Watersheds may not recover from drought Peterson, Tim J; Saft, M; Peel, M C ...
Science (American Association for the Advancement of Science),
05/2021, Letnik:
372, Številka:
6543
Journal Article
Recenzirano
The Millennium Drought (southeastern Australia) provided a natural experiment to challenge the assumption that watershed streamflow always recovers from drought. Seven years after the drought, the ...runoff (as a fraction of precipitation) had not recovered in 37% of watersheds, and the number of recovered watersheds was not increasing. When recovery did occur, it was not explained by watershed wetness. For those watersheds not recovered, ~80% showed no evidence of recovering soon, suggesting persistence within a low-runoff state. The post-drought precipitation not going to runoff was found to be likely going to increased evapotranspiration per unit of precipitation. These findings show that watersheds can have a finite resilience to disturbances and suggest that hydrological droughts can persist indefinitely after meteorological droughts.
As the population ages, increasing numbers of older adults are undergoing surgery. Frailty is prevalent in older adults and may be a better predictor of post-operative morbidity and mortality than ...chronological age. The aim of this review was to examine the impact of frailty on adverse outcomes in the 'older old' and 'oldest old' surgical patients.
A systematic review was undertaken. Electronic databases from 2010 to 2015 were searched to identify articles which evaluated the relationship between frailty and post-operative outcomes in surgical populations with a mean age of 75 and older. Articles were excluded if they were in non-English languages or if frailty was measured using a single marker only. Demographic data, type of surgery performed, frailty measure and impact of frailty on adverse outcomes were extracted from the selected studies. Quality of the studies and risk of bias was assessed by the Epidemiological Appraisal Instrument.
Twenty-three studies were selected for the review and they were assessed as medium to high quality. The mean age ranged from 75 to 87 years, and included patients undergoing cardiac, oncological, general, vascular and hip fracture surgeries. There were 21 different instruments used to measure frailty. Regardless of how frailty was measured, the strongest evidence in terms of numbers of studies, consistency of results and study quality was for associations between frailty and increased mortality at 30 days, 90 days and one year follow-up, post-operative complications and length of stay. A small number of studies reported on discharge to institutional care, functional decline and lower quality of life after surgery, and also found a significant association with frailty.
There was strong evidence that frailty in older-old and oldest-old surgical patients predicts post-operative mortality, complications, and prolonged length of stay. Frailty assessment may be a valuable tool in peri-operative assessment. It is possible that different frailty tools are best suited for different acuity and type of surgical patients. The association between frailty and return to pre-morbid function, discharge destination, and quality of life after surgery warrants further research.
This guide to estimating daily and monthly actual, potential, reference crop and pan evaporation covers topics that are of interest to researchers, consulting hydrologists and practicing engineers. ...Topics include estimating actual evaporation from deep lakes and from farm dams and for catchment water balance studies, estimating potential evaporation as input to rainfall-runoff models, and reference crop evapotranspiration for small irrigation areas, and for irrigation within large irrigation districts. Inspiration for this guide arose in response to the authors' experiences in reviewing research papers and consulting reports where estimation of the actual evaporation component in catchment and water balance studies was often inadequately handled. Practical guides using consistent terminology that cover both theory and practice are not readily available. Here we provide such a guide, which is divided into three parts. The first part provides background theory and an outline of the conceptual models of potential evaporation of Penman, Penman-Monteith and Priestley-Taylor, as well as discussions of reference crop evapotranspiration and Class-A pan evaporation. The last two sub-sections in this first part include techniques to estimate actual evaporation from (i) open-surface water and (ii) landscapes and catchments (Morton and the advection-aridity models). The second part addresses topics confronting a practicing hydrologist, e.g. estimating actual evaporation for deep lakes, shallow lakes and farm dams, lakes covered with vegetation, catchments, irrigation areas and bare soil. The third part addresses six related issues: (i) automatic (hard wired) calculation of evaporation estimates in commercial weather stations, (ii) evaporation estimates without wind data, (iii) at-site meteorological data, (iv) dealing with evaporation in a climate change environment, (v) 24 h versus day-light hour estimation of meteorological variables, and (vi) uncertainty in evaporation estimates. This paper is supported by a Supplement that includes 21 sections enhancing the material in the text, worked examples of many procedures discussed in the paper, a program listing (Fortran 90) of Morton's WREVAP evaporation models along with tables of monthly Class-A pan coefficients for 68 locations across Australia and other information.
