@inproceedings{HeMolkenthinWendlandetal., author = {He, Qianwen and Molkenthin, Frank and Wendland, Frank and Herrmann, Frank}, title = {Evaluation of different interpolation schemes for precipitation and reference evapotranspiration and the impact on simulated large-scale water balance in Slovenia}, series = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {Precipitation and reference evapotranspiration (ET0) are two main climate input components for hydrological models, which are often recorded or calculated based on measuring stations. Interpolation schemes are implemented to regionalize data from measuring stations for distributed hydrological models. This study had been conducted for 5 months, with the aim of: (1) evaluating three interpolation schemes for precipitation and reference evapotranspiration (ET0); (2) assessing the impact of the interpolation schemes on actual evapotranspiration and total runoff simulated by a distributed large-scale water balance model - mGROWA. The study case was the Republic of Slovenia, including a high variability in topography and climatic conditions, with daily meteorological data measured in 20 stations for a period of 44 years. ET0 were computed by both FAO Penman-Monteith equation and Hargreaves equation. The former equation is recommended as the standard equation, while the ET0 calculated by the latter one for Slovenia had a certain deviation (+150 mm/a) from it. Ordinary Kriging, Regression Kriging and Linear Regression were selected to regionalize precipitation and ET0. Reliability of the three interpolation schemes had been assessed based on the residual obtained from cross-validation. Monthly regionalized precipitation and ET0 were subsequently used as climate input for mGROWA model simulation. Evaluation of the interpolation schemes showed that the application of Regression Kriging and Linear Regression led to an acceptable interpolation result for reference evapotranspiration, especially in case the FAO Penman-Monteith equation was used. On the other hand, Regression Kriging also provided a more convincing interpolated result for precipitation. Meanwhile, mGROWA simulation results were affected by climate input data sets generated by applying difference interpolation schemes. Therefore, it is essential to select an appropriate interpolation scheme, in order to generate a convincing climate input.}, language = {en} } @inproceedings{SchleyMolkenthinMejstrik, author = {Schley, Frank and Molkenthin, Frank and Mejstrik, M.}, title = {Netzbasiertes Kollaborationsmodell im Spezialtiefbau - Virtuelle Baubude -}, series = {Junge Wissenschaftler forschen, 13. Forum Bauinformatik, M{\"u}nchen 2001}, booktitle = {Junge Wissenschaftler forschen, 13. Forum Bauinformatik, M{\"u}nchen 2001}, publisher = {VDI-Verlag}, address = {D{\"u}sseldorf}, isbn = {3-18-316904-5}, pages = {70 -- 77}, language = {de} } @misc{HeWendlandMolkenthin, author = {He, Qianwen and Wendland, Frank and Molkenthin, Frank}, title = {The analysis of nitrogen load and simulation uncertainty using SWAT in a catchment with paddy field in China}, series = {Water Science \& Technology Journal}, volume = {80}, journal = {Water Science \& Technology Journal}, number = {4}, issn = {0273-1223}, doi = {10.2166/wst.2019.326}, pages = {806 -- 816}, language = {en} } @inproceedings{MolkenthinHolz, author = {Molkenthin, Frank and Holz, Klaus-Peter}, title = {Generalised Information Systems for Physical State Variables in Hydroscience}, series = {Water engineering for the future, Vol. 1., Abstracts of XXXI IAHR Congress, Coex, Seoul, September 11 - 16, 2005}, booktitle = {Water engineering for the future, Vol. 1., Abstracts of XXXI IAHR Congress, Coex, Seoul, September 11 - 16, 2005}, editor = {Jun, Byong-Ho}, publisher = {Korea Water Resources Association}, address = {Seoul}, isbn = {89-87898-25-3}, pages = {S. 107}, language = {en} } @inproceedings{HolzHildebrandtMolkenthin, author = {Holz, Klaus-Peter and Hildebrandt, Gerald and Molkenthin, Frank}, title = {Virtual Laboratories for Projects in Environment Water}, series = {The information society and enlargement of the European Union, 17th International Conference Informatics for Environment Protection, Cottbus 2003}, booktitle = {The information society and enlargement of the European Union, 17th International Conference Informatics for Environment Protection, Cottbus 2003}, editor = {Gnauck, Albrecht}, publisher = {Metropolis-Verlag}, address = {Marburg}, isbn = {3-89518-440-3}, abstract = {Modern information and communication technology (ICT) enables new technical solutions to support collaboration in environmental engineering over distance. The establishment of "virtual laboratories" including