The hydrogeological schematisation of the multi-layered stratigraphical sequence and the results of groundwater flow modelling by MODFLOW code for the Quaternary aquifer system of the south-eastern part of Lithuania have been discussed in the paper. The regional groundwater steady-state flow model has been calibrated applying hydrochemical and isotope data. A tritium isotope data set for groundwater in upland, transit and lowland sites has been used to identify the flow model for water residence time.
Keywords: Groundwater flow model; Tritium isotope; Hydrogeological schematisation; Lithuania
Sustainable use of marine resources requires effective monitoring and management of the world’s fish stocks. Acoustic and electromagnetic remote sensing techniques are being used to help manage fisheries at sustainable levels, while also guiding fishing fleets to locate fish schools more efficiently. Fish tend to aggregate in ocean areas that exhibit conditions favored by specific fish species. Some of the relevant oceanographic conditions, such as sea surface temperature, ocean color (productivity) and oceanic fronts, which strongly influence natural fluctuations of fish stocks, can be observed and measured by remote sensors on satellites, aircraft and ships. The remotely sensed data are provided in near-real time to help fishermen save fuel and ship time during their search for fish, to modelers who produce fisheries forecasts, and to scientists who help develop strategies for sustainable fisheries management. This article describes how acoustic, optical and radar sensors on ships, satellites and aircraft are used with forecast models to improve the management and harvesting of fisheries resources.
Keywords: Fisheries remote sensing; Fish environmental indicators; Fisheries management; Acoustic fish detection; Fisheries forecasts
Based on geostatistical modelling the authors compared relative sea level records for the Litorina and post-Litorina Sea with tide gauge and GPS derived crustal velocity measurements in Fennoscandia and in the Baltic region. Results show good fit between the geological record and GPS derived crustal velocity measurements indicating that the postglacial rebound (PGR) centre on the northwest coast of the Bothnian Sea and the isostatic zero-line in the southern Baltic remained stable during the last 8000 14C yrs BP (8900 cal yrs BP). An average Baltic Sea level rise of 1.4±0.4 mm/y for the 20th century was estimated, which is found to be at about one fifth compared to the mid-Holocene sea level rise. However, considering the recent estimates of eustatic sea level rise for the 21st century the slowly uplifting coastal areas in southern Sweden, SE Finland, Estonia, Latvia and NW Russia, which have experienced a long term relative sea level fall, will probably also be affected by future sea level rise reminiscent of the mid-Holocene one.
Keywords: Relative sea level; Tide-gauge measurements; Postglacial rebound; Litorina Sea; Eustatic sea level rise; Vertical crustal movements; Baltic Sea
Efficient use of natural resources is a global goal. A specific way of improving resource productivity in Estonia is utilisation of Maardu granite deposit as a joint goal for producing granite aggregates and construction in the caverns of the granite mine and a pumped hydroaccumulation plant. The environmental impact assessment in connection with construction of a Maardu deep granite mine was accepted by the Estonian Ministry of Environment in 2009. The most challenging engineering task, causing also the biggest environmental risks, is safe penetration of aquifers and aquitards during construction of vertical and/or inclined tunnels for granite mine and/or pumped hydroaccumulation plant. A major problem is also the high radiation level in the Maardu area and in the planned deep mine. High radon concentrations up to 10 000 Bq/m3 have been recorded on the outcrops of alum shale in the mine area and they can be dangerous to human health. Based on the hydrogeological modelling it was found, that under normal circumstances the construction and operation of the Maardu deep granite mine is environmentally safe. The territory of the former Maardu phosphorite opencast is highly polluted and damaged and therefore the foundation of the granite mine with overground buildings is the best way for the environmental improving of the area.
Keywords: Granite mine; Jõelähtme commune; Maardu town; Radon emissions; Phosphorite opencast; Groundwater; Pumped hydro-accumulation station; Northern Estonia
The dynamics in dryness over the Baltic Sea region during the observation period of 1960–2009, as well as the climate prediction for the 21st century have been evaluated in this research. The dryness of the investigated area has been examined using the Standardized Precipitation Index (SPI). The precipitation amount data provided by the Climate Research Unit (CRU) at the University of East Anglia have been used in this study. Projections of future dryness changes are based on the output data of the regional CCLM model driven by A1B and B1 emission scenarios. The increase of SPI values, i.e. a decline in dryness, have been found over the last fifty years in the major part of the investigated area. However, the probability of short-term droughts remain high against the background of a general decrease in dryness. The increased dryness during the analyzed period has been found only in the southern part of the Baltic Sea region. Similar changes are also foreseen for the 21st century. The dryness is expected to increase in the south (especially in summer), while the central and northern parts of the region are likely to witness the recurrence of a drought decrease.
