Ancient civilizations may have dispersed or collapsed under extreme dryconditions. There are indications that the same may hold for modernsocieties. However, hydroclimatic change cannot be the sole predictor of thefate of contemporary societies in water-scarce regions. This paper focuses ontechnological change as a factor that may ameliorate the effects ofincreasing water scarcity and as such counter the effects of hydroclimaticchanges. We study the role of technological change on the dynamics of coupledhuman–water systems, and model technological change as an endogenous processthat depends on many factors intrinsic to coupled human–water dynamics. Wedo not treat technology as an exogenous random sequence of events, but assumethat it results from societal actions.While the proposed model is a rather simple model of a coupled human–watersystem, it is shown to be capable of replicating patterns of technological,population, production and consumption per capita changes. The modeldemonstrates that technological change may indeed ameliorate the effects ofincreasing water scarcity, but typically it does so only to a certain extent.In general we find that endogenous technology change under increasing waterscarcity helps to delay the peak of population size before it inevitablystarts to decline. We also analyze the case when water remains constant overtime and find that co-evolutionary trajectories can never grow at a constantrate; rather the rate itself grows with time. Thus our model does not predicta co-evolutionary trajectory of a socio-hydrological system wheretechnological innovation harmoniously provides for a growing population. Itallows either for an explosion or an eventual dispersal of population. Thelatter occurs only under increasing water scarcity. As a result, we draw theconclusion that declining consumption per capita despite technologicaladvancement and increase in aggregate production may serve as a usefulpredictor of upcoming decline in contemporary societies in water-scarcebasins.
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