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Environmental Implications of East Rapti Irrigation Project for Royal Chitwan National Park, Nepal

Dr. Sara L. Bennett, Water Environment International / Northwest Hydraulic Consultants, Dhaka, Bangladesh / Edmonton, Canada
U. R. Sharma , Chief Warden, Royal Chitwan National Park, Department of National Parks and Wildlife Conservation, POB 860 Kathmandu Nepal

This unpublished 1989 paper was the basis for a 1990 Asian Wetland News article.  ERIP was eventually revised, and became a case study used for environmental training by the Government of Nepal. 


The proposed East Rapti Irrigation Project (ERIP), funded by His Majesty's Government of Nepal and the Asian Development Bank, is a large-scale (9500 ha) surfacewater irrigation scheme in the Nepal Inner Terai. A low dam will divert water from the river into a canal network for distribution to farmers' fields. There is absolutely nothing in ERIP's concept or engineering to distinguish it from dozens of similar irrigation schemes already operating in Asia.

But ERIP is not just another irrigation project: the river it will dam and divert forms the northern boundary of Royal Chitwan National Park (RCNP) (Fig. 1). ERIP will include reduction of East Rapti low flow to one-quarter of its natural value and construction of civil works, including part of the dam, on Park land. These and possibly other aspects of the project pose potentially serious threats to Rapti aquatic and floodplain habitat, which are important components of the Park ecosystem and home of the endangered Great One-Horned Rhinoceros (Rhinoceros unicornis).

RCNP, Nepal's first national park, is internationally renowned both for its beauty and for its role in preserving endangered habitats and genetic stocks of plant and animal species. It is a UNESCO World Heritage Natural Site (?UNESCO verification being sought?) and has received funding from a wide range of sources since its official gazetting in 1973, among them Food and Agriculture Organization/United Nations Development Programme (FAO/UNDP), Smithsonian Institute, World Wildlife Fund (WWF), and International Union for the Conservation of Nature (IUCN). Fieldwork carried out in RCNP has yielded scores of scientific papers in journals of international stature and Ph.D. dissertations at universities worldwide. In a typical year, the Park is visited by upwards of 10,000 tourists, including several foreign heads of state, numerous ambassadors, and many other visiting dignitaries.

Unfortunately, the ERIP feasibility study executive summary (Nippon-Koei, 1986) and appraisal report (ADB, 1987) do not even mention RCNP's existence, let alone consider how ERIP might affect it. Despite these spectacular oversights, the appraisal report still states that ERIP 'is not expected to have significant environmental impact' (ADB, 1987, p. 20).

The environmental departments and guidelines of His Majesty's Government of Nepal (HMGN) and the Asian Development Bank (ADB) have been almost entirely ignored in the planning of ERIP. In particular, the Department of National Parks and Wildlife Conservation of HMGN knew nothing of ERIP until research for this paper began in November, 1989.

The ADB Environmental Guidelines (ADB, 1987), agreed to by HMGN according to ADB (1988), call for an Initial Environmental Examination (IEE) during project appraisal or before.1But ERIP's appraisal mission passed the task on to the project implementors to perform any time during during detailed design, which does not conclude until after the dam becomes partially operational. The report is silent on the qualifications of consultant personnel advising and assisting in the performance of the IEE, and no consultant person-months were allocated. The ADB Guidelines further indicate that an environmental impact analysis (EIA) should follow the IEE if it identifies significant environmental effects, yet no provision was made for this contingency.

This paper is not intended to take the place of IEE or EIA. It does not, and cannot from the limited information available to the authors, attempt more than speculative characterization of ERIP's environmental effects, nor does it advocate specific changes to or termination of the project. Such judgements must be based on the kind of information that the IEE and EIA will provide.

The authors do hope to promote prompt initiation of an environmental review of ERIP by presenting background information on ERIP and RCNP, with some preliminary thoughts on likely impacts and possible mitigating measures, for the use of ERIP proponents and of conservationists in a position to encourage the proponents to action. It appears that an IEE, and if needed an EIA, can still be completed before construction starts, at the earliest in late 1990 after the monsoon, if the proponents act quickly.

