The question to be answered is "How should we allocate financial resources while constructing irrigation (and drainage) networks?". We'd like to know about the factors affecting this decision. What countries finance main canals first and tertiary canals after them, and what countries do this process in a different way? What factors affect this decision? Is there any standard related to chronological order of the construction of different components of irrigation networks?
in the Danube Delta we have several hundreds of km cannals built since 1870 (most of them in the second half of the XXth century)
for details please contact me at the following address: [email protected]
may be we can set-up a long-term, comparative study related to this issue...
allocating financial resources vary from one geographical area to another.
Hi, I am a designer engineer of canals and drainage networks for 13 years in Euphrates Center for Studies and Designs of Irrigation Projects in Baghdad. I designed many kilometers of canals and drainage networks as I worked for many irrigation projects.I taught this subject for civil students for many years too in Al-Mustenseriaya university in Baghdad too. I think Iraqi engineers are experts in doing this. Please contact me on the following address daily at 10 pm: [email protected]
Regards
Saad Mulahasan
There could be different approaches for the financial support. It is common that the whole system (irrigation/drainage) is not build in one go, though it must be planned and designed in one go. In case of financial limitations, the whole system is divided into spatial segments, each segment consisting of the main (conveyance), distribution and tertiary (delivery) channels. The segment could be added gradually. But, the economic returns must start as early as possible.
Within each segment, construction hierarchy follow the direction of flow in case of irrigation network, starting from the main canals and moving downstream. The main system is build first for the drainage network as well and then the collection systems added.
Ms. Habib:
Do you know any reference for what you stated? Some thing like a standard or guideline from a well-known institute?
For the drainage design, criteria and technical information can be downloaded from many sites, pls check FAO, Delft-Netherland and WAPDA-pakistan website for information.
Lot of info are available about canal design procedures in North india & Pakistan. My organization (IWMI) has worked on the hydraulic aspects of 2 large irrigation systems. If you send me email, I can share some references.
please can anyone assist me on a full report of the effects of cow dungs on physical and chemical properties of a degraded soil?
The design of irrigation system starts from the field level and moves higher up in the irrigation system from tertiary to main canal while the correct procedure for construction is just the reverse, i.e. starting from the intake and main canal you go down the hierarchy to secondary, tertiary and field level canals. The logic behind this is that the benefits can be achieved earlier as we need not wait for the whole construction to be completed in order to operate the system.
All systems are planned starting from the investigation of area to be served (like topographical surveys), estimation of water demands and calculations of the physical capacities of the channels and structures. the capacities are determined from the downstream to upstream - considering efficiencies, safety margins, future options etc. All design drawings are prepared before starting construction. Practically work on various components starts simultaneously. While, to maintain the required velocity, slope and structure characteristics, construction is normally from the upstream to the downstream.
My main question is about the order financial resources are allocated to these parts, not the order they are designed. We'd like to know whether we should start from upstream and continue to downstream (while allocating resources and constructing the network) or vise versa? It is important to us because we are going to finance the construction of irrigation networks and we want to know whether it is better to construct main canals or secondary canals first? Please let me know if you have any suggestion on available guidelines or standards in this regard, i.e. standards or guidelines on construction management and financial issues.
Dear Behnam,
The irrigation network consists of the following:
a) the main canal b)the branch canal c)the secondary canal d) water course e)field channel
first you need to collect the surveying map of scale 1:10000 for your project, then you need to decide the alignment of the main canal first then the branch canal, the secondary canal and the water course channel. These channels have limitations in their flow rates to be called so (main, branch,....) after that you have to be start from the field channel which must be designed with 25 cm higher than the ground level of the field channel to be surveyed. After that the water level in the water course must be added to the water level of the field channels (may be each one water course survey many field channel) so you must design your water course on worst case of these field channel (i.e the highest one). and add 25 cm water level difference between the critical water level of the field channels and so on for the other canals (secondary, branch and main channels) taking into account the slope and length of each canal to add the last water level. i.e it must start from the smallest channel then water course, secondary canal, branch canal and main canals. By the way there are limit and condition about the water levels between each two types of channel which you find them in the irrigation books. Next time I will send you the criteria of designing these canals.