Gait speed is a quick, inexpensive, reliable measure of functional capacity with well-documented predictive value for major health-related outcomes. Numerous epidemiological studies have documented ...gait speed in healthy, community-dwelling older people. The purpose of this study is to undertake a systematic review and meta-analysis of gait speed in a specific group with mobility limitations-geriatric patients in clinical settings.
Relevant databases were searched systematically for original research articles published in February 2011 measuring gait speed in persons aged 70 or older in hospital inpatient or outpatients settings. Meta-analysis determined gait speed data for each setting adjusting for covariates.
The review included 48 studies providing data from 7,000 participants. Across the hospital settings, the gait speed estimate for usual pace was 0.58 m/s (95% confidence interval CI: 0.49-0.67) and for maximal pace was 0.89 m/s (95% CI: 0.75-1.02). These estimates were based on most recent year of publication (2011) and median percentage of female participants (63%). Gait speed at usual pace in acute care settings was 0.46 m/s (95% CI: 0.34-0.57), which was significantly slower than the gait speed of 0.74 m/s (95% CI: 0.65-0.83) recorded in outpatient settings.
Gait speed is an important measure in comprehensive geriatric assessment. The consolidation of data from multiple studies reported in this meta-analysis highlights the mobility limitations experienced by older people in clinical settings and the need for ongoing rehabilitation to attain levels sufficient for reintegration in the community.
Highlights • Frailty is prevalent in CKD patients with those on dialysis being the most frail. • Frailty is associated with an increased risk of mortality and hospitalization. • Most common method of ...frailty assessment in the CKD cohort is the Fried phenotype. • Reported frailty prevalence changes depending on the method of frailty assessment.
The choice of hydrological model structure, that is, a model's selection of states and fluxes and the equations used to describe them, strongly controls model performance and realism. This work ...investigates differences in performance of 36 lumped conceptual model structures calibrated to and evaluated on daily streamflow data in 559 catchments across the United States. Model performance is compared against a benchmark that accounts for the seasonality of flows in each catchment. We find that our model ensemble struggles to beat the benchmark in snow‐dominated catchments. In most other catchments model structure equifinality (i.e., cases where different models achieve similar high efficiency scores) can be very high. We find no relation between the number of model parameters and performance during either calibration or evaluation periods nor evidence of increased risk of overfitting for models with more parameters. Instead, the choice of model parametrization (i.e., which equations are used and how parameters are used within them) dictates the model's strengths and weaknesses. Results suggest that certain model structures are inherently better suited for certain objective functions and thus for certain study purposes. We find no clear relationships between the catchments where any model performs well and descriptors of those catchments' geology, topography, soil, and vegetation characteristics. Instead, model suitability seems to relate strongest to the streamflow regime each catchment generates, and we have formulated several tentative hypotheses that relate commonalities in model structure to similarities in model performance. Modeling results are made publicly available for further investigation.
Key Points
Conceptual model structure uncertainty is high across different catchments and objective functions
There is no evidence of systematic overfitting for models with up to 15 calibrated parameters
Model performance relates more to streamflow signatures than to climate or catchment descriptors
frailty is proposed as a summative measure of health status and marker of individual vulnerability. We aimed to investigate the discriminative capacity of a frailty index (FI) derived from interRAI ...Comprehensive Geriatric Assessment for Acute Care (AC) in relation to multiple adverse inpatient outcomes.
in this prospective cohort study, an FI was derived for 1,418 patients ≥70 years across 11 hospitals in Australia. The interRAI-AC was administered at admission and discharge by trained nurses, who also screened patients daily for geriatric syndromes.
in adjusted logistic regression models an increase of 0.1 in FI was significantly associated with increased likelihood of length of stay >28 days (odds ratio OR: 1.29 1.10-1.52), new discharge to residential aged care (OR: 1.31 1.10-1.57), in-hospital falls (OR: 1.29 1.10-1.50), delirium (OR: 2.34 2.08-2.63), pressure ulcer incidence (OR: 1.51 1.23-1.87) and inpatient mortality (OR: 2.01 1.66-2.42). For each of these adverse outcomes, the cut-point at which optimal sensitivity and specificity occurred was for an FI > 0.40. Specificity was higher than sensitivity with positive predictive values of 7-52% and negative predictive values of 88-98%. FI-AC was not significantly associated with readmissions to hospital.
the interRAI-AC can be used to derive a single score that predicts multiple adverse outcomes in older inpatients. A score of ≤0.40 can well discriminate patients who are unlikely to die or experience a geriatric syndrome. Whether the FI-AC can result in management decisions that improve outcomes requires further study.
