A study on improvement needs for the soil water balance

One critical problem confronting mankind today is how to manage the intensifying competition for water among expanding urban centres, traditional agricultural activities and in-stream water uses dictated by environmental concerns based solely on the soil water balance. In the agricultural sector, the prospects of increasing the gross cultivated area are limited by the dwindling number of economically attractive sites for large-scale irrigation and drainage systems whose correct evaluation depends on the understanding of groundwater movement in three dimensions. The failure of present systems, and inability of sustainable extraction from surface and groundwater sources may be attributed, essentially, to poor planning, design, management and development, as not much is known about groundwater flow systems. Each flow system has different chemical quality, path of travel, recharge area, as well as water age. To take full advantage of investment in agriculture, a major effort is required to modernize irrigation and drainage systems and to further develop appropriate management strategies compatible with financial and socio-economic trends, considering the functioning of groundwater components in the environment. This calls for a holistic approach to irrigation, drainage management, and monitoring if the aim is to increase food production, conserve water, prevent soil salinization and water logging, and to protect the environment. Sustainable development should be based on a full understanding of the relationship between the used water source and the environment. To tackle this challenge, there is a need to focus on the following issues: affordability with respect to the application of new technologies; procedures for integrated planning and management of irrigation and drainage systems; analysis to identify causes and effects constraining irrigation and drainage system performance; evapotranspiration and related calculation methods; estimation of crop water requirements; technologies for the design, construction, and modernization of irrigation and drainage systems; strategies to improve irrigation and drainage system efficiency; environmental impacts of irrigation and drainage systems and suitable measures for creating and maintaining sustainability. Institutional strengthening, proper financial assessment, capacity building, training and education actions are also required to achieve a successful on the soil water balance.