Saad Mulahasan
Designer Engineer
Dear Colleagues,
My question is about irrigation network CONSTRUCTION and FINANCE, not DESIGN PROCEDURE. Please let me know your comments.
Dear Behnam, the construction and finance is actually dependent on the design and the design depends on your requirements. So the first step is to precisely define your requirements. In Engineering works we start from the end. It means in your case we would start from the end user, calculate output demands at the watercourse level, then step wise minor, then distributary canal and then main canal.
When you have finalized ur design then start construction from main canal then distributary then minor and finally water courses.
Financial calculations would depend upon design, local cost and transportation cost of material and the manpower cost of course.
Zafar Hashmi
Dear colleagues,
I am in urgent need for references about construction phase and financial issues of irrigation networks. My main wuestions are:
1) How a project must be financed? Fully financed or phase by phase financed?
2) What phases are distinguished in construction?
3) Is it better to buid a network from 0 to 100%, or we should put financial resources in different projects and complete them in a number of phases?
4) If we have a few semi-completed nerworks (e.g. only mail canals or tertiary canals constructed), should we spend our financial resources to complete them, or should we start construting other networks' main canals?
Plz let me know any proper references you would suggest.
Dear Ababaei,
It is very difficult to answer your questions without knowing the size of your project, total costs, expected return, financial conditions of the donors and the type of beneficiaries. Also, it is not clear what do you mean by the phases. Is it a desk study or assignment?
I try to provide some feedback here.
1, Large Irrigation project are split into phases or different stages to manage the size of work or due to financial limitations. Mostly, donors control & decide about the financing. There could be other reasons, but, I think there is no hard rules.
2, Preferable, each phase should have a complete segment of the network, to avoid the situation you mentioned later.
3, Depends upon the local situations, for example, if different communities, interest groups or donors are involved, large projects can be split into more manageable units.
4, Why a scheme is left incomplete and new similar schemes are considered? If not abandoned due to technical or social reasons, incomplete project should be given a preference, it must be cost effective.
zaigham
Dr Zafar Hashmi has already given answer on your queries. Finance is different issue. If you have budget and allocation for a year, you can go for entire project. If project is too big or large, you can go Phase by Phase as priority. Zaigham Habib has highlighted this matter. It's you and your client's decision.
Dear Behnam,
Read chapter 5 of the following books .
Regards
Saad Mulahasan
Our main questions related to the construction and financing of irrigation networks:
1. Given the fact that our financial resources are quite limited and in many irrigation networks only main canals have been constructed by now, what would you think we should focus on first: finishing the incomplete networks (by constructing secondary canals and developing field systems) OR starting new irrigation networks (by constructing their main canals)? Why?
2. What mechanism do you suggest for financing and construction of irrigation networks: main canals first, secondary canals and field systems second? Upstream to downstream or vice versa? Why?
3. What mechanism do you suggest for the participation of private sector and farmers associations in the construction of irrigation networks? Why?
4. Given considerable amount of water delivery losses in our old networks, should we put our resources mostly on the improvement and rehabilitation of these networks OR on the construction of new networks? Why?
5. Do you think allocating considerable amount of financial resources for switching from surface irrigation to pressurized irrigation is a sustainable decision? Have all the impacts of this decision on the hydrologic cycle been considered? Do you think this decision is going to have positive impacts on effective irrigation efficiency (evaluated on the basin scale) as equally as on field efficiency? Why?
6. Are you willing to cite an appropriate reference related to these questions?
Thank you very much. I am under pressure to finish my analysis on this topic and really appreciate your comments.
Yes, you must complete from intake, main and conveyance.............. then distributary canals............... Cash flow is very important for the implementation...........
Who is responsible for the construction? If not you or your group, you should follow proper implementation policy phase by phase.......................... I am sure that the Govt should be responsible for the implementation................ Yes, your implementation plan or master plan should be prepared based on allocation by year or special allocation......
I am not the expert of large scale irrigation networks, but this link could be helpfull...
http://www.amazon.com/Optimization-Irrigation-Distribution-Networks-Drainage/dp/9251026661
Regards...
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