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Irrigation Satisfaction Index
ISI

1.                                paradigm  shift

The value and impact of water provided to agricultural lands defers widely based on the climate, the crop, the soil, the technology available for plowing and the modalities of water distribution. Despite large efforts paid by scientist of various disciplines to establish optimum for the irrigation systems, these methods are not well accepted by most of the users of the irrigation systems as they involve large amount of data collection and computation.

A large corpus of studies demonstrate that the access of water for agriculture usage is involving a common effort and this effort is usually rewarded by the participation into a group mediating the consistent access to the irrigation water.

These groups are highly pressed to produce satisfaction to their members.

The basis of the satisfaction derived from the supply of irrigation water has observable descriptors which were expressed by farmers questioned in 13 irrigation systems rehabilitated by IDP-MWR.

The present methodology is an attempt to shift the concern

from objectively measured quantities (discharge, ETO, yield) which fit into the hydrological models but are not available in most of the actual irrigation systems

to systematically assessed empirical perceptions which fulfill the requirements of social consensus building and management evaluation but do not provide the possibility to compute the Penman Montheit model.

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2.                                The satisfaction descriptors

The choice of the satisfaction descriptors have been based on the description of practice and constraints expressed by the farmers operating small, gravity fed, surface irrigation systems. They have qualified their systems with the following concepts :

         Timeliness : it relates to the capacity of the system to deliver water at period of the year which are the most suitable for the crop. It is related to the broad timeframe of the whole agriculture calendar.

         Appropriate quantity : it is related to what the farmers perceive as appropriate quantity, it has to satisfy their perceived requirements for land preparation, submersion of paddy fields, seepage losses ..... This descriptor refer to the overall quantity provided during the cropping season.

         Time predictability : it relates to the very exact day(s) during which the water is supplied to a particular area and the advance notice given to the tenders of a particular land.

         Quantity predictability : it relates to the very exact quantities of water supplied to a particular area and the advance notice given to the tenders of a particular land.

         Time flexibility : it relates to the possibility to adopt an irrigation pattern linked to the individual plot and farmers request.

         Quantity flexibility : it relates to the possibility to obtain water quantities as per the individual plots and farmers request.

         Cost acceptability : the satisfaction related to the cost is an empirical perception of the appropriateness of the cost to get access to the water. The contribution may take the form of cash, work, political and social allegiance .....The descriptor expresses how well accepted is the contribution and not how much contribution is required.

3.                                The context and the priority perceptions

The descriptors explained above could provide a relevant and self consistent picture of the satisfaction related to a particular group of users, at a particular time, in a particular portion of the irrigation system. It falls short to describe and evaluate the system from head to tail and judge the satisfaction under various climatic and cropping circumstances. The following context descriptors are meant to weight the previous satisfaction descriptors to reflect their meaning in a broader perspective (enlarging the time, space and agriculture framework).

The satisfaction descriptors have to be weighted according to :

         The spatial distribution of the water distribution system ( tail, mid and head reaches)

         The seasonallity of the irrigation requirements.

         The impact of unusually low rainfall.

         The relative value of the satisfaction descriptors.

Each of these context descriptors is expressed by a coefficient, the coefficients for the various situations expressed under each descriptors have a sum equal to one.

3.1                            The spatial distribution of the water distribution system ( tail, mid and head reaches)

The coefficient linked to each portion of the CA are the proportion of land cultivated into the different portion.

Example : if the tail portion is 15 ha, the mid reaches 20 ha and the head reaches 15 ha. The tail coefficient will be 0.30, the mid reached 0.40 and the head reaches 0.30

3.2                            The seasonallity of the irrigation requirements

This coefficient is the result of a ranking exercise based on the perception of the farmers regarding how important is the irrigation system to promote successful crop at the different cropping season (in IDP-MWR areas : winter, spring, monsoon).

A group of farmers can be asked to divide  a total of 10 little stones and to place them in front of the card symbolizing the three seasons. The coefficient is the number of stones divided by 10.

3.3                            The impact of unusually low rainfall

The capacity to supply water during years of lower rainfall takes a higher value than during year of normal rainfall.

This context descriptor is assessed by asking a group of farmers to divide  a total of 10 little stones and to place them in front of the card symbolizing the two rainfall conditions : low and normal. The coefficient is the number of stones divided by 10.

3.4                            The relative importance of the satisfaction descriptors

The various satisfaction descriptors are not supposed to have an equal importance therefore their importance is to be ranked and expressed by a coefficient.

A group of farmers can be asked to divide  a total of 10 little stones and to place them in front of the card symbolizing the 7 satisfaction descriptors (timeliness, appropriate quantity, time predictability, quantity predictability, time flexibility, quantity flexibility, cost acceptability) . The coefficient is the number of stones divided by 10.

4.                                The calculation of the irrigation satisfaction index

4.1                            Scoring the satisfaction descriptors

The satisfaction descriptors are scored 0 to 5 by farmers from a particular portion of the irrigation systems. Two to three sets of scores are required to calculate the irrigation satisfaction index for a particular year.