Keywords: Droughts; Standardized Precipitation Index; Precipitation; CCLM; Baltic Sea region
The hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning model) has been applied to six river basins in Latvia to assess climate change and its impacts on the river runoff regime at the end of the 21st century. Climate change has been predicted by applying the regional climate model RCAO with the driving boundary conditions from the global general circulation model HadAM3H applied for the IPCC scenarios A2 and B2 and the following time periods: 1961–1990 (control) and 2071–2100 (scenario). Changes have been found under both scenarios. Major changes in the future hydro-climate data were forecasted according to the A2 scenario, where the trends of increase are identified for the annual mean air temperature (by 4°C), the precipitation (by 12%) and the evapotranspiration (by 21%), while the river runoff will decrease by 15% at the same time. The changes in the length of the growing season and heavy rainfall have been predicted. Both scenarios forecast changes in the seasonal runoff regime where the major part of the runoff will be generated in winter, followed by spring, autumn and summer. The maximum river discharge will occur in winter instead of spring.
Keywords: Climate change; Hydrological model; River runoff; Forecast scenario; Latvia
The consistent patterns of chemical composition of wet deposits and drainage runoff concentration have been permanently studied in two stationary sites in the Middle Lithuania for the last decades since late 1980s. The results of simultaneous observations presented in this paper show that the concentration of SO4 -2–S, Mg+2, PO4 -3-P, NO3 –N, NH4 +-N and Ca+2 in wet deposits positively correlates with the concentration of these ions in drainage runoff water (R=0.59, 0.61, 0.51, 0.49, 0.42 and 0.35, correspondingly, R05=0.35). A sharp decrease in SO4 -2–S concentration from 5.5 to 2.5 mg l-1 and periodical decrease versus increase in NO3 –N and NH4 +- N concentration and load are determined in the agroecosystems studied from 1988–1989 with short intervals to 2007. This outcome has mainly an economic character: impact of changes in animal numbers, increase of transport load, fuel consumption and industrial emissions.
Keywords: Wet deposits; Chemical concentration; Drainage runoff;·Agroecosystems; Lithuania
The distribution of benthic invertebrates is one of the key parameters for the marine spatial planning and management, however traditionally the data on benthic invertebrates are based on point sampling. Recently statistical methods of predictive modelling are used to create maps of species distribution, nevertheless, no comparative analysis of different modelling methods has been yet performed in the Baltic Sea region. In this study the occurrence and biomass distribution of 23 benthic species in the southeastern Baltic Sea were modelled. A comparison of the following predictive modelling methods was performed: random forests (RF), generalized additive models (GAM), multivariate adaptive regression splines (MARS) and maximum entropy (MaxEnt). In order to assess the consistency of the methods, 100 iterations with different train/test datasets were made for each of them. Random forests achieved the highest predictive performance for both species occurrence and biomass distribution models; also it was the most consistent for different iterations. Predictive performance of GAMs and MARS followed RF, whereas MaxEnt accurately predicted occurrence only for the species with a relatively low distribution range.
Keywords: Marine benthic invertebrates; Random forests; Generalized additive models; Multivariate adaptive regression splines; Maximum entropy; Lithuanian waters area; south-eastern Baltic Sea
Shoreline position measurements at various time instants can be used to derive quantitative estimates of the rate of shoreline change and help to understand the magnitude and timing of erosion or accretion processes. Aerial photographs and topographic maps from 1947 to 2010 have been used to derive instantaneous shoreline positions, from which shoreline change rates have been estimated using statistical parameters: shoreline change envelope (SCE), net shoreline movement (NSM), and end-point rate (EPR). Non-metric multi-dimensional scaling (nMDS) has been applied for shoreline classification into dynamic sectors. This study was carried out along 90.6 km of Lithuanian Baltic Sea coast over the time span 1947 to 2010. The study demonstrated that combined use of cartographic data and statistical methods could be a reliable method for shoreline related studies. Application of such data seems to be trustworthy in qualitative monitoring of shoreline changes, while it is the only available method for long term studies.
Keywords: Shoreline change; Erosion; Accumulation; Digital shoreline analysis system; Aerial photography; south-eastern Baltic Sea
The Holocene saline water inflow changes into the Baltic Sea (INFLOW) was one of the BONUS Research Programme projects (2009–2011) that generate new knowledge in support of decision-making in the Baltic Sea region. The INFLOW project integrated sediment multi-proxy studies and modelling aiming to reconstruct past changes in the Baltic Sea ecosystem; to identify the forcing mechanisms of those environmental changes; and to provide scenarios of the impact of climate change on the Baltic Sea ecosystem at the end of the 21st century. The main efforts have been directed towards studies of the saline water inflow strength, salinity, temperature, redox, and benthic fauna activity over the past 6000 years, concentrating on the time period that covers two natural climate extremes, the Little Ice Age and Medieval Climate Anomaly.
Keywords: The Baltic Sea; Sedimentation; Environmental change; Climate change; Holocene; Inflow; Multi-proxy analyses; Modelling