6.3.3. Stability Stability of productivity as well as equity are important. Stability can either be short-term stability or long-term sustainability. The short-term or interseasonal stability refers to the variations in productivity and equity between irrigation seasons, and is a function of climate, water supply, storage and control, system management, and other factors such as pests, diseases, and availability of labour and other inputs. It can be measured by comparing performance between seasons. The long-term sustainability has been described as ‘‘environmental stability’’ (12) and ‘‘durability’’ (13) and refers to the prevention or minimising of adverse physical changes such as waterlogging, leaching of nutrients from soils, salinity, erosion, silting, the ‘mining’ of ground water, and infestations with weeds (1). Sustainability can be monitored by measuring
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ground water levels, salinity, erosion, or silting through inspecting works, and by measuring long-term trends in productivity and equity.
Well-being is a broad objective achieved through productivity, equity, and stability. There are several aspects of well-being which must be borne in mind at all stages of the project with both positive and negative effects. These aspects include health, nutrition, amenity (especially water for washing and bathing, raising ground water for domestic purposes, and so on), and psychological factors such as freedom from domination, feeling of participation, etc.
