Pertti Ala-aho

Environmental tracers and indicators bringing together groundwater, surface water and groundwater-dependent ecosystems: importance of scale in choosing relevant tools

Groundwater–surface water (GW–SW) interactions cover a broad range of hydrogeological and biological processes and are controlled by natural and anthropogenic factors at various spatio-temporal scales, from watershed to hyporheic/hypolentic zone. Understanding these processes is vital in the protection of groundwater-dependent ecosystems increasingly required in water resources legislation across the world. The use of environmental tracers and indicators that are relevant simultaneously for groundwater, surface water and biocenoses–biotope interactions constitutes a powerful tool to succeed in the management task. However, tracer type must be chosen according to the scale of interest and tracer use thus requires a good conceptual understanding of the processes to be evaluated. This paper reviews various GW–SW interaction processes and their drivers and, based on available knowledge, systemises application of conservative tracers and semi-conservative and reactive environmental indicators at different spatial scales. Biocenoses–biotopes relationships are viewed as a possible transition tool between scales. Relation between principal application of the environmental tracers and indicators, examples and guidelines are further proposed for examining GW–SW interactions from a hydrogeological and biological point of view by demonstrating the usability of the tracers/indicators and providing recommendations for the scientific community and decision makers.

Impact of peatland drainage and restoration on esker groundwater resources: modeling future scenarios for management

Esker aquifers are common groundwater bodies in Europe. Management of these aquifers should take account of the sustainability of groundwater-dependent ecosystems and land use in an integrated way. An unconfined esker aquifer in northern Finland was modelled with MODFLOW to determine how groundwater resources are impacted by the surrounding peatland drainage scheme and to simulate scenarios for possible drainage restoration. The impacts of groundwater abstraction and climate change were also simulated. A calibration-constrained Monte Carlo method was used to provide information on the uncertainties associated with model predictions. The results suggest that peatland drainage in the vicinity of eskers can have a significant role in lowering the water table, even though climate variability may mask these impacts. Drainage restoration by filling the ditches might have positive impacts on the aquifer water levels. Comparison of water-table changes caused by peatland drainage with the changes brought by water abstraction and climate variability helped to quantify impacts of different land-use scenarios and facilitated discussion with the local stakeholders. Based on this study, more attention should be devoted to peatland drainage schemes in integrated groundwater management of esker aquifers.RésuméLes aquifères au sein des eskers sont des masses d’eau souterraine communes en Europe. La gestion de ces aquifères doit tenir compte de la durabilité des écosystèmes tributaires des eaux souterraines et de l’utilisation des terres de manière intégrée. Un aquifère libre au sein d’esker dans le nord de la Finlande a été modélisé avec MODFLOW afin de déterminer comme les ressources en eau souterraine sont impactées par les modalités de drainage des tourbières environnantes et pour simuler des scénarios de restauration possible de drainage. Les impacts de prélèvement des eaux souterraines et du changement climatique ont également été simulés. La méthode de calibration Monte Carlo a été utilisée pour fournir une information sur les incertitudes associées aux prévisions du modèle. Les résultats suggèrent que le drainage des tourbières dans le voisinage des eskers peut avoir un rôle significatif sur l’abaissement du niveau phréatique, même si la variabilité climatique peut masquer ces impacts. La restauration du drainage en comblant des fossés peut avoir des impacts positifs sur les niveaux piézométriques de l’aquifère. La comparaison des modifications des niveaux piézométriques causés par le drainage des tourbières avec les modifications induites par les prélèvements en eau souterraine et la variabilité climatique a aidé à quantifier les impacts des différents scénarios d’utilisation des terres et a facilité la discussion avec les parties prenantes locales. A partir de cette étude, plus d’attention devrait être accordée aux modalités de drainage des tourbières dans la gestion intégrée des eaux souterraines des aquifères d’esker.ResumenLos acuíferos en esker son cuerpos comunes de agua subterránea en Europa. El manejo de estos acuíferos debe tener en cuenta la sostenibilidad de los ecosistemas que dependen del agua subterránea y del uso de la tierra de una forma integrada. Se modeló un acuífero esker no confinado en el norte de Finlandia con MODFLOW para determinar como los recursos de agua subterránea son impactados el esquema de drenaje de una turbera circundante y para simular escenarios para una posible restauración del drenaje. También se simularon los impactos de la extracción de agua subterránea y del cambio climático. Se utilizó el método Monte Carlo restringido por el calibrado para proveer información sobre las incertidumbres asociadas con las predicciones del modelo. Los resultados sugieren que el drenaje de turberas en la vecindad de los eskers puede tener un rol significativo en el descenso del nivel freático, aun cuando la variabilidad climática pueda enmascarar estos impactos. La restauración del drenaje mediante el relleno de las zanjas podría tener impactos positivos sobre los niveles de agua del acuífero. La comparación de los cambios en el nivel freático causado por el drenaje de las turberas con los cambios acarreados por la extracción del agua y la variabilidad del clima ayudaron para cuantificar los impactos de diferentes escenarios de uso de la tierra y facilitaron la discusión con los actores locales. Basado en este estudio, se debe dedicar más atención a los esquemas de drenaje de las turberas en un manejo integrado del agua subterránea de los acuíferos eskers.摘要蛇形丘含水层是欧洲常见的地下水体。这些含水层的管理应该综合考虑依赖地下水的生态系统的可持续性和土地利用。采用MODFLOW模拟了芬兰北部一个非承压蛇形丘含水层,以确定地下水资源是怎样受到周围泥炭地排水方案影响的,并模拟了可能排水恢复的各种方案。同时还模拟了地下水抽取和气候变化的影响。采用校准约束的蒙特卡洛法提供了与模型预测相关的不确定性方面的信息。结果表明,蛇形丘附近的泥炭地排水在降低水位中具有重要作用,尽管气候变异可能掩饰着这些影响。通过填充壕沟使排水恢复可能对含水层水位有积极影响。泥炭地排水造成的水位变化与抽水及气候变异导致的变化对比有助于定量不同土地利用方案的影响,促进与当地利益相关人之间的探讨。在本研究的基础上,应该更加注重蛇形丘含水层综合管理中的泥炭地排水。ResumoOs aquíferos esker são massas de água subterrânea comuns na Europa. A gestão destes aquíferos deve ter em conta, de forma integrada, a sustentabilidade dos ecossistemas dependentes de água subterrânea e o uso do solo. Um aquífero esker não confinado no norte da Finlândia foi modelado com o MODFLOW para determinar como os recursos hídricos subterrâneos são afetados na envolvência de um sistema de drenagem de turfeiras e para simular cenários para uma possível restauração da drenagem. Os impactes da captação de águas subterrâneas e de alterações climáticas também foram simulados. O método de Monte Carlo com restrições de calibração foi utilizado para fornecer informações sobre as incertezas associadas às previsões do modelo. Os resultados sugerem que a drenagem das turfeiras na vizinhança de eskers pode ter um papel significativo no rebaixamento do nível freático, apesar da variabilidade climática poder encobrir esses impactes. A restauração da drenagem através do preenchimento das valas pode ter impactes positivos sobre os níveis da água no aquífero. A comparação das variações do nível freático causadas por drenagem de turfeiras com as variações resultantes da captação de água e da variabilidade climática ajudou a quantificar os impactes de diferentes cenários de uso do solo e facilitou a discussão com os atores locais interessados. Com base neste estudo, conclui-se que se deve dedicar mais atenção aos sistemas de drenagem de turfeiras na gestão integrada das águas subterrâneas em aquíferos esker.

