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VOLUME 14(36)Content
ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute for Water Management 2001 vol. 14(36) THE CHANGES OF SUBSURFACE DRAINAGE FUNCTIONINGAleksandras RIMIDISSummaryIt is very important to estimate the drainage functioning according to the unified methods. From this point of view the water level depths and run-off modules are considered as the main indices of water regime in the subsurface drain systems. The article analyses the draining intensity of the drainage, where the protective organic filter materials and glass fiber for the pipes were used to protect them from silt. On the basis of the interrelation between water level depths in soil and drainage run-off modules the drainage efficiency was determined in the initial period of subsurface drain functioning and after 10 years from its arrangement. Keywords: drainage, monitoring, water level, run-off, changes, efficiency.
Article received 04 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute for Water Management 2001 vol. 14(36) NUTRITIOUS MATTER LEACHING FROM THE ROTATION FIELDS APPLIED WITH SLURRY
SummaryThe investigations were carried out in the research object in Juodkiškis, in the soils of light sandy loam. It was established that the nutritious matter leaching depends upon the amount getting into the soil and the drainage run-off head. During the first investigation period (1994 11 01-1995 10 01), when sugar beet was grown, 40 t/ha of slurry were applied together with which and with mineral fertilizers 232.4 kg/ha of nitrogen, 33.1 kg/ha of phosphorus and 121.1 kg/ha of potassium got into the soil. During the second investigation period (1995 10 01-1996 09 01), when barley was grown, the rate of slurry was 20 t/ha, together with which 43.5, 16.9 and 27.4 kg/ha accordingly got into the soil and during the fourth period (1997 09 01-1998 09 10), when summer rape was grown, the rate of slurry was 30 t/ha, together with which accordingly 65.8, 14.5 and 89.9 kg/ha got into the soil. The drainage run-off head in sugar beet field was 230.5 mm in the first variant; in the second variant it was 190.3 and in third variant it was 174.6 mm. In barley field the drainage run-off head was accordingly 43.5, 28.0 and 38.3 mm, in summer rape field it was 241.1, 214.7 and 202.2 mm. The investigations have showed that nitrogen leaching is predestined by fertilization rate. In 1995 and 1998, when drainage run-off heads in the first two variants were almost the same, the nitrogen leaching in the sugar beet field of the 1st variant was 37.2 and of the second one it was 29.7 kg/ha; the nitrogen leaching in summer rape field was accordingly 28.9 and 26.8 kg/ha. The leaching of potassium and phosphorus was predestined by their amounts in the soil. In 1998 their amounts were bigger than in 1995, therefore phosphorus leaching was 0.08 kg/ha bigger in the 1st variant and 0.01 kg/ha bigger in the 2nd one; potassium leaching was bigger 0.76 and 1.12 kg/ha accordingly. Applying slurry, the greatest amount of nutritious matter was leached with drainage water in the variant applied in autumn. When slurry was applied, 23. 8 kg/ha of nitrogen, 0.10 kg/ha of phosphorus and 1.85 kg/ha of potassium were leached on average during the period of three years. Applying slurry in spring, the leached amounts of the most dangerous biogenic matter - nitrogen and phosphorus - were accordingly 3.5 and 0.02 kg/ha less, while applying half of slurry rate in autumn, half of it in spring the leached nitrogen and phosphorus quantities are 3.6 and 0.05 kg/ha less. Therefore, seeking to decrease the leaching of biogenic matter and soil pressing (in the 3rd variant the manure spreading machinery is used twice), spring is the best time for applying slurry. The investigations have showed that there is a close connection between the drainage run-off head and nutritious matter leaching. In linear regressive equations the correlation ratio was no less than 0.7, and in most cases it was even bigger than 0.9. No reliable connection between nutritious matter leaching and drainage distances was revealed. Keywords: slurry, drainage run-off, biogenic matter, environment.
