Factors affecting seasonal and spatial patterns of water quality in Lithuanian rivers

In this study the main processes influencing water quality of the Lithuanian rivers have been identified. Factor analysis was tested on river hydrochemical data from 108 sites for the period of 1999–2004. It enabled the identification of main factors determining water quality each season. As a result, monitoring stations were grouped into clusters each representing the influence of relevant factor. The tested multivariate statistical procedures can be applied in practice when the reasons for water quality impairments are to be investigated. The findings reveal that Wastewater factor is prominent in small rivers downstream larger towns; Agro-geological factor – in Northern Lithuania's rivers of heavy carbonated soils and intensive agriculture lands as well as in South eastern Lithuania's rivers of more acidic soils; Hardly degradable organics factor – in Northern and Middle Lithuania's rivers of heavy-textured and fertile agricultural soils. The photosynthesis-vegetation and Aeration factors are predominant in major rivers. First published online: 14 Dec 201

Klimato kaitos iššūkiai kaimo vandentvarkai

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Source apportionment and retention of nutrients and organic matter in the merkys river basin in southern Lithuania/Skirtingų šaltinių poveikis biogeninių ir organinių medžiagų pernašai ir sulaikymui Merkio upės baseine pietų Lietuvoje/

The assessment of the type of human activity in a basin area that may cause an impact on the status of a water body is needed for successful implementation of the EU Water Framework Directive. Lack of necessary information often makes it difficult to perform the task. Therefore, the statistical MESAW model based on export coefficients approach has been used in this study for evaluation of the impact of different sources of nutrients and organic matter on the water quality in the Merkys River in southern Lithuania. The model was tested on the basis of data from 5 water quality monitoring sites with corresponding subbasin data on land use, point sources and atmospheric deposition. Nonlinear regression was used for simultaneous estimation of the export coefficients and retention. The results revealed that the impact of anthropogenic sources accounted for 73% of COD, 56% of BOD, 90% of Ntot and 78% of Ptot loads measured in the Merkys River. Forest and wetlands contribute from 9.5 to 44% to the corresponding load. The retention in the Merkys River, Basin was found to be high for nitrogen and phosphorus and low for organic matter. Santrauka Įgyvendinant vandensaugos uždavinius turi būti įvertintas konkretaus upės baseino vandens taršos lygis ir numatytos priemonės, padėsiančios pasiekti gerą būklę. Kiekvienos upės baseinas yra sudėtinga ekosistema, kurioje susipina gamtiniai ir antropogeniniai veiksniai. Jie veikia kompleksiškai, todėl analizuojant vandens terpėje migruojančias medžiagas sunku įvertinti kiekvieno jų įtaką. Gamtinių ir antropogeninių veiksnių poveikiui biogeninių ir organinių medžiagų srautams bei jų sulaikymui Merkio upės baseine įvertinti buvo pritaikytas statistinis MESAW modelis. Jis pagrįstas emisijos koeficientų nustatymu įvertinant baseino žemėnaudą, taškinius taršos šaltinius ir atmosferines iškritas. Taikant netiesinės regresijos metodus nustatytas skirtingų veiksnių poveikis upės vandens kokybei. Rezultatai parodė, kad antropogeninių šaltinių poveikis sudaro 73 % ir 56 % (pagal ChDSCr ir BDS7 ) bendro pernešamo organinių medžiagų kiekio Merkio upėje. Žmogaus veikla lemia 90 % pernešamo metinio bendrojo azoto ir 78 % bendrojo fosforo kiekio. Miško poveikis biogeninių ir organinių medžiagų srautams sudaro nuo 9,5 % iki 44 %. Bendrojo azoto ir bendrojo fosforo sulaikymas upės baseine siekia 79 % ir 64 %. Organinių junginių sulaikymas mažas – 9,7 % pagal BDS7 ir 42,3 % pagal ChDSCr. Резюме При решении задач по водоохране должна быть учтена степень загрязненности воды каждого конкретного бассейна реки и намечены меры по улучшению его состояния. Бассейн каждой реки является сложной экосистемой, на которую комплексное воздействие оказывают разные природные и антропогенные факторы, определить влияние каждого из которых довольно трудно. Для оценки воздействия природных и антропогенных факторов на потоки биогенных и органических веществ и их задержание в бассейне реки Меркис была применена статистическая модель MESAW, основанная на определении коэффициентов эмиссии. Результаты показали, что воздействие антропогенных источников составляет 73% общeго объемa химического потребления кислородa (XпK), 56% биохимического потребления кислородa (бпK), 90% общeго количества азота и 78% общeго количества фосфора, измеренных в реке. Воздействие лесов и болот на поток биогенных и органических веществ составляет от 9,5% до 44% общeго объемa веществ. Было устaнoвлeнo, что в бассейне реки Meркис задерживается много азота (79%) и фосфора (64%) и мало органического вещества (9.7–42.3%). First Published Online: 14 Oct 2010 Reikšminiai žodžiai: biogeninės ir organinės medžiagos, šaltinių pasiskirstymas, medžiagų sulaikymas, MESAW modelis, Merkio upė. Ключевые слова: биогенныe вещества, органическое вещество, распределение источников, задержание веществ, модель MESAW, рекa Meркис, Литвa

