Sustainability Exchange

e-Discussion on Sustainable Water Management and Value Chains

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Discussion
  • What are simple, low costs tools and technologies to measure water use at field level?
  • What is an appropriate data collection frequency?
  • Are there ways to remotely monitor water use at plot level?
  • How can farmers be best included in the monitoring and measuring procedures?

The efficient and effective use of water in irrigation systems is of critical importance for sustainable agricultural development and overall economic growth. The key to sustainable water management is balancing supply and demand. Sustaining irrigated agriculture and crop production with limited water supplies thus requires increasing water use efficiency (water consumed by crop/water applied) and optimising the productivity of water (beneficial biomass/unit of water applied).

Several standards for sustainable crop production include indicators of water use efficiency and/or water productivity. Measuring water – efficiency or productivity – however is a challenge. Measuring stations are often absent in irrigation systems and farmers do not regularly record irrigation time or volumes.

HELVETAS Swiss Intercooperation in a consortium with the Better Cotton Initiative (BCI) and the Sustainable Rice Platform (SRP)  is implementing a project to increase water efficiency and food production in the key commodity value chains rice and cotton. A factsheet on the WAPRO Project can be found here.

While the standards and indicators developed by the organisations are clear, water use efficiency and water productivity are expected to progressively improve, there is little meaningful guidance on how water efficiency or water productivity have to be measured especially in surface irrigation systems. This is one of the main challenges in our Water Productivity Project and very likely in other similar projects as well. The questions we would thus like to discuss – among others - in this forum are:

  • What are simple, low costs tools and technologies to measure water use at field level?
  • What is an appropriate data collection frequency
  • Are there ways to remotely monitor water use at plot level
  • How can farmers be best included in the monitoring and measuring procedures

In addition, we would be very interested to get links to similar projects to start an experience exchange and a possible cooperation on the issue of sustainable water management, irrigation efficiency and water productivity.

We are looking forward to your contributions!

Puede contribuir tambien en Español!

Vous pouvez contribuer aussi en Français!
November 19, 2015 16:38
Replies

Chris, I’m not sure I can answer your question, but I feel the need to raise the issue that ‘water use’ measured by volume that comes out of a pipe is a very poor indicator of environmental or social impact.

The real impacts are to do with availability and quality. Water that goes back into the hydrological cycle (e.g. through recharging groundwater) isn’t really used at all. However water that’s abstracted unpolluted and discharged polluted is much more ‘used’.

And then there’s local context. 1,000 litres of water ‘used’ in Colombia has a fraction of the impact of 1,000 litres ‘used’ in Chile.

I hope you get a useful answer from a discussion here. 

Mike

November 23, 2015 12:24

Dear Mike, thanks a lot for your comment and in fact I fully agree with you: water productivity or water use efficiency are strictly speaking  not indicators of sustainable water management, environmentally, socially or even economically. Water productivity or efficiency are "single factor indicators" and decisions are rarely taken based on one indicator alone. 

Water availability and quality are certainly better to asses impacts of water management. For water management to be sustainable, water depletion - water actually consumed or rendered unuseable -  have to remain within the limits of average annual supply. As you mention, not all water diverted or applied is really used up, there are returnflows and recharge to groundwater that can still be used - provided it is still in good quality.

One of the main problem with the concepts of water productivity or water use efficiency is that the terms are often used interchangeably while in fact they are not the same. A good discussion of the issue is provided in the following paper: http://www.water4crops.org/wp-content/uploads/2014/08/RR_Water-use-efficiency-and-water-productivity.pdf

Similarly, many people take an improvement of either one or the other as an indicator that water management has improved and water is managed sustainably, which again may not be the case. But this would be another discussion ...

Regarding our issue at hand: in the WAPRO we have indicators on water productivity and that requires to measure water flows and irrigation quantities. To know these figures has certainly its merits, as water managers we should know how much water we divert or apply and how much is used up by the crop. Without this knowledge, we operate an irrigation system somewhat blindfolded. Only by knowing the amount of water used - and used up - we can assess whether we are within the limits of the average annual supply. Hence, there is certainly a justified need to measure water. That's what this discussion is all about and I sure hope to get some interesting experiences from the members of this community!

Chris

November 28, 2015 05:59

I agree with your points with regard to irrigation water not necessarily being lost. In our rice project in India using surface runoff water to irrigate organic fields reduces excessive run-off during the monsoon season and may even contribute to re-charging water bodies downstream. However, for much of the crucial periods in the year water is a scarce good for many farmers in that area. Usually they only get a certain amount of water allocated to them by water user groups or irrigation authorities (means: for some hours every few days they can use water from a small irrigation channel). If they can use water more efficiently for example by applying the alternate wetting and drying method in rice we observed that they use the "saved" water for irrigating a larger part of their land. Thus with the same amount of water they can produce more ("more crop per drop").

