Over the past decade, we have witnessed a growing scarcity of and competition for water around the world. As the demand for water for domestic, municipal, industrial, and environmental purposes rises in the future, less water will be available for agriculture. But the potentials for new water resource development projects and expanding irrigated area are limited. We must therefore find ways to increase the productivity of water used for irrigation. This paper reviews the literature on irrigation efficiency and on the potential for increasing the productivity of water in rice-based systems. It stresses the continuing confusion over the concepts of irrigation efficiency and water productivity. It identifies the reasons for the wide gap between water requirement and actual water input (both irrigation diversions and rainfall) in irrigated rice production systems and discusses potential opportunities for increasing water productivity both on-farm and at the system level. Based on the reported low farm and system level irrigation efficiencies, the potentials for water savings in rice production appear to be very large. But we do not know the degree to which various farm and system interventions will lead to sustainable water savings in the water basin until we can quantify the downstream impact of the interventions. Studies on the economic benefits and costs, and environmental aspects of alternative interventions are also lacking. This paper emphasizes the need to measure the productivity of water at farm, system, and basin levels, and to understand how the productivity at one level relates to the productivity at another. Without water balance studies to measure productivity at these different scales, it is not possible to identify the potential economic benefits of alternative interventions and the most appropriate strategies for increasing irrigation water p productivity in rice-based systems.

This paper is a synthesis of IIMI's research on irrigation management for crop diversification in Indonesia, the Philippines and Sri Lanka. It provides some conclusions and recommendations, the potentials and constraints to more intensive non-rice production during the drier part of the year in irrigation systems that have been developed primarily for rice production. The research results obtained from selected irrigation systems sites in the three countries from 1985 to date were analyzed and compared by establishing common reference points where they existed, such as common constraints, potentials and institutional arrangements and by explaining differences based on observed data for each system. Relevant secondary data other than from the research sites were located to shed further insight in the synthesis.

Fragile lives in fragile ecosystems: Feeding the world's poor from neglected rice ecosystems was the theme of the 1995 International Rice Research Conference. During the February meeting, participants assessed progress in rice research and identified new research approaches for reducing constraints and improving productivity and sustainability of less favored and fragile rice producing areas - these are the upland, rainfed lowland, and flood-prone ecosystems.