Noora Veijalainen

Effects of climate change and agricultural adaptation on nutrient loading from Finnish catchments to the Baltic Sea

Climate change is expected to increase annual and especially winter runoff, shorten the snow cover period and therefore increase both nutrient leaching from agricultural areas and natural background leaching in the Baltic Sea catchment. We estimated the effects of climate change and possible future scenarios of agricultural changes on the phosphorus and nitrogen loading to the Baltic Sea from Finnish catchments. In the agricultural scenarios we assumed that the prices of agricultural products are among the primary drivers in the adaptation to climate change, as they affect the level of fertilization and the production intensity and volume and, hence, the modeled changes in gross nutrient loading from agricultural land. Optimal adaptation may increase production while supporting appropriate use of fertilization, resulting in low nutrient balance in the fields. However, a less optimal adaptation may result in higher nutrient balance and increased leaching. The changes in nutrient loading to the Baltic Sea were predicted by taking into account the agricultural scenarios in a nutrient loading model for Finnish catchments (VEMALA), which simulates runoff, nutrient processes, leaching and transport on land, in rivers and in lakes. We thus integrated the effects of climate change in the agricultural sector, nutrient loading in fields, natural background loading, hydrology and nutrient transport and retention processes.

IMPACT OF CLIMATE CHANGE ON FUTURE DISCHARGES AND FLOW CHARACTERISTICS OF THE TANA RIVER, SUB‐ARCTIC NORTHERN FENNOSCANDIA

Abstract. Climate change is expected to have a substantial impact on hydrology on both a global and regional scale. Although the anticipated warming is expected to be greatest in the northern regions and cause alteration in the hydrological cycle, it has yet to be resolved, to what extent these hydrological changes will alter such flow characteristics as flow velocity, bed shear stress and stream power in Sub‐Arctic rivers. Future changes in the fluvial erosion potential are studied in the Sub‐Arctic Tana River, on the border of Finland and Norway. We modelled future discharge scenarios for the years 2070 to 2099 with a conceptual hydrological model incorporating three emission scenarios, with two global and one regional climate model. These simulated flood discharges were used as input hydrographs to model flow characteristics with a two‐dimensional hydraulic model. Differences in the spatial distribution of flow characteristics between frequent (HQ1/2a) and infrequent floods (HQ1/250a) were examined. Compared to the present, in most simulations, both HQ1/250a and HQ1/2a flood discharges diminished, with spring floods occurring earlier also. Although the relative reduction in flow characteristics (velocities, bed shear stresses and stream powers per unit area) was more notable in 1/2a compared to 1/250a floods, the discharge peaks of the former would theoretically still be able to transport the fine sediments that form the river bed. Based on most of the climate scenarios, autumnal floods become more frequent in the future and hence, their role in sediment transport may become more significant compared to the present‐day situation.

Defining the natural flow regimes of boreal rivers: relationship with benthic macroinvertebrate communities

Despite the fundamental role of river flow in determining the structure and function of lotic ecosystems, few studies have directly related features of the natural flow regime to variation in stream invertebrate assemblage composition. We classified 240 near-pristine, snowmelt-dominated Finnish streams into hydrological river types. We assessed the relationship of these types with benthic macroinvertebrate assemblage structure and examined the relative importance of hydrological variables, local-habitat variables, and geographical location in predicting variation in assemblage structure. We used a hydrological model to obtain site-specific daily discharges for a 30-y period (1981–2010) and calculated 223 flow indices based on flow index modeling tools. We used a combination of principal component and cluster analysis to classify the sites into 6 distinct hydrological types that were separated mainly by geographical location and catchment-size-related factors. Nonmetric multidimensional scaling and multiresponse permutation procedure showed that macroinvertebrate assemblage structure differed significantly among the hydrological types, but the associated A-statistic indicated wide variation among sites within type. Redundancy analysis indicated that assemblage structure was related more closely to hydrological variables than to local-habitat and spatial variables. The role of hydrology was confirmed further by functional trait structure that showed close relationships to hydrological variables in three-table ordination (RLQ) and fourth-corner analyses. Traits representing organism size and microhabitat preference were correlated most closely with hydrological variables describing variability or seasonality of flows. Our study highlights the role of hydrology in structuring stream assemblages in seasonal, snowmelt-dominated river systems. Modeling hydrological variables in combination with species distribution models may provide a tool for predicting future changes in species distributions in stream ecosystems.

Energy security impacts of a severe drought on the future Finnish energy system

Finland updated its Energy and Climate Strategy in late 2016 with the aim of increasing the share of renewable energy sources, increasing energy self-sufficiency and reducing greenhouse gas emissions. Concurrently, the issue of generation adequacy has grown more topical, especially since the record-high demand peak in Finland in January 2016. This paper analyses the Finnish energy system in years 2020 and 2030 by using the EnergyPLAN simulation tool to model whether different energy policy scenarios result in a plausible generation inadequacy. Moreover, as the Nordic energy system is so heavily dependent on hydropower production, we model and analyse the impacts of a severe drought on the Finnish energy system. We simulate hydropower availability according to the weather of the worst drought of the last century (in 1939-1942) with Finnish Environment Institutes Watershed Simulation and Forecasting System and we analyse the indirect impacts via reduced availability of electricity imports based on recent realised dry periods. Moreover, we analyse the environmental impacts of hydropower production during the drought and peak demand period and the impacts of climate change on generation adequacy in Finland. The results show that the scenarios of the new Energy and Climate Strategy result in an improved generation adequacy comparing to the current situation. However, a severe drought similar to that experienced in 1940s could cause a serious energy security threat.

The Climate Change and Groundwater Regimes in Finland

The boreal climate zone, which Finland is situated in, causes four seasons: cold winters, cool springs, short summers, and wet autumns. The aquifers are shallow and residence times are from a few months to a few years. The groundwater levels increase or decrease according to season changes. The annual cycle depends on the groundwater regime. The analysis of the years 1974-2007 indicates that the groundwater regimes have slightly moved northwards. The climate change scenarios for temperature and precipitation together with the Watershed Simulation and Forecast-ing System project that this trend will continue. The prognosis is, that winters will shorten, and the summer periods will become longer and warmer. Dryness will increase during summertime while wetness will increase during wintertime. It is possible that in the future there will only be two sea-sons: wet winters and dry summers.

Spatiotemporal Hydroclimate Variability in Finland: Past Trends

AbstractOver the past decades, Finland has experienced changes in its climate: temperature and precipitation have increased, resulting in varying runoff patterns. These trends are well studied, but the changes in interannual variability are less known, despite their importance for understanding climate change. This research aims to assess spatiotemporal changes in variability of temperature, precipitation, and runoff for 1962–2014 at the subbasin scale in Finland. Temporal changes in variability were analyzed by constructing moving-window median absolute deviation time series at annual and seasonal scales. Subbasins with similar patterns of temporal variability were identified using principal component analysis and agglomerative hierarchical clustering. Presence of monotonic trends in variability was tested. Distinct areas with similar patterns of statistically significant changes in variability were found. Decreases in annual, winter, and summer temperature variability were discovered across Finland, in ...