Kirsti Korkka-Niemi

Mapping the low enthalpy geothermal potential of shallow Quaternary aquifers in Finland

BackgroundEU member states have concluded an agreement that renewable energy will cover 20% of the total energy production by 2020. To achieve this target, it is essential to investigate all possibilities for renewable energy production. We investigated whether groundwater could provide a shallow geothermal energy resource, and to what extent it could meet the demands for heating buildings in Finland. Our research focused on classified aquifers, namely, groundwater areas that are zoned for urban or industrial use.MethodsThe heating potential of Finnish aquifers was estimated based on the flux, temperature and heat capacity of groundwater and the efficiency of heat pumps. The design power of residential buildings was then simulated. Finally, the design power was divided by the groundwater power to determine the ability of groundwater to heat buildings.ResultsApproximately 56,500 ha of Finnish aquifers are zoned for urban or industrial land use. These aquifers contain 40 to 45 MW of power. In total, 55 to 60 MW of the heat load could be utilised with heat pumps, meaning that 25% to 40% of annually constructed residential buildings could be heated utilising groundwater in Finland.ConclusionsThere are several hundred sites in Finland where groundwater could be used for energy utilisation, and groundwater could thus be a significant source of local renewable energy. However, because of geological and geographical factors, groundwater cannot be considered as a nationwide energy source. Future research should define the area-specific limiting factors for groundwater energy use.

Comparison of the AVI, modified SINTACS and GALDIT vulnerability methods under future climate-change scenarios for a shallow low-lying coastal aquifer in southern Finland

