Lake Volume Monitoring from Space

Lakes are integrators of environmental change occurring at both the regional and global scale. They present a wide range of behavior on a variety of timescales (cyclic and secular) depending on their morphology and climate conditions. Lakes play a crucial role in retaining and stocking water, and because of the significant global environmental changes occurring at several anthropocentric levels, the necessity to monitor all morphodynamic characteristics [e.g., water level, surface (water contour) and volume] has increased substantially. Satellite altimetry and imagery are now widely used together to calculate lake and reservoir water storage changes worldwide. However, strategies and algorithms to calculate these characteristics are not straightforward, and specific approaches need to be developed. We present a review of some of these methodologies by using lakes over the Tibetan Plateau to illustrate some critical aspects and issues (technical and scientific) linked to the observation of climate change impact on surface waters from remote sensing data. Many authors have measured water variation using the limited remote sensing measurements available over short time periods, even though the time series are probably too short to directly link these results with climate change. Indeed, there are many processes and factors, like the influence of lake morphology, that are beyond observation and are still uncertain. The time response for lakes to reach a new state of equilibrium is a key aspect that is often neglected in current literature. Observations over a long period of time, including maintaining a constellation of comprehensive and complementary satellite missions with service continuity over decades, are therefore necessary especially when the ground gauge network is too limited. In addition, the design of future satellite missions with new instrumental concepts (e.g., SAR, SARin, Ka band altimetry, Ka interferometry) will also be suitable for complete monitoring of continental waters.     

Use of SARAL/AltiKa over Mountainous Lakes,Intercomparison with Envisat Mission

The SARAL/AltiKa project is based on a single Ka band altimeter (35.75 GHz), which is the first oceanography altimeter to operate at such a high frequency. Ka band offers reduced radar footprint in comparison to traditional Ku band altimeters and negligible ionospheric effects. In this paper we present and evaluate benefits of AltiKa altimeter applied in the study of lakes in Andean chain in South America. Water levels time series obtained with Envisat/RA-2 and SARAL/AltiKa altimeters over 17 lakes of various sizes are calculated and compared to in situ observations. SARAL/AltiKa measurements tend to be extremely well correlated with in situ measurements and offer significant improvements compared to the Envisat mission.     

Petrographische und magnetische Untersuchungen an einem Vorkommen von Basalt und einem genetisch damit verbundenen Quarzit im Mittleren Buntsandstein der Eifel

Zusammenfassung Die plateauf?rmige Kuppe des Stromberges südlich von Blankenheim (Eifel) wird als lokal begrenzter Einkieselungshorizont im Mittleren Buntsandstein erkannt. Die zur Kl?rung seiner Genese durchgeführten petrographischen und magnetischen Untersuchungen haben ergeben, da? der Stromberg von einem ann?hernd pilzf?rmigen Vorkommen von Olivin-Nephelinit unterlagert ist. Es wird wahrscheinlich gemacht, da? über dem fast zentral gelegenen Zufuhrkanal durch Einwirkung von postvulkanischen alkalischen L?sungen und erh?hter W?rmeausstrahlung im Buntsandstein eine L?sung von Kiesels?ure erfolgte, die nach Abklingen dieser Einwirkungen im Grundwasserbereich dann zur Bildung eines Einkieselungshorizontes führte. Herrn Prof. Dr.Carl W. Correns zum 70. Geburtstag gewidmet.