The paper also documents the continuing gap between environmental policies and their realization within actual projects; the importance of timely environmental input to sensible water resources project development; the vulnerability of protected areas' to water resources (and other) development; and the need for protected-area managers to inform themselves of, and involve themselves in, the development plans of their regions.



Until the 1950s, the Chitwan lowlands were but thinly settled by indigenous, malaria-resistant people, mostly Tharus and some Bhote and Bharai. Government prohibition and endemic malaria kept immigration at low levels: in the early 1800s, cultivation in Chitwan valley was actually prohibited by government decree for a time, in order to preserve the malarial forest as a defensive barrier to invasion from the south. Later, under the Rana regime (1846-1950), Chitwan was administered as a private hunting reserve.

The overthrow of the Ranas in 1950 effectively opened Chitwan to immigration, which was then facilitated by the malaria eradication efforts of HMGN/USAID during the period 1954 to 1960 (the disease was officially declared eradicated in 1960). From 1950 to 1960, the population of Chitwan District nearly tripled. The spreading settlements caused the disappearance of almost two-thirds of Chitwan's forests during the decade, and numerous wildlife species were almost eliminated through hunting and habitat destruction. The rhino was hunted especially intensively for its enormously valuable horn (in 1981, up to US$17,000 kg-1; Martin, 1981).

The first modern conservation effort in Chitwan was the formation in the late 1950s of a 130-man Gaida Gasti (Gaida=rhino, Gasti=patrol) from Forest Territorial Service recruits to protect the rhino, an effort that met with limited success. Protected areas were first formally recommended by the British naturalist E.P. Gee in 1959. He suggested a national park to the north and a wildlife sanctuary to the south of the Rapti, based on the results of his survey of Chitwan for the Fauna Preservation Society (FPS). In 1961-2, a Park was declared by the Forestry Department north of the Rapti, but not officially gazetted (Bolton, 1975). (Remnants of this area, now highly degraded forest, are still administered by the Forest Department and function as buffer and corridor forests for RCNP). In 1963 Gee resurveyed Chitwan under the auspices of FPS and IUCN. He recommended that the existing Park be extended south of the Rapti to include rhino habitat still existing there.

Also in 1963, the legal status of settlers within the nominal park and sanctuary areas was investigated by a government committee. The Land Commission of 1964 subsequently resettled 22,000 people from these areas to other locations in the valley. In 1964, His late Majesty King Mahendra created a Rhino Sanctuary south of the Rapti (HMGN, 1986).

In 1968, G.J. Caughley and H.R. Mishra surveyed the area and estimated that the total remaining rhino population was only 81 to 108 individuals.

In 1970, His late Majesty King Mahendra approved the establishment of RCNP south of the Rapti (except for the Park gate area near Sauraha which is north of the Rapti). In 1971, Park boundaries were delineated to include an area of 546 km2, and development of Park facilities begun. In 1973, official gazetting (legal establishment) was accomplished by HM King Birendra, making RCNP the first national park in Nepal. Also in 1973, the Smithsonian Institution/World Wildlife Fund Nepal Tiger Ecology Project began, and in 1975, a management plan for the Park (Bolton, 1975) was produced with the assistance of FAO/UNDP.

In 1978-9, the Park was enlarged to 932 km2 and a gharial (gavialis gangeticus) hatching and rearing center established, both with the assistance of the Frankfurt Zoological Society. As a result of the enlargement, Padampur Panchayat, south of the Rapti and previously on the eastern edge of the Park, was completely surrounded by Park land and river, making it an isolated enclave of settlements and agricultural land.

In 1980, HM King Birendra visited RCNP and indicated that a study should be undertaken of the feasibility of another Park enlargement taking in areas to the east possibly as far as Amlehganj, including the Thori-Shikaribas area believed to contain a remnant population of wild elephants. Also in 1980, HMGN established the King Mahendra Conservation Trust, a quasi-autonomous body that takes a leading role in environmental activities in Nepal, including participation in continuing programs at the Nepal Tiger Ecology Project facility.

In the 1980's, RCNP was enlisted as a UNESCO World Heritage Natural Site.

As of the late 1980s, the Nepal protected areas system had grown to 11 areas covering 11,000 km2 or 7% of the country's area (Upreti, 1985): six national parks, four wildlife reserves and one hunting reserve. One of the Wildlife Reserves, Parsa, is contiguous with RCNP's eastern boundary and contains the proposed RCNP eastern extension area.


