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Titel |
Transpirative Deficit Index (TDI) for the management of water scarcity in irrigated areas: development and application in northern Italy |
VerfasserIn |
Anna Borghi, Arianna Facchi, Michele Rienzner, Claudio Gandolfi |
Konferenz |
EGU General Assembly 2016
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Medientyp |
Artikel
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Sprache |
en
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 18 (2016) |
Datensatznummer |
250132295
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Publikation (Nr.) |
EGU/EGU2016-12789.pdf |
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Zusammenfassung |
In Europe, the monitoring and assessment of drought is entrusted to the European Drought
Observatory (EDO). EDO indicators are calculated considering rainfed agriculture and
delivered on a 5 km grid. However, in southern Europe, irrigation may compensate for
potentially severe agricultural droughts and specific water scarcity indicators that explicitly
consider irrigation are needed.
In the Po River Plain, irrigated crops cover more than 70% of the agricultural land,
massive amounts of water are diverted from rivers for irrigation, and surface irrigation
methods are largely applied. Nowadays, the region is not a water scarce basin, but irrigation
water shortages have occurred with increased frequency during the last two decades.
Moreover, a recent EU report shows that the Po River Plain is included among areas in
Europe that by 2030 shall be affected by water scarcity.
In this context, a study was started to select and develop indicators for the management
and prevention of Water Scarcity and Drought (WS&D) based on the synergic use of
hydrological modelling and Earth Observation data applied at a spatial scale of interest for
end-users (250m grid). These indicators shall be better suited for the assessment of WS&D in
Italy as well as in other southern European countries.
This work presents the development and the application of the TDI (Transpirative Deficit
Index) to a study area, within the Po River Plain. TDI is an agricultural drought index based
on the transpiration deficit (TDx, calculated as the difference between potential and
actual transpiration), computed by the spatially distributed hydrological model
IDRAGRA and cumulated over a period of x days. TDx for each day of a specific year is
compared to the long-term TDx probability distribution (e.g., over 20-30 years),
which is transformed into a standardized normal distribution. The non-exceedance
probability of TDx is finally expressed in terms of unit of standard deviation (TDI),
following the approach proposed for the well-known Standard Precipitation Index
(SPI).
IDRAGRA is a distributed-parameters conceptual model, which allows the simulation of
the water balance in the soil-plant-atmosphere system on a daily basis. It accounts for the
spatial variability of soils, crops, meteorological and irrigation inputs by dividing study
areas with a regular mesh. Modules for the simulation of crop development and
irrigation water sources conveyance and distribution are moreover included. IDRAGRA
was modified to allow the computation of TDI, both in absence and presence of
irrigation.
The simulation system was applied to a pilot study area of about 230 km2, located in the
Po River Plain. TDI was computed considering a reference meteorological data series of 22
years (1993-2014). TDI patterns were analysed for two years, one (2003) with very scarce
and the other (2014) with abundant precipitations. Results showed that the irrigation supply
cannot compensate severe droughts in some districts of the pilot area, and were confirmed by
yield data and by the staff of the Irrigation Consortium managing irrigation water in the area. |
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