The C-Band All-Sky Survey (C-BASS) is an all-sky full-polarization survey at a frequency of 5 GHz, designed to provide complementary data to the all-sky surveys of WMAP and Planck, and future CMB ...B-mode polarization imaging surveys. The observing frequency has been chosen to provide a signal that is dominated by Galactic synchrotron emission, but suffers little from Faraday rotation, so that the measured polarization directions provide a good template for higher frequency observations, and carry direct information about the Galactic magnetic field. Telescopes in both northern and southern hemispheres with matched optical performance are used to provide all-sky coverage from a ground-based experiment. A continuous-comparison radiometer and a correlation polarimeter on each telescope provide stable imaging properties such that all angular scales from the instrument resolution of 45 arcmin up to full sky are accurately measured. The northern instrument has completed its survey and the southern instrument has started observing. We expect that C-BASS data will significantly improve the component separation analysis of Planck and other CMB data, and will provide important constraints on the properties of anomalous Galactic dust and the Galactic magnetic field.
The objective of this paper is to identify better performing Coupled Model Intercomparison Project phase 3 (CMIP3) global climate models (GCMs) that reproduce grid-scale climatological statistics of ...observed precipitation and temperature for input to hydrologic simulation over global land regions. Current assessments are aimed mainly at examining the performance of GCMs from a climatology perspective and not from a hydrology standpoint. The performance of each GCM in reproducing the precipitation and temperature statistics was ranked and better performing GCMs identified for later analyses. Observed global land surface precipitation and temperature data were drawn from the Climatic Research Unit (CRU) 3.10 gridded data set and re-sampled to the resolution of each GCM for comparison. Observed and GCM-based estimates of mean and standard deviation of annual precipitation, mean annual temperature, mean monthly precipitation and temperature and Köppen-Geiger climate type were compared. The main metrics for assessing GCM performance were the Nash-Sutcliffe efficiency (NSE) index and root mean square error (RMSE) between modelled and observed long-term statistics. This information combined with a literature review of the performance of the CMIP3 models identified the following better performing GCMs from a hydrologic perspective: HadCM3 (Hadley Centre for Climate Prediction and Research), MIROCm (Model for Interdisciplinary Research on Climate) (Center for Climate System Research (The University of Tokyo), National Institute for Environmental Studies, and Frontier Research Center for Global Change), MIUB (Meteorological Institute of the University of Bonn, Meteorological Research Institute of KMA, and Model and Data group), MPI (Max Planck Institute for Meteorology) and MRI (Japan Meteorological Research Institute). The future response of these GCMs was found to be representative of the 44 GCM ensemble members which confirms that the selected GCMs are reasonably representative of the range of future GCM projections.
Hydrological models are traditionally calibrated against observed discharge. However, for a given model, similar performance for discharge simulation can be achieved through a variety of parameter ...combinations, some of which produce unrealistic simulations of non‐discharge variables. Thus, considering non‐discharge variables in calibration can help to reduce equifinality and give more realistic simulations. Few studies considered non‐discharge variables in calibration and evaluation and across a large sample of catchments. In this study, we calibrate the lumped SIMHYD model with several combinations of different hydrological variables such as discharge, actual evapotranspiration, soil wetness, and total water storage. The various calibration scenarios are conducted across 550 catchments in Australia spanning arid, tropical and temperate regions. We show that the performance of the discharge‐calibrated model for actual evapotranspiration, soil wetness, and total water storage is strongly related to the co‐seasonality of discharge and the respective variable. Considering actual evapotranspiration, soil wetness, or total water storage in addition to discharge in calibration improves the simulation of the added variable on average by 53%, 58%, and 41%, respectively, which comes at the expense of decrease in discharge performance by 5%. Cross‐benefits, that is, the improved simulation of a variable by considering another variable in calibration, mainly occurs between actual evapotranspiration and total water storage and are most pronounced in humid catchments with highly seasonal soil wetness. We also find that when using all four variables in model calibration, the trade‐off in model performance between discharge and the other variables gets more pronounced with increasing catchment wetness.
Key Points
Using four different hydrological variables, multivariate calibration and evaluation were undertaken in 550 Australian catchments
Benefit of multivariate calibration across non‐discharge variables is higher in humid than in (semi‐) arid climates
Pronounced evaluation cross‐benefits between evapotranspiration and total water storage in temperate climates with seasonal soil wetness
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