RCNP contains three main terrestrial habitats: grassland (20% of Park area), riverine forest (7%), and sal forest (70%) (HMGN, 1986). The grassland generally occurs on the lowest, floodplain land; the riverine forest at slightly higher elevations along the margins of water bodies; and the sal forest on high ground, all the way up to the ridge crests. The habitats grade into each other and intermix. Patches of riverine forest are found on the floodplain, and stands of grass are found under breaks in the forest canopy, including those from old settlements.

Important grassland species include thatch grass or khar (Imperata cylindrica); tall cane or kharai species including Phragmites, Arundo, Themeda, phank (Narenga porphorycoma), and baruwa (Saccharum spp.); babiyo (Eulaliopsis binata); and the shrub simti (Helicteres isora) (Laurie, 1978, and Lehmkuhl et al., 1988).

The grasses reach their full height, up to 7.5 m for the tall canes, at the end of the monsoon in September and flower from then until November. In January, the now-dead grass is cut by villagers, who are admitted into the Park for this purpsose, and uncontrolled burning follows. The burning continues off and on, gradually progressing from the valleys up into the forested ridges, until the monsoon begins in late May or June. The burning, a practice apparently as old as human habitation of the valley, tends to prevent the conversion of grassland to forest and tends to increase the biomass produced per unit area of grassland by removing old growth. The cutting and burning are discussed further below under 'park-people interactions.'

The riverine forest is principally inhabited by the trees khair (Acacia catechu), shisham (Dalbergia sissoo), kapok (Bombax cieba L.), jamun (Syzygium cuminii), bilar (Trewia nudiflora), and palash ( Butea monosperma). For much of the year the riverine forest is a favored habitat for birds and animals, because it provides cover, food, and water, and has greater floristic diversity than either the grasslands or the sal forest.

The sal forest occupying the well-drained higher ground is often monotypic with sparse undergrowth. A number of the sal forest's undergrowth plants are valued for medicinal or other uses, such as dye, fish poison, material for household objects, and fruit.


The habitats preserved within RCNP provide food and refuge for many imperilled species of mammals, reptiles, amphibians, and birds.  Non-technical life histories of the more prominent species and a partial bibliography of scientific references are given by Gurung (1983).

Park Visitors and Tourism

There are privately operated tourist facilities within the park (Chitwan Jungle Lodge, Gaida Wildlife Camp, Hotel Elephant Camp, Tiger Tops Lodge, Tiger Tops Tented Camp).  All cater to more affluent tourists, most visiting Nepal on pre-packaged tours. The concession terms allow them to expand their capacities gradually (R. Ale, pers. comm.).

In addition, many unofficial private guest houses, restaurants, shops, and tour/guide businesses have been opened outside RCNP in the vicinity of the Park gate at Sauraha, some operated by local residents. These businesses are patronized mostly by young independent travellers who book tours to the Park out of Kathmandu. The number of these business has been growing and will probably continue to grow, paralleling the growth of tourism to Nepal.


Irrigation in the Nepal Terai

Accelerated expansion of irrigation in the Nepal Terai, which includes the Inner Terai where ERIP/RCNP is located, is an important component of HMGN's program to increase agricultural production.3Agriculture itself is a key economic sector in Nepal. It employs almost all (90%) of the workforce and produces over half (55%) of Gross Domestic Product (GDP).

The Terai contains over half (54%) of the country's cultivable land, and produces a significantly disproportionate share of its crops (64%). Value-added in Terai agriculture is relatively high, reflecting a greater proportion of cash cropping in response to better transportation and marketing facilities, on average, than in the Hill and Mountain zones.

In the Terai, as elsewhere, irrigation is a fundamental to increased agricultural production. Irrigation can benefit agriculture in several distinct ways, by (i) lessening crop damage from insufficient moisture, (ii) increasing cropping intensity - a greater number of crops on a particular piece of land in each year; (iii) allowing replacement of dryland crops with more productive wetland crops; and (iv) allowing introduction of high-yielding varieties (HYVs), specially-bred strains that require more water, nutrients, and pest control (inputs) than local varieties and have much higher yields (as much as 100% higher).