Article received 06 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute for Water Management 2001 vol. 14(36) THE REGIME OF BIOGENIC MATTER IN POLDER WATER OF THE NEMUNAS DELTA
SummaryIn 1993-1998 in the three basic and one subsidiary polder (Rusnė, Vorusnė, and Šyša polders and Tulkiaragė polder accordingly) within the Nemunas Lowlands there was a study conducted on the concentration analysis of biogenic (Ntotal, NH+4-N, NO-3, Ptotal, PO3-4-P) and organic matter (BOD7, ChDScr) found in polder inland waters as well as water of their receivers (bordering rivers). It was established that greater concentrations were in water discharging from peaty soils and from Rusnė winter type polder that was intensively used. In view to the concentrations analyzed the purity of the polder water was of the same rate as that of the polder water receivers (rivers). Thus, it did not affect the qualitative indicators of the rivers-receivers. Time factor (duration of the study period) had influenced just the decrease of Ntotal and PO3-4-P and the increase of BOD7 and ChDSCr. Direct dependency between Ntotal rate and annual average day temperature was established. After having the pumping station dismantled, the water logging processes of the polder re-occurred. However, it did not improve the water quality. Besides, Ptotal and PO3-4-P concentrations even increased by 3 times. Keywords: polders, nitrogen, phosphorus, organic matter, run-off.
Article received 11 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute for Water Management 2001 vol. 14(36) THE CONCEPTUAL MODELS OF USAGE AND POSSESSION OF LAND RECLAMATION PROPERTYValentinas ŠAULYSSummaryLand reclamation is very important in Lithuania: under the climatic conditions of our country it is necessary to drain land indeed. Today approximately 90 % of the whole agricultural production is grown in drained land. In this article financial problems of land reclamation works are analysed. Not taking into account our country's financial abilities, the maintenance of land reclamation systems must be done properly and in time - only then we will be able to guarantee the best long-lasting functioning of drainage systems, and in the future there will be no greater damage and it will be unnecessary to do preliminary expensive reconstruction works. We can fulfill the maintenance of drainage systems properly and in time when increasing the financing for land reclamation works up to the necessary level (any subsidiary resources and payments are possible, as well as different labour variants and other alternatives) or diminishing the maintained drained areas, so that we could thoroughly keep an eye on land reclamation systems. Keywords: land reclamation equipment, maintenance systems, financing.
Article received 11 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute for Water Management 2001 vol. 14(36) CHEMICAL ELEMENT MIGRATION INTO THE STREAMS AND GROUND WATER IN KARST ZONE
SummaryIn this paper the peculiarities of chemical compounds migration in drained soils of karst zone (glacial-lacustrive clay and moraine sandy loam) are discussed. It has been established that the mineralization level and chemical composition of stream water are predetermined by drainage water, while these of drainage water are predestined not only by soil formation rocks, but by land - use as well. Due to agricultural activity the sequence of anti-ions in water of moraine sandy loam is as follows: HCO3>NO3>SO4>Cl. As the gravitation water depth increases, its mineralization increases as well, but the concentrations of the main ions change differently. Keywords: water mineralization, land-use, chemical compounds migration.
Article received 12 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Institute of Water Management, 2001 vol. 14 (36) WATER ECOLOGY: HYDROCHEMICAL AND HYDROBIOLOGICAL EVALUATION OF LITHUANIAN RIVERSRimvydas TUMASSummaryThe goal of this study is to find relation among river biota and pollution by nitrogen and phosphorus. River basins in East Lithuania have large groundwater aquifers in which substantial amount of nutrients are retained. Several East Lithuanian river basins have provided examples of efficient reduction of riverine loads of nutrients, compare to the Middle Lithuanian rivers. Quantitatively no direct relation between pollution of East and Middle Lithuanian rivers by nitrogen and zooplankton index of saprobity have been found. Zoobenthos prefer more clean water of the East part of Country Rivers. Abundance and biomass of fish community first of all depend on river size, type, flow velocity and water temperature. Along big river channel relation between zooplankton and fish biomass have been found. Keywords: nitrogen, phosphorus, zooplankton, saprobity, fish.
