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University of Technology Delft (1996)

Canal water distribution at the secondary level in the Punjab, Pakistan : development of a simplified tool to estimate the canal water distribution at the distributary level

Visser, S.

Titre : Canal water distribution at the secondary level in the Punjab, Pakistan : development of a simplified tool to estimate the canal water distribution at the distributary level.

Auteur : Visser, S.

Université de soutenance : University of Technology Delft

Grade : Master of Science 1996

Résumé
l’his slritly is part of the research of the hterndianal Irrigation Management It ?stilute (m - Pakistan) at the main system level of the Fordwah Eastern-Sadiqia Irrigation Project (Chishtian Sub-Division) in the I’unjab, Pakistan. This study is part of the Integrated Approach, conducted by llMl in the area of study, in order to develop a methodology to evaluate the economic and environmental impact of (changes in) irrigation management. This study is focussing on canal water distribution at the secondary level (distributary level). Water distribution in Pakistan is mainly based on the principles of proportionality and equity. At present, the water distribution within the distributary, i.c. supply of watcr to the tertiary outlct structures, is characterized by a high variability and inequity. The main objective of this study is to develop a tool that predicts the canal water distribution to the tertiary units (4) as a function of the inflow (Q), state of the tii&britnry, outlet slructurc characteristics and intcrvcntions thcrcin. By quantifying the effect or these paramctcrs on the water distribution, a better understanding of how to improve the present distribution will bc obtaincd. To develop a tool, i.c. a simplificd hydro-dynamic flow model, that predicts the water distribution for the distributarics in the area of study, many parameters must be dctcrniinctl. -1.0 niininiiic the amount of input data for the simplified flow models (thereby enabling an easier application of the model), the sensitivity of thcsc parameters on the canal water distribution was studied, bascd on simulations with a hydro-dynamic flow model SIC, of one distributary (SIC software is developed by Cemagref ; Montpellier, France). The first application of these simplified models will be to predict water distribution at the distributary level for all distributaries in the Chishtian sub-division, which will serve as one of the major components of an integrated approach to evaluate the effect of changes in canal watcr management on salinity/sodicity and agricultural productivity. In future, the (simplified) methodology to set up flow models, will be applied in other research studies. A methodology was proposed to study the sensitivity of parameters determining the canal water distrihution at the distributary Ievcl, simulating a defined inflow pattern at the head or the canal using a “low model of a distributary. An indicator was suggested (R-index) to quantify the impact of a change in different parameters on the re-distribution of canal water to the outlet structures. Data which arc sensitive and should be defined precisely for the simplified flow model : discharge coeflicient, opening height and opening width of outlet structures, and crest level and width of cross structures (drop structures). Data which are insensitive and can be simplified for the flow model : cross sectional profile, crest levels of outlet structures, seepage (inflow and outflow) and Manning’s coefficient. The general simplified method to set up a flow model is bascd on thc inscnsitivc parameters. It can be concluded that the simplificd mcthod results in a reduction of time and money spend on developing those models, to investigate canal water distribution (accuracies of the simplified method up to 20%). Uesides that, an attempt was made to study the distribution of canal water for the actual and design state ol‘a distributary. It can be concluded that the performance at present is inequitable and non-proportional, based on the design principles of irrigation in the area. At least three irrigation indicators are necessary to study actual canal water distribution : (1) DPK ; (2) S, proportionality ; (3) MIQR or CV(DPR).

Mots Clés : WATER MANAGEMENT, DISTRIBUTARY CANALS, IRRIGATION CANALS, ESTIMATION, SIMULATION MODELS, SENSITIVITY ANALYSIS, IRRIGATION DESIGN, CASE STUDIES

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Page publiée le 17 octobre 2012, mise à jour le 19 octobre 2018