Agricultural Water Use: Towards a sustainable irrigation

Transcription

1 DipNET Department of Sciences for Nature and Environmental Resources IAFENT Sassari Division Agricultural Water Use: Towards a sustainable irrigation XXI Giornata mondiale dell acqua Risorse idriche e cambiamento climatico nel Mediterraneo Noemi Mancosu Simone Mereu Richard L. Snyder Donatella Spano Università Bocconi 22 Marzo 2013 Milano 1

2 WATER IS THE MOST IMPORTANT RESOURCE FOR LIFE! WATER SCARCITY Misuse Climate change Population growth Economic growth Land use change (including urbanization) WATER STRESSED BASINS 7% of the world s population POPULATION NOW = 6.4 billion billion billion 67% < 1,000 >2,000 m 3 per person per year (Source: Wallace, 2000) (from Roetter and Van Keulen (2008) 2

3 CLIMATE CHANGE A1B ( ) 2099) ( ) 1999) Reduced water availability Increased drought Temperature data Irrigation demand => yield Economy of a country Precipitation IPCC 2007 WG1 AR4 soil moisture (Bates et al., 2008) Data (Bates et al., 2008) 3

4 WATER IN FIGURES 12% cultivation 22% pastures and rangelands (Leff at al., 2004) Global Agricultural Land 80% rain fed 20% irrigated land (FAO, 2003) 1 billion tonnes of grain agricultural sector uses 2/3 of the world water withdrawals (Shiklomanov, 1997) European agricultural water consumption 24% (EEA, 2000) 4

5 COPE WITH WATER SCARCITY: SUSTAINABLE MANAGEMENT OF AVAILABLE WATER RESOURCES How much water is needed by crops in regards to climate conditions? Application of soil water balance models to assess crop water requirements How can I use the water resources in a sustainable way? ADAPTATION STRATEGIES Scheduling Irrigation Events Modifying Agricultural Practices Improving Irrigation Systems Irrigation Deficit Shift Planting Date INCREASE WATER PRODUCTIVITY 5

6 SIMETAW Simulation of Evapotranspiration of Applied Water (Snyder et al., 2004) University of California, Davis LAWR Department California Department of Water Resources State of California Agricultural water demand planning for the California Water Plan SIMETAW# (Snyder et al., 2012) Non uniformity of irrigation Irrigation deficit Changes in CO 2 Stress coefficient (Ks) Yield reduction under deficit irrigation and rain fed conditions 6

7 The SIMETAW# model is an useful tool to: evaluate different irrigation strategies to support irrigation planning suggest possible strategies to reduce water consumption maximize the water productivity find the most suitable solution in terms of income and water savings for farmers improve the agricultural policy measures at regional and international level 7

8 ETaw - Evapotranspiration of Applied Water Evapotranspiration of water that is diverted from streams and canals or pumped from ground water that is applied and contributes to seasonal crop evapotranspiration climate data + Irrigation Requirements by crop = soil information user friendly + weather generator crop & irrigation management evapotranspiration fluxes daily soil water balance hypothetical irrigation scheduling

9 MODEL INPUTS Observed or projected climate data Soil water holding characteristics solar radiation (MJ mˉ²dayˉ¹) max & min temperature ( C) wind speed (m s 1 ) dew point temperature ( C) precipitation (mm) Crop management Irrigation management planting and ending date hectares planted maximum rooting depths percentage shading of the ground presence of cover crops rain fed or irrigated conditions (gravity, sprinkler, micro sprinkler, drip) irrigation frequency during the initial growth percentage of the full irrigation requirement system distribution uniformity

10 OUTPUTS Net irrigation application for event Seasonal net application (ETaw or ΣNA) Seasonal gross application ΣGA Irrigation requirements (full or deficit irrigation) Yield reduction (deficit irrigation & rain fed)

11 ASSESSMENT OF CLIMATE CHANGE IMPACT ON CROP WATER REQUIREMENT IN SARDINIA USING THE SIMETAW# MODEL Estimating the climate change impact on irrigation requirements (IR) for artichokes, grain and silage maize, olives, grapevines, and citrus using the SIMETAW# model in Sardinia (WASSERMed case study) Suggesting some adaptation strategies to reduce water consumption in agriculture 11

12 Data collection Planted area and irrigation system by crop Consorzi di Bonifica della Sardegna the consorzia that manage irrigation Crop management information Laore the agency for technical assistance in agriculture Soil available water holding capacity ARPAS specialist regional hydro weather climate department of Sardinia 12

13 Crop data and management summary REGIONAL IRRIGATED AREA = 22,249 ha IRRIGATION SYSTEMS Sprinkler (maize & artichokes) Drip (olives & grapevines) Micro sprinkler (citrus) 13

14 Scheme of methodology 14

15 The current regional irrigation water demand (Mancosu, 2013) 15

16 Impact of climate change on regional future irrigation demand : 2050 (Mancosu, 2013) 16

17 Adaptation strategies for a sustainable water use The model is able to account for changes in crop and irrigation management Shift in planting date Modification of the percentage shading of the ground Modification of the cover crop period Irrigation system efficiency Changes in the runtime of the irrigation system Application of irrigation deficit

18 Assessment of adaptation strategies CITRUS CURRENT CROP MANAGEMENT Micro sprinkler system Full irrigation Every four days ADAPTATION STRATEGIES odrip system o< 20% irrigation oevery two days RESULTS 24% ΣGA in % mean yield 18

19 Assessment of adaptation strategies GRAIN MAIZE CURRENT CROP MANAGEMENT Sprinkler system Sowing = May (beginning) Harvest= September (end) ADAPTATION STRATEGIES Earlier planting date (D 30 days) Later planting date (D+30 days) RESULTS 6% IR (earlier planting date) 16% IR (delayed growing season) 19

20 Conclusions Modeling is a low cost method with both scientific and operational applications Synergy and cooperation among institutions for a sustainable water use in agriculture 20

21 THANKS 21