Estimating irrigation-induced changes of water and salinity levels in Karagan Lewaya lagoon, Sri Lanka

The imminent extension of the large-scale Uda Walawe irrigation scheme in the south of the tropical island of Sri Lanka will have serious ecological effects on the development area. The International Water Management Institute is trying to assess these effects by a long-term study, in which the pre-development status is investigated and the changes are monitored in biological, hydrological and water quality and socio-economic surveys. The study described here contributes to the hydrological assessment, focusing on a coastal lagoon called Karagan Lewaya and its small catchment area in the south of the development area. The lagoon will receive high quantities of drainage flows, which could deteriorate its quality as a habitat for migratory birds and lead to flooding of settlements. With the objective of improving the understanding of the hydrological dynamics and forecasting the impact of irrigation development, a simulation model was set up. Applying a simple spreadsheet modeling approach, a model of the lagoon was developed and combined with an adapted existing runoff model of the catchment area. The water balance model generates simulated lagoon water levels; a simulation of salinity levels was also attempted. Various scenarios concerning irrigation and lagoon management were defined. In order to collect data for the development and improvement of the models and to be able to monitor the future changes, the previously established hydrometric monitoring network was extended. Additional information was obtained from topographical maps and remote sensing images. Resulting from the lack of long data series needed for a calibration of the model, the simulation results remain preliminary. It was possible, however, to investigate the effects of different scenarios and to show general trends: Drainage flows from the extended irrigation scheme will lead to a significant rise of water level and decrease of salinity in the lagoon, with less fluctuations than at present. To prevent flooding of town areas close to the lagoon, an existing outlet channel will have to be opened during long periods. These changes will lead to a deterioration of the quality of Karagan Lewaya as a habitat for birds, but could be of benefit for the local settlers (washing, fishing, cattle bathing)

Ereignisbasierte Modelldiagnose von Niederschlag-Abfluss-Modellstrukturen

Ziel dieser Arbeit ist ein Vergleich verschiedener Niederschlag-Abfluss-Modellstrukturen. In vergleichenden Modelldiagnosen werden Stärken und Schwächen von konzeptionellen und physikalisch basierten Modellansätzen analysiert. Die parallele Anwendung von vier unterschiedlichen Modellstrukturen ermöglicht die Untersuchung der Modellunsicherheit, die der Parameterunsicherheit und der Unsicherheit aus der Schätzung des Niederschlaginputs gegenübergestellt werden. Insgesamt erreichen alle Modelle eine vergleichbare Güte der Abflusssimulation. Ereignisse aus Infiltrationsüberschuss können mit den physikalisch basierten Ansätzen besser abgebildet werden. Mit den konzeptionellen Modellen ist eine bessere Anpassung an Abflusscharakteristika in unterschiedlichen Einzugsgebieten möglich. Für alle Modelle ergeben sich aus systematisch auftretenden Abweichungen von den Beobachtungen Hinweise auf Defizite in den Modellstrukturen. Die Unsicherheit in der Abflusssimulation aufgrund der Modellstruktur liegt in der Größenordnung der anderen untersuchten Unsicherheiten. In der Simulation der Bodenfeuchte zeigen physikalisch basierte Ansätze einen dynamischeren Verlauf und stimmen damit eher mit Beobachtungen überein. Die größten Differenzen zwischen den Modellen treten in der Simulation der Anteile der Abflusskomponenten Oberflächenabfluss, Zwischenabfluss und Basisabfluss auf. Mit den konzeptionellen Modellen sind je nach Parameterwahl viele verschiedene Zusammensetzungen möglich, mit tendenziell hohen Anteilen an Oberflächenabfluss. In den physikalisch basierten Modellen sind die simulierten Anteile von Oberflächenabfluss immer sehr niedrig. Beobachtungen der Abflusskomponenten liegen selten und auch nicht für die hier untersuchten Gebiete vor. Für konzeptionelle Modelle kann die Kenntnis der Abflussanteile in der Natur den möglichen Parameterraum einschränken, im Zusammenhang mit physikalisch basierten Modellen zeigt sich ihr großes Potential zur Unterstützung der Modellwahl.The objective of this research is a comparative evaluation of different rainfall-runoff model structures. Comparative model diagnostics facilitates the assessment of strengths and weaknesses of conceptual and physically based modeling approaches. Four differently structured models were compared and analyzed with respect to model uncertainty, parametric and input uncertainty. It can be concluded that catchment runoff is simulated satisfactorily by all models. Physically based model structures do not generally outperform conceptual models but they capture runoff events better which originate from infiltration excess. Conceptual model structures are more flexible in fitting to runoff characteristics in different basins. For all models, systematic deviations from runoff observations provide insight into model structural deficiencies. Model structural uncertainty is comparable to parameter and input uncertainty. Large differences between the four models are detected for simulations of soil moisture and, even more pronounced, for simulations of the runoff components. Soil moisture changes are more dynamically simulated by the physically based model structures, which is in better agreement with observations. Simulated streamflow contributions of overland flow are very low in these models. Conceptual approaches tend to higher portions of overland flow, but allow simulations with different compositions of runoff components depending on parameters. Therefore, observations of runoff components, which are usually not available, could enhance parameter estimation for conceptual models and could assist in hypotheses testing of physically based model.eingereicht von Philipp StanzelAbweichender Titel laut Übersetzung der Verfasserin/des VerfassersZsfassung in engl. SpracheWien, Univ. für Bodenkultur, Diss., 2012OeBB(VLID)193156