If we compare two different methods (the normal practice versus an improved practice) a very rough approximation for water productivity could be the total production achieved with a specified amount of allocated water (e.g. 3 hours every 10 days) in both practices (splitting the plot in two parts). This would allow calculating a relative water productivity gain even without quantifying the amount of water. In rice we also collected data through surveys among farmers on the number of irrigations and days the paddy fields were flooded. With this simple method we could already observe remarkable differences between the promoted system (System of Rice Intensification, SRI) and the farmer's normal practice without quantifying water flows.

But of course it is useful to estimate the amount of water used per hectare under different systems in order to express water productivity as kg/litre - or the water footprint as litre per kg product. In our plot trials at a research station in India we therefore calculated the flow of water applied through a pump (a formula of pump strength and pipe diameter - would need to look it up...). This allowed comparing the water productivity of different practices, expressed as kg/hacm (1 hectare centimeter = 100'000 litres). The SRI treatment was 5 times more efficient than the noraml practice, and an intercrop of rice and soy (on ridges) was 8.5 times more efficient! Of course this is more difficult to measure at farmers' fields where water sources and plot sizes are less precizely defined.

A last note: if comparing the water productivity of different crop rotations it is probably more appropriate to express water productivity as value generated per water volume (e.g. USD/litre).

Cheers, Frank

November 25, 2015 19:10

Dear Frank,

when we talk about water productivity it is always important to specify what the reference water use is. Is it the water diverted from a source, water applied at the field or water consumed by the crop. From a water resource perspective water consumed is the most relevant productivity indicator because it does not include return flows. However, its also the most difficult one to achieve productivity gains. In my answer to Mike I provided a link to a paper on water use efficency and water productivity which in regard to the consumed fraction states that "productivity gains much in excess of 10% seem unlikely, and the level of management is high".I tend to agree with this statement.

Coming back to your exapmple of the farmer who used the "saved" water to irrigate a larger part of the land and increasing crop production, what happened to the water? The water productivity of the water diverted or applied certainly increased but the farmer used former return flows and increased the consumed fraction, possibly without changing the productivity of the water consumed significantly. From his own perspective as a producer this is certainly a good thing, from the point of view of the environment it may not look so positive. This water will no longer be available to downstream farmers, recharge an acquifer or return to a surface water body. Figures 2 and 3 in a paper by Scheierling et al. (2014) on "How to assess Water Productivity" provide a good illustration of water savings at different levels on the different water productivities.

Do we really need to measure water or is a rough approximation not sufficient? Of course in some cases it seems obvious that a new method uses less water. This is especially the case when the water is coming out of a pipe with a very regular and uniform flow. In canal systems we usually do not have this uniformity, flows vary in time and also in space and 3 hours one day may not be the same as another day or 3 hours in one field is not the same as in another. This is why often it is still necessary to measure water flow or we can at best provide a very rough estimate of the water applied which may not alway be sufficient.

Your comparison of water productivities involving SRI shows that  there is confusion about the concepts of water productivity and water efficiency and you even mention the water footprint. Some specification which water productivity you are talking about would thus be necessary. My assumption is that it is water diverted or applied but in any case the water footprint as defined by the Water Footprint Network is clearly the "water consumed" per kg of crop and nothing else. In the beginning of that paragraph you talk about "water productivity" but then later you say that the "SRI treatment was 5 times more efficient", again terminology and concepts are important, water productivity and efficiency are not interchangeable.  I'm also not quite sure whether in the second example you compare the SRI intercropped rice and soybean with a monocrop rice, because I'm not sure whether you can intercrop soybean with a permanently submerged rice crop. 

In your last note you enter another dimension, the economic efficiency and that would open the door for again a completely different discussion: should farmers grow low value staple crops or should not everybody switch to high value cash crops to increase the economic output per unit of water!  I'll leave it at that - I hope I did not create more confusion but the forum is still open for further discussions.

Chris

November 29, 2015 03:56

This is a reminder that this e-discussion is running for just another week until December 15. So far we have not received many posts on the main topics:

  • What are simple, low costs tools and technologies to measure water use at field level?
  • What is an appropriate data collection frequency?
  • Are there ways to remotely monitor water use at plot level?
  • How can farmers be best included in the monitoring and measuring procedures?

We would still be interested to learn about your experiences and I wish to encourage everybody to use the last days to do so!

Thanks and looking forward to your comments

Chris

December 08, 2015 08:31

Dear community

There are some interesting activities on water monitoring going on in Central Asia. The iMoMo hub, a service and innovation center for water monitoring, develops simple and cost effective water measurement tools for small scale water measurement. The service center is based in Bishkek and active in Kazakhstan, Uzbekistan, and Kyrgyzstan. The link is here: http://imomohub.kg/eng/home/

Cheers, Stefanie

December 08, 2015 14:49

Below you will find a contribution from Manesh Man Shresta

Dear Christoph Morger,

Thank you for initiating the e-discussions on above important topics. I would like to directly answer to your four inquiries.