application of Internet based project platforms, distributed team work and collaboration methods require new kinds of soft skills, knowledge and experience and a new "technological culture" to be generated just by doing - a task for education, training and profession in Hydro-Informatics. This is a challenge for the European dimension, where in future experts and engineers from different countries with different languages, different mentalities as well as different specialization and professional experience have to collaborate in research, teaching and practice. Training of collaborating in such new environment is the challenge of the courses HydroWeb and HydroEurope which by collaboration of 23 universities world-wide will help to establish common high quality university teaching courses and establish links between students from the involved countries. The students are solving a given environmental engineering task in distributed teams in the Internet. The students acquired in this course experience in interdisciplinary team work, net based project co-ordination and Web based reporting. They strengthened their social competence to collaborate in heterogeneous teams with members of different habits, nationalities, ages, educational backgrounds. The described experiment might be the basis to introduce Web based collaborative engineering in the regular course programme of water-environment related curricula at universities.}, language = {en} } @misc{FrimpongMolkenthin, author = {Frimpong, Bernard Fosu and Molkenthin, Frank}, title = {Tracking Urban Expansion Using Random Forests for theClassification of Landsat Imagery (1986-2015) and PredictingUrban/Built-Up Areas for 2025: A Study of the KumasiMetropolis, Ghana}, series = {Land}, volume = {10}, journal = {Land}, number = {1}, issn = {2073-445X}, doi = {10.3390/land10010044}, pages = {1 -- 21}, abstract = {Kumasi is a nodal city and functions as the administrative and economic capital of the Ashanti region in Ghana. Rapid urbanization has been experienced inducing the transformation of various Land Use Land Cover (LULC) types into urban/built-up areas in Kumasi. This paper aims at tracking spatio-temporal LULC changes utilizing Landsat imagery from 1986, 2013 and 2015 of Kumasi. The unique contribution of this research is its focus on urban expansion analysis and the utilization of Random Forest (RF) Classifier for satellite image classification. Change detection, urban land modelling and urban expansion in the sub-metropolitan zones, buffers, density decay curve and correlation analysis were methodologies adopted for our study. The classifier yielded better accuracy compared to earlier works in Ghana. The evaluation of LULC changes indicated that urban/built-up areas are continually increasing at the expense of agricultural and forestlands. The urban/built-up areas occupied 4622.49 hectares (ha) (23.78\%), 13,447.50 ha (69.18\%) and 14,004.60 ha (72.05\%) in 1986, 2013 and 2015, respectively of the 19,438 ha area of Kumasi. Projection indicated that urban/built-up areas will occupy 15,490 ha (79.70\%) in 2025. The urban expansion was statistically significant. The results revealed the importance of spatial modeling for environmental management and city planning.}, language = {en} } @misc{HeMolkenthin, author = {He, Qianwen and Molkenthin, Frank}, title = {Improving the integrated hydrological simulation on a data-scarce catchment with multi-objective calibration}, series = {Journal of Hydroinformatics}, volume = {23}, journal = {Journal of Hydroinformatics}, number = {2}, issn = {1464-7141}, doi = {10.2166/hydro.2021.132}, pages = {267 -- 283}, abstract = {The process-based hydrological model Soil and Water Assessment Tool ensures the simulation's reliability by calibration. Compared to the commonly applied single-objective calibration, multi-objective calibration benefits the spatial parameterization and the simulation of specific processes. However, the requirements of additional observations and the practical procedure are among the reasons to prevent the wider application of the multi-objective calibration. This study proposes to consider three groups of objectives for the calibration: multisite, multi-objective function, and multi-metric. For the study catchment with limited observations like the Yuan River Catchment (YRC) in China, the three groups corresponded to discharge from three hydrometric stations, both Nash-Sutcliffe efficiency (NSE) and inversed NSE for discharge evaluation, and MODIS global terrestrial evapotranspiration product and baseflow filtered from discharge as metrics, respectively. The applicability of two multi-objective calibration approaches, the Euclidean distance and nondominated sorting genetic algorithm II, was analyzed to calibrate the above-mentioned objectives for the YRC. Results show that multi-objective calibration has simultaneously ensured the model's better performance in terms of the spatial parameterization, the magnitude of the output time series, and the water balance components, and it also reduces the parameter and prediction uncertainty. The study thus leads to a generalized, recommended procedure for catchments with data scarcity to perform the multi-objective calibration.