For centuries the Upper Guadiana Basin has been irrigated with groundwater. In the 1980s the irrigated areas increased more than four fold in ten years. This increase resulted in a drop in the water table of more than 20 meters.
This had a severe impact on several wetlands; the flooded surface area of the “Tablas de Daimiel” National Park, for instance, declined from about 6,000 Ha to less than 1,000 Ha. Several curative measures were introduced, including new regulations restricting aquifer abstraction and economic incentives to encourage farmers to improve irrigation efficiency and plant alternative crops. Between 1995 and 2000 the water table level recovered by more than 10 meters.
Understanding of the development of the Basin’s water resources, and their relation to the legislative and economic measures introduced in the last decade, demonstrate the value of integrated water management. The changes in the Basin irrigation, forced managers to seek to balance economic growth that implied high irrigation water consumption, with wetlands conservation, of significant national importance to the environment.
The use of administrative tools helped control and reduce the impact of over-exploitation of the aquifer. However, although water use was reduced, many jobs were lost in agriculture and small industries.
The two most important lessons learned from this case are:
- Good water management needs to consider the whole hydrological cycle - surface and underground waters cannot be managed separately or independently of the ecosystems on which they depend.
- Good water management requires sustaining a balance between pumping of groundwater and recharging the aquifer. Aquifer management needs planning to accommodate medium and long-term use of the resource.
Importance of the case for IWRM
The case study illustrates the importance of taking into account several factors in an integrated manner:
- Water use for irrigation
- Impacts related to the overexploitation of underground water
- Water uses accounts between different water uses
- Incentives for water savings.
Photo credit: Bert Kaufmann