Article received 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2001 vol. 14(36) RESEARCH OF POSSIBILITIES FOR REDUCING DITCH DEPTH DURING THE MAINTENANCE INTERVENTIONS
SummaryStudy presents the analysis of the feasibility for reducing the depth of land reclamation ditches. The quality of design and construction of ditches and drainage systems, as well as periodicity and quality of maintenance works have a direct impact on the actual depth of ditches. To be able to evacuate adequate water discharge by the ditches their depth, as well as the elevation of drainage outlets above the ditch bottom and the cross-section of free water flow should be respected. Authors analyze the need of deepening ditches and cleaning out of deposits from the bottom depending on the factors affecting the process. The recommendations for detailed analysis of technical parameters while designing the intervention measures are presented. Keywords: ditch maintenance, water free flow cross-section.
Article received 13 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management 2001 vol. 14(36) EFFECT OF INTERACTION BETWEEN MULTIFRACTION SUSPENDED SEDIMENTS AND TURBULENT FLOW TO THE DEPOSITION PROCESS AND ITS CALCULATIONAlfonsas RIMKUSSummaryThe suspended material has been settled in rivers when the stream velocity is decreased (for example in the ponds or in the flooded valleys). At first the coarse particles are settled, the fine ones are transported further. The deposition of each sediment fraction was still calculated un-coupled. The effect of their interaction was not estimated because of complexity of this process. Sediments alter the structure of turbulent flow. They suppress the turbulent whirlpools, which in the turn affect the transport of sediments. Therefore, the sediments of high enough concentration attenuate the whirlpools strong enough to begin the sedimentation. Interaction of different sediment fractions reveals itself by helping each other to damp the turbulence and make the critical deposition state of flow. On the basis of known investigation data, this interaction is studied and some improvements of calculations are proposed in this paper. Keywords: suspended sediment deposition, turbulence vortices, hydraulic calculation.
Article received 13 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management 2001 vol. 14(36) RESULTS OF MATHEMATICAL MODELLING ON DYNAMICS OF FLOOD SEDIMENT WITHIN THE FLOODED NEMUNAS DELTASaulius VAIKASASSummaryWithin the downstream of the Nemunas Delta close to Pagėgiai settlement the sediments raised up during the flood time and carried water deposit by the flood within the grassland area along the River. In the result not only formation process of alluvial soils within the area but also clearing of turbid water in the Curonean Lagoon were affected. As the modelling of the flood activities covering the period of 1950 - 1991 had been done (based on the "Delta" mathematical model elaborated by us), it was established that about 37 % of sediments were deposited total by depending on a flood extent. The greatest amount of the sediments in the form of clay and silt including small sediment units deposited during the great floods of 1 %-3 % probability, since more than a half of the flood water discharge flew over the valley then. The greatest deposition load of the sediments was observed after the spring flood in 1958, i.e., 750000 t. Total amount of the sediments in the modelled area was 2.25 mln. t within the study period. As a result of the sand particles' deposition the bank of the River was lifted up by 0.3 m during the 42 study years. Small clay as well as silt particles would deposit more uniformly within the total study area making a 2-3 mm sediment layer. It made about 50 t/ha -60 t/ha of small clay and silt sediments. Keywords: flood, sediment, mathematical modelling.