The value of scientific information on climate change: a choice experiment on Rokua esker, Finland

This article presents an application of the choice experiment method in order to provide estimates of economic values generated by water quantity improvements in the environment. More importantly, this is the first choice experiment study valuing scientific information and in particular scientific information on climate change. The case study of interest is Rokua in Northern Finland, a groundwater dependent ecosystem very sensitive to climate change and natural variability. The study deals with the uncertainty about the actual dynamics of the system and the effect of future climate change by exploring whether the public values sustained provision of resources for scientific research to better understand long-term environmental changes in Rokua. Data are analysed using a nested multinomial logit and an error component model. Evidence from this study suggests that individuals are willing to pay in order to assure scientific research so as to better understand long-term environmental changes. As a result, policy should consider investing in and supporting related research. Other aspects of water management policy valued by the public are water quantity, recreation, and total land income.

The Contribution of Non-Use Values to Inform the Management of Groundwater Systems: The Rokua Esker, Northern Finland

Rokua in Northern Finland is a groundwater dependent ecosystem very sensitive to climate change and natural variability. As such, the water level of most of the lakes is a function of the level of the groundwater table of the esker which is naturally recharged. The management of an ecosystem like this is very challenging and complex because of the many associated use and non-use values. The scope of this study is to expose, apart from the use values, the nonmarket values attached to the ecosystems services of groundwater systems and reveal their importance. In particular, this chapter illustrates the contribution of stated preference methods to orient policy making and presents results from an application of a choice experiment and contingent valuation method regarding ground water quantity. General public�s elicited values highlight the importance of water management policy which contributes to the sustainability of groundwater dependent ecosystems. Importantly results highlight the need to broaden the policy options beyond the consideration of market and use values of groundwater systems. Instead these systems should be considered as part of the broader ecosystems and broader services considered in decision making.

A GIS-based method for predicting groundwater discharge areas in esker aquifers in the Boreal region

In the Boreal region, anticline eskers aquifers are recharged in upland hillslopes and water discharges in the surrounding lowlands. Organic peat soils often confine the aquifer discharge area and drainage of these confining peat layers can decrease the flow resistance in the peat soil, which may cause unintentional groundwater level drawdown. This poses a risk to groundwater bodies and their good water status in the Boreal region. To increase awareness of the risk areas and to assess potential areas for drainage restoration, a model based on geographical information systems (GIS) was developed to predict the locations of high groundwater discharge. The output of the model is a map highlighting the potential areas where groundwater is more likely to discharge. The model output was validated with stream flow data collected from two eskers located in Finland. The developed GIS model is recommended as a tool to delineate groundwater protection areas where drainage of the peat soil should not be allowed and for assessing areas where such drainage networks could be restored to protect vulnerable groundwater systems.