Impact modelling of water resources development and climate scenarios on Zambezi River discharge

Study region: The Zambezi River basin (1.4 × 106 km2) in southern Africa, which is shared by eight countries and includes two of the World's largest reservoirs. Study focus: Impacts on future water resources in the Zambezi basin are studied, based on World Bank projections that include large scale irrigation and new hydropower plants. Also the impacts of climate change scenarios are analysed. Modelling challenges are the large basin area, data scarcity and complex hydrology. We use recent GPCC rainfall data to force a rainfall-runoff model linked to a reservoir model for the Zambezi basin. The simulations are evaluated with 60 years of observed discharge and reservoir water level data and applied to assess the impacts on historical and future discharges. New hydrological insights for the region: Comparisons between historical and future scenarios show that the biggest changes have already occurred. Construction of Kariba and CahoraBassa dams in the mid 1900s altered the seasonality and flow duration curves. Future irrigation development will cause decreases of a similar magnitude to those caused by current reservoir evaporation losses. The discharge is highly sensitive to small precipitation changes and the two climate models used give different signs for future precipitation change, suggestive of large uncertainty. The river basin model and database are available as anopen-online Decision Support System to facilitate impact assessments of additional climate or development scenarios

Open Access Monitor Reloaded

Der von der Zentralbibliothek des Forschungszentrums Jülich betriebene Open Access Monitor Deutschland (OAM; gefördert vom BMBF, FKZ16OAMO001) steht seit 2019 zur frei zugänglichen Datenanalyse zur Verfügung. Seit August 2021 präsentiert sich der OAM mit einem neu designten Frontend der Website. Das alte Frontend basierte auf Vue (Progressive JavaScript Framework), Vuetify und Echarts, wohingegen das neue Frontend auf ASP.NET, Blazor, MudBlazor sowie Plotly aufbaut. Die Filterfunktionen sind als Steuerungstool für Datenanalysen vom Seitenrand in den Mittelpunkt der Anwendung gerückt. Die bisherige Darstellung der Auswertungen in Aggregationsstufen wurde durch selbst wählbare Gruppierungsoptionen abgelöst. Die Darstellung der OA-Farben ist weiter ausdifferenziert und eine Auswahl des genauen Publikationsdatums ist möglich. Neu sind die englischsprachige Oberfläche sowie eine umfangreichere Dokumentation incl. FAQ

