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Assessment of water distribution, types of assessments

Assessment of water distribution is the systematic process of indicator comparison to identify fluctuations in water management.

The process of assessment implies comparison of different indicators

  • Base periods (day, ten-day, season, year, several years),
  • Type of irrigation system (IS),
  • Sites of irrigation system (balance sites),
  • Types of water users (farm, WUA, district, province, republic),
  • Types (actual, plans, norms).

If source information is reliable, then an assessment is of

  • Theoretical and
  • Practical importance.

Assessment is of practical importance, i.e. virtually contributes to better water management when responsible persons

  • Wish and (or) have to make assessment.
  • Know how to make an assessment.
  • Wish and (or) have to make decisions for better water management.
  • Have (financial, technical, personnel) capacities to fulfill the decisions made.

Factors constraining better quality of assessments and water management:

  • Financial and economic factors:
    • Lack of financial incentives among water managers and water users for water saving and better water management.
    • Significant costs to be born for effective monitoring of water management.
    • Lack of water pricing. This is essential but not enough to improve assessments and water management.
  • Social and institutional factors:
    • Performance of water managers is judged by water managers but not by water users (deficit of public participation).
    • Other factors.

Types of assessment

The water distribution assessment can be external and internal.

  • Internal assessment characterizes costs and results of irrigation system performance; it makes it possible to compare performance of one system with other similar systems.
  • Internal assessment characterizes processes taking place inside a system that lead to results achieved from performance of the system; it serves for comparison of actual results with planned ones.

While analyzing water distribution, one should find answers to the following questions:

  • Am I doing everything right?
  • Is that I am doing right?

By asking on the first question, you assess the quality of water management (compare actual figures with planned (limit) ones), while with the second question you assess the quality of water governance (compare achieved results with a target, a set norm).

Let assume that indicators of water availability, stability and uniformity in pumped irrigation area of the main canal are acceptable (i.e. actual figures are close to the plan). Then it would follow that water supply is right and that the canals operation service manages water well. However, from the internal assessment it is impossible to know whether the water policy in the area of the main canals is effective compared to systems of other regions and countries? To answer this question, an external assessment should be made.

The external assessment (detection of physical and economic productivity of water) may call into question necessity of water supply to pumped irrigation area or give an idea about adoption in this area of water-conservation technologies or production of high-value crops.

Procedure of assessment

Analysis of on-line (daily, ten-day) indicators is conducted during the whole season, and final indicators are analyzed after the season.

It is recommended to make an assessment of water distribution in the following sequence:

  • Calculate indicators by off-take, pumping station, ten-day, season, water user, district, province, balance site, control post, pilot canal, etc.
  • Plot comparison diagrams.
  • Identify on the diagrams peaks (visually under- or overestimated values) of original data and indicators.
  • Study and explain those fluctuations.
  • Correct mistakes (if any) in original information.
  • Analyze diagrams and evaluate trends (in time and space) observed in water distribution governance and management and causes of such trends.

Sharp fluctuations can result from mistakes in original information or other causes:

  • Efficiency factor is larger than 1 available unregistered lateral inflow, etc.
  • Abrupt drop in the efficiency factor water theft or unregistered outflow, etc.
  • Overestimated unit water supply and water availability incorrect recording of transit flow, etc.
  • Underestimated water availability lack of consideration of return flow, theft, unreliable information on irrigated areas, etc.
  • High stability available regulating structures (reservoirs), unreliability of reporting data, etc.

In the course of assessment, trends and their causes can be identified:

  • Growth of uniformity and stability factors can result from increasing public participation in water governance.
  • Growth of water availability factor can result from the increased flow probability or more accurate evaluation of water demand (consequently, reduction of planned water supply).
  • Decrease in a water availability factor can be caused by low flow probability of given year or an updated evaluation of irrigated areas (counting of double-season and inter-season crops), as well as result from adoption of charges for water services.
  • Relatively high factor of physical water productivity in canal area does not mean that the factor of economic water productivity is also high. The cause can be low cotton purchasing prices (as compared to world prices).
  • Decrease in one or another indicator of water distribution can be the result of external factors: social upheaval, large-scale engagement of water managers in work that is not connected with their direct functions, as well as incident interventions in water distribution process (cut of water releases from reservoirs), etc.

Source: Manual on implementation of IWRM. Volume 2 Water management in irrigation systems