IAHS Scientific Assembly 2017
10–14 July 2017
Port Elizabeth, South Africa
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Session 5

Land use change impacts on water resources
Convener: Magdalena Rogger  | Co-Conveners: Graham Jewitt , Alberto Viglione , Michele Toucher 
Supporting commission(s) / organisations: ICWRS, Panta Rhei

Human induced land cover changes have strongly modified natural landscapes all over the World. Population growth and industrialisation have lead to increased deforestation, an expansion of agricultural land and settlements impacting strongly on the hydrological regime and related water management. In developing countries a move to large scale commercialisation of agricultural lands is an aspect of concern. In this workshop we want to focus on the impacts of such changes on the hydrological regime. Agricultural practices, especially the use of heavy machinery for soil tillage, often lead to soil modification and compaction decreasing the infiltration capacities of the soils and potentially enhancing erosive processes. Agricultural drainage and irrigation can lower the groundwater table and influence subsurface flow paths. Deforestation generally results in a decrease of rainfall interception and modified soil conditions with lower soil storage capacities and enhanced erosion. A large scale replacement of seasonally dormant natural vegetation types with evergreen crops such as sugarcane can also significantly change the local water budget. Moreover, afforestation with alien species may decrease the groundwater table and low flows due to their higher demand for water compared to indigenous species. Finally, also the expansion of settlements and urbanisation lead to surface sealings and increased surface runoff. All these changes thus strongly modify hydrological processes and may lead for instance to larger flood events or to a reduced water availability during dry seasons. This workshop welcomes contributions that analyze the impact of such land use changes on the water cycle, on hydrological extremes such as floods and low flows and on the overall water availability. We encourage contributions that discuss issues from developing countries.