Abstract: In 2003 examination of aerial photographs revealed a series of previously unknown relict shorelines on the arcuate ridge, possibly a clay lunette dune, that marks the western boundary of Etosha Pan in Namibia. The shorelines are 120–600m wide and the most prominent extend for tens of km around the lunette dune. The shorelines were examined on the ground in 2004 and an attempt was made to date the three lowest levels at ca. 5, 2.5 and 1m above the present pan surface. The OSL ages obtained indicate higher and more prolonged lake conditions than today at ca. 6.4, 4.0 and 2.1ka with the youngest shoreline sediments resting on an ancient pan surface dating to ca. 13ka. The evidence indicates dry conditions in the pan at ca. 13ka, wetter conditions and higher lake levels in the middle Holocene followed by a decline in lake levels to the present. Periods of inundation were of sufficient duration to produce shorelines at the southwestern end of the pan due to the prevailing northeasterly winds that would have maximized wave action along this section of the pan margin. The Etosha findings, together with other regional paleoclimate data, suggest four periods of increased wetness in SW Africa during the Holocene at 7–5, 4.5–3.5, 2.5–1.7 and ca. 1.0ka. There is widespread evidence for the oldest of these periods suggesting that it was a prominent and widespread interval of wetness. Prior to ca. 8.0ka the climate may have been drier than today.

Abstract: Humans have relied on agriculture to feed their communities for thousands of years. Irrigation is practiced in many different forms over the years in countries all over the world. Although modern irrigation systems have been developed, and are in use in many countries, ancient irrigation systems (AISs) have also played a major role in sustaining food production, especially in smallholder farming in least developed and developing countries. The editorial team of Agricultural Systems put out a call for a special issue on restoring AISs for sustainable agro-ecosystems development to capture ancient marvels of traditional irrigation technology across the world. The objectives of this special issue were to: (i) understand and analyse the hydrological and socio-economic networks anchored by AISs; (ii) explain the nature and sustainability of management of these systems in relation to local agro-ecosystems; (iii) analyse the implications of the AISs for land, soil and water quality, and agro-ecosystem services; (iv) qualitative and quantitative analysis of AISs, including bio-physical and bio-economic modelling of these systems; and (v) assess the feasibility of alternative technological, institutional and management strategies to enhance the productivity, profitability, and environmental sustainability of the systems. The overall goal of the special issue was to develop a useful repository for this information as well as to use the journal’s international reach to share this information with the agricultural systems research community and journal readership. This paper provides reflections of papers published in the special issue. The special issue resulted in twelve high quality original research articles and one review article from Asia, Africa and Europe. The findings from various papers revealed that the AISs have been degraded due to human interventions or the anthropogenic activities across the world. Various papers emphasized that as a corrective measure, there is a need for developing and implementing rehabilitation projects in these systems. Authors identified that appropriate policy interventions by the relevant authorities would be a major step towards such rehabilitation process. However, resetting the ecosystem structure of the AISs strictly towards their historical manifestation is neither required nor feasible in the present context as it would contradict the expectations of stakeholders from these systems. The knowledge generated through the special issue provides evidence-based information on various aspects of AISs. It helps aware governments, private sectors and development agencies for improved policy planning and decision making and for prioritizing the restoration, rehabilitation, and management of various AISs around the world.

Abstract: Guideline values are prescribed for drinking water to ensure long term protection of the public against anticipated potential adverse effects. There is a great public and regulatory agencies interest in the guideline values of uranium due to its complex behavior in natural aquatic system and divergent guideline values across the countries. Wide variability in guideline values of uranium in drinking water may be attributed to toxicity reference point, variation in threshold values, uncertainty within intraspecies and interspecies, resource availability, socio-economic condition, variation in ingestion rate, etc. Although guideline values vary to a great extent, reasonable scientific basis and technical judgments are essential before it could be implemented. Globally guideline values are derived considering its radiological or chemical toxicity. Minimal or no adverse effect criterions are normally chosen as the basis for deriving the guideline values of uranium. In India, the drinking water limit of 60 µg/L has been estimated on the premise of its radiological concern. A guideline concentration of 2 µg/L is recommended in Japan while 1700 µg/L in Russia. The relative merit of different experimental assumption, scientific approach and its methodology adopted for derivation of guideline value of uranium in drinking water in India and other countries is discussed in the paper.