}, language = {en} } @misc{TrinhMolkenthin, author = {Trinh, Manh Xuan and Molkenthin, Frank}, title = {Flood hazard mapping for data-scarce and ungauged coastal river basins using advanced hydrodynamic models, high temporal-spatial resolution remote sensing precipitation data, and satellite imageries}, series = {Natural Hazards}, volume = {109}, journal = {Natural Hazards}, number = {1}, issn = {0921-030X}, doi = {10.1007/s11069-021-04843-1}, pages = {441 -- 469}, abstract = {This paper presents an integrated approach to simulate flooding and inundation for small- and medium-sized coastal river basins where measured data are not available or scarce. By coupling the rainfall-runoff model, the one-dimensional and two-dimensional models, and the integration of these with global tide model, satellite precipitation products, and synthetic aperture radar imageries, a comprehensive flood modeling system for Tra Bong river basin selected as a case study was set up and operated. Particularly, in this study, the lumped conceptual model was transformed into the semi-distributed model to increase the parameter sets of donor basins for applying the physical similarity approach. The temporal downscaling technique was applied to disaggregate daily rainfall data using satellite-based precipitation products. To select an appropriate satellite-derived rainfall product, two high temporal-spatial resolution products (0.1 × 0.1 degrees and 1 h) including GSMaP_GNRT6 and CMORPH_CRT were examined at 1-day and 1-h resolutions by comparing with ground-measured rainfall. The CMORPH_CRT product showed better performance in terms of statistical errors such as Correlation Coefficient, Probability of Detection, False Alarm Ratio, and Critical Success Index. Land cover/land use, flood extent, and flood depths derived from Sentinel-1A imageries and a digital elevation model were employed to determine the surface roughness and validate the flood modeling. The results obtained from the modeling system were found to be in good agreement with collected data in terms of NSE (0.3-0.8), RMSE (0.19-0.94), RPE (- 213 to 0.7\%), F1 (0.55), and F2 (0.37). Subsequently, various scenarios of flood frequency with 10-, 20-, 50-, and 100-year return periods under the probability analysis of extreme values were developed to create the flood hazard maps for the study area. The flood hazards were then investigated based on the flood intensity classification of depth, duration, and velocity. These hazard maps are significantly important for flood hazard assessments or flood risk assessments. This study demonstrated that applying advanced hydrodynamic models on computing flood inundation and flood hazard analysis in data-scarce and ungauged coastal river basins is completely feasible. This study provides an approach that can be used also for other ungauged river basins to better understand flooding and inundation through flood hazard mapping.}, language = {en} } @misc{GourbesvilleGomezValentinMolkenthinetal., author = {Gourbesville, Philippe and Gomez Valentin, Manuel and Molkenthin, Frank and Hewett, Caspar and Sinicyn, Grzegorz and Griensven, Ann van}, title = {HydroEurope—WaterEurope: 20 years of Practice in Collaborative Engineering for Hydroinformatics}, series = {Advances in Hydroinformatics : Models for Complex and Global Water Issues—Practices and Expectations Springer Water}, journal = {Advances in Hydroinformatics : Models for Complex and Global Water Issues—Practices and Expectations Springer Water}, editor = {Gourbesville, Philippe and Caignaert, Guy}, publisher = {Springer}, address = {Singapore}, isbn = {978-981-19-1600-7}, doi = {10.1007/978-981-19-1600-7_80}, pages = {1255 -- 1280}, abstract = {Since 2000 and under the various Erasmus and Erasmus + frameworks of the European Commission, 6 European universities have initiated an ve innovatiintensive training program dedicated to hydroinformatics and supported by the data of the Var catchment, France. Over the two decades, the HydroEurope/WaterEurope course has welcome more than 2000 M.Sc students with the ambition to equip them with the competences and skills related to hydrological analyst, flood modeling, damage assessment