Using Spatial Data for Geo-Environmental Studies

The physically-based spatially-distributed model PROMET (Processes of Radiation, Mass and Energy Transfer) is applied to the Greater Damascus Basin, which is considered as one of the most important basins in Syria, to serve as a case study of using spatial data for Geo-environmental studies. Like most areas of the Middle East, the study area is characterized by large temporal and spatial variations in precipitation and by limited water resources. Due to the increasing water demand caused by the economic development and the rapid growth of population, the study area is expected to suffer from further water shortages in the future. This highlights the necessity of developing an integrated Decision Support System (DSS) to evaluate strategies for efficient and sustainable water resources management in the basin, taking into consideration global environmental changes and socio-economic conditions. The work presented here represents the first steps toward achieving this goal through applying a distributed hydrological model (an important component of any integrated DSS for water resources management) to the Greater Damascus Basin utilizing different types of spatial data used as time-dependent (e.g., meteorology) and time-independent (e.g., topography and soil) input parameters. The model PROMET, which was developed within the GLOWA-Danube project as part of the decision support system DANUBIA, is run on an hourly time step (for the period from 1991 to 2005) and a 180*180m spatial resolution to simulate the water and energy fluxes in this basin. The model is embedded within a raster-based GIS-structure which facilitates the integration of the diverse types of spatial data. The spatial information related to topography (such as elevation, slope, and exposition) as well as those related to runoff routing (such as upstream-area, channel width, and downstream proxel) are automatically extracted from Digital Elevation Model (Shuttle Radar Topography Mission, SRTM-90m DEM). The spatial patterns of the different land use/land cover classes are derived from remote sensing data (classification of a cloud-free LANDSAT 7 ETM+ image using the supervised classification algorithm). The spatial fields of meteorological input data are provided on an hourly basis through spatiotemporal interpolation of the measurements of the available weather stations. Spatial information about the soil texture is provided through generalization and aggregation of the soil type classes of the Soil Map of Syria (prepared by USAID) and transferring the soil types to texture classes. Several pedotransfer functions are then used to estimate the soil hydraulic properties for each soil texture class (and each soil layer) found in the study area. While plant physiological parameters (which are assumed to be static, such as minimum stomatal resistance) are estimated for each vegetation class using information taken from literature sources, the temporal evolution of Albedo and Leaf Area Index (LAI) are derived from five cloud-free LANDSAT-7 images acquired at different seasons of the year. The goodness of the results obtained by the model PROMET are verified and/or validated by comparing them either with their corresponding data observed in the filed or with remote sensing-derived information (e.g., snow cover). Two subcatchments are selected for the purpose of calculating the spatially-distributed annual water balances. The results indicate that the modelled mean annual runoff volume fits well with the measured discharge for both chosen subcatchment. In addition, the simulated discharge is compared to the observed one (at seven gauge stations) on a monthly basis, covering the whole simulation period (15 years). The results of the regression analysis for each of these gauge stations (with slope of regression line ranges from 0.79 to 1.04; coefficient of determination 0.69-0.90; and Nash-Sutcliffe Coefficient 0.73-0.95) indicate that there is a good correlation between simulated and observed monthly mean discharge volumes

A soil temperature and energy balance model for integrated assessment of Global Change impacts at the regional scale

The investigation of the impact of Global Change on the basic resources on which life, and man, depends, is the main objective of the environmental science community at the beginning of the 21st century. Advances in information technology, new methods of spatially distributed data retrieval and increased understanding of the physical, chemical and biological processes in the Earth system facilitate integrative models of the dynamic processes under change. Together with the integration of deep actors models from social and economical sciences into a common model framework, scenario runs based on inputs from Regional Climate Models (RCMs) and constrained by prognoses of the future developments in demography, economy and human behaviour are now possible. The objective of the integrative project GLOWA-Danube is the development of such a modelling system and its application on the mesoscale catchment of the Upper Danube river with an area of about 77,000 km2. The decision support system DANUBIA is designed for plausible predictions of the impact of changes in climate, human behaviour and land use on the future of the water and related matter cycles. DANUBIA is able to assist knowledge-based management decisions, by predicting the effects of adaptation and mitigation strategies on the natural resources of the Upper Danube basin. The closure of the water, energy, nitrogen and carbon cycles in the soil-vegetation-atmosphere system relies on the adequate representation of all processes involved and their interaction. To close the energy cycle in the soil-vegetation-atmosphere system and provide valuable input data for biochemical models of soil nitrogen and carbon transformation, this thesis presents the Soil Heat Transfer Module (SHTM) together with an energy balance algorithm of the soil surface for regional scale simulations. SHTM combines simplified physical algorithms for the computation of the actual temperature in the upper soil layers and a dynamic lower boundary condition to represent Climate Change conditions. Changes in soil moisture and soil freezing are explicitly taken into account. The surface ground heat flux as the driving force of the model is provided by an explicit solution of the soil surface energy balance and a snow-soil coupling algorithm, respectively. This thesis shows, that the soil temperature and energy balance modules developed as extensions of PROMET (PROcesses of Matter and Energy Transfer) are ready to bridge the gap between regional scale (up to 100,000 km2) application and the requirement of physical process models in predictive, coupled modelling systems like DANUBIA

