The value of water in the South African economy: Some implications

The South African Water Research Commission (WRC) initiated a number of research projects aimed at determining the value of water in different sectors of the economy and in different parts of the country. This research is reviewed. Water values were found to differ significantly between sectors, between geographic areas and within geographic areas. As agriculture is a large consumer of water several studies along different rivers were undertaken, including studies on water quality. Average ratios indicate that agriculture is an inefficient user of water in terms of gross income generated per unit of water and also in terms of jobs created per unit of water. Irrigation farming is, however, an important employer of labour while it contributes 30% to the value of farm output. A marginal approach and water demand elasticities also indicate that non-agriculture generally places a high value on water assurance but little value on more than what it already uses. This may indicate that although water is expected to transfer out of agriculture in the longer run, in the short run agriculture may be its best use. Water efficiency could be significantly enhanced if transfers within and between river reaches are promoted, as water shadow prices differ. Inputs from the Department of Water Affairs and Forestry (DWAF) are important in water allocation due to socio-economic and environmental externalities of water allocation.Resource /Energy Economics and Policy,

Suitability indicators to assess specific site, risk-based irrigation water quality

In the first of this two-paper series, we introduced readers to a newly developed electronic Decision Support System (DSS) that helps the user to assess the fitness for use of irrigation water (du Plessis et. al., 2019). In this paper, we provide an overview of the suitability indicators used by the DSS to assess the fitness for use of water for irrigation.http://www.sabi.co.za/magazine.htmlam2019Town and Regional Plannin

Help to assess the fitness for use of irrigation water at a specific site using a risk-based approach

Water quality guidelines have two main applications. Firstly, and more commonly, water quality guidelines are used to assess the fitness for use (FFU) of a given water for a specific purpose. Secondly, water quality guidelines are used to determine the desired composition of water that would pose minimal risk when used for a specific purpose, the so-called Water Quality Requirements (WQR). In this article we will focus on the first of these applications and specifically introduce a newly developed electronic Decision Support System (DSS) that guides the user to assess the fitness for use of a potential irrigation water.http://www.sabi.co.za/magazine.htmlam2019Plant Production and Soil Scienc

Experimental studies with Strongyloides papillosus in goats

Unusual clinical and pathological observations in the field in goats and sheep suffering from Strongyloides papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously with either single or multiple, low or high levels of S. papillosus. Young goats up to 12 months of age were found to be the most susceptible. Some animals, however, showed substantial resistance to infective doses. Clinical signs included transient diarrhoea, misshapen, elongated faecal pellets terminally, dehydration, anorexia, cachexia, gnashing of teeth, foaming at the mouth, anaemia and nervous signs such as ataxia, a wide-based stance, stupor and nystagmus. A 'pushing syndrome' was seen in 22 % of the animals. The pathological changes are described and included enteritis, status spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema, interstitial pneumonia and pneumonia. About 6 % of the goats died acutely from fatal hepatic rupture. The development of an acquired immunity was determined. The immunity elicited an allergic skin reaction at the application site of larvae or injection sites of larval metabolites. This immunity, however, could be breached by large doses of larvae. The most profound clinicopathological changes induced by the parasites were an anaemia (most pronounced in the young goats) and hypophosphataemia. Trace element analyses provided evidence of Cu, Mn and possibly Se deficiencies in some goats.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

The concept and application of transdisciplinarity in intellectual discourse and research

By orientation transdisciplinarity is an approach that recognises a united and borderless intellectual terrain. It is an attempt to formulate an integrative process of knowledge production and distribution in reaction to the twentieth century narrow discipline focus and hyper-specialisation. It responds to the multi-layered challenges of diffused disciplines, interlinked socio-economic problems, the impact of globalisation, the de-territorialised nation state, technological advancements, environmental concerns, agriculture and food security and health. And it recognises that, in history some of the most revolutionary breakthroughs in science and technology in fact happened on the margins of narrow disciplines.

The value of water in the South African economy: Some implications

The South African Water Research Commission (WRC) initiated a number of research projects aimed at determining the value of water in different sectors of the economy and in different parts of the country. This research is reviewed. Water values were found to differ significantly between sectors, between geographic areas and within geographic areas. As agriculture is a large consumer of water several studies along different rivers were undertaken, including studies on water quality. Average ratios indicate that agriculture is an inefficient user of water in terms of gross income generated per unit of water and also in terms of jobs created per unit of water. Irrigation farming is, however, an important employer of labour while it contributes 30% to the value of farm output. A marginal approach and water demand elasticities also indicate that non-agriculture generally places a high value on water assurance but little value on more than what it already uses. This may indicate that although water is expected to transfer out of agriculture in the longer run, in the short run agriculture may be its best use. Water efficiency could be significantly enhanced if transfers within and between river reaches are promoted, as water shadow prices differ. Inputs from the Department of Water Affairs and Forestry (DWAF) are important in water allocation due to socio-economic and environmental externalities of water allocation

Calibration models for interpretation of soil salinity measurements using an electromagnetic induction technique

A commercially available salinity sensor (model EM-38 of Geonics Ltd., Canada) has been developed for diagnosing and quantifying soil salinity in the field. There is a need, however, to calibrate the instrument reading against a more commonly used measure of soil salinity. Linear regression equations are reported that allow the interpretation of field instrument readings in terms of electrical conductivity of the saturation extract (ECe) measured in the laboratory. Instrument measurements and soil samples were taken at some 110 sites on various irrigation schemes distributed across South Africa. Samples were analysed in the laboratory and soils categorized according to texture, water status and salinity distribution with depth. Calibration equations were developed firstly by relating field instrument readings, taken either in the vertical or horizontal position, to a depth-integrated ECe value which was weighted for depth according to instrument response. Secondly, the mean of the readings taken in the vertical and horizontal positions at each site was related to the arithmetic mean ECe for the 0- to 1.2-m soil depth. A set of 12 linear regression equations was established in the first approach, and eight in the second. Two of the relationships showed statistical significance at the 5% level, the remainder at the 1% level. These equations enable the user of the EM-38 to derive a realistic index of soil salinity in terms of ECe, but calibration of the instrument for local soil conditions is preferable.Articl