and engineering design with the most advanced simulation tools. The concept of collaborative engineering associated to a project based pedagogic approach has been used to develop teamwork distributed over time—almost 3 months—and space with team members located in the different European participating institutions. The activities are built around the Var catchment that is regularly affected by Mediterranean flood events associated to major damages. The various teams have to elaborate within a holistic approach, mitigation actions. Since the origins, the program has been integrated within the master degree curriculum of each participating institution and academic recognition has been achieved through credits (ECTS). Industrial actors from the hydroinformatic field have been associated to the program since the early stage and have provided support with expert staff and simulation tools that are today offered through a modelling platform. The 20 years of development have underlined the efficiency of the pedagogic approach and have contributed to equip the new generation of water professionals with new concepts and methods for a better water management.}, language = {en} } @inproceedings{TrinhNguyenMolkenthin, author = {Trinh, Manh Xuan and Nguyen, Mai Dang and Molkenthin, Frank}, title = {Flood risk assessment in the Tra Bong river catchment, Vietnam}, series = {International Symposium on Lowland Technology (ISLT 2018), Hanoi, Vietnam}, booktitle = {International Symposium on Lowland Technology (ISLT 2018), Hanoi, Vietnam}, publisher = {Construction Publishing House}, address = {Hanoi}, isbn = {978-604-82-2483-7}, pages = {8}, abstract = {Extreme flood events often cause tremendous damage and enormous risks to our life and nature. Flooding is one of the most costly kinds of natural disasters in Vietnam. Tra Bong is a river catchment located in Quang Ngai province, Vietnam. Due to the effect of typhoons originated from the East Sea, many extreme floods occur in this river annually. Therefore, considering the impacts of flooding and flood risk assessment in this river plays an important role in mitigating and adapting to flood risk. In this paper, a hydrological model (MIKE NAM) and some hydro-dynamic models such as the MIKE 11 HD, MIKE 21 FM and MIKE Flood models were applied as the effective tools to simulate flooding and inundation in the downstream area of the catchment. Two flood risk maps for 2009 and 100 year return period were created based on the intersection of hazard and vulnerability maps which were obtained from flood maps, land-use and population density. Accordingly, more than 80\% of total flooded area is at high and very high risk. Almost 35 km2 of the flooded area were under high and very high risk in the year 2009, while, approximately 45.5 km2 would be under high and very high risk in the design flood event of 100 year return period.}, language = {en} } @inproceedings{ReichertMolkenthin, author = {Reichert, Nora and Molkenthin, Frank}, title = {Which numerical model is suitable for the simulation of hyporheic residence times and metabolic activity? FE model vs. FV model}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {Numerical models have experienced a steady increase in popularity in the scientific community, espe-cially where historically isolated disciplines more and more acknowledge their need for interdisciplinarity. A frequently mentioned example is the interstitial between surface water and ground water in lotic systems, referred to as hyporheic zone. Due to its temporal and spatial heterogeneity, the prediction of hydraulic properties e.g. the residence time remains a challenge in science. Moreover, the hyporheic zone is often described as a reaction chamber due to its repertoire of chemical reactivity, which in turn is highly influenced by the residence times. Ecologically, this habitat is populated by a microbial community that has the potential to alter the chemical characteristics of their environment under the right hydraulic conditions. This small example illustrates the complexity of interdisciplinary research and elucidates the growing requirements concerning numerical models. While the number of numerical models offering to bridge some of these gaps is growing, the decision-making process for the modeler becomes increasingly difficult. It is the objective of this study to identify a suitable model for reproducing measured data from a laboratory flume experiment, in which oxygen was measured as a proxy for metabolic activity under changing dissolved organic carbon inflow in a hyporheic zone with varying residence times. The decision-making process for a suitable numerical model was hereby exemplified by comparing the two numerical models FEFLOW, based on the finite element method (FEM), and MIN3P, based on the finite volume method (FVM). Various aspects of both models are taken into account and evaluated from software technological, numerical or end-user point of view. These include among others the mass balance, meshing algorithm, computational effort and coupling interfaces to surface water models.