Water models and scenarios inventory for the Danube region

This technical report presents an inventory of existing models currently used in the Danube Region by local, regional, national authorities and scientific institutes for the development of a hydro-economic multi-model ensemble for the Danube with a common database. It also presents a first identification of regional scenarios of policy options relevant for river basin management planning.JRC.H.1-Water Resource

The Segmentation of Reflectances from Moderate Resolution Remote Sensing Data for the Retrieval of Land Cover Specific Leaf Area Index

A method is developed to incorporate prior fuzzy knowledge about reflectance behavior of land cover types into the segmentation of reflectances from moderate scale remote sensing data. The procedure is applied to aggregated Landsat TM data and to MODIS data and used to derive land cover type specific leaf area index

Using wind fields from a high resolution atmospheric model for simulating snow dynamics in mountainous terrain

It is widely known that the snow cover has a major influence on the hydrology of Alpine watersheds. Snow acts as temporal storage for precipitation during the winter season. The stored water is later released as snowmelt and represents an important component of water supply for the downstream population of large mountain-foreland river systems worldwide. Modelling the amount and position of the snow water stored in the headwater catchments helps to quantify the available water resources and to estimate the timing of their release. The presented work investigates wind induced snow transport processes which are considered to be crucial for the snow distribution in Alpine catchments. In contradiction to the importance that is attributed to this process, there are only a few studies available which have quantified the transport intensities on the catchment scale. This can be attributed to the fact that the even today not much is known about the spatial characteristics of wind fields which are the driving force for snow transport processes. The presented thesis tries to overcome this lack of information by using physically based wind fields predicted by an atmospheric model (PSU_NCAR MM5 model) for the modelling of the snow cover (simulated by SnowModel). All of the used models are described in great detail in the literature, validated in many different regions, and can be seen as applicable with regard to the goal of this work. As snow transport processes are particularly important on a comparatively small scale a numerical inclusion of the responsible processes into regional models is inadequate. Hence, while this study itself mainly uses smaller scale physically based models, a parameterisation scheme is presented at the end of this thesis that is able to incorporate its main findings into larger scale models. All of the presented work was carried out at the Berchtesgaden National Park. The site is highly appropriate because of the extremely rough terrain and the good accessibility. Furthermore, the instrumentation of the area is comparatively good and the data sources (GIS, field campaign data) are excellent. The thesis deals with the winter seasons (August - July) 2003/2004 and 2004/2005. For this period, data of 5 meteorological stations, 1 field campaign and two Landsat ETM+ images were available. As mentioned before, physically based wind fields were used as input for the snow transport modelling. An operational coupling between atmospheric model and snow transport model was not pursued because of the high computational costs of the atmospheric model. Thus, a library of representative wind fields was produced in advance and linked to the snow transport model via operational German weather service Lokalmodell results. This becomes possible because of the comparability of a MM5 model layer with one of the Lokalmodell model layers. To link the wind field library to the snow model all of the predicted MM5 wind fields were characterised by information available from the Lokalmodell. This enable an easy detection of the MM5 wind field which is closest to the real climatic wind conditions at any Lokalmodell time step (1 hour). The produced MM5 wind fields have a spatial resolution of 200 meters. As an initial check if the snow cover simulation of SnowModel in association with the wind field library delivers adequate results with respect to the snow distribution, model runs were first carried out at the 200m scale. An analysis of the results showed that the coupled routine delivers acceptable results. It could