Suchergebnisse
Filter
6 Ergebnisse
Sortierung:
Land degradation in South Africa: Conventional views, changing paradigms and a tradition of soil conservation
In: Development Southern Africa: quarterly journal, Band 15, Heft 3, S. 449-469
ISSN: 0376-835X
Bodenzerstörung durch Erosion, Überbevölkerung, Überstockung und ungeeignete Bewirtschaftungsmethoden ist seit langem ein großes Problem Südafrikas, ohne daß sich bisher die Verhaltensweisen der Bevölkerung wesentlich verändert haben. Vor dem Hintergrund des bisher kaum in Anspruch genommenen traditionellen Wissens über eine schonende menschliche Nutzung der Umwelt wird die Situation jedoch heute etwas optimistischer gesehen. Am Beispiel des früheren Venda untersuchen die Autoren die lokalen Traditionen der Terrassierung und anderer Maßnahmen gegen die Bodenerosion, die eine bemerkenswerte Kenntnis von Ursachen und Folgen menschlicher Bewirtschaftung widerspiegeln. Alte Anbautraditionen sollten beim Umweltschutz stärker als bisher berücksichtigt werden. (DÜI-Hlb)
World Affairs Online
Aqueduct Management Planning: Thirlmere, Haweswater and Vyrnwy Aqueducts
In: Water and environment journal, Band 8, Heft 5, S. 502-512
ISSN: 1747-6593
ABSTRACTBetween 1988 and 1992, an asset study of North West Water Limited's three largest aqueducts was carried out to assess their condition and rehabilitation needs. About 360 km of the aqueduct system, including approximately 1700 structures, 160 km of tunnel and conduit, 700 km of pipeline and 4000 valves, were covered by the study. A wide range of survey techniques was used, some being specially developed as part of the study, and a unified system of condition assessment and prioritization of rehabilitation needs was devised.The paper (a) describes the overall approach and survey techniques, (b) discusses the methods of assessment used, (c) summarizes the conditions of the assets whose ages vary from 20–100 years, and (d) reviews some of the rehabilitation works proposed and executed.
Automatic Coagulation Control at Water‐Treatment Plants in the North‐West Region of England
In: Water and environment journal, Band 4, Heft 6, S. 535-543
ISSN: 1747-6593
North West Water has evaluated several automatic coagulation control systems covering a range of raw waters and treatment facilities.The experiences have shown that streaming‐current type systems are effective in controlling coagulant dose automatically, provided that appropriate plant conditions exist. In particular, rapid fluctuations in flow or poor mixing of chemicals can lead to unstable signals. Recent investigations indicate that for some waters streaming‐current voltage is sensitive to small changes in pH, and precise control of pH is therefore necessary.The main observed benefits have been treated water of a more consistent high quality, together with improved security of service, as the systems will respond reliably and effectively over long periods. Significant savings in coagulant usage can be obtained in certain cases.
Elective surgery cancellations due to the COVID-19 pandemic. Global predictive modelling to inform surgical recovery plans
Background: The COVID-19 pandemic has disrupted routine hospital services globally. This study estimated the total number of adult elective operations that would be cancelled worldwide during the 12 weeks of peak disruption due to COVID-19. Methods: A global expert response study was conducted to elicit projections for the proportion of elective surgery that would be cancelled or postponed during the 12 weeks of peak disruption. A Bayesian β-regression model was used to estimate 12-week cancellation rates for 190 countries. Elective surgical case-mix data, stratified by specialty and indication (surgery for cancer versus benign disease), were determined. This case mix was applied to country-level surgical volumes. The 12-week cancellation rates were then applied to these figures to calculate the total number of cancelled operations. Results: The best estimate was that 28 404 603 operations would be cancelled or postponed during the peak 12 weeks of disruption due to COVID-19 (2 367 050 operations per week). Most would be operations for benign disease (90·2 per cent, 25 638 922 of 28 404 603). The overall 12-week cancellation rate would be 72·3 per cent. Globally, 81·7 per cent of operations for benign conditions (25 638 922 of 31 378 062), 37·7 per cent of cancer operations (2 324 070 of 6 162 311) and 25·4 per cent of elective caesarean sections (441 611 of 1 735 483) would be cancelled or postponed. If countries increased their normal surgical volume by 20 per cent after the pandemic, it would take a median of 45 weeks to clear the backlog of operations resulting from COVID-19 disruption. Conclusion: A very large number of operations will be cancelled or postponed owing to disruption caused by COVID-19. Governments should mitigate against this major burden on patients by developing recovery plans and implementing strategies to restore surgical activity safely.
BASE