}, language = {en} } @inproceedings{AltenkirchMutzMolkenthinetal., author = {Altenkirch, Nora and Mutz, Michael and Molkenthin, Frank and Zlatanović, Sanja and Trauth, Nico}, title = {Untangling hyporheic residence time distributions and whole stream metabolisms using a hydrological process model}, series = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2016, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, abstract = {The interaction of the water residence time in hyporheic sediments with the sediment metabolic rates is believed to be a key factor controlling whole stream metabolism. However, due to the methodological difficulties, there is little data that investigates this fundamental theory of aquatic ecology. Here, we report on progress made to combine numerical modeling with a series of manipulation to laboratory flumes overcoming methodological difficulties. In these flumes, hydraulic conditions were assessed using non-reactive tracer and heat pulse sensor. Metabolic activity was measured as the consumption and production of oxygen and the turnover of reactive tracers. Residence time and metabolic processes were modeled using a multicomponent reactive transport code called Min3P and calibrated with regard to the hydraulic conditions using the results obtained from the flume experiments. The metabolic activity was implemented in the model via Monod type expressions e.g. for aerobic respiration rates. A number of sediment structures differing in residence time distributions were introduced in both, the model and the flumes, specifically to model the biogeochemical performance and to validate the model results. furthermore, the DOC supply and surface water flow velocity were altered to test the whole stream metabolic response. Using the results of the hydrological process model, a sensitivity analysis of the impact of residence time distributions on the metabolic activity could yield supporting proof of an existing link between the two.}, language = {en} } @misc{MagbalotFernandezHeMolkenthin, author = {Magbalot-Fernandez, Alminda and He, Qianwen and Molkenthin, Frank}, title = {Effect of Climate Change in the Stream Flow, Crop Yields and NP Levels at White Oak Bayou Watershed Using SWAT simulation: A Case Study}, series = {Asian Journal of Geographical Research}, volume = {2}, journal = {Asian Journal of Geographical Research}, number = {2}, pages = {1 -- 9}, abstract = {Projected changes in temperature due to global climate change may have serious impacts on hydrologic processes, water resources availability, irrigation water demand, and thereby affecting the agricultural production and productivity. Therefore, understanding the impacts of climate change on crop production and water resources is of utmost importance for developing possible adaptation strategies. The White Oak Bayou, one of the several waterways that give Houston, Texas, United States its popular nickname "The Bayou City" was selected in this case study. SWAT model is process based and can simulate the hydrological cycle, crop yield, soil erosion and nutrient transport. It is operated with an interface in ArcView GIS using raster or vector datasets including the digital elevation model (DEM), soil properties, vegetation, LULC, and meteorological observations observed which were derived from the Consortium for Geospatial Information, National Cooperative Soil Survey, National Land Cover Database 2006, NCEP Climate Forecast System Reanalysis and USGS website in 2005-2008. The climate change scenario was based on the projected increase in temperature by the IPCC by 2100. This case study showed a decrease in streamflow from observed actual scenario (2005-2008) to projected increase of 4°C temperature in future climate change scenario by 2100. The evapotranspiration increased but there was a decrease in surface runoff and percolation. Moreover, there were greater average plant biomass and more average plant yields. Hence, the nitrogen and phosphorus uptake and removed in yield increased. Thus, the total nitrogen decreased while the total phosphorus is zero indicating loss of the Phosphorus content in the soil. Yet, this case study needs to be validated and calibrated with actual data to support the projected outcome.