Article received 13 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management 2001 vol. 14(36) ENVIRONMENTAL ASPECTS OF DRAINAGE
SummaryProtection of ecosystems is becoming one of the principal overall goals, and there is the need to address the environmental protection issues on drained land and for the water resources with a policy approach, structured in a similar manner, integrated under progressing in parallel based on the same mechanisms as for agricultural policy reform. Along with this, drainage systems built in accordance with existing structure and technologies are not operating always successfully and safely without negative effect upon the environment resulting in the emergence of ecological changes. Besides employing agricultural drainage criteria, we also employ environmental drainage criteria (to minimize the environmental damage). Transport of contaminants in the aeration zone depends mainly on moisture migration. Therefore one of the most important tasks is to reveal the regularities and quantification of moisture migration in soil layers of the aeration zone, and the second related task is to investigate contaminant migration in the pore solutions and ground water. Investigations were carried out in the experimental systems with various degrees of draining. Observed data of influence of drainage on physical soil properties, soil moisture, ground water table, drainage discharge, concentration of dissolved nitrates in ground water are analyzed in the report. Keywords: drainage degree, soil properties, discharge, ground water, soil water content, nitrate concentration.
Article received 16 12 2000, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2001 vol. 14(36) INVESTIGATION OF TECHNICAL STATE OF HYDRAULIC STRUCTURES IN LITHUANIA
SummaryIn the period of 1950-1989 a number of middle and small dams were constructed in Lithuania for the purpose of irrigation, energetics, recreation, fishing, antierosion, 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 serious projects and in hydro-geologically unsuitable sites. Technology of building used to be broken frequently due to the haste of planned economy. After restoring the Independence of the country, lots of reservoirs and dams lost their former destination and became less necessary. During the transitional period of recessive 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: earth dam, drop inlet spillway, defects, state of dams.
Article received 01 2001, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management 2001 vol. 14(36) THE IMPACT OF GROUND MOISTURE DYNAMICS UPON THE SUPPRESSION OF ULTRASONIC IMPULSERomualdas PUKŠTASSummaryIn this article the researches of moisture dynamics in ground carried out using the ultrasonic ground sound are given. Taking into consideration that the level of ultrasonic impulse suppression depended upon the structure of impulse spectrum, a certain means had been invented which allowed us to observe the moisture motion phases in ground. In this article the presumption is motivated that the changes of ultrasonic impulse suppression depending upon the changes of moisture amount in ground enables us to observe moisture dynamics in it, and the rising angle of suppression curve at the time of moisture motion in ground characterizes the penetrability coefficient of ground moisture. Keywords: ground, ultrasound, suppression, moisture.
Article received 01 2001, given to print 05 2001. ISSN 1392-2335 TRANSACTIONS OF THE LITHUANIAN UNIVERSITY OF AGRICULTURE AND LITHUANIAN INSTITUTE OF WATER MANAGEMENT, 2001 VOL. 14 (36) ENVIRONMENTAL FLOW OF LITHUANIAN RIVERSGražina ŽIBIENĖSummaryThe term ,,environmental flow" in Lithuania is equivalent to the terms ,,instream flow", ,,residual flow", ,,minimum flow", ,,minimum acceptable flow", ,,ecologically acceptable flow" which are used in foreign countries. Environmental flow of river in Lithuania is defined as the estimated minimal flow of the river necessary for maintenance of minimal requirements of riverine ecosystem. Up to the end of 1997 minimum flows of all Lithuania's rivers had been equated to mean of minimum flows of 30 days in dry period of 95 % probability. Since December 1997 the environmental flows have been defined according to the methodology presented in the normative document LAND 22-97. This methodology is based on hydrological characteristics as mean of minimum flows of 30 days in the dry period of 95 % or 80 % probabilities, factor of natural regulation of run-off. The methodology is presented briefly in this article. The significance of our research work is in substantiation of the necessity and possibilities of environmental flow estimation in Lithuania from various points of view, evaluation of valid methodology for estimation of environmental flows of dammed rivers in Lithuania. Environmental flows of Lithuanian dammed rivers have been established according to the valid methodology and the analysis of these results is presented in the article. Values of environmental flows of Lithuanian rivers, except the biggest Lithuanian river - the Nemunas, are from 6.96 m3/s to 0.001 m3/s and even lower. Environmental flows of 89 % of dammed Lithuanian rivers are lower than 0.1 m3/s. The established environmental flows of Lithuanian rivers were compared with values of minimum flows of the same rivers to maintain fish habitat requirements established according to some foreign methods (Tennant, Montana, Tesman, etc.). Comparison of results showed that environmental flows established according to valid methodology in Lithuania in most cases are less than flows maintaining minimal requirements of fish habitats (estimated according to mentioned foreign methods). This proves necessity of environmental flows estimation taking into account hydraulic and, especially, hydrobiological characteristics in near future. Following the experience and general tendencies of instream flow determination in Europe the possible ways and stages of methodology for establishment of environmental flow of Lithuania's rivers development are suggested. Keywords: environmental flow, minimal flow, hydrology, river ecology.