As I have worked mostly in Asian country, such as Nepal for a quite number of years along with the farmers and their Water Users Group’s as well as with the Government Agencies. My experience shows that it is quite possible to measure water use at the field level if we are using simple non-conventional irrigation technologies such as drip irrigation or sprinkler irrigation where we apply water directly at the field level. But, when we talk about surface irrigation systems it is quite difficult to measure water use at field level due to non availability of water measuring structures as well as timing of water application at the field level. Most of the large and medium scale irrigation systems have water measuring structures only at the main and some are in secondary canal level only. Without knowing volume of water delivered, types of soil, crop grown and its yield it is useless to talk about water use at the field level. Therefore, in such condition it is very difficult to measure it accurately.

  • However with simple, low cost tools and technologies it is quite possible to measure water use at the field level with some moderate accuracy are as follows:

Know the area of the plot to be irrigated, Crops grown and their yield, Soil types (medium, low, and heavy), Find out the delivered volume of water through crude method as used by farmers (however, using some portable Parshall flume to calibrate the inlet of farmers plot whenever required is useful), duration of water delivered, number of irrigation during the crop season, some rough idea about the water distribution condition at the plot level after irrigation. My experience shows that farmers are good judge in this aspect, effective rainfall of the area. With these data we can find out the water use at field level to some practically useful extent.

  • Data collection frequency should be for each irrigation of the crop if possible, otherwise during each crop season try to collect all the information’s needed to assess the water use at field level.
  • Yes, Manager/Farmer of the irrigation system should be trained to collect the above information’s and send it to the responsible agency by email for calculating the water use at plot level (A simple computer based software could be developed to calculate the water use efficiencies which could be used by managers, farmers or project in charge of the systems).
  • Yes, farmers should be practically trained at field level to keep and collect the records of their irrigation timing, size of stream, water measuring methodologies, number of irrigation, water distribution condition after each irrigation (farmers could be trained in using tension-meter to know the soil moisture conditions at the field before and after irrigation), soil type, field conditions, and crops grown and their yield for each season.

 Best regards,

Mahesh Man Shrestha

December 14, 2015 08:54

 

Dear Chris,

Within its first phase one of the training topics of On-Farm Water Management Project (SEP project) was “water measurement”.

During those trainings main water measuring devices on field level were Thompson and Chipoletty , SANIIRI and Satarkulov water weirs were less used.  In my opinion abovementioned weirs are most simple and low cost. Of course those nice remotely controlled devices mentioned and seen during iMoMo project visit are easy to use and up to date. But I am not sure if it is possible to cover all water users in close future with such devices especially knowing their price (what if it breaks?). Of course simple water weirs like Thompson and Chipoletty cannot guarantee exact figures but those which can measure exactly also cost a lot and actually require extra software than smart stick itself. Besides smart sticks and additional software could be damaged and then all process is stacked.

In using simple weirs the accuracy of figures could be guaranteed by more frequent checking of installed weirs during irrigation process (I guess with that smart stick you also should check regularly, water fluctuations happen always) and proper recording the data. Demo farmers were perfectly doing that, of course after trainings.

December 16, 2015 05:30

DISCUSSION SUMMARY

First of all we wish to thank you all for your contributions and for sharing your interesting experiences.

The first issue brought up by Mike was that "water use" measured by volume that comes out of a pipe is a very poor indicator of environmental or social impact. This is of course correct and “water efficiency” or “water productivity” are thus not indicators of “sustainable water management”. Mike also brought up the importance of the local context, it’s all a matter of balancing water supply and demand locally to stay within the limits of environmental sustainability.

Frank provided an example of the “paradox of efficiency”, meaning that the result of more efficient use of a resource is often more  - and not less – use of the resource. Farmers converting to more efficient irrigation methods use the saved water to irrigate a larger area and this means a higher total water consumption.

This leads to the basic question of the scale and the boundaries of the water efficiency or water productivity assessment. Is it the water abstracted from the source, applied at field level or consumed by the plant we are talking about. From an environmental point of view it is the water consumed that is relevant, water abstracted or applied still contains a “reflow fraction” of water that is not really used at all.

Another issue raised by Frank was whether we really need to quantify water flows precisely.  Relative water productivity estimates are often sufficient to compare two different irrigation methods and this is certainly true for local comparisons under similar climatic and soil conditions.

Manesh Man addressed the difference of measuring water in piped systems - which is relatively easy - and in open canals - which is very difficult to do accurately. Nevertheless, he suggests portable flumes to measure water with moderate accuracy. Similarly, Altynbek mentions simple portable weirs such as Thompson or Cipoletti to measure water with reasonable accuracy. On the other hand, Altynbek thinks that high tech devices as promoted by iMoMo hub (see comment of Stefanie) may still be too costly or too complicated to be used in everyday water monitoring.

DISCUSSION CLOSURE

January 05, 2016 12:31