Estimatio of Variability of the Coefficient of Rougness

Bibliogr.: p. 38Vytauto Didžiojo universitetasŽemės ūkio akademij

Trends in riverine concentrations of phosphorus in agricultural catchments in Lithuania

Vytauto Didžiojo universitetasŽemės ūkio akademij

Hydrological effect of artificial drainage in lowland river catchments in Lithuania

Although in Lithuania artificial land drainage is a common water management practice, there are still concerns about its downstream hydrological effects. Due to the complexity of flow driving factors, the hydrological effect of drainage is very uncertain, making it difficult to determine its relative importance. Aiming to distinguish between the influence of drainage and other factors in this study, the extent of changes of twenty hydrologic variables (flow magnitude, frequency, duration, timing and rate of change) downstream of drained areas and five explanatory factors that described different aspects of streamflow regimes in a non-redundant way were analysed. The resolution of the task involved the application of principal component and canonical correlation analyses. The results based on data collected from six tile-drained lowland river catchments (A=167-2290 km2) within the period 1940-1990 revealed that weather and catchment soil conditions were the primary factors determining the variability of most streamflow variables. The extent of the drained land area in river catchments affects only a few hydrologic variables - it tends to extend the duration of high pulses and causes later occurrence of annual peaks. The extended duration of high pulses along with the lag in occurrence of annual peaks are attributed to the “sponge effectˮ of drainage. The study also showed that artificial drainage results in a reduced number of low pulses by creating a more pronounced hydrological connection to groundwater. Most probably this occurs due to the greater depth of tile drains, providing a deeper outlet for shallow groundwater drainage. A larger groundwater inflow may also contribute through deepened streches of channelized streams and newly dug ditches collecting water from lateral tilesVytauto Didžiojo universitetasŽemės ūkio akademij

Erosion and Nutrient Transport Prediction : an Evaluation of Agricultural Non-point Pollution Models

Angl. - Santr. lietBibliogr.: p. 19 (10 pavad.)Vytauto Didžiojo universitetasŽemės ūkio akademij

GIS taikymas jautrioms dirvožemio erozijai teritorijoms nustatyti

Santr. anglBibliogr.: p. 31 (12 pavad.)Vytauto Didžiojo universitetasŽemės ūkio akademij

Management practises and environmental effects of agricultural drainage in Lithuania

In Lithuania, artificial drainage is a common agricultural practice. It remains one of the most extensively drained countries in the world. The total drained land area occupies 47% of the country‘s land area and 87% of agricultural land area, of which 87% is tile-drained. Although the introduction of drainage has improved the quality of agricultural land, the benefits of drainage were associated with many alterations in the local environments. Therefore, a review is presented of the results from various investigations and research studies conducted in Lithuania that have reported diverse aspects of the development of agricultural drainage, as well as its environmental impacts on local hydrology and nutrient losses in the soil. The effect of various measures (i.e. lime filter drainage, controlled drainage and woodchip denitrification bioreactors) aiming to reduce nutrient losses via drainage is presented. Temporal changes in drainage runoff over the last four decades along with projected effect of climate change on nutrient fluxes via drainage are also discussedVytauto Didžiojo universitetasŽemės ūkio akademij

Nutrient Retention in Surface Waters of Lithuania

The statistical model MESAW was applied to simultaneously estimate export coefficients and retention of nutrients in four Lithuanian river basins (area range: 2,634-6,140 km2). The estimated results revealed substantial capabilities to retain nitrogen and phosphorus in river basins: from 67 to 78% of total nitrogen and from 24 to 63% of total phosphorus relative to the input is retained in surface waters. Estimation of retention was found to be larger in lakes: 27-59% for nitrogen and 11-31% for phosphorus. In-stream retention appeared to be much lower and varied from 11 to 15% for total N and from 3 to 12% for total PVytauto Didžiojo universitetasŽemės ūkio akademij