Quantifying the Errors Involved in Transferring Suspended Sediment Rating Equations Across Ablation Seasons

Bias-corrected suspended sediment rating equations are developed for the data from six separate ablation seasons in the Glacier de Tsidjiore Nouve basin. These equations differ significantly from one another. Suspended loads as predicted by equations used beyond their year of origin fall in the range of 34-278% of the true load. Mean absolute-percentage errors (MAPE) based on forecasts computed from each year’s model applied to the other 5 years of data range from 35 to 81%, with a mean of 52%. The equivalent MAPE for a lumped multi-year model is 38%, for an autocorrelation-correcting generalized least-squares (GLS) regression model, is 15%, and for a transfer function (TF) developed from a single 25 d period, only 5%. Simple structure-transfer functions appear to be more robust to temporal transfer than the usual type of rating equation, and offer the possibility of greatly improving upon the poor performance of OLS rating equations in providing estimates of suspended loads for periods beyond frames of origin.</jats:p

Quantifying the Errors Involved in Transferring Suspended Sediment Rating Equations Across Ablation Seasons

Bias-corrected suspended sediment rating equations are developed for the data from six separate ablation seasons in the Glacier de Tsidjiore Nouve basin. These equations differ significantly from one another. Suspended loads as predicted by equations used beyond their year of origin fall in the range of 34-278% of the true load. Mean absolute-percentage errors (MAPE) based on forecasts computed from each year’s model applied to the other 5 years of data range from 35 to 81%, with a mean of 52%. The equivalent MAPE for a lumped multi-year model is 38%, for an autocorrelation-correcting generalized least-squares (GLS) regression model, is 15%, and for a transfer function (TF) developed from a single 25 d period, only 5%. Simple structure-transfer functions appear to be more robust to temporal transfer than the usual type of rating equation, and offer the possibility of greatly improving upon the poor performance of OLS rating equations in providing estimates of suspended loads for periods beyond frames of origin.</jats:p

The Boscastle flood of 16 August 2004: Characteristics, causes and consequences

On 16 August 2004, exceptionally intense and prolonged storm conditions centred over the North Cornwall coast and the headwaters of Bodmin Moor generated extreme flooding in and above the coastal villages of Boscastle and Crackington Haven. The event – which wreaked havoc and damage, but led to no direct loss of life – captured considerable media attention. “What happened? Why there? How? How unusual was it? What’s the risk of it happening again, there and elsewhere? What’s being done? [and yes] Is climate change to blame?” style questions peppered the press, and occupied the minds of many, at the time and after. This paper addresses the “what happened?” question. It reports on a flood forensics study carried out for the Environment Agency by HR Wallingford, with support from Halcrow, Royal Haskoning, The Met Office, CEH Wallingford and others. The event, from storm to runoff to flood to impact, has been reconstructed using best available evidence and applying best possible analyses (meteorological, hydrological and hydraulic). Propagation mechanisms – and features like the reported “walls of water” observed during the event - are investigated with a numerical model calibrated against evidence of peak water levels. Estimates are provided of the peak flow and peak water levels experienced, and their probabilities; these place the event amongst the most extreme ever to have occurred in the region and in the UK

Lipidomic analysis of the molecular specificity of a cholinephosphotransferase in situ

Dynamic lipidomics using ESI–MS (tandem electrospray ionization mass spectrometry) of 9-deuterated choline (choline-d9) incorporation into mammalian cell PtdCho (phosphatidylcholine) permits assessment of the molecular specificity of synthesis. Bulk cell PtdCho synthesis occurs in spatially distinct locations, using separate CPTs (1,2 diacylglycerol CDP:choline cholinephosphotransferases). We assessed whether in vitro molecular selectivity of DAG (diacylglycerol) incorporation between CPTs is manifest in situ, by monitoring choline-d9 incorporation into PtdCho and lyso-PtdCho molecular species over 3 h in control cells and in CHO-K1 cells overexpressing hCEPT1. Compared with controls, the basal molecular species composition of hCEPT1 overexpressors was significantly enriched in arachidonate. This was not due to net accretion of cellular PtdCho arguing against effects of inadequate unsaturated PtdCho degradation or remodelling. Rather, time-course analyses of PtdCho and lyso-PtdCho pools showed that both arachidonate-containing DAG incorporation and turnover of PtdCho is increased in hCEPT1 overexpressors. Increased choline-d9 incorporation into arachidonyl lyso-PtdCho shows that both phospholipase A1- and A2-mediated turnover is involved. Spatially distinct molecular specificity of DAG incorporation into cellular PtdCho at the level of hCEPT1 exists in situ

Establishing suspended sediment rating curves for a pro-glacial stream Two studies

1.25SIGLELD:3597.851(21) / BLDSC - British Library Document Supply CentreGBUnited Kingdo