be seen that with the use of the MM5 wind fields, the snow cover becomes more anisotropic and that transport processes over crests as well as sublimation processes are predicted to become more intensive. Nevertheless, a higher resolution was needed to quatify the effects and to validate the results. In a subsequent step the MM5 wind fields were downscaled to a 30m resolution. The downscaling procedure lead to a better agreement between modelled and measured wind speeds. The resulting 30m wind fields were used for high resolution model runs which were validated on the basis of the field campaign and remotely sensed data. A comparison with model runs using wind fields interpolated from station data showed that the runs performed with the MM5 wind fields deliver more consistent and comprehensible results. Subsequently, the validity of the model is discussed on the basis of selected results. High resolution model results indicated that snow transport processes are effective at high elevations but virtually negligible for regions below of 1800m a.s.l.. Furthermore, it could be seen that the correct estimation of snow transport from the surrounding areas to glaciers becomes possible by using the MM5 wind fields. Very high modelled sublimation rates at the mountains crests are discusses with respect to their importance on the water balance. Furthermore, the influence of preferential snow deposition and snow slides which were not numerically predicted in this work were discusses. Additionally, the applicability of atmospheric model results as input for land-surface models could be confirmed. In a final step a model scheme is presented that would make the generated information available for regional scale models. This model parameterization scheme which is based on the modelled 30m snow water equivalent distribution within the test area was used for this area. The scheme allows for a quick and simple description of the subscale snow heterogeneity in regional scale models. This can lead to considerable model improvements with respect to the description of the energy and moisture fluxes to and from the surface. An accurate description of these fluxes is essential for an accurate simulation of the melt period and, therefore, for an acceptable calculation of the runoff generation in larger scale models.Der Einfluss der Schneedecke auf die Hydrologie Alpiner Einzugsgebiete ist weithin bekannt und in der Literatur eindrucksvoll beschrieben. Saisonale Schneedecken fungieren als temporäre Speicher für den Niederschlag. Das gebundene Wasser wird den Fließgewässern verzögert als Schmelzwasser zugeführt und bestimmt damit zumindest zeitweise deren Abflusshöhe und –menge. Die Modellierung von mengenmäßigem Inhalt und räumlicher Ausdehnung des Schneespeichers ist hilfreich für die Quantifizierung der vorhandenen Wasserressourcen und für die Bestimmung des Zeitpunkts, zu dem die gespeicherten Wassermengen verfügbar werden. Die Intensität der Schneeschmelze hängt dabei, neben der absoluten räumlichen Lage, auch von der räumlichen Heterogenität der Schneedecke ab. In der vorliegenden Arbeit wurde der Einfluss von wind-induzierten Schneetransportprozessen auf die Heterogenität der Alpinen Schneedecke untersucht. Als Testgebiet wurde der Nationalpark Berchtesgaden ausgewählt. Dieses Testgebiet kann aufgrund seiner hohen Reliefenergie als ideal für die durchgeführten Untersuchungen gelten, da Schneetransportprozesse hier besonders effektiv sind. Die Instrumentierung des Parks ist im Hinblick auf die verfügbaren meteorologischen Stationen außerordentlich gut. Darüber hinaus liegen flächendeckende Informationen über die Geländehöhe und die Vegetation in Form eines hoch aufgelösten (10m) Geographischen Informationssystems (GIS) vor. Für den Untersuchungszeitraum (Wintersaison 2003/2004 und 2004/2005, jeweils gerechnet von August bis Juli) liegen Daten von 5 meteorologischen Stationen, einer Feldkampagne und zwei Landsat ETM+ Bildern vor. Windinduzierter Schneetransport wird in der Literatur häufig als der bestimmende Prozess für die Heterogenität der Schneedecken in gebirgigen Gebieten angesehen. In starkem Kontrast zu der diesem Prozess zugestandenen Bedeutung, steht die Anzahl der Veröffentlichungen, die die numerische Untersuchung der Effektivität desselben zum Inhalt haben. Das liegt vor allem in der Tatsache begründet, dass die Berechnung von qualitativ hochwertigen Windfeldern in gebirgigem Terrain bis heute nahezu unmöglich ist. Diese allerdings sind von zentraler Bedeutung, um quantitative Aussagen über die Richtung der Verlagerung von Schneemengen