Risikoorientierte Bewilligung von Erdwärmesonden

Zusammenfassung: Die Zahl an Erdwärmesonden nimmt in ganz Europa stetig zu. Wie mit anderen Technologien der Energiegewinnung sind auch mit Erdwärmesonden Risiken verbunden. Deshalb bedarf es Leitlinien als Grundlage für die Bewilligungsverfahren, die den Bau und Betrieb einer solchen Anlage regeln. Um dabei den zu erwartenden Nutzen gegen mögliche Risiken abwägen zu können, sind Kenntnisse über die hydrogeologischen Verhältnisse am Standort und die dort stattfindenden Prozesse erforderlich. Am Beispiel des Erdwärmenutzungskonzepts des Kantons Basel-Landschaft wird gezeigt, wie die Bewilligung von Erdwärmesonden differenziert geregelt werden kann, und wie die geologischen Merkmale einer Region in ein Erdwärmenutzungskonzept integriert werden können. Dabei werden insbesondere Karstgebiete, Gebiete mit der Gefahr des Gebirgsquellens und der Subrosion, Gewässerschutzbereiche, und Gebiete mit Grundwasserstockwerkbau oder gespannten Grundwasserverhältnissen berücksichtigt. Der Artikel will damit einen Beitrag zur derzeit stattfindenden gesellschaftlichen Diskussion über den Nutzen und die Risiken der untiefen Geothermie leisten, indem er Risiken durch den Bau und Betrieb von Erdwärmesonden beschreibt, und Möglichkeiten aufzeigt, diese Risiken in der Bewilligungspraxis zu berücksichtige

Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review

Background, aim, and scope: Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated. Approach: We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries. Have climate change and land-use change increased erosion and sediment loads in rivers? Do we have indications of an increase in riverbed clogging? Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging? Results: Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish. Discussion: Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades. Conclusions: Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor. Recommendations and perspectives: Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently neede

Methods to describe and predict soil erosion in mountain regions

Suitable methods to describe and predict soil degradation in mountain areas with low accessibility, steep topography and extreme climate are urgently needed for suitable planning processes in Alpine regions under global change regime. Aerial photograph mapping has been proven to be a valuable tool in surveying landslide development over time. However, landslides> 10 m(2) as well as sheet erosion have been difficult to detect. Thus, the beginning of potentially heavy soil degradation cannot be tracked with aerial photographs. As an early warning system for soil degradation, we analyzed gradients of stable isotopes of carbon and nitrogen from upland (erosion source) to wetland soils (erosion sink). Oxic upland soils and anoxic wetlands differ in their isotopic signature, due to differing isotopic fingerprints of aerobic and anaerobic metabolism in soils. Gradients of delta N-15 and delta C-13 in soils reflected erosion of material. However, if soils were fertilized with manure, the delta N-15 profiles were obscured. To quantify soil erosion, we noted that existing soil erosion models are generally unsuitable for mountain regions. As a first step, we developed a new modelling concept with a special algorithm for spatial discretization with irregular grids. The latter ensures three-dimensional water flow routing that is controlled by topography and not by the underlying algorithm. Regarding quantification of soil erosion an improvement and validation of existing modelling approaches or development of new models is urgently needed. (C) 2008 Elsevier B.V. All rights reserved

Reflectance Modeling for Real Snow Structures Using a Beam Tracing Model

It is important to understand reflective properties of snow, for example for remote sensing applications and for modeling of energy balances in snow packs. We present a method with which we can compare reflectance measurements and calculations for the same snow sample structures. Therefore, we first tomograph snow samples to acquire snow structure images (6 x 2 mm). Second, we calculated the sample reflectance by modeling the radiative transfer, using a beam tracing model. This model calculates the biconical reflectance (BR) derived from an arbitrary number of incident beams. The incident beams represent a diffuse light source. We applied our method to four different snow samples: Fresh snow, metamorphosed snow, depth hoar, and wet snow. The results show that (i) the calculated and measured reflectances agree well and (ii) the model produces different biconical reflectances for different snow types. The ratio of the structure to the wavelength is large. We estimated that the size parameter is larger than 50 in all cases we analyzed. Specific surface area of the snow samples explains most of the difference in radiance, but not the different biconical reflectance distributions. The presented method overcomes the limitations of common radiative transfer models which use idealized grain shapes such as spheres, plates, needles and hexagonal particles. With this method we could improve our understanding for changes in biconical reflectance distribution associated with changes in specific surface area.ISSN:1424-822

Evaluation and application of a portable rainfall simulator on subalpine grassland

