Climate change and irrigation expansion: Land-water-atmosphere interactions in the Aral Sea basin
2007 (English)In: Proceedings of the third international conference on climate and water, 2007, 430-435 p.Conference paper (Other academic)
The Aral Sea drainage basin (ASDB), covering an area of totally 1,874,000 km2 in Central Asia, has experienced an enormous expansion of irrigated agriculture during the past century. Presently, water is diverted from the two principal rivers, Amu Darya and Syr Darya, to such an extent that the Aral Sea receives only about 10% of its former 70 km3 annual freshwater input through river discharge. As a result, the Aral Sea started to shrink in the 1960’s, and is expected to continue to shrink in the foreseeable future accompanied by desertification of surrounding areas. In addition to these water diversions, however, regional climate may also have changed significantly in the region since the 1960’s as a regional manifestation of global climate change over this period. We investigate here land -water-atmosphere interactions in the Aral Sea basin using a basin-scale hydrological balance modelling approach, in which the locally created runoff (i.e., precipitation minus evapotranspiration) is estimated using precipitation and temperature as driving boundary conditions. The runoff is routed through a flow network derived from a 30” 30” digital elevation model. Results show that the major irrigation areas in the ASDB yields a considerable 17% increase in evapotranspiration flux from land to the atmosphere, which is not balanced by a corresponding increase in observed precipitation. Despite the expected surface cooling effects of increased evapotranspiration, temperature data shows that the basin manifestation of global climate change appears to be a warming trend. In addition, our results show specifically that more than 90% of the irrigation water input in the ASDB returns to the atmosphere by evapotranspiration, which is at the high end of previous estimates. This indicates possible non-local and climate driving effects of water management that are relatively large.
Place, publisher, year, edition, pages
2007. 430-435 p.
Aral Sea Basin, climate change, irrigation, hydrological modelling runoff, evapotranspiration fluxes, net water fluxes to the atmosphere
Oceanography, Hydrology, Water Resources
IdentifiersURN: urn:nbn:se:su:diva-21099ISBN: 978-952-11-2790-8OAI: oai:DiVA.org:su-21099DiVA: diva2:187625