research interests – evaluation
of technical state of reinforced concrete constructions on hydraulic structures.
Research interests – evaluation
of technical state of reinforced concrete constructions on hydraulic structures.
Research interests – evaluation
of technical state of hydraulic structures, protection of water resources. e–mail: juozapas.vycius@lzuu.lt. Received 10 2009. |
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