Abstract
The concept of water–energy–food (WEF) nexus is gaining favor as a means to highlight the functions of the three individual nexus elements as interrelated components of a single complex system. In practice, the nexus approach projects forward from the present, seeking to maximize future WEF synergies and avoid undesirable tradeoffs. A complementary approach was employed here to gain insights into how the ancients dealt with WEF relationships, whether currently relevant nexus principles were practiced long ago, and how past WEF dynamics compare to those of today. Two examples, both dating to before the common era (BCE), are considered in detail. The qanats of ancient Persia brought groundwater to the surface and directed it to clusters of agricultural fields in arid areas where crop production was not otherwise feasible. In contrast, the Dujiangyan irrigation scheme of ancient China harnessed previously destructive surface water flows to stabilize food production across a vast agricultural plain. Designed and constructed under highly uncertain conditions and with a long-term perspective, both relied on local resources and expertise to exploit the tight coupling of water and the intrinsic energy from its flows to produce food. Ingenious infrastructure combined with sound governance allowed both to achieve remarkable synergies among the WEF components with minimal apparent tradeoffs. Although both are now challenged by climate change and the increasing complexity of modern WEF relationships, qanat systems and the Dujiangyan irrigation scheme have survived for millennia and still exist in recognizable form. This is due in large part to the persistence of governance systems that devolved significant decision-making authority to those who used water and energy for food production. Although it is not feasible to roll back technology to that of an earlier time, the successful attributes of earlier WEF governance systems warrant more attention in the future.
Highlights
Efforts to boost food production by harnessing water began before the Common Era (BCE) and evolved over a period of millennia
Water entering the channel through the flow away from the irrigation inlet, and facilitated its movement through an overflow rock face was divided and further subdivided by water gates and other smaller diversion spillway that had structures been installed to direct floodwater back to the outer channel and on into a web-like network of increasingly finer channels as gravity distributed it across the plain [78,104]
Agricultural practices and the timing and details of irrigation policies differed from linpan to linpan, the interwoven nature of the irrigation channels ensured that water was distributed equitably and in sufficient amounts throughout the irrigation area [93,106,108]. Such finegrained local control has been sustained over the centuries as agricultural practices evolved and as the network of canals was reconfigured in the irrigation area. Sustaining such systems is rare [106], but two millennia after construction of the Dujiangyan scheme, the resilient agricultural landscape that emerged continues to support the highest level of food productivity in inland China [104,111,114]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The earliest primitive attempts to harness water for food production in these areas are well documented [34,35,36,37], the need for WEF approaches would have become more evident as humans grappled with the greater complexity associated with increasing scale This made the nexus too complicated for individual or family control, setting the stage for cooperation and innovation. The second, western China’s Dujiangyan irrigation scheme, is site-specific and provides an instructive contrast [49] In both instances, efforts to boost food production by harnessing water began before the Common Era (BCE) and evolved over a period of millennia. Analysis is broadened to consider patterns of evolution of WEF interrelationships as well as contemporary and future implications
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