Increases in agricultural production are critically important if food production and employment are to keep pace with or exceed growth in population. Population is growing rapidly in the country as a whole (>2.5% yr-1 during 1975/76 to 1985/86) and even more rapidly in the Terai (4% yr-1) as a result of in-migration from the Hill and Mountain agro-ecological zones.

As of 1985/6, irrigation facilities had been developed on only about a third of the potentially irrigable area of the Nepal Terai, over half by farmers themselves. HMGN has ambitious plans to develop a fifth of the remaining irrigable area during just five years, 1985/6 - 1989/90, the period of the Seventh Plan. Surfacewater irrigation schemes in the Nepal Terai are classified as small if <500 ha, medium if 500-2000 ha, and large if >2000 ha. ERIP is thus a very large surfacewater irrigation scheme, equivalent to 4% of the Seventh Plan Terai irrigation goal (Table 1), though ERIP is not expected to begin providing partial benefits until late 1991 during the Eighth Plan.
Table 1 - Nepal Terai Irrigation Areas (As of 1985/6, in 103 ha)
Potential area 1,600
Existing area    466 29% of potential
   Farmer-managed   298      64% of existing
   Government-managed   160      36% of existing
   Of which groundwater    77     17% of existing
Seventh Plan (85/6-89/90) goal   236  15% of potential
ERIP     9.5       4% of 7th Plan goal

Project History

The evolution of projects like ERIP is characterized by numerous stages, most of which culminate in a report or study. In 1984, ERIP was first identified with a formal request from HMGN to ADB requesting assistance in the preparation of a feasibility study for the project. The feasibility study was funded by ADB as HMGN requested, and the final feasibility report completed in July 1986 (summarized in Nippon-Koei, 1986). An ADB appraisal mission then reviewed the feasibility study, producing their final report in June 1987 (ADB, 1987). The ERIP loan agreement between ADB and HMGN was signed in May 1988 and declared official in September 1988 (reported in ADB, 1988). According to the appraisal report, the detailed design phase of the project began in third-quarter 1987, and construction was scheduled to begin in third-quarter 1989. As of this writing (December 1989), no construction has yet taken place.

The roots of ERIP extend back even further, to the Chitwan Valley Development Project (CVDP), first identified in 1972 and still underway, due to delays from economic constraints associated with the 1973 oil crisis and technical problems. The CVD Board will oversee ERIP, and ERIP will incorporate into its command area the Lothar Irrigation Scheme (1900 ha) currently being improved under CVDP.

Project Description

ERIP will divert at most 14.3 m3 s-1 of the Rapti flow by means of a 370 m barrage (overflow weir type) to be constructed 2 km downstream from the Rapti's confluence with the Lothar and Manahari rivers. The Rapti's lowest mean monthly flow is 17.4 m3 s-1, occurring in March, including 4.3 m3 s-1 diverted from an adjacent watershed by the Kulekhani dam (operational since 1983). The frequency and duration of Rapti no flow periods will also increase unless operational measures are taken to prevent it.

Thus the post-ERIP Rapti mean March flow will be 3.1 m3 s-1 or 24% of its pre-Kulekhani value, assuming that ERIP operates at full capacity in March. This is almost certain to be the case if only agronomic and engineering considerations are taken into account.

Rapti flood flows are 1850 m3 s-1, based on a five year return period, and will not be significantly affected by irrigation water withdrawals.

The diverted flow will be distributed via a canal system to 9500 ha of already cultivated land to irrigate at least two crops a year. Average farm size in the project area is 1.32 ha, few (3.8%) farms are larger than 5 ha, and most (89%) farmers are owner-operators.

The project area already produces marketable surpluses of paddy, wheat, maize, and oilseeds under pre-project conditions. These surpluses will increase substantially under post-project conditions.

ERIP will also provide drainage into the Rapti of excess water from maize, wheat, and oilseed fields. Drainage water typically exhibits significantly higher concentrations of sediments, salts, nutrients, etc., than the parent river water.

ERIP includes river engineering works, mostly on the north bank of the Rapti, to prevent flooding and erosion of farmer's fields during high water periods. These interventions may have the potential to alter flooding and erosion/sedimentation conditions in the southern Rapti floodplain within RCNP.