zu treffen, und um die entsprechenden Erosions- wie Akkumulationsgebiete zu lokalisieren. Für eine möglichst genaue Charakterisierung der Windfelder im Untersuchungsgebiet wurden in der vorliegenden Arbeit physikalisch basierte Windfelder mit Hilfe des PSU-NCAR MM5 Atmosphärenmodells berechnet. Diese wurden im Anschluss in dem etablierten Schneemodell SnowModel als Antrieb für die Schneetransportroutine (SnowTran-3D) verwendet. Da eine direkte Kopplung von Atmosphärenmodell und Schneemodell unter den heute gegebenen technischen Voraussetzungen zu einer unrealistisch hohen Modell-Laufzeit geführt hätte, wurde eine alternative Methode gewählt: die Windfelder wurden separat berechnet und eine Bibliothek repräsentativer Windfelder für das Untersuchungsgebiet erzeugt. Die zeitliche Synchronisation zwischen Windfeldbibliothek und Schneemodell wurde über das operationelle, mesoskalige Wettervorhersage-Modell des Deutschen Wetterdienstes (DWD), das Lokalmodell hergestellt. Dies wurde aufgrund der Tatsache möglich, dass bestimmte Modellausgaben von Lokalmodell und MM5 im 700 hPa Niveau vergleichbar sind. Um das richtige Windfeld für einen Schneemodellzeitschritt aus der zuvor erzeugten MM5 Windfeldbibliothek auszuwählen, wurden mittlere Windvektoren der MM5 Windfelder mit mittleren Vektoren der entsprechenden Lokalmodell Windfelder verglichen. So wurde es möglich, zu jedem Modellzeitschritt des Lokalmodells (eine Stunde) ein MM5 Windfeld zu selektieren und im Schneemodel anzuwenden. Die generierten MM5 Windfelder haben eine räumliche Auflösung von 200m. Für eine prinzipielle Überprüfung der Funktionalität des Schneemodels in Verbindung mit einer MM5 Windfeldbibliothek, wurden erste Schneemodelläufe auf der 200m Skala initialisiert. Die zugehörigen Ergebnisse waren plausibel und bestätigten die Anwendbarkeit der Kombination von Schneemodell und MM5 Windfeldern. Die Schneewasseräquivalentverteilung im Gebiet wurde durch die Applikation der MM5 Windfelder weniger abhängig von der allgemeinen niederschlagsbedingten Zunahme des Schneewasseräquivalents mit der Höhe. Ein Zusammenhang mit der Exposition des Geländes konnte nun auch aufgezeigt werden. Zudem konnten Transportprozesse über die Bergkämme hinweg simuliert werden. Eine Intensitätszunahme aller Transportterme unter Anwendung der MM5 Windfelder im Vergleich zu interpolierten Windfeldern konnte ebenfalls festgestellt werden. Die Ergebnisse auf der 200m Skala machten deutlich, dass für eine ausreichende und tiefgreifende Beschreibung und Validierung von Schneetransportprozessen ein feineres Modellgrid erforderlich ist. Als Konsequenz wurden die MM5 Windfelder auf eine Auflösung von 30m skaliert. Durch die Skalierungsprozedur konnte eine bessere Korrelation zwischen Stationsmessungen und MM5 Ergebnissen erreicht werden. Die resultierenden 30m Windfelder wurden für hochauflösende 30m Schneemodellläufe genutzt, die auf der Basis von Ergebnissen der durchgeführten Feldkampagnen und Fernerkundungsdaten validiert werden konnten. Auch hier konnte nachgewiesen werden, dass die unter Verwendung der MM5 Windfeldbibiliothek generierten Resultate von höherer Validität waren, als die Ergebnisse die mit Hilfe von interpolierten Windfeldern erzeugt wurden. Im Weiteren wurden die Modellergebnisse anhand ausgewählter Resultate diskutiert. Es konnte gezeigt werden, dass die Effektivität von Transportprozessen unter 1800m ü. NN. zu vernachlässigen ist und ab 2200m ü. NN. stark zunimmt. Zudem konnte unter Nutzung der MM5 Windfelder der Transport von Schnee auf vergletscherte Flächen modelliert werden. Hohe modellierte Sublimationsraten an den Gipfeln wurden diskutiert und ihre Wichtigkeit im Bezug auf die alpine Wasserbilanz aufgezeigt. Im Ganzen konnte nachgewiesen werden, dass die Einbindung von Ergebnisdaten von Atmosphärenmodellen zu einer deutlichen Verbesserung der Beschreibung der Prozesse an der Erdoberfläche führt. In einem letzten Schritt wurden die Ergebnisse der hochaufgelösten Schneemodellläufe genutzt, um die Schneedeckenheterogenität im Gebiet zu parametrisieren. Ziel war es, eine Möglichkeit aufzuzeigen, die generierte kleinskalige Information auch für regionale Landoberflächenmodelle nutzbar zu machen. Infolgedessen wurde eine einfach zu implementierende Routine für regionale Modelle vorgestellt, die die subskalige Beschreibung der Schneedeckenheterogenität erlaubt. Dies kann in entsprechendem Relief zu einer Verbesserung der Energie- und Feuchteflüsse in regionalen Modellen und damit zu einer akkurateren Beschreibung der Ablationsperiode der Schneedecke und der Abflussgenerierung führen