Sociohydrology: a new science

Posted on September 23, 2013

The way that we view our relationship with water resources is changing.   Traditional approaches to water management have been based on the assumptions that natural systems fluctuate within a defined range of variation and that human activities can be treated as essentially external factors imposed on the natural water cycle.  However, the extent and complexity of human influences on aquatic systems, including unpredictable effects on climate, demand that we treat human actions as an integral part of water cycle dynamics.  The aim of the emerging science of sociohydrology is to understand the coevolution of coupled human-water systems, where there’s a continual interplay between water availability and the organisation of people in the landscape.  This will require something of a paradigm shift towards holistic, bigger-picture thinking and an openness to new and unexpected patterns.  A recent commentary paper illustrates the sociohydrological approach by reference to case studies in Australia and Africa.  From the 1920s, in response to increased demand for food, irrigated farming close to the Murrumbigee river in Australia expanded rapidly, mainly in an upstream direction, and by 1950 rates of water abstraction during low rainfall periods had reached almost 100% of the natural flow.  In response to unsustainable farming and extended  drought the health of the river declined and eventually, in 2007, the government introduced a scheme to buy back water from irrigators to protect the environment. The sale of water by upstream rice-growers and the purchase of water by more water–efficient horticulturists downstream now means that irrigated farming is moving in a downstream rather than upstream direction, and this is leading to unforseen changes to the landscape and human population patterns.  In the second case study, land use changes in east Africa caused a decrease in moisture cycling to the west.  This reduced the amount of rain falling in the Sahel, which was a serious problem given that 60% of Sahel’s rainfall derives from terrestrial evaporation upwind.  Lower rainfall led to overgrazing, which reduced rates of evaporation and further depressed rainfall, in a continuing feedback loop.  This was the background to the Sahel drought of the 1980s, which was accompanied by desertification, famine and mass human migration.  Among the important messages of this example is the fact that local people are often disconnected from the cause of the problem, and can therefore be powerless in the face of sociohydrological pressures.  

Reference:  Sivapalan, M., Savenije, H.H.G. & Blöschl, G.  2012 Socio-hydrology: A new science of people and water.  Hydrological Processes 26, 1270–1276.

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