Article received 01 2001, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management 2001 vol. 14(36) RESEARCH IN GEOHYDRODYNAMICS AT LITHUANIAN UNIVERSITY OF AGRICULTURE
SummaryResearch in geohydrodynamics at Lithuanian University of Agriculture (LUA) takes its origin back to 1951. Many various geohydrodynamic problems, both theoretical and practical, have been solved using analytical, analogical (mainly based on electroanalogy) and combined methods. Research in geohydrodynamics by means of its numerical simulation on PC started in 1989-1990. An effective computer programme named PLAFI was worked out, several complicated geohydrodynamic problems were successfully solved. Among them the most significant results were obtained during the simulation of the geohydrodynamics in surroundings of Kruonis pumped storage hydropower plant (KPSHP). The numerical model of the active seepage from the upper reservoir (UR) of the KPSHP covers the territory of ~25 km2. Hydrogeological, hydrological and technical situation of the territory is very complicated. The main simulation task was the prognosis of geohydrodynamic conditions in the above territory at the time, when water level (WL) in the UR will be raised as designed - up to the elevation of 153.5. The results of prognosis showed that the essential changes of geohydrodynamic conditions in the above territory do not occur and there is no negative influence on the environment. Keywords: geofiltration, hydrogeology, hydrology, filtration coefficient.
Article received 02 2001, given to print 05 2001. ISSN 1392-2335 Transactions of the Lithuanian University of Agriculture and Lithuanian Institute of Water Management, 2001 vol. 14 (36) ANALYSIS OF INTEGRATED WATER RESOURCES MANAGEMENT IN LITHUANIAAntanas MAZILIAUSKASSummaryThe study deals with the water resources management principles applied in different sectors on the national level and administrated on the regional level through a number of regional agencies. The major principles are under development, taking on consideration specific conditions of each sector. Lithuania does not have water shortage problems. The available resources calculated on the basis of mean annual run-off are of 26.1 km3, most of them being from surface water. The total volume of freshwater available per capita is approximately 7000 m3. In optimising water use the abstraction of water has decreased around two times to compare with the level of 1991. The sustainability of water resources with regard to the quality has became an important issue. 40 % of discharged water is not adequately treated or not treated at all. The eutrophication has became one of the main environmental problems in the Baltic Sea region. Lithuania has rather large area of drained land which amounts to 2.6 million of ha. The irrigated areas have decreased significantly during last decade due to the changed structure of landholders. The rehabilitation and maintenance of drainage systems remain the priority objective in agricultural water management. The managament and administration still need to be improved. The decrease in agricultural and industrial production and the introduction of new water protection measures are likely to have a positive effect on river water quality. Agricultural productivity is expected to reestablish in the nearest future and this will threaten environment. The SAPARD programme will provide the support of investments into agricultural holdings, which will create a good basis for modernization. The application of the good agriculture practice will become a necessity. The administration and control of introduced measures is becoming a necessity. In implementing the programme of support for agri-environment Lithuania undertakes to prepare and apply the agri-environmental measures in accordance with the provisions set out in the Council Regulation 1257/1999 under the Rural Development Plan. There is no adequate coordination among all institutions involved in water resource use and management. The river basin based administration and management of water resources is to be adopted based on the provisions of the EU Water Framework Directive. Keywords: water resources, integrated management, sustainable use.
Article received 02 2001, given to print 05 2001.
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