Taking the following symbols:

Tw : Timeliness score for the winter crop

Qw : Appropriate quantity score for the winter crop

TPw: Time predictability score for the winter crop

QPw: Quantity predictability score for the winter crop

TFw: Time flexibility score for the winter crop

QFw : Quantity flexibility score for the winter crop

Cw: Appropriate cost score for the winter crop

 

Ts : Timeliness score for the spring crop

Qs : Appropriate quantity score for the spring crop

TPs : Time predictability score for the spring crop

QPs : Quantity predictability score for the spring crop

TFs : Time flexibility score for the spring crop

QFs : Quantity flexibility score for the spring crop

Cs : Appropriate cost score for the spring crop

 

Tm : Timeliness score for the monsoon crop

Qm : Appropriate quantity score for the monsoon crop

TPm : Time predictability score for the monsoon crop

QPm : Quantity predictability score for the monsoon crop

TFm : Time flexibility score for the monsoon crop

QFm : Quantity flexibility score for the monsoon crop

Cm : Appropriate cost score for the monsoon crop

4.2                            Establishing the context descriptors coefficients

With the method explained in heading 3. the context coefficients will be established by a group of farmers representing an fair proportion of the different part of the CA.

Taking the following symbols :

St : coefficient of tail area

Sm: coefficient of mid reaches

Sh : coefficient of head reaches

 

Mi : coefficients for the monsoon season

Si : coefficients for the spring season

Wi : coefficients for the winter season

 

Li : coefficients for low rainfall

Ni : coefficients for normal rainfall

 

RTi : coefficients for the relative importance of timeliness

RQi : coefficients for the relative importance of appropriate quantity

RTPi : coefficients for the relative importance of time predictability

RQPi : coefficients for the relative importance of quantity predictability

RFTi : coefficients for the relative importance of time flexibility

RFQi : coefficients for the relative importance of quantity flexibility

RCi : coefficients for the relative importance of cost acceptability

 

The i refers the group of farmers which have expressed the ranks and scores (head, mid and tail reaches farmers)

 

4.3                            Calculation of the satisfaction index in the tail portion for the winter crop in case of normal rainfall.

At the end of the winter cropping season, a group of farmers farming the tail of the CA are asked to score the 7 satisfaction descriptors.

The scores of the satisfaction descriptors are multiplied by their relative importance and them summed. This sum is multiplied by the cropping season coefficient, then by the spatial coefficient, then by the rainfall coefficient

(Twt*RTt + Qwt * RQt + TPwt * RTPt + QPwt * RQPt + TFwt * RFTt + QFwt * RFQt + Cwt * RCt) *Stt * Wt * Nt

The  t refers to the ranks and scores given by the tail reaches farmers.

This number is the winter tail normal satisfaction index. Its symbol is SI(wtn).

 

4.4                            Calculation of the satisfaction index in the mid reaches portion for the winter crop in case of normal rainfall.

At the end of the winter cropping season, a group of farmers farming the mid reaches portion of the CA are asked to score the 7 satisfaction descriptors.

The scores of the satisfaction descriptors are multiplied by their relative importance and them summed. This sum is multiplied by the cropping season coefficient, then by the spatial coefficient, then by the rainfall coefficient.

(Twm *RTm + Qwm * RQm + TPwm RTPm + QPwm * RQPm + TFwm*RFTm + QFwm * RFQm + Cwm * RCm) *Sm * Wm * Nm

The  m refers to the ranks and scores given by the mid reaches farmers.

This number is the winter mid normal satisfaction index. Its symbol is SI(wmn).

4.5                            Calculation of the satisfaction index in the head reaches portion for the winter crop in case of normal rainfall.

At the end of the winter cropping season, a group of farmers farming the mid reaches portion of the CA are asked to score the 7 satisfaction descriptors.

The scores of the satisfaction descriptors are multiplied by their relative importance and them summed. This sum is multiplied by the cropping season coefficient, then by the spatial coefficient, then by the rainfall coefficient.

(Twh * RTh + Qwh * RQh + TPwh * RTPh + QPwh * RQPh + TFwh * RFTh + QFwh * RFQh + Cwh * RCh) *Sh * Wh * Nh

The  h refers to the ranks and scores given by the head reaches farmers.

This number is the winter head normal satisfaction index. Its symbol is SI(whn).

4.6                            Calculation of the overall winter crop irrigation satisfaction index

It is the sum the three winter normal satisfaction indexes : SI(wtn) + SI(wmn) + SI(whn).

This numberís symbol is SIW

4.7                            Calculation of the spring and summer crop irrigation satisfaction index

The same process as described here above is performed for the spring and summer crop. These gives a SIS and SIM.

4.8                            Calculation of an annual irrigation satisfaction index

The sum of SIW + SIS + SIM gives the ISI for the whole command area under the condition of normal rainfall.

If the year appears to be a year of low rainfall the coefficient L has be used instead of N in the previous formula.

 

download the PDF file                             or                             see the photos

Albert Grela - Agriculture, M&E, Irrigation