Comparative predictions of discharge from an artificial catchment (Chicken Creek) using sparse data

Ten conceptually different models in predicting discharge from the artificial Chicken Creek catchment in North-East Germany were used for this study. Soil texture and topography data were given to the modellers, but discharge data was withheld. We compare the predictions with the measurements from the 6 ha catchment and discuss the conceptualization and parameterization of the models. The predictions vary in a wide range, e.g. with the predicted actual evapotranspiration ranging from 88 to 579 mm/y and the discharge from 19 to 346 mm/y. The predicted components of the hydrological cycle deviated systematically from the observations, which were not known to the modellers. Discharge was mainly predicted as subsurface discharge with little direct runoff. In reality, surface runoff was a major flow component despite the fairly coarse soil texture. The actual evapotranspiration (AET) and the ratio between actual and potential ET was systematically overestimated by nine of the ten models. None of the model simulations came even close to the observed water balance for the entire 3-year study period. The comparison indicates that the personal judgement of the modellers was a major source of the differences between the model results. The most important parameters to be presumed were the soil parameters and the initial soil-water content while plant parameterization had, in this particular case of sparse vegetation, only a minor influence on the results

Soil and water bioengineering: practice and research needs for reconciling natural hazard control and ecological restoration

Soil and water bioengineering is a technology that encourages scientists and practitioners to combine their knowledge and skills in the management of ecosystems with a common goal to maximize benefits to both man and the natural environment. It involves techniques that use plants as living building materials, for: (i) natural hazard control (e.g., soil erosion, torrential floods and landslides) and (ii) ecological restoration or nature-based re-introduction of species on degraded lands, river embankments, and disturbed environments. For a bioengineering project to be successful, engineers are required to highlight all the potential benefits and ecosystem services by documenting the technical, ecological, economic and social values. The novel approaches used by bioengineers raise questions for researchers and necessitate innovation from practitioners to design bioengineering concepts and techniques. Our objective in this paper, therefore, is to highlight the practice and research needs in soil and water bioengineering for reconciling natural hazard control and ecological restoration. Firstly, we review the definition and development of bioengineering technology, while stressing issues concerning the design, implementation, and monitoring of bioengineering actions. Secondly, we highlight the need to reconcile natural hazard control and ecological restoration by posing novel practice and research questions

Changing climate both increases and decreases European river floods

Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere1. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe2. Any changes in river floods would have lasting implications for the design of flood protection measures and flood risk zoning. However, existing studies have been unable to identify a consistent continental-scale climatic-change signal in flood discharge observations in Europe3, because of the limited spatial coverage and number of hydrometric stations. Here we demonstrate clear regional patterns of both increases and decreases in observed river flood discharges in the past five decades in Europe, which are manifestations of a changing climate. Our results\u2014arising from the most complete database of European flooding so far\u2014suggest that: increasing autumn and winter rainfall has resulted in increasing floods in northwestern Europe; decreasing precipitation and increasing evaporation have led to decreasing floods in medium and large catchments in southern Europe; and decreasing snow cover and snowmelt, resulting from warmer temperatures, have led to decreasing floods in eastern Europe. Regional flood discharge trends in Europe range from an increase of about 11 per cent per decade to a decrease of 23 per cent. Notwithstanding the spatial and temporal heterogeneity of the observational record, the flood changes identified here are broadly consistent with climate model projections for the next century4,5, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management

Cytotoxicity and DNA damage in the neutrophils of patients with sickle cell anaemia treated with hydroxyurea

Hydroxyurea (HU) is the most important advance in the treatment of sickle cell anaemia (SCA) for preventing complications and improving quality of life for patients. However, some aspects of treatment with HU remain unclear, including their effect on and potential toxicity to other blood cells such as neutrophils. This study used the measurement of Lactate Dehydrogenase (LDH) and Methyl ThiazolTetrazolium (MTT) and the comet assay to investigate the cytotoxicity and damage index (DI) of the DNA in the neutrophils of patients with SCA using HU.In the LDH and MTT assays, a cytoprotective effect was observed in the group of patients treated, as well as an absence of toxicity. When compared to patients without the treatment, the SS group (n=20, 13 women and 07 men, aged 18-69 years), and the group of healthy individuals (AA) used as a control group (n=52, 28 women and 24 men, aged 19-60 years), The SSHU group (n=21, 11 women and 10 men, aged 19-63 years) showed a significant reduction (p20 months), demonstrating that despite the cytoprotective effects in terms of cell viability, the use of HU can induce DNA damage in neutrophils

Una metodologia per l'analisi dell'effetto della variabilità spaziale della precipitazione sui deflussi simulati con un modello idrologico distribuito

Molti studi hanno analizzato l’effetto della variabilità della precipitazione sulla risposta simulata a scala di bacino. Generalmente la finalità di questi studi è quella di valutare le scale spaziali e temporali più efficaci da adottare nel monitoraggio della precipitazione e nella simulazione dei processi idrologici. I risultati di questi studi sono spesso difficili da confrontare e generalizzare, essendo fortemente dipendenti dalle scale spaziali di analisi e dagli approcci modellistici adottati per la simulazione dei deflussi a scala di bacino. Questo lavoro presenta una procedura analitica per valutare l’effetto della variabilità spaziale e temporale della precipitazione sui deflussi simulati, applicabile in modo generalizzato a tutti i modelli idrologici distribuiti. Sulla base di poche ipotesi semplificatrici, comuni a gran parte dei modelli idrologici proposti in letteratura, la sensitività del modello alla variabilità spaziale e temporale della pioggia è definita da indici adimensionali che disaggregano la risposta simulata in una componente globale, integrata a scala di bacino, ed in una componente distribuita. La componente distribuita è rappresentata dalle covarianze spaziali e temporali tra il campo di precipitazione ed il campo della variabile di stato simulata rappresentativa del coefficiente di deflusso locale. Si dimostra come la componente distribuita può rappresentare una componente di non stazionarietà nella risposta simulata con modelli globali, che può essere compensata solo attraverso una calibrazione specifica dei parametri ed una distorsione delle grandezze di stato aggregate a scala di bacino. Lo studio presenta anche un esempio applicativo della procedura proposta, con riferimento ad un bacino avente un’estensione di circa cinquanta chilometri quadrati

Generalised synthesis of space-time variability in flood response: An analytical framework

We extend the method developed by Woods and Sivapalan (1999) to provide a more general analytical framework for assessing the dependence of the catchment flood response on the space–time interactions between rainfall, runoff generation and routing mechanisms. The analytical framework focuses on three characteristics of the flood hydrograph: the catchment rainfall excess rate, and the first and second temporal moments of the flood response. These characteristics are described by analytical relations, which are derived with a limited number of assumptions concerning the catchment response that comply well with many modelling approaches. The paper illustrates the development of the analytical framework and explains the conceptual meaning of the mathematical relations by taking a simple and idealised “open-book” catchment as a case study. It is shown how the components of the derived equations explicitly quantify the relative importance of processes and the space–time interactions among them during flood events. In particular, the components added to the original framework of Woods and Sivapalan (1999), which account for storm movement and hillslope routing variability in space, are demonstrated to be important and in some cases decisive in combining to bring about the flood response. The proposed analytical framework is not a predictive model but a tool to understand the magnitude of the components that contribute to runoff response, similar to the components of the St. Venant equations in fluid dynamics