Flood risk, climate change and settlement development: a micro-scale assessment of Austrian municipalities

Abstract in dt. Sprache nicht verfügbarThis paper analyses the influence of climate change and land development on future flood risk for selected Austrian flood-prone municipalities. As part of an anticipatory micro-scale risk assessment we simulated four different inundation scenarios for current and future 100- and 300-year floods (which included a climate change allowance), developed scenarios of future settlement growth in floodplains and evaluated changes in flood damage potentials and flood risk until the year 2030. Findings show that both climate change and settlement development significantly increase future levels of flood risk. However, the respective impacts vary strongly across the different cases. The analysis indicates that local conditions, such as the topography of the floodplain, the spatial allocation of vulnerable land uses or the type of land development (e.g. residential, commercial or industrial) in the floodplain are the key determinants of the respective effects of climate change and land development on future levels of flood risk. The case study analysis highlights the general need for a more comprehensive consideration of the local determinants of flood risk in order to increase the effectiveness of an adaptive management of flood risk dynamics.(VLID)164915

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Zeitlich hochaufgelöste inverse Modellierung von Gebietsniederschlägen aus Abflussmessungen

Das Ziel dieser Arbeit ist die zeitlich hochaufgelöste Berechnung von Gebietsniederschlägen auf der Grundlage von Abflussbeobachtungen. Es werden auf Basis des konzeptionellen Niederschlags-Abfluss-Modells COSERO zwei unterschiedliche Methoden präsentiert, um inverse Simulationen, mit Abflussbeobachtungen als Eingangsgröße, durchzuführen. Um die Existenz, Eindeutigkeit und Stabilität der invers berechneten Gebietsniederschläge zu überprüfen, werden numerische Experimente mit synthetischen Abflussganglinien als Input erfolgreich durchgeführt. Die Anwendung und Berechnung von Gebietsniederschlägen mit realen Abflussbeobachtungen zeigen, dass das inverse Modell sehr gut in der Lage ist, Gebietsniederschläge zu berechnen. Im Vergleich zu Stationsbeobachtungen haben die inversen Niederschlagssummen und -zeitreihen eine ähnliche Güte und Qualität, wie die von der inversen Modellierung unabhängigen INCA-Niederschlagsanalysen der Zentralanstalt für Meteorologie und Geodynamik. Tendenziell weisen die inversen Niederschläge dabei höhere Intensitäten und Varianzen auf. Zusätzlich wird der Einfluss unterschiedlicher Berechnungsmethoden der potentiellen Evapotranspiration auf den inversen Niederschlag untersucht. Aufgrund der Verfügbarkeit der raum-zeitlich hochaufgelösten INCA-Analysen (1x1 km, 15-/60-min) der Parameter Globalstrahlung, Lufttemperatur, Windgeschwindigkeit und relativen Feuchte werden potentielle Evapotranspirationsberechnungen für Gesamtösterreich (84 000 km) durchgeführt. Vor allem über 1500 m ü.A. zeigen sich nach der Energiebilanzmethode nach ASCE-Penman-Monteith signifikant höhere potentielle Evapotranspirationssummen als bei den temperaturbasierten Methoden nach Hargreaves und Thornthwaite. Es kann geschlossen, dass die Verwendung der Lufttemperatur als Ersatzwert, vor allem in höheren Lagen mit niedrigeren Lufttemperaturen, unzureichend ist, um die potentielle Evapotranspiration zu berechnen.The aim of this work is the calculation of areal rainfall on the basis of runoff measurements. Based on the conceptual rainfall-runoff model COSERO, two different methods are presented to inversely simulate rainfall with runoff observations as input. To verify the existence, uniqueness and stability of the inverse rainfall, numerical experiments with synthetic hydrographs are carried out successfully. The application of the inverse model with runoff observations as driving input is performed for 2 catchments in the northern Austrian Alpine foothills. The results show that the inverse model is able to calculate areal rainfall in a high temporal resolution successfully. Compared to station observations, the inverse rainfall sums and time series have a similar goodness of fit, as the independent INCA rainfall analysis of Austrian Central Institute for Meteorology and Geodynamics (ZAMG). Compared to observations, the inverse rainfall estimates show larger rainfall intensities and a higher variance, due to oscillations in the inverse rainfall. It is however shown, that the oscillations can be eliminated with a simple weighted moving average filter. In addition, the influence of different methods for calculating potential evapotranspiration on the inverse rainfall is investigated. Due to the availability of high-resolution meteorological data (1x1 km, 15-/60-min) of global radiation, air temperature, wind speed and relative humidity, different calculations of potential evapotranspiration are performed and analyzed for Austria (84 000 km). Especially above 1500 m a.s.l., the potential evapotranspiration estimates calculated with the energy-balance based approach of ASCE Penman-Monteith are significantly higher, compared to the temperature-based methods of Hargreaves and Thornthwaite. It can be concluded that the usage of air temperature as a proxy is, especially at higher altitudes with lower air temperatures, insufficient to calculate potential evapotranspiration.eingereicht von Mathew HerrneggerAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in engl. SpracheWien, Univ. für Bodenkultur, Diss., 2013OeBB(VLID)193012

