72 research outputs found

    Changing climate both increases and decreases European river floods

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    Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe. 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 Europe, 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—arising from the most complete database of European flooding so far—suggest 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 century, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management

    Energy and nutrient deposition and excretion in the reproducing sow: model development and evaluation.

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    Air and nutrient emissions from swine operations raise environmental concerns. During the reproduction phase, sows consume and excrete large quantities of nutrients. The objective of this study was to develop a mathematical model to describe energy and nutrient partitioning and predict manure excretion and composition and methane emissions on a daily basis. The model was structured to contain gestation and lactation modules, which can be run separately or sequentially, with outputs from the gestation module used as inputs to the lactation module. In the gestating module, energy and protein requirements for maintenance, and fetal and maternal growth were described. In the lactating module, a factorial approach was used to estimate requirements for maintenance, milk production, and maternal growth. The priority for nutrient partitioning was assumed to be in the order of maintenance, milk production, and maternal growth with body tissue losses constrained within biological limits. Global sensitivity analysis showed that nonlinearity in the parameters was small. The model outputs considered were the total protein and fat deposition, average urinary and fecal N excretion, average methane emission, manure carbon excretion, and manure production. The model was evaluated using independent data sets from the literature using root mean square prediction error (RMSPE) and concordance correlation coefficients. The gestation module predicted body fat gain better than body protein gain, which was related to predictions of body fat and protein loss from the lactation model. Nitrogen intake, urine N, fecal N, and milk N were predicted with RMSPE as percentage of observed mean of 9.7, 17.9, 10.0, and 7.7%, respectively. The model provided a framework, but more refinements and improvements in accuracy of prediction (particularly urine N) are required before the model can be used to assess environmental mitigation options from sow operations

    Determination of protein and amino acid requirements of lactating sows using a population-based factorial approach.

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    Determination of appropriate nutritional requirements is essential to optimize the productivity and longevity of lactating sows. The current recommendations for requirements do not consider the large variation between animals. Therefore, the aim of this study was to determine the amino acid recommendations for lactating sows using a stochastic modeling approach that integrates population variation and uncertainty of key parameters into establishing nutritional recommendations for lactating sows. The requirement for individual sows was calculated using a factorial approach by adding the requirement for maintenance and milk. The energy balance of the sows was either negative or zero depending on feed intake being a limiting factor. Some parameters in the model were sow-specific and others were population-specific, depending on state of knowledge. Each simulation was for 1000 sows repeated 100 times using Monte Carlo simulation techniques. BW, back fat thickness of the sow, litter size (LS), average litter gain (LG), dietary energy density and feed intake were inputs to the model. The model was tested using results from the literature, and the values were all within ±1 s.d. of the estimated requirements. Simulations were made for a group of low- (LS=10 (s.d.=1), LG=2 kg/day (s.d.=0.6)), medium- (LS=12 (s.d.=1), LG=2.5 kg/day (s.d.=0.6)) and high-producing (LS=14 (s.d.=1), LG=3.5 kg/day (s.d.=0.6)) sows, where the average requirement was the result. In another simulation, the requirements were estimated for each week of lactation. The results were given as the median and s.d. The average daily standardized ileal digestible (SID) protein and lysine requirements for low-, medium- and high-producing sows were 623 (CV=2.5%) and 45.1 (CV=4.8%); 765 (CV=4.9%) and 54.7 (CV=7.0%); and 996 (CV=8.5%) and 70.8 g/day (CV=9.6%), respectively. The SID protein and lysine requirements were lowest at week 1, intermediate at week 2 and 4 and the highest at week 3 of lactation. The model is a valuable tool to develop new feeding strategies by taking into account the variable requirement between groups of sows and changes during lactation. The inclusion of between-sow variation gives information on safety margins when developing new dietary recommendations of amino acids and protein for lactating sows
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