Nepal - Sunsari Morang Headworks Project

C)Z 2 '1 Zg Cl - - Docuet of The World Bank FOR OMCLAL US ONLY MrCROFICHE COPY Report No. :P- 5696-NEP Type: (PR) Title: SUNSSARI MORAING HEADWORKS PROJE( (Author: (ALBINSON, B. bport ND. P-5696-NEP Ext. :81928 Room:E-3C)49 Dept.:(ASTAG Y 2 VOIS 141ORANWDW AND REtMDATI OF THE PRESIDENT OF THE INTRNATIONAL DEVELOPET ASSOCIATION TO THE EXECTIVE DIRECTORS ON A PROPOSED CREDIT OF SDR 19.0 MLLION TO THE KINGDOM OF NEPAL FOR A SIINSARI MORANIG EADWORKS PROJECT OCTOBER 15, 1992 Ts document has a resticted distribution and may be und by recipients only in the performace of their official duties. Its contents may not otherwise be disclosed without World Bank aothorization.  NEAL SUNSARI MORANG HEADWORKS PROJECT CURRENCY EQUTVALENTS (as of September 1991) Currency Unit Nepalese Rupees (NRs) US$1.00 NRs 42.80 WEIGHIS AND MEASURES 1 meter (m) 3.28 feet (ft) 1 hectare (ha) - 2.47 acres (ac) A*IBRITATTONS AND ACRONYMS CCP - Chatra Canal Project CMC - Chatra Main Canal DOI - Department of Irrigation ERR - Economic Rate of Return GOI - Government of India HMGN - His Majesty's Government of Nepal ICB - International Competitive Bidding LCB - Local Competitive Bidding 1/s - Liter per Second m3ts - Cubic Meter per Second o&M - Operation and Maintenance POE - Panel of Experts PCR - Project Completion Report SA - Special Account SAR - Staff Appraisal Report SOE - Statement of Expenditure SMIDB - Sunsari Morang Irrigation Development Board SMIP - Sunsari Morang Irrigation Project SMHP - Sunsari Morang Headworks Project Chak - Tertiary Service Area Kharif - Monsoon Cropping Period (July - October) Rabi - Winter Cropping Period (December - March) WUG - Water User Group FISCAL YEAR July 16 - July 15  FOR OFFICIAL USE ONLY UNPAT . STNSARI MORANG HEADWORKS PROJECT Cradit anA Project Summary Bor*ower: Kingdom of Nepal AM=SnD: SDR 19.00.million (US$28.00 million equivalent) QL.ma: Standard. with 40 years' maturity Financing Plan: Loual Foreign Total --- (USS million)------ Government 1.68 0.00 1.68 IDA 1.0l 27.00 28.00 TOTAL 2.68 27.00 29.68 Rcnnmie{ Ratea f Raturn: 22% Staff Appraisal Report: Not applicable han.: IBRD No.23548 Location IBRD No.23549 Detailed Layout This document has a restrktod distribution and may be used by recipients only in the perormanc of their oMcial duties. Its contents may not otherwib be disclosed without World Bank Luthorution |  MEMORANDUM AND RECOMMENDATION OF THE PRESIDENT OF THE INTERNATIONAL DEVELOPMENT ASSOCIATION TO THE EXECUTIVE DIRECTORS ON A PROPOSED CREDIT TO THE KINGDOM OF NEPAL FOR A ShJNSART M HRN ADWOR PROJRCTr The following memorandum and recommendation on a proposed Development Credit to the Kingdom of Nepal for SDR 19.0 million (US$28.0 million equivalent) is submitted for approval. The proposed credit would be on standard IDA terms with a maturity of 40 years, to help finance the completion of the ongoing Sunsari Morang Irrigation II Project (SMIP I)Y - Credit 1814-NEP. ProjmE-t flAsnript1nn and Object{vas 1. The project would provide new headworks facilities for the Sunsari Morang Irrigation Project, initiated by the Government of India (GOI) under the Kosi Agtreement of 1954. The project commands an area of about 68,000 ha, of which about 58,000 ha are effectively irrigable. Problems with siltation began soon after the project was completed, and have defied small-scale remedial works. Two previous credits (Cr. 812-NEP, US$30 million and Cr. 1814-NEP, US$40 million), which provided for desilting facilities as well as development of the distribution system, failed to address the technical difficulties with sufficiently radical solutions and siltation has caused the loss of function of a significant part of the completed works. The search for the correct technical solution to the siltation problem has been actively supported by the Bank, but has proved extremely lengthy and difficult. Finally, an international Panel of Experts (POE) was convened and this project would implement their recommendations which include moving the intake structure 1,300 m upstream into the Chatra Gorge, and providing a very large desilting basin. The new site of the intake would allow easy extraction of water, and the desilting basin would permit desilting of the extracted water. Project Annkground 2. Background and Early levalo ment. Under the Kosi