Presenter/Author Information

P. C. Smith
P. Calanca
J. Fuhrer

Keywords

grassland model, water deficiency, yield, irrigation requirement, switzerland

Start Date

1-7-2010 12:00 AM

Description

We examine irrigation demand in Switzerland under current climatic conditionson the basis of simulations with a process-based grassland model. Two sites are considered:Oensingen, on the Swiss Plateau, benefits from a humid climate and is rarely affected bydrought; Sion, located in the Rhone Valley, is highly water-limited, with critical soilmoisture conditions every year. Water requirements to sustain productivity therefore varysubstantially between the sites and in time, with needs up to 800 mm per year at Sion, andaverage needs of the order of 300 mm at Oensingen if a shallow soil is assumed. We showthat simple relations can be found between water requirements and key variables such asthe so-called atmospheric water budget, i.e. the difference between precipitation andpotential evapotranspiration. Such relations are not only useful to quantify waterrequirements at other sites, but also for assessing the benefits of irrigation. At Sion, we findfor instance that even while restricting the water requirement fulfilment to 500 mm peryear, irrigation can increase productivity by 9 t/ha compared to a rainfed situation.

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Jul 1st, 12:00 AM

Modelling irrigation demand from two grasslands in Switzerland under contrasting climatic conditions and soil properties

We examine irrigation demand in Switzerland under current climatic conditionson the basis of simulations with a process-based grassland model. Two sites are considered:Oensingen, on the Swiss Plateau, benefits from a humid climate and is rarely affected bydrought; Sion, located in the Rhone Valley, is highly water-limited, with critical soilmoisture conditions every year. Water requirements to sustain productivity therefore varysubstantially between the sites and in time, with needs up to 800 mm per year at Sion, andaverage needs of the order of 300 mm at Oensingen if a shallow soil is assumed. We showthat simple relations can be found between water requirements and key variables such asthe so-called atmospheric water budget, i.e. the difference between precipitation andpotential evapotranspiration. Such relations are not only useful to quantify waterrequirements at other sites, but also for assessing the benefits of irrigation. At Sion, we findfor instance that even while restricting the water requirement fulfilment to 500 mm peryear, irrigation can increase productivity by 9 t/ha compared to a rainfed situation.