Proposed Civil Works Within RCNP

The ERIP barrage, the southern guide-bank leading up to the barrage,4/ and any river training works on the southern bank5/ will all lie completely or partially within RCNP, if constructed as proposed. The original 1973 legislation placed the Park boundary along the deepest channel of the Rapti (wherever the boundary followed the river), while more recent maps (Upreti, 1985) place the boundary along the river's northern edge, possibly a high water mark (a more sensible location from a park-management standpoint). Construction within Park boundaries without the Warden's written approval is prohibited, again according to the 1973 legislation.

The nominal project area also overlaps the Park (i) along the Rapti anywhere the project boundary extends south of the deepest channel, or the river's northern edge, whichever is the current legal boundary, where this defines the northern limit of the Park, and (ii) in the vicinity of Sauraha where the Park's northern boundary jogs north of the Rapti and then back south around Padampur Panchayat. Contained within the Sauraha overlap area are the Park main gate, museum, and elephant stables; the Nepal Tiger Ecology Project research facilities and government rest house; Gaida Wildlife Camp, a tourist lodge concession and surrounding buffer forest; and Bhalu Jungle Island, the largest of three islands in the Rapti south of Sauraha.

No Mention of RCNP in ERIP Documents

The ERIP feasibility study summary and appraisal report do not mention the Park. The failure to identify RCNP on the documents' various maps is especially curious, given that RCNP is the most widely known geographical feature in the region. Indeed, RCNP (93,200 ha2) occupies almost half (42%) of the area of Chitwan District (221,800 ha2). RCNP and contiguous Forest Department areas account for the large difference between the district's mean population density (117 km-2) and the ERIP project area population density (420 km-2). This fact was noted but not explained in the appraisal report.

Environment Sections of ERIP Documents

The feasibility study executive summary (Nippon-Koei, 1986) contains no mention whatever of environment, environmental considerations, identification of environmental concerns, or environmental impact assessment.  The appraisal report (ADB, 1987) mentions environmental considerations in two places. In the description of project environmental impact (para. 62), it states:
"The Project is not expected to have significant negative environmental impact. The changes in the siltation...would be negligible. The river training and bank protection works...will prevent seasonal flooding of farmland in the Project area. While intensification of cropping...will increase use of fertilizers, [but] this would not be at levels likely to have any negative effects. The use of chemical pesticides is expected to remain at low levels."
Later, in the description of the tasks to be done during detailed design of the Project by the consultant firm ("Scope of Consultants Services and Terms of Reference", Appendix 8), it states:
"The consultants shall assist and advise the Executing Agency [HMGN Department of Irrigation, Hydrology, and Meteorology] in...preparation of Initial Environmental Examination (IEE) using the draft 'Environmental Guidelines for Irrigation Projects' prepared by the Bank's Environment Specialists and incorporation of major environmental issues, if any, in the detailed design and construction stages."
The appraisal report does not indicate when within detailed design the IEE shall be performed. Detailed design phase ends (nominally second quarter 1992) after the barrage becomes partially operational (nominally third quarter 1991). Neither does the report specify the disciplinary background or experience level of, nor supply person months for, the person who is to assist and advise. The specified personnel for detailed design consists of six engineers (71 person-months), a hydrologist (two person-months), and special consultants hired on an as-needed basis (four person-months, to cover the requirements of all four implementation units: detailed design, construction supervision, operation and maintenance, and project benefit monitoring and evaluation).


Irrigation in Padampur Panchayat Not Mentioned in Project Documents

Padampur Panchayat is an anomaly. It is surrounded on the south, east, and west by RCNP, and on the north by the Rapti. It is the only agricultural land south of the Rapti and downstream of the proposed ERIP barrage. Estimating roughly from maps of population density, Padampur is at least 1500 ha in size with a population of at least 5000.  Farmer-developed irrigation in Padampur covered 1040 ha in 1980 (Milton and Binney, 1980).

Padampur Panchayat is not, and perhaps cannot be, part of the ERIP command area. In any case, ERIP documents do not mention its existence.  ERIP's economic analysis should be revised to reflect any costs to Padampur agriculture of lower post-ERIP water levels, etc.

