In the last 150 years the area under irrigation has increased dramatically, particularly in the drylands of the developing world, having a relatively scarce but renewable water supply. The latter applies to two broad physiographic settings: continental deserts and arid zones in the vicinity of high mountain ranges, where snow-melt provides for large flows in summer, and arid zones where water supply originates in areas of higher rainfall and is conveyed by rivers over large distances. In these regions irrigation has been practised for centuries, but on a significantly smaller scale and the relatively recent expansion, obtained at the cost of huge investments, has brought major improvements in the population welfare as well as environmental degradation through salinization, waterlogging and overdraft of groundwater reservoirs.
To some extent the agricultural production system (irrigated agriculture) has developed a significant resilience to climate variability. The rise of intersectoral water competition together with the higher demand for agricultural water use, generated by increasing trade flows, contribute, however, to increase the vulnerability of this production system. For internal drainage basins these trends may imply the disappearance of the remnants of ecosystems which formerly were receiving river water. Possible climate change, especially lower precipitation in arid and semi-arid zones, add a further vulnerability factor to these systems.
The network intends to collect and analyze information on hydrological variability in the recent past, 200-300 years, and on the impact of this variability on agricultural production. The latter will focus on test areas, studied in detail by the network members, where a wealth of data and results exists already. The test areas are: Argentina: the watersheds of Rio Mendoza and Rio Atuel; China: the rims of the Taklimakan desert and the Hei He and Shiyang He watersheds in north-western China; India: the basins of the rivers Luni and Yamuna; Egypt: oases in the Western Desert of Egypt and the eastern Nile Delta; Niger: rainfed agricultural lands. These studies will provide the basis for assessing the sensitivity of these production systems to expected climate variability. The network is one of a few attempts to establish a unique cooperative mechanism among research organizations and countries which have scarce opportunities for joint research efforts on specific subjects, notwithstanding the similar, and at times identical, scientific and development issues they face. The cooperative efforts will also be an opportunity to compare techniques used at the participating institutes: 1) analysis of historical archives and archaeological studies; 2) geomorphological studies; 3) use of tree-rings chronologies; 4) numerical modelling of regional hydrological processes and of crop growth in farming systems; 5) experimental and modelling studies of land- surface-atmosphere interactions in relation with land use (irrigated lands vs. deserts); 6) remote sensing and geographical information systems; 7) computational decision support tools for water management; 8) analysis of policy and institutional constraints on resource management.
The network participants (fifteen in eight countries) intend to establish a baseline, against which the impact of forecast climatic variability may be assessed, both by looking at the effects of past climate variability on farming systems (with special reference to irrigated agriculture) and on water resources, and by taking into account the history of land use, of farming systems and of socio-economic conditions.
This approach will also provide useful insights into sustainable management of land and water resources in drylands.
Funding SchemeCSC - Cost-sharing contracts
13621 Delta Barrage
EH2 2EN Edinburgh
35020 Legnaro (Pd)