}, language = {en} } @book{GourbesvilleGomezBathurstetal., author = {Gourbesville, Philippe and Gomez, Manuel and Bathurst, James and Molkenthin, Frank and Ler, Lian Guey and Kawka, Marcin}, title = {HydroEurope, Flood Risks Management and Resilience in Europe : 2016, 2017, 2018}, publisher = {University of Nice Sophia Antipolis [u.a.]}, address = {Nice}, pages = {154}, abstract = {Since 2002, the pedagogic teams of six European universities are continuously exploring new trends and approaches in education for water engineers. Over the last decade, the water sector is facing the digital revolution challenges. The water uses have reached a high level of complexity that request scientific, technical and social skills in order to answer the demands of users and to preserve a precious resource that request constant cares. Developing new pedagogic practices is strongly needed for integrating the new methods and tools of hydroinformatics and to promote emerging concept like resilience for future professionals who will be in charge of this essential sector. The European programs like Erasmus and Erasmus+ have been, over the years, the main supporting instrument for developing these innovations that request nothing less than the European perspective and spirit. The current book presents the recent results achieved within the Erasmus+ Strategic partnership dedicated to develop pedagogic practices and resources for promoting the resilience concept in flood protection. HydroEurope is targeting MSc students specialised in flood management who will be deeply involved in natural hazards mitigation strategies development in Europe and worldwide. The innovative pedagogic approach and the concept of resilience introduced contribute to develop specific skills and competences which are highly needed for these young professionals. At the same time, the use of ICT in the pedagogic approach contributes to renovate the classical higher education practice in civil engineering. This book introduces HydroEurope by providing the rationale for implementing HydroEurope and the need to conduct HydroEurope transnationally. It justifies the choosing of the HydroEurope partners and provides attestation of the experiences and competences each of the partners will bring to HydroEurope. The partners of HydroEurope are University of Nice Sophia-Antipolis, France (UNS), Brandenburg University of Technology Cottbus Senftenberg, Germany (BTU), Technical University of Catalonia, Spain (UPC), Newcastle University, United Kingdom (NU), Warsaw University of Technology, Poland (WUT) and Vrije Universiteit Brussel, Belgium (VUB). The objective of HydroEurope is using the collaborative engineering approach to provide the participants of HydroEurope skills and knowledge on flood management in terms of hydrological and hydraulic modelling and flood resilience measures. The methodology on how to achieve this objective as well as the anticipated outcomes and impacts are carefully explained. In addition, this book presents the strategies for resilience approach implementation within the city where it is envisioned that this book will help to spread awareness on flood risk and resilience not just only in the public but also in the education and water domain. The high level of commitments from all partners has ensured the success of the HydroEurope project. All participants have underlined the interest of the approach and recognised the added value for their future professional career. (PDF) HydroEurope, Flood Risks Management and Resilience in Europe,. Available from: https://www.researchgate.net/publication/328784960_HydroEurope_Flood_Risks_Management_and_Resilience_in_Europe [accessed Nov 20 2018].}, language = {en} } @inproceedings{NotayMendozaLeraFederleinetal., author = {Notay, Kunwar Vikramjeet and Mendoza-Lera, Clara and Federlein, Laura L. and Molkenthin, Frank}, title = {A coupled subsurface-flow and metabolism model to study the effects of solute fluxes in the hyporheic zone}, series = {Proceedings of the 28th EnviroInfo 2014 Conference, Oldenburg, Germany September 10-12, 2014}, booktitle = {Proceedings of the 28th EnviroInfo 2014 Conference, Oldenburg, Germany September 10-12, 2014}, publisher = {BIS-Verlag}, address = {Oldenburg}, isbn = {978-3-8142-2317-9}, abstract = {The hyporheic zone and the streambed host a great part of the energy and material fluxes through river ecosystems. However, the role of heterogeneities in the hyporheic zone in metabolism is not clearly understood. This paper proposes a new way to approach the question by using a coupled subsurface-flow and metabolism model for investigating the role of heterogeneities in the hyporheic metabolism. Our results show that (i) our coupled model is feasible for investigating solute fluxes in the hyporheic zone under heterogeneous set-ups, and (ii) the incorporation of heterogeneities seems be of relevance for hyporheic metabolism estimations.