Impacts locaux attendus de l'augmentation du CO2 dans l'atmosphère sur la productivité de l'eau du maïs dans la Drôme, France
✍ Scribed by Juan Manuel González-Camacho; Jean Claude Mailhol; Françoise Ruget
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 165 KB
- Volume
- 57
- Category
- Article
- ISSN
- 1531-0353
- DOI
- 10.1002/ird.332
No coin nor oath required. For personal study only.
✦ Synopsis
This study was conducted to assess local impacts of doubling of the rate of atmospheric CO 2 (660 ppm) on irrigation demand and maize crop water productivity in the Dro ˆme valley (SE France). This region is characterised by severe water shortages in the summer season. A comparison of historical records, between the periods of 1990-2001 and 1960-89, shows that in July, the mean temperature increased by 2 8C and the river stream flow diminished by 16%. At peak periods, the maize irrigation requirements represent 80% of the seasonal irrigation demand. The ARPEGE-CLIMAT atmospheric model, regionalised at high resolution on the Rho ˆne catchment, was used to calculate monthly climate variations. For a doubled rate of CO 2 , in July, an increase of 4 8C in average temperature and a decrease of 30% of rainfall are expected. Monthly climate variations were introduced into the stochastic weather generator LARS-WG to simulate local daily climate scenarios for present (1 Â CO 2 ) and future (2 Â CO 2 ) climates. Then, the STICS crop model was applied to simulate the direct and indirect effects of increasing atmospheric CO 2 on irrigation demand and maize crop production. Several simulation conditions, such as soil types, sowing dates and water stress levels, were studied for current climate and future climate scenarios. Principal results show that global warming increases water irrigation demand by 14%; lowers the maize cultivation cycle by 20%; and reduces the yield by 15%. On the other hand, a direct increase in CO 2 concentration induces an average yield increase of 18%; these opposite effects balance the maize yield. The maize crop water productivity increases by 13% but it depends greatly on the water stress level. Similarly, earlier sowing dates allow earlier irrigation and a reduction of the water application depth by 40 mm in peak water demand periods and low water availability.