Climate change impact on West African rivers under an ensemble of CORDEX climate projections

In the context of a region-wide hydropower potential study, the impact of climate change on the hydrology of West Africa was assessed. Climate data of 30 Regional Climate Model simulations of the CORDEX initiative based on two emission scenarios (Representative Concentration Pathways RCP4.5 and RCP8.5) were applied in a water balance model. Future changes in the water balance for an area of 3.7 million km2 and resulting changes in river discharge in 500,000 river reaches were investigated for two future periods, 2026–2045 and 2046–2065. This article focuses on 12 key locations in the 10 largest river basins, and all results for the entire West Africa region are publicly available via the ECOWAS Observatory for Renewable Energy and Energy Efficiency (www.ecowrex.org/smallhydro).For large parts of the region, projected changes in climate do not lead to substantial reductions in river discharge, with median results of the model ensemble in the range of ±5%. Stronger decreases in discharge are projected for regions in the north and east of West Africa, pronounced increases mainly for the southwest. The application of a large climate model ensemble exhibits the high uncertainty related with these projections, but also shows regions with high agreement between results with different models. The regional climate change impact analysis provides a baseline for climate-informed decision making for hydropower development and other fields of water management and water policy and enables regional focus for initiating further research and developing adaptation pathways. Keywords: Climate change impact, CORDEX, West Africa, Water balance model, River discharge, Hydropowe

Open Access bei Monographien: Machbarkeitsstudie für den Open Access Monitor

Monographien sind in vielen Wissenschaftsbereichen von zentraler Bedeutung, jedoch in der Open-Access-Transformation derzeit noch weniger repräsentiert. Die meisten Bestrebungen für das Publizieren im Open Access wurden bisher im Bereich der Zeitschriften unternommen. Diese Dokumentart wird in Publikationsdatenbanken in großem Umfang erfasst. Darauf aufbauend kann der Open Access Monitor den Transformationsprozess mit einer soliden Datenbasis für Zeitschriftenartikel unterstützen. Die Ergänzung von Monographien wäre wünschenswert, jedoch bedarf es dafür einer geeigneten Datenquelle. Ob eine solche Einbindung möglich ist und was eine geeignete Datenquelle wäre, soll in dieser Studie untersucht werden

Big Scholarly Data im Open Access Monitor: ein Werkstattbericht

In the light of the Open Access transformation, the analysis of large amounts of data is increasingly important for libraries, whereas the number of scholarly publications is constantly growing. Large amounts of data must first be made usable before any substantiated analysis can be made, e.g. regarding institution-related publication outputs. This is where the Open Access Monitor (OAM) comes in, which acts as an interface for merging data from various source systems such as Unpaywall, Dimensions, Web of Science and Scopus. For this purpose, the OAM is structurally divided into three parts: the backend hosts the data, which can be queried via the API, and is presented and visualized in the frontend. All data, coming from various source systems, must be homogenized in order to realize complete data sets without creating duplicates. Journal titles or institution names have to be standardized to allow assigning the original entries from the source systems to the corresponding data records in the OAM. In the case of institution names, these are enriched with persistent identifiers. Given the way the data is organized in some of the source databases, the institution names cannot be mapped directly to organization identifiers (ROR-IDs) in some cases. Therefore, the raw forms of the author’s affiliation information are used in the mapping process. Affiliation mapping is an extensive and complex task, since the data provided are often ambiguous and at the same time a clear distinction of institutions, especially in the case of university hospitals, requires intellectual processing. The highly complex process of generating a uniform data set from a multitude of data sources will be demonstrated, with a special focus on the normalization processes as well as the assignment of Open Access categories. Metadata quality remains a constant challenge, as does the issue of availability and sustainability of the connected source systems. The use and integration of open data sources is generally desirable – it would be in line with the OAM’s goal of unrestricted (re-) usability of the OAM data. The pros and cons of using non-commercial databases are discussed using OpenAlex as an example