Agriculture, and particularly irrigated agriculture, has significant impacts on environment and people's health. Pursuing a narrow development goal of increased productivity has lead, in many instances, to the breakdown of the resilience of natural eco-systems. But it is a mixed picture. In some settings there is an obvious need to relax the pressures on the ecosystems. In others, productivity is still low and can be improved while keeping within acceptable environmental limits. The negative externalities linked to agriculture and water management in agriculture, are fundamentally related to land and water uses, agricultural practices (application of pesticides and fertilizers), water quality management (health), drainage management (salinity, water logging). These externalities have to be accounted for explicitly if the long term productivity of the natural systems and their dependant populations is to be assured.
Where agricultural practice is stretching the limits of the land and water resource base and breaking down the integrity and value of the associated aquatic ecosystems, attaining a sustainable level of production will need agricultural practices to search for viable alternatives. Such alternatives, such as re-introducing natural flows, may enhance the overall productivity of the natural systems even if they foreclose on immediate, local economic gains.
The bulk of agricultural abstraction occurs in lowland areas where slack hydraulic gradients have produced extensive wetlands. Raw water extraction from rivers and lakes and the construction of irrigation infrastructure on these lowlands along river banks, invariably displaces the natural wetlands. These wetlands are in themselves highly productive as agricultural and ecological systems. While the application of water may expand extend the life of a wetland, the drainage and return of flows from irrigation often result in un-wanted impacts - loss of water quality, the spread of water related diseases and soil degradation through waterlogging and salinization. It is currently estimated that the lack of adequate drainage is threatening some 500 million hectares of agricultural land across the globe.
Finding alternative ways for agricultural water use and management to alleviate these impacts is therefore essential, not only to maintain the integrity and productivity of ecosystem, but more importantly to create conditions for agriculture to continue to contribute to food security, poverty alleviation and economic growth.
These complex issues depend very much on local conditions and available solutions. Therefore the search for alternatives can only be made a local, case by case basis. However, there are elements of a common approach in this search for alternatives. These technical and policy tools include;
These tools need to be based on clear principles of; shared and transparent information amongst water users, environmental regulators and agricultural producers; participation in the planning and investment process as a step-by-step learning process, and facilitation of local initiatives through national and regional policy-setting.