A Near Real-Time Hydrological Information System for the Upper Danube Basin

The multi-national catchment of the Upper Danube covers an area of more than 100,000 km2 and is of great ecological and economic value. Its hydrological states (e.g., runoff conditions, snow cover states or groundwater levels) affect fresh-water supply, agriculture, hydropower, transport and many other sectors. The timely knowledge of the current status is therefore of importance to decision makers from administration or practice but also the interested public. Therefore, a web-based, near real-time hydrological information system was conceptualized and developed for the Upper Danube upstream of Vienna (Upper Danube HIS), utilizing ERA5 reanalysis data (ERA5) and hydrological simulations provided by the semi-distributed hydrological model COSERO. The ERA5 reanalysis data led to comparatively high simulation performance for a total of 65 subbasins with a median NSE and KGE of 0.69 and 0.81 in the parameter calibration and 0.63 and 0.75 in the validation period. The Upper Danube HIS was implemented within the R programming environment as a web application based on the Shiny framework. This enables an intuitive, interactive access to the system. It offers various capabilities for a hydrometeorological analysis of the 65 subbasins of the Upper Danube basin, inter alia, a method for the identification of hydrometeorological droughts. This proof of concept and system underlines how valuable information can be obtained from freely accessible data and by the means of open source software and is made available to the hydrological community, water managers and the public

Impacts of soil erosion and climate change on the built heritage of the Pambamarca Fortress Complex in northern Ecuador

The Pambamarca fortress complex in northern Ecuador is a cultural and built heritage with 18 prehispanic fortresses known as Pucaras. They are mostly located on the ridge of the Pambamarca volcano, which is severely affected by erosion. In this research, we implemented a multiscale methodology to identify sheet, rill and gully erosion in the context of climate change for the prehistoric sites. In a first phase, we coupled the Revised Universal Soil Loss Equation (RUSLE) and four CMIP6 climate models to evaluate and prioritize which Pucaras are prone to sheet and rill erosion, after comparing historical and future climate scenarios. Then, we conducted field visits to collect geophotos and soil samples for validation purposes, as well as drone flight campaigns to derive high resolution digital elevation models and identify gully erosion with the stream power index. Our erosion maps achieved an overall accuracy of 0.75 when compared with geophotos and correlated positively with soil samples sand fraction. The Pucaras evaluated with the historical climate scenario obtained erosion rates ranging between 0 and 20 ton*ha-1*yr-1. These rates also varied from -15.7% to 39.1% for four future climate change models that reported extreme conditions. In addition, after identifying and overflying six Pucaras that showed the highest erosion rates in the future climate models, we mapped their gully-prone areas that represented between 0.9% and 3.2% of their analyzed areas. The proposed methodology allowed us to observe how the design of the Pucaras and their concentric terraces have managed to reduce gully erosion, but also to notice the pressures they suffer due to their susceptibility to erosion, anthropic pressures and climate change. To address this, we suggest management strategies to guide the protection of this cultural and built heritage landscapes

Impacts of soil erosion and climate change on the built heritage of the Pambamarca Fortress Complex in northern Ecuador.

The Pambamarca fortress complex in northern Ecuador is a cultural and built heritage with 18 prehispanic fortresses known as Pucaras. They are mostly located on the ridge of the Pambamarca volcano, which is severely affected by erosion. In this research, we implemented a multiscale methodology to identify sheet, rill and gully erosion in the context of climate change for the prehistoric sites. In a first phase, we coupled the Revised Universal Soil Loss Equation (RUSLE) and four CMIP6 climate models to evaluate and prioritize which Pucaras are prone to sheet and rill erosion, after comparing historical and future climate scenarios. Then, we conducted field visits to collect geophotos and soil samples for validation purposes, as well as drone flight campaigns to derive high resolution digital elevation models and identify gully erosion with the stream power index. Our erosion maps achieved an overall accuracy of 0.75 when compared with geophotos and correlated positively with soil samples sand fraction. The Pucaras evaluated with the historical climate scenario obtained erosion rates ranging between 0 and 20 ton*ha-1*yr-1. These rates also varied from -15.7% to 39.1% for four future climate change models that reported extreme conditions. In addition, after identifying and overflying six Pucaras that showed the highest erosion rates in the future climate models, we mapped their gully-prone areas that represented between 0.9% and 3.2% of their analyzed areas. The proposed methodology allowed us to observe how the design of the Pucaras and their concentric terraces have managed to reduce gully erosion, but also to notice the pressures they suffer due to their susceptibility to erosion, anthropic pressures and climate change. To address this, we suggest management strategies to guide the protection of this cultural and built heritage landscapes

Can local nutrient-circularity and erosion control increase yields of resource-constraint smallholder farmers? A case study in Kenya and Uganda

As many regions in sub-Saharan Africa, the border region of Kenya (KE) and Uganda (UG) has faced a declining soil fertility for decades, resulting from soil erosion, intensely managed agricultural soils due to population pressure and small inputs of mineral and organic fertilizers. With limited financial means, farmers need measures and/or technologies that effectively reduce nutrient losses or increase inputs at a low cost. In this study, four such measures are in focus, namely erosion reduction practices, vermicomposting of animal manure, collection of human urine in jerry cans and, collection of human excreta in urine-diverting dry toilets. Current soil nutrient balances in five districts in the Sio-Malaba-Malakisi River Basin and the potential of these measures to reduce the soil nutrient deficit are studied using the method of material flow analysis and the software STAN. Furthermore, crop-nutrient-response functions are used to determine their potential impact on maize harvests. Overall, results reveal that there exists a non-negligible and exploitable potential of local resources to reduce the soil nutrient deficit, improve harvests and in turn food security of the smallholder farmers in the region. Soil nutrient deficits could be reduced by 20–30%, 23–42% and 9–15% for nitrogen (N), phosphorus (P) and potassium (K), respectively. Subsequently, maize harvests could be increased by 8–40%, depending on the applied technology and area. This research provides useful insights for agricultural extension workers, politicians and researchers alike, highlighting that simple and easily available technologies can harness similar amounts of nutrients as more complex and expensive ones if all specific technology-constraints are adequately incorporated in the analyses.1171

Twenty-three unsolved problems in hydrology (UPH)–a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come