Is it a better parameter than water use efficiency with respect to water management in crops and cropping systems? What will be the most appropriate parameter for fish or aquaculture production systems under the umbrella of pond-based farming system?
Sir, water use efficiency and productivity are two different terms. When we talk about efficiency, basically we are comparing different irrigation systems like surface irrigation vs. drip vs. sprinkler. Based upon this, one conclude that if we apply 100 liter water, maximum water utilized by the plants (may be for growth, biomass, yield etc) was under drip. It means, there is a minimum loss/wastage of water via drip, hence drip is more efficient method. But when we talk about water productivity, it is essentially a production terminology. Means, what we are getting in terms of biomass/yield per unit of water applied.
Therefore, these two terms having their own significance in agricultural water management strategies.
Water productivity takes an integrated approach to water resources management which means recognising that a successful strategy must meet multiple objectives
through a variety of means. What these objectives are and the most appropriate means of meeting them is highly dependent on the scale of the environmental system to be managed but an effective strategy will invariably address a mixture of environmental, economic, social and political issues. Clearly, identifying all the important issues means taking an overview of the whole system to select those features that might help or hinder the attainment of Water productivity through management goals. Water productivity approach underpins the whole concept of integrated water resources management (IWRM) in that it seeks to link the management of water use sectors that had previously been handled separately. It is believed that by doing this, plans can be devised to maximise the benefits obtainable from water resources without causing significant adverse effects. These benefits will only be obtained, however, if the management plan can be successfully implemented and this relies on the support of all those affected by management changes. Consequently, ideas of stakeholder participation in planning processes will become fundamental to this approach.
water use efficiency comes in when one is able to accomplish so much with the same quantity of volume of water with the least waste of time and effort. eg, same water used for fish ponds which runs through the crops to take up the fish waste and back to the pond for re-use.
Certainly water productivity is a better parameter for making a decision to allot particular amount of water to an activity. However this has to be subjected to social and physical constraint. Like you will get more water productivity of steel making than using it for agriculture. i.e. for different sectoral uses, but you cannot ignore agriculture. within agricultural activities you may get more productivity for aquaculture but you cant produce fish beyond a limit. It is also very useful when deciding threshold level of irrigation by using irrigation water productivity . Finally your decision will depend upon opportunity cost of saved water.
Productivity is just one of the factors to be considered in públic policies tending to rationalize the administration of natural resources. Just considering productivity in physical and biological terms, may lead to enlarge social inequities in the acces of resources. Policy makers have to consider a healthy equilibrium among productivity, social equity and environmental sustainability when designing public policies. Unfortunately the most common trend is just to consider economic dimensions of the concept of "productivity". The social and environmental yield of the decisions involving the use of a natural resource wil help the political system to redress huge mistakes done in the past.
I suggest you consult the following review about water productivity:
M.H. Ali and M.S.U. Talukder published in Agricultural Water Management (2008), and the paper from J. Passioura y the same Journal: 80 (2006): 176-196
I hope they could be useful for you.
indeed it is important . A simple example is to build scenario and see the impact of different intervention on water productivity-this will lead to development of strategies. we did some work and might be helpful..
Dear Dr. Amare
Thank you so much for your attachment and enabling me to see a good research work.
Dear Mandal: great that it is helpful. I will be happy to give further support if needed.
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