Evaluating multiple performance criteria to calibrate the distributed hydrological model of the upper Neckar catchment

Performance criteria are used in the automated calibration of hydrological models to determine and minimise the misfit between observations and model simulations. In this study, a multiobjective model calibration framework is used to analyse the trade-offs between Nash–Sutcliffe efficiency of flows (NSE), the NSE of log-transformed flows (NSE_logQ), and the sum-squared error of monthly discharge sums (SSE_MQ). These criteria are known to put different emphasis on average and high flows, low flows, and average volume-balance components. Twenty-two upper Neckar subbasins whose catchment area ranges from 56 to 3,976 km² were modelled with the distributed mesoscale hydrological model (mHM) to investigate these trade-offs. The 53 global parameters required for each instance of the mHM model were estimated with the global search algorithm AMALGAM. Equally weighted compromise solutions based on the selected criteria and extreme ends of all bi-criterion Pareto fronts were used after each calibration run to analyse the trade-off between different performance criteria. Calibration results were further analysed with ten additional criteria commonly used for evaluating hydrological model performance. Results showed that the trade-off patterns were similar for all subbasins irrespective of catchment size and that the largest trade-offs were consistently observed between the NSE and NSE_logQ criteria. Simulations with the compromise solution provided a well-balanced fit to individual characteristics of the streamflow hydrographs and exhibited improved volume balance. Other performance criteria such as bias, the Pearson correlation coefficient, and the relative variability remained largely unchanged between compromise solutions and Pareto extremes. Parameter sets of the best NSE fit and the compromise solution of the largest basin (gauge at Plochingen) were used to simulate streamflow at the other 21 internal subbasins for a 10-year evaluation period without re-calibration. Both parameter sets performed well in the individual basins with median NSE values of 0.74 and 0.72, respectively. The compromise solution resulted in similar NSE_logQ-ranges and a 14.6 % lower median volume-balance error which indicates an overall better model performance. The results demonstrate that the performance criteria for hydrological model calibration should be selected in accordance with the anticipated model predictions. The compromise solution provides an advance to the use of single criteria in model calibration.     

On long-term evolution of seasonal precipitation in southwestern Europe

Annual cycles in long time series of precipitation from sixteen southwest European observatories have been analysed using complex demodulation. The stations have been clustered into two distinct regions and a hybrid one. They are referred to as the southwestern Europe precipitation Atlantic regime (SEPAR) and the southwestern Europe precipitation Mediterranean regime (SEPMER), with the hybrid regime referred to in terms of the mean amplitude ratios between semiannual and annual rainfall components. Some evidence of linking between seasonal cycle harmonic amplitudes and the zonal circulation has been found for SEPAR stations and a more obscured relationship for the SEPMER region. Within the SEPAR region the strength of the relationship is diminished towards the north. A trend analysis of the amplitudes against time since 1920 has also been carried out and the results reveal a divergent pattern in trends between annual and semiannual component amplitudes for the SEPAR region. In fact, both an increasing annual-amplitude trend and a decreasing semiannual-amplitude trend are observed, in each case statistically significant. The fact that the seasonal cycle variability of rainfall in southwestern Europe becomes more sensitive southwards to changes in atmospheric zonal circulation over the North Atlantic might, in our opinion, be related to the swing of the circumpolar vortex.     

Every single street? Rethinking full coverage across street‐level imagery platforms

Street‐level images taken by vehicles and pedestrians have found a role in various companies’ location‐based intelligence services. Some platforms collect their images using their own cars and drivers, while others rely on crowdsourcing; however, to what extent can we expect crowdsourced approaches to reach the imagery coverage levels obtained by paid drivers? Is capturing every single street a useful or obtainable goal? We use online coverage maps to compare Google Street View, Mapillary, and OpenStreetCam in 24 major world cities and 25 differently sized cities in Brazil. We find that Google has often taken an all‐or‐nothing approach to collecting coverage in world cities, whereas crowdsourced platforms have achieved a more even distribution of coverage across space. Extremely low‐ and high‐income neighborhoods are sometimes omitted due to visible and invisible barriers. Coverage patterns are influenced by how and why each company procures imagery, along with other social, economic, and geographic factors.     

The IWAS-ToolBox: Software coupling for an integrated water resources management

Numerical modeling of interacting flow and transport processes between different hydrological compartments, such as the atmosphere/land surface/vegetation/soil/groundwater systems, is essential for understanding the comprehensive processes, especially if quantity and quality of water resources are in acute danger, like e.g. in semi-arid areas and regions with environmental contaminations. The computational models used for system and scenario analysis in the framework of an integrated water resources management are rapidly developing instruments. In particular, advances in computational mathematics have revolutionized the variety and the nature of the problems that can be addressed by environmental scientists and engineers. It is certainly true that for each hydro-compartment, there exists many excellent simulation codes, but traditionally their development has been isolated within the different disciplines. A new generation of coupled tools based on the profound scientific background is needed for integrated modeling of hydrosystems. The objective of the IWAS-ToolBox is to develop innovative methods to combine and extend existing modeling software to address coupled processes in the hydrosphere, especially for the analysis of hydrological systems in sensitive regions. This involves, e.g. the provision of models for the prediction of water availability, water quality and/or the ecological situation under changing natural and socio-economic boundary conditions such as climate change, land use or population growth in the future.     

Crustal thinning and mafic underplating beneath the Neogene Volcanic Province (Betic Cordillera,SE Spain): evidence from crustal xenoliths

Three metapelitic xenolith suites in the Neogene Volcanic Province (NVP) of SE Spain (from SW to NE: El Hoyazo, Mazarrón and Mar Menor) originated by partial melting at different crustal depths, decreasing from 20–25 km in the SW to 9–12 km in the NE. Peak temperatures reached c. 900 °C. The xenolith source level is equated with the base of a felsic upper crust of high melting potential (‘fertility’). At El Hoyazo, this matches a thin, intracrustal low‐velocity zone recently inferred from seismic studies. Isostatic calculations indicate that this zone increases in thickness from SW to NE. A model of increasing upper crustal thinning from SW to NE in the NVP, accompanied by mafic underplating, is consistent with the 9 Ma petrological data, with current heat flow, seismic data and gravimetry. It is concluded that significant crustal extension occurred in the NVP in the late Miocene, i.e. after the main phase of widespread extension, exhumation of high‐pressure rocks and formation of the Alborán Sea.     

Recovery of Normal Cytogenetic Records in Mussels After Cessation of Pollutant Effluents in Puerto Madryn (Patagonia,Argentina)

The capacity of coast recovering after interruption of pollution sources has been explored employing mussels as biomarkers. In an area polluted by sewage sludge in Puerto Madryn (Argentina), abnormally high cytogenetic records (micronuclei) had been detected in the mussel Mytilus edulis, even higher than those obtained in this and other mussel species (Brachydontes rodriguezi, Aulacomya atra atra, Perumytilus purpuratus) sampled from heavily polluted industrial areas, and much higher than those recorded in samples from unpolluted areas of the same region. Normal cytogenetic patterns were recovered in Puerto Madryn less than 1 year after cessation of sewage sludge discharges, without additional treatment of the affected area. This discovery opens the possibility of considering restored coastal areas for aquaculture purposes instead of endangering natural populations in virgin areas.