}, language = {en} } @misc{FrimpongKorantengMolkenthin, author = {Frimpong, Bernard Fosu and Koranteng, Addo and Molkenthin, Frank}, title = {Analysis of temperature variability utilising Mann-Kendall and Sen's slope estimator tests in the Accra and Kumasi Metropolises in Ghana}, series = {Environmental Systems Research}, volume = {11}, journal = {Environmental Systems Research}, issn = {2193-2697}, doi = {10.1186/s40068-022-00269-1}, pages = {13}, abstract = {Temperature variability may have direct and indirect impacts on the environments of the Accra and Kumasi Metropolises in Ghana. This study analysed temperature and trends in temperature in both cities using in-situ measurements from one meteorological station in both cities from 1986 to 2015. The temperature indices were computed using the RClimdex package from the Expert Team on Climate Change Detection Monitoring Indices (ETCCDMI). The temperature time series was pre-whitened before the Mann-Kendall trend and Sen's slope estimator analysis were applied. Initial analysis revealed minimal variation in temperature in both cities. The results from the analysed temperature indices revealed an increase in warm days and a general rise in the minimum temperature compared to maximum temperatures. Mann Kendall and Sen's slope revealed significant trends in the annual and seasonal (dry and wet seasons) in minimum temperature in both cities. These might lead to an increased rate of heat-stressed diseases and an overall rise in urban warming in both cities. The analysis of temperature, indices and trends provided comprehensive insights into the temperature of Accra and Kumasi. The results highlight the essence of evaluating temperature indices and trends in light of Climate Change concerns. It is recommended that urban green and blue spaces should be incorporated into land use plans as these policy directions can aid regulate the temperature in both cities.}, language = {en} } @misc{RamirezSermetMolkenthinetal., author = {Ramirez, Carlos and Sermet, Yusuf and Molkenthin, Frank and Demir, Ibrahim}, title = {HydroLang: An open-source web-based programming framework for hydrological sciences}, series = {Environmental Modelling \& Software}, volume = {157}, journal = {Environmental Modelling \& Software}, issn = {1364-8152}, doi = {10.1016/j.envsoft.2022.105525}, pages = {1 -- 13}, abstract = {This paper introduces HydroLang, an open-source and integrated community-driven computational web framework for hydrology and water resources research and education. HydroLang employs client-side web technologies and standards to carry out various routines aimed at acquiring, managing, transforming, analyzing, and visualizing hydrological datasets. HydroLang consists of four major high-cohesion low-coupling modules: (1) retrieving, manipulating, and transforming raw hydrological data, (2) statistical operations, hydrological analysis, and model creation, (3) generating graphical and tabular data representations, and (4) mapping and geospatial data visualization. To demonstrate the framework's capabilities, portability, and interoperability, two detailed case studies (assessment of lumped models and construction of a rainfall disaggregation model) have been presented. HydroLang's unique modular architecture and open-source nature allow it to be easily tailored into any use case and web framework, and it encourages iterative enhancements with community involvement to establish the comprehensive next-generation hydrological software toolkit.}, language = {en} } @misc{TrinhMolkenthin, author = {Trinh, Manh Xuan and Molkenthin, Frank}, title = {Numerical Modeling of Extreme Flooding for Flood Risk Assessment in the Tra Bong River Basin, Vietnam}, series = {Recent Trends in Environmental Hydraulics : 38th International School of Hydraulics}, journal = {Recent Trends in Environmental Hydraulics : 38th International School of Hydraulics}, editor = {Kalinowska, Monika B. and Mrokowska, Magdalena M. and Rowiński, Paweł M.