Rainfall simulators are commonly used instruments to study sheet erosion, since they can be set to predefined values like rainfall duration and quantity. The comparison between different irrigation studies is difficult, because general standards or methodological protocols do not exist for rainfall simulators. One goal of this study was to assess the suitability of a novel field hybrid rainfall simulator (FH simulator) that combines characteristics of a spray nozzle and a drop former rain simulator for erosion research. The FH simulator was compared to a larger scale laboratory drop former simulator (DF simulator) with a 7 mdrop height by looking at the raindrop distribution, kinetic energy and the triggered runoff and sediment yield. Two soils with different textures were irrigated. A second goal of this study was to quantify the influence of vegetation and soil structure stability on soil erosion and runoff in a subalpine grassland area. Soil erosion and runoff reduction in relation to plant cover have been studied by numerous scientists in Mediterranean ecosystems, but researches in alpine grassland are spare. The kinetic energy, drop size, triggered runoff and sediment yield of both rain simulators were comparable, but kinetic energy and drop size differed for both simulators from natural rain. The clayish soil with stable soil structure and the silty soil with loose single grain structure differed significantly in runoff and sediment yield. Vegetation cover and sediment yield were correlated exponentially and soil structure stability improved significantly with increasing vegetation cover. Vegetation cover had no influence on surface runoff. These results demonstrate that vegetation cover plays a crucial role in alpine soils for soil structure stability and erosion. Even though it was not possible to achieve natural rain conditions with the used simulators, the proposed field simulator is a useful tool in steep alpine terrain to study relative differences in the effects of rain erosion on soils with differing characteristics and vegetation cover

Risikoorientierte Bewilligung von Erdwärmesonden

Die Zahl an Erdwärmesonden nimmt in ganz Europa stetig zu. Wie mit anderen Technologien der Energiegewinnung sind auch mit Erdwärmesonden Risiken verbunden. Deshalb bedarf es Leitlinien als Grundlage für die Bewilligungsverfahren, die den Bau und Betrieb einer solchen Anlage regeln. Um dabei den zu erwartenden Nutzen gegen mögliche Risiken abwägen zu können, sind Kenntnisse über die hydrogeologischen Verhältnisse am Standort und die dort stattfindenden Prozesse erforderlich. Am Beispiel des Erdwärmenutzungskonzepts des Kantons Basel-Landschaft wird gezeigt, wie die Bewilligung von Erdwärmesonden differenziert geregelt werden kann, und wie die geologischen Merkmale einer Region in ein Erdwärmenutzungskonzept integriert werden können. Dabei werden insbesondere Karstgebiete, Gebiete mit der Gefahr des Gebirgsquellens und der Subrosion, Gewässerschutzbereiche, und Gebiete mit Grundwasserstockwerkbau oder gespannten Grundwasserverhältnissen berücksichtigt. Der Artikel will damit einen Beitrag zur derzeit stattfindenden gesellschaftlichen Diskussion über den Nutzen und die Risiken der untiefen Geothermie leisten, indem er Risiken durch den Bau und Betrieb von Erdwärmesonden beschreibt, und Möglichkeiten aufzeigt, diese Risiken in der Bewilligungspraxis zu berücksichtigen. The number of borehole heat exchangers (BHEs) is continuously rising in Europe. Just like other energy producing technologies, there are risks associated with BHE systems. Therefore, guidelines are necessary for regulating the construction and operation of such installations. In order to be able to trade-off the expected benefits against possible risks, knowledge about the local hydrogeological conditions, and the processes taking place, is required. Using the geothermal energy use concept developed for Canton Basel-Landschaft as an example, it is shown how the approval of BHE systems can be regulated in a differentiated way, and how the geological characteristics of a region can be integrated into a geothermal energy use concept. In particular, karst areas, areas with the risk of ground swelling and subrosion, water protection areas, and areas with multiple or confined aquifers are considered. The article aims at making a contribution to the present societal discussion about the benefits and risks of shallow geothermal energy systems by describing the risks associated with BHEs, and by presenting options to account for these risks in approval practice. Geothermie in der Nordwestschwei

Climate and land-use changes affecting river sediment and brown trout in alpine countries--a review

BACKGROUND, AIM, AND SCOPE: Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated. APPROACH: We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries. Have climate change and land-use change increased erosion and sediment loads in rivers? Do we have indications of an increase in riverbed clogging? Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging? RESULTS: Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish. Discussion: Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades. Conclusions: Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor. Recommendations and perspectives: Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently needed