Project Agreement of 1954 between GOI and His Majesty's Government of Nepal (HMGN), GO undertook to finance and construct the Chatra Canal Project (CCP) in Nepal to irrigate an area of about 58,000 ha using water diverted from the left bank of the Kosi River about 20 km upstream of the Kosi Barrage at the Indian border. Construction of the system started in 1964, and after trial operations between 1970 and 1975, the project works were handed over to HMGN in 1975. The project was later renamed the Sunsari Morang Irrigation Project (SMIP). The intake and head reach of the Chatra Main Canal (CMC) were designed for a capacity of 45.30 m3/s, equivalent to about 0.66 1/s/ha over the original command area. The distribution system was terminated at turnouts serving an area of 100-200 ha. Because no minor canals were built below this level, the system could not irrigate the whole command area. Siltation problems troubled the project from its inception, and these problems became progressively worse over the years as the river migrated 1J The acronyms used for the various stages are: SNIP: The whole irrigable area commanded by the Chatra main Canal, about 58,000 ha. SMIP I: Stage I development, about 9,750 ha (Cr. 812-NEP, USS30.00 million, 1978, project cost US$41.90 million). SNIP II: Stage II development, about 16,700 ha (Cr. 1814-NEP, US$40.00 million, project estimated cost US$50.00 million). SNIP III The unimproved balance of about 31,550 ha which will benefit partially from SNHP.  -2- westward. As a result of these deficiencies, the project as originally built did not fulfill its objectives and HMGN requested IDA assistance to overcome the shortcomings of the original project. IDA involvement in the project has been divided into two stages: Stage I (9,750 ha) and Stage II (16,700 ha). 3. Sunmari Morang Irrigation andt nrainage I Projant - (:x A12-ISIP, UsR50.0 mdillion. 17ra. In 1978, IDA approved this project (SMIP I), which was designed to rehabilitate and improve the irrigation and drainage system on the command area of the CXC. The physical works included: (a) arrangements for river control and flood protection along the Kosi River in the vicinity of the CMC intake; (b) sediment control arrangements on the canal system and restoration, improvement and expansion of the existing canal system; (c) design and construction of minor distribution systems extending to outlets each serving 10 ha on 18,000 ha: (d) drainage improvements for 15,000 ha; (e) a pilot tubevall irrigation scheme: and (f) pilot hydroelectric schemes. Implementation of the project was delayed, mainly because of procurement problems. In 1983, the project was modified to provide an improved irrigation and drainage system for about 12,000 ha. The original proposal to provide a desilting basin with dredger at the head reach of the CMC was postponed in favor of a supposedly cheaper maintenance solution, and the pilot hydroelectric schemes were deleted from the project. The area of 12,000 ha intended for improvement was reduced to 9,750 ha because about 1,400 ha of very sandy soils within the area were found unsuitable for surface irrigation; and, a local contractor, who was awarded the works on 850 ha, failed to perform. 4. SMIP I, now called Stage I, was completed in 1985, but the steps taken to deal with the siltation problem were not effective, and increasing siltation prevented the full benefits from being obtained. Moreover, the distribution system design was too complex, attempting to provide demand-based irrigation to very small groups of farmers. The siltation problem, and the complexity of the distribut'.on network, made the system impossible to operate as designed. S. sungari Morang Irrigation II Project - tCr. 8l4-NREP, USS40.0 millio,. li8.Il. In 1987, IDA processed a second project (SMIP II, Stage II), which provided for the rehabilitation of 16,700 ha of the command area and facilities to eliminate the siltation problem. The physical works included: (a) improvements to the main canal; (b) improvements in the desilting operation; (c) rehabilitation and improvement of irrigation distribution and drainage works in 16,700 ha in the Stage II area; (d) improvement of the irrigation and drainage system in the Stage I area (9,750 ha); Ce) construction of buildings for offices and staff quarters, and also the provision for (i) purchase of equipment and vehicles for O&N (including spares) and (ii) radio communication for the canal system operation; (f) expatriate technical assistance, training, monitoring and evaluation and studies: and (g) support for incremental project establishment and maintenance costs. 