}, publisher = {Springer Nature}, address = {Switzerland}, isbn = {978-3-030-37105-0}, issn = {2190-5193}, doi = {10.1007/978-3-030-37105-0_26}, pages = {299 -- 308}, abstract = {Flooding and inundation are of the most concerns in Vietnam. Many extreme floods have been occurring in Vietnam frequently, especially during the period of 1999-2009. Considering the impacts of flooding plays an important role in mitigating and adapting to flood risks. In this study, a rainfall-runoff model, two hydrodynamic models, and a coupling model were successfully applied as effective tools to simulate flooding and inundation in the Tra Bong River Basin, which is located in central Vietnam and considered as an ungauged basin. These models simulated the high flows accurately by depicting all of the peak flow discharges in accordance with observed high flows. The low flows were also simulated fairly well. In general, there is a good fit between the observed and simulated hydrographs for both calibration and validation. According to the model performance, 80\% of the floodplain area would be flooded during the future extreme flood event. Eventually, the model results indicate that the integration of these models is significantly suitable for the flood risk assessment in the basin.}, language = {en} } @misc{NuswantoroDiermanseMolkenthin, author = {Nuswantoro, Riyandi and Diermanse, F. and Molkenthin, Frank}, title = {Probabilistic flood hazard maps for Jakarta derived from a stochastic rain-storm generator}, series = {Journal of Flood Risk Management}, volume = {9}, journal = {Journal of Flood Risk Management}, number = {2}, issn = {1753-318X}, doi = {10.1111/jfr3.12114}, pages = {105 -- 124}, abstract = {Generally, the methods to derive design events in a flood-modelling framework do not take into account the full range of extreme storm events and therefore do not take into account all aleatory uncertainties originating from rainfall intensity and spatial variability. The design event method uses a single simulation in order to represent an extreme event. The study presents a probabilistic method to derive flood inundation maps in an area where rainfall is the predominant cause of flooding. The case study area is the Jakarta Basin, Indonesia. It typically experiences high-intensity and short-duration storms with high spatial variability. The flood hazard estimation framework is a combination of a Monte Carlo (MC)-based simulation and a simplified stochastic storm generator. Several thousands of generated extreme events are run in the Sobek rainfall-runoff and 1D-2D model. A frequency analysis is then conducted at each location in the flood plain in order to derive flood maps. The result shows that in general, design events overestimate the flood maps in comparison with the proposed MC approach. The MC approach takes into account spatial variability of the rainfall. However, this means that there is a need to have a high number of MC-generated events in order to better estimate the extreme quantiles. As a consequence, the MC approach needs much more computational resources and it is time-consuming if a full hydrodynamic model is used. Hence, a simplified flood model may be required to reduce the simulation time.}, language = {en} } @misc{AltenkirchZlatanovićWoodwardetal., author = {Altenkirch, Nora and Zlatanović, Sanja and Woodward, K. Benjamin and Trauth, Nico and Mutz, Michael and Molkenthin, Frank}, title = {Untangling hyporheic residence time distributions and whole stream" "metabolism using a hydrological process model}, series = {Procedia Engineering}, volume = {154}, journal = {Procedia Engineering}, issn = {1877-7058}, doi = {10.1016/j.proeng.2016.07.598}, pages = {1071 -- 1078}, abstract = {The interaction of the water residence time (RT) in hyporheic sediments with the sediment metabolic rates is believed to be a key factor controlling whole stream metabolism. However, due to the methodological difficulties, there is little data that investigates this fundamental theory of aquatic ecology. Here, we report on progress made to combine numerical modelling with a series of modification to laboratory flumes overcoming methodological difficulties e.g. by creating steady flow paths for assessment of metabolic rates. To model the biogeochemical performance and to validate the model results, sediment structures were introduced in both, the model and the flumes, leading to differing RT distributions. Furthermore, the DOC supply in the flumes was manipulated to test the whole stream metabolic response with regard to RT distributions. In the flumes, hydraulic conditions were assessed using conservative tracer and heat as tracer. Metabolic activity was assessed using oxygen dynamics as a proxy of community respiration (CR). Residence time and metabolic processes were modelled using a multicomponent reactive transport code called MIN3P and calibrated with regard to the hydraulic conditions using the results obtained from the flume experiments. Monod type expressions were used to implement metabolic activity terms in the model. Using the results of the hydrological process model, a sensitivity analysis of the impact of RT distributions on the metabolic activity could yield supporting proof of an existing link between the two.}, language = {en} }