A shallow unconfined low-lying coastal aquifer in southern Finland surrounded by the Baltic Sea is vulnerable to changes in groundwater recharge, sea-level rise and human activities. Assessment of the intrinsic vulnerability of groundwater under climate scenarios was performed for the aquifer area by utilising the results of a published study on the impacts of climate change on groundwater recharge and sea-level rise on groundwater–seawater interaction. Three intrinsic vulnerability mapping methods, the aquifer vulnerability index (AVI), a modified SINTACS and GALDIT, were applied and compared. According to the results, the degree of groundwater vulnerability is greatly impacted by seasonal variations in groundwater recharge during the year, and also varies depending on the climate-change variability in the long term. The groundwater is potentially highly vulnerable to contamination from sources on the ground surface during high groundwater recharge rates after snowmelt, while a high vulnerability to seawater intrusion could exist when there is a low groundwater recharge rate in dry season. The AVI results suggest that a change in the sea level will have an insignificant impact on groundwater vulnerability compared with the results from the modified SINTACS and GALDIT. The modified SINTACS method could be used as a guideline for the groundwater vulnerability assessment of glacial and deglacial deposits in inland aquifers, and in combination with GALDIT, it could provide a useful tool for assessing groundwater vulnerability to both contamination from sources on the ground surface and to seawater intrusion for shallow unconfined low-lying coastal aquifers under future climate-change conditions.RésuméUn aquifère côtier libre, peu profond, du Sud de la Finlande, entouré par la mer baltique, est vulnérable aux changements de recharge de la nappe, d’élévation du niveau de la mer, et des activités humaines. L’évaluation de la vulnérabilité intrinsèque des eaux souterraines sous des scénarios climatiques a été effectuée pour la zone aquifère en utilisant les résultats d’une étude publiée sur les impacts du changement climatique sur la recharge de la nappe et l’élévation du niveau de la mer sur l’interaction eau souterraine - eau de mer. Trois méthodes de cartographie de la vulnérabilité intrinsèque, l’indice de vulnérabilité de l’aquifère (AVI), la méthode SINTACS modifiée et la méthode GALDIT, ont été appliquées et comparées. D’après les résultats, le degré de vulnérabilité des eaux souterraines est fortement impacté par les variations saisonnières de la recharge de la nappe durant l’année, et il varie également en fonction de la variabilité du changement climatique sur le long terme. Les eaux souterraines sont potentiellement très vulnérables aux contaminations issues de la surface lors des périodes de forte recharge de la nappe suite à la fonte des neiges, tandis qu’une forte vulnérabilité à l’intrusion de l’eau de mer pourrait avoir lieu lorsque le taux de recharge de la nappe est faible en saison sèche. Les résultats de l’AVI suggèrent que la variation du niveau de la mer aura un impact négligeable sur la vulnérabilité de la nappe, en comparaison des résultats des méthodes SINTACS modifiée et GALDIT. La méthode SINTACS modifiée pourrait être utilisée comme référence pour l’évaluation de la vulnérabilité des eaux souterraines des dépôts glaciaires et inter-glaciaires dans les aquifères à l’intérieur des terres. Combinée à la méthode GALDIT, elle pourrait constituer un outil utile pour évaluer la vulnérabilité des eaux souterraines aux contaminations issues de la surface et à l’intrusion d’eau de mer, pour des aquifères côtiers libres et peu profonds dans des conditions de changement climatique.ResumenUn acuífero costero somero no confinado en tierras bajas en el sur de Finlandia, rodeado por el mar Báltico es vulnerable a los cambios en la recarga del agua subterránea, al ascenso del nivel del mar y a las actividades humanas. La evaluación de la vulnerabilidad intrínseca del agua subterránea para los escenarios climáticos en el área del acuífero se llevó a cabo mediante la utilización de los resultados de un estudio publicado sobre los impactos del cambio climático en la recarga del agua subterránea y el ascenso del nivel del mar en la interacción del agua subterránea - agua de mar. Se aplicaron y compararon tres métodos de mapeo de la vulnerabilidad intrínseca, el índice de vulnerabilidad del acuífero (AVI), un SINTACS modificado y GALDIT. Según los resultados, el grado de vulnerabilidad del agua subterránea es impactado considerablemente por las variaciones estacionales durante el año de la recarga del agua subterránea, y también varía en función de la variabilidad a largo plazo del cambio climático. El agua subterránea es potencialmente altamente vulnerable a la contaminación a partir de fuentes de la superficie del suelo durante las altas tasas de recarga del agua subterránea después del derretimiento de la nieve, mientras que una alta vulnerabilidad a la intrusión de agua de mar podría existir cuando hay una baja tasa de recarga del agua subterránea en la estación seca. Los resultados de AVI sugieren que un cambio en el nivel del mar tendrá un impacto insignificante sobre la vulnerabilidad del agua subterránea en comparación con los resultados del SINTACS modificado y del GALDIT. El método SINTACS modificado podría ser utilizado como una guía para la evaluación de la vulnerabilidad del agua subterránea en los acuíferos de depósitos glaciares y deglaciales del continente, y en combinación con el GALDIT, podría proporcionar una herramienta útil para evaluar la vulnerabilidad del agua subterránea tanto de la contaminación de fuentes en la superficie del suelo como de la intrusión de agua de mar en los acuíferos costeros no confinados poco profundos de las zonas de tierras bajas en las condiciones futuras del cambio climático.摘要芬兰南部一个被波罗的海围绕的浅层低洼沿海含水层很容易受到地下水补给、海平面上升和人类活动变化的的影响。通过利用已经发表的气候变化对地下水补给的影响及海平面上升对地下水—海水相互作用的影响的研究成果,对含水层区域进行了各种气候条件下固有的地下水脆弱性评价。对三种固有的脆弱性绘图方法,即含水层脆弱性指数(AVI)方法、改进的SINTACS方法和GALDIT方法进行了应用和对比。根据结果,地下水脆弱性程度受到一年间地下水补给季节变化的极大影响,长期看也随着气候变化的可变性而变化。地下水在融雪后地下水补给率很高的情况下极易受到地表源的污染,而在干旱季节地下水补给率低的情况下存在着海水入侵的极高风险。与改进的SINTACS方法和GALDIT方法相比,含水层脆弱性指数(AVI)方法结果表明,海平面变化对地下水的脆弱性有重要影响。改进的SINTACS方法可用作内陆含水层冰川沉积和冰消期沉积地下水脆弱性评价的指南,与GALDIT方法结合在一起,可提供一个有用的工具,来评价将来气候变化条件下浅层非承压低洼沿海含水层地下水对地表源污染和海水入侵的脆弱性。ResumoUm aquífero costeiro raso de baixa altitude não confinado no sul da Finlândia cercado pelo Mar Báltico é vulnerável a mudanças na recarga das águas subterrâneas, elevação do nível do mar e atividades humanas. Avaliação da vulnerabilidade intrínseca das águas subterrâneas sob cenários climáticos foi realizada para a área do aquífero utilizando os resultados de um estudo publicado nos impactos da mudança climática na recarga das águas subterrâneas e na elevação do nível do mar na interação entre águas subterrâneas e água do mar. Três métodos de mapeamento de vulnerabilidade intrínsecos, o índice de vulnerabilidade do aquífero (IVA), o SINTACS modificado e GALDIT, foram aplicados e comparados. De acordo com os resultados, o grau de vulnerabilidade das águas subterrâneas é impactado com grandeza por variações sazonais na recarga das águas subterrâneas durante o ano, e também varia dependendo da variabilidade de mudanças climáticas a longo prazo. As águas subterrâneas são potencialmente muito vulneráveis a contaminação a partir de fontes superficiais durante as altas taxas de recarga das águas subterrâneas após derretimento da neve, enquanto a alta vulnerabilidade à intrusão de água do mar pode existir quando há uma baixa taxa de recarga de águas subterrâneas na estação seca. Os resultados do IVA sugerem que uma alteração no nível do mar irá ter um impacto insignificante na vulnerabilidade das águas subterrâneas em comparação com os resultados dos SINTACS modificado e GALDIT. O método SINTACS modificado poderia ser usado como um guia para a avaliação da vulnerabilidade das águas subterrâneas de depósitos glaciais e não glaciais em aquíferos interiores, e em combinação com GALDIT, poderia fornecer uma ferramenta útil para avaliar a vulnerabilidade das águas subterrâneas para ambas contaminações a partir de fontes superficiais e a intrusão da água do mar para aquíferos rasos costeiros de baixa altitude não confinados sob futuras condições de mudanças climáticas.

Observations on groundwater‐surface water interactions at River Vantaa, Finland

Purpose – The purpose of this paper is to emphasize the importance of groundwater‐surface water interaction when studying, modeling and assessing climate change impacts on river water management.Design/methodology/approach – The investigations were focused on River Vantaa and its tributaries in southern Finland. The main methods used involved aerial infrared photography, thermal profiling of river sediments, water quality measurements, isotopic composition of oxygen and hydrogen δ18O, δ2H and river water temperature measurements. The authors present the first results of the field measurements targeted to identify the groundwater recharge and discharge zones within the river system.Findings – Groundwater discharge zones were found to have a significant impact on water quality and volume in River Vantaa and its tributaries. In the drainage basin, the aerial infrared photography seemed to be a feasible and cost‐effective method to identify areas of groundwater discharge across the entire river basin. Around ...