6. The rehabilitation of the command area has proceeded on schedule and about 40% of the distribution system has been completed. However, the siltation problem, exacerbated by the continued westward migration of the Kosi River, has proved extr emly difficult to solve technically, and HNGK obtained the advice of an international Panel of Experts, which recommended the following modifications to the Stage 1I concept: (a) moving the intake 1,300 m upstream, (b) constructing a larger capacity desilting basin, (c) utilizing larger capacity dredgers, and (d) constructing a microhydro unit to provide power for the dredger operations. 7. Although the silt ingestion was the major problem in Stage I, difficulties were also experienced with the over-complex irrigation system adopted. The design of the Stage II distribution network has been modified in light of the Stage I experience and a simplified design is now being implemented with construction for 7,000 ha completed in June 1992. Until the increasing levels of  -3- silt inhibited operation, this simplified system proved effective and easy to operate and shows that once the silt problem is solved, the project will yield the benefits projected at the time of appraisal. FndaMentals of tha Siltatinrn Problem 8. The siltation problem has two components: (a) extraction of water from the river: and (b) removal of the silt from the water, once it is in the head of the canal. During the wet season, water is easy to extract, but it is silt laden; during the dry season, water is difficult to extract, but it is silt free. 9. Extraction of Wate-a The existing intake structure was sited on the outside of a slight bend of the original river channel, which is the classically correct arrangement. However the detailed design, together with the main channel migration, has resulted in the site now being marooned in a minor branch of the main river. The resulting configuration unfortunately encourages the ingestion of bed and suspended material and acts as a surface trash trap, both of which cause serious operational problems. The main difficulty arises in the dry season when the river falls and the shoals of boulders, cobbles and sand which have been dropped in front of the intake must be removed to allow water to pass for the dry season irrigatio . It is important to provide the first irrigation on time for the dry season crop because this produces the majority of the incremental benefits. To overcome the extraction problem, the POE has recommended re-siting the intakes in the Chatra Gorge about 1,300 m upstream of the present location where direct access to the river can be assured. 10. Desilting Extracted Water. Silt is carried in the river in two ways, bed load and wash load. The bed load rolls and skids along close to the bed and can be largely excluded by correct intake design. The wash load is distributed through the section by turbulence and can only be removed by a settling process in a settling basin which reduces the turbulence. From the settling basin the silt has to be either mechanically removed or sluiced by gravity if enough head is available. For Sunsari Morang, there is not enough head available for gravity sluicing, thus mechanical dredging, as recommended by the POE, has to be adopted. 11. Ouantity of Silt. The quantity of silt to be handled has been analyzedl/ and the desilting basin has been designed to trap both coarse and fine silt. In an average year about 370,000 m3 would be trapped and removed by dredging. In a high flood year the quantity would be in the order of 500,000 i3. However, the quantity of silt can be reduced by judicious operation of the intake gates, and the new headworks would be provided with gates which are easy to operate and which can be closed during the short periods of very high silt load in the river. 