Padampur's agricultural potential is high, though crops sustain frequent, extensive damage from wild animals [rhino, chital (axis axis), wild boar (sus scrofa), parakeet (Psittacula spp.); Sharma, 1989]. Crop damage from wildlife is severe enough that many residents would prefer resettlement on reasonable terms to staying on; which would also allow the area to incorporated into RCNP with considerable boundary shortening and simplification. Resettlement has long been discussed (Bolton, 1975) and studied (Milton and Binney, 1980), but never seriously taken up. The results of a fence-and-moat project to protect fields from animals was not very satisfactory.

Conclusions Preparation of ERIP to this point is not consistent with HMGN's and ADB's stated environment policies and guidelines, including those related to World Heritage Sites.  It seems likely that implementation of ERIP as currently conceived will harm important Park ecosystems and species; may compromise Park landholdings for construction; and may disbenefit Padampur irrigators thereby compromising overall Project economic returns. The need to address these issues would appear to be urgent, if HMGN and ADB are at all committed to good environmental and economic practice.


1/HMGN's commitment to environmental protection and impact assessment is also articulated in the National Conservation Strategy for Nepal, HMGN and IUCN, 1988 and the Master Plan for Irrigation Development, Can. Intl. Water Energy Cnslts., 1989, p. 30.  Return to text

2/This discussion draws heavily on Gurung (1983). Information from other references as noted. Return to text

3/'Terai' here refers to the Terai proper, the northern extension of the Gangetic Plain, plus the Inner Terai, the zone of the lowest Himalayan foothills. Return to text

4/Guide-banks upstream of the barrage serve to align the approaching river flow to minimize erosion and prevent flow around the ends of the barrage (outflanking). Return to text

5/E.g. the T-head spur dykes mentioned in ADB, 1987, p. 13.  Return to text

References Asian Dev. Bank, 1988: Appraisal of the irrigation sector project in Nepal. Report No. NEP:Ap-52, October. 136 pp.

_____, 1987a: Appraisal of the East Rapti Irrigation Project. Report No. NEP:Ap-49, June. 42 pp. plus 17 appendices.

_____, 1987b: Environmental guidelines for selected agricultural and natural resources development projects. Environ. Unit, Infrastructure Dept. 180 pp.

Bolton, Melvin, 1975: Royal Chitwan National Park Management Plan 1975-1979. Report FO NEP/72/002 of the Food and Agriculture Organization of the United Nations/United Nations Development Programme (FAO/UNDP). 107 pp.

Gurung, K.K., 1983: Heart of the jungle. Andre Deutsch London/Tiger Tops Nepal. 197 pp.

HM Govt. Nepal, 1988: Nepal - population density maps, hill districts. Suspension Bridge Division, Dept. Roads, Min. Works Transport. Based on 1981 census. 59 pp.

_____ and Intl. U. Conserv. Nature Natural Resources, 1988: Building on success - the national conservation strategy for Nepal. 179 pp.

_____, 1986: Royal Chitwan National Park - visitor information. Dept. Natl. Parks and Wildlife Conserv., 6 pp.

_____, 1985: The seventh plan (1985-1990). 919 pp.

Lehmkuhl, J.F., R.K. Upreti, and U.R. Sharma, 1988: National parks and local development - grasses and people in Royal Chitwan National Park, Nepal. Environ. Conserv., 15(2), 143-8.

Milton, J.P., and J.A. Binney, 1980: Ecological planning in the Nepalese Terai - a report of conflicts between wildlife conservation and agricultural land use in Padampur P anchayat. Threshold, Intl. Cent. Environ. Renewal, Washington DC. 35 pp.

Nippon-Koei Co. Ltd., 1986: Feasibility study on East Rapti Irrigation Project - executive summary. 11 pp.

Sharma, Uday R., 1989: An overview of park-people interactions in Royal Chitwan National Park, Nepal. Landscape and Urban Planning. In press. 12 pp.

Upreti, B.N., 1985: The park-people interface in Nepal - problems and new directions. In: People and Protected Areas in the Hindu Kush-Himalaya, Proc. Intl. Workshop Mgmt. Nat. Parks Prot. Areas in the Hindu Kush-Himalaya , 6-11 May, Kathmandu, pp. 19-24.

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