12. PropRoed Solution. When it became clear that the entire Sunsari Morang * command area (58,000 ha) would fail unless the ever-worsening siltation problem * was solved, IDA actively assisted and supported the efforts of HMGN to find an effective solution. from a number of options, two possible approaches were considered in detail: (a) provide facilities for dealing with the extraction and siltation problem, or (b) abandon the surface water distribution system and use groundwater. After the technology for solving the surface supply problem was developed by the POE, a study of the groundwater option showed that the rates of return from a groundwater project would be significantly lower than from completing the surface system with adequate desilting facilities. The rates of return achieved in two recently completed groundwater projects and estimated for one ongoing project are: Bhairawa Lumbini Stage I - 10% (PCR); Bhairawa Lumbini Stage IT - 15% (PCR); and Bhairawa Lumbini Stage III - 18% (SAR). lU Details are on Technical Annex 1 (Siltation), in the Project File.  -4- 13. The works proposed for the surface system can be completed in three years; and if correctly planned, the installation would provide most of the required water supply, both in quality and quantity, after the first two years. Most of the 58,000 ha command area is still receiving some irrigation water, and can benefit almost immediately. 1?tf6nnal for Aditinnal 1AL AsiatanO 14. SMIP is the largest surface irrigation project in Nepal and would be successful it a sound technical, financial and management base were provided. The technical solutions proposed for the silt problem are certain to be successful; they have been proved in numerous projects throughout the world, including many projects in developing countries. There is unlimited water, the soils are good and the farmers competent. The water management problems have been greatly reduced by the adoption of simple structured irrigation layouts. 15. Support of this project is consistent with HMGN's irrigation development strategy, which gives priority to improving the performance of existing systems. The technical solutions to be implemented would have widespread use throughout the larger irrigation schemes in Nepal. Pr.ojact CgMpon4antg Awid DTI-ailed fleaign41/ 16. The project would be implemented over a five-year period and would have the following main construction components: (a) a new intake in the Chatra Gorge about 1,300 m upstream of the present intake; (b) a culvert to carry the supply from the new intake to a new pre-settling basin; (c) a new pre-settling basin immediately upstream of the existing intake; (d) modification to the existing intake to make it hydraulically more efficient, together with a lead channel to the enlarged desilting basin; te) an enlarged desilting basin about 990 mn long and 70 m wide; (f) dredge facilities for removing silt from the basin; (g) a microhydro plant to provide energy for the dredge equipment; (h) technical assistance including training and consultancy services; and (i) hydrological equipmex't. In addition, support would be provided for operating the dredging equipment ror two years after installation. Project Cost MEtimates 17. Tha Project Costs. summarized in Schedule A are estimated at US$29.68 million, including price and physical contingencies, but excluding tax and duties from which foreign funded projects are exempt. The cost estimates are based on tendered rates established in 1992.2/ 18. The foreign exchange component would be US$27.00 million or about 91% of the total project costs. Physical contingencies have been included at 10-15% of the base cost for civil works and equipment depending on the perceived risks involved. Price contingencies have been added at 3.90% annually for foreign expenditures, and at 10, 7, 7, 6 and 6% annually for local expenditures, for the years 1993 to 1997. 19, Naintenance Costs for the new headworks are estimated at NRs 6.30 million per annum. Other recurrent costs for the main canal are expected to be about NRS 11 million per annum. At full development of the 58,000 ha, the total annual recurrent headworks and main canal costs would therefore be about NRs 17.30 million or NRS 298 per ha. The direct operation and maintenance (O&M) cost of L' Details are on Technical Annex 2 (Engineering), in the Project File. 2) Details are on Technical Annex 3 (Construction & Estimate), in the Project File,  -5- the distribution system would be about NRs 220 per ha, making a recurrent annual total OM cost of NRs 520 per ha. RLUA=