Case study 10.2 Accelerated Mahaweli Development Programme

Notes: This case study can be used to make matrices and grade them.

Name of project: Accelerated Mahaweli Development Programme.
Type of environmental analysis: Full-scale EIA.
Project location: Mahaweli basin in Sri Lanka.
Type of project: Rural socio-economic development.

Table 10.1 Calculation of direct capital and OM&R costs of alternative wastewater disposal options (in Pesos)

Brief description

The programme includes the construction of storage and irrigation facilities sufficient to supply water for the cultivation of 128,000 hectares of new lands and for the upgrading of 32,000 hectares of existing agricultural lands in the irrigation systems designated as A, B, C, and D.

Approximately 175,000 families will find permanent employment in agricultural or agricultural-related activities. New and improved cultivation will produce more than 600,000 tons of rice and other crops annually and therefore meet the current import demand for rice as well as satisfy a major portion of future demands. In addition, the proposed reservoirs will substantially increase hydroelectric power output for the country.

Table 10.2 Calculation of environmental and resource cost of alternative waste-water disposal options (in Pesos)

Option 1 - Reinjection

The environmental cost cannot be estimated, although it involves: (i) possible loss of potential energy; (ii) treatment cost for dissolved solids in reinjection pipes; and (iii) additional environmental problems from chemicals used to keep the reinjection pipe from being clogged.

Option 2 - Discharge to Mahiao River without treatment

The environmental effects in this case include both the quantifiable and the non-quantifiable consequences, namely:

1 rice productivity: 4,000 ha per season serviced by BRIS;
2 river fishery: no data;
3 stock health;
4 laundry, bathing and human health; and
5 sea ecosystems.

Quantifiable effects:

Value of rice production loss:
Total rice area = 4,000 ha
Return/ha for irrigated rice
(average 1975-8) = 1,838 - 1,492 = P346

Annual loss if irrigation water cannot be used due to heavy contamination

= 4,000 × 346 × 2 - (4,000 × 324)
= 2,768,000 - 1,296,000
= P1.47 million

Present value of rice loss at 15 percent discount rate (years 3-30)

1.47 × 4.9405 = P7.26 million

Value of fishery product loss:
assuming total loss of product currently obtained

From data on average cost and return profile of fishing operation in Leyte, the nett return

= 6,914 - 4,918
= 1,996
or
= 29 percent of gross return

Total value of fishery product in the Camotos Sea and Ormoc Bay in 1980

= P39.4 million

Annual loss of fishery product = 39.4 × 0.29 gross return

Present value of fishery loss at 15 percent discount rate (years 3-30)

11.4 × 4.9405 = P56.3 million

Non-quantifiable effects:

River fishery, stock health, human health, loss of water use for laundry and bathing, effects on the marine ecosystems, plus possible family dislocation.

Option 3 - Discharge to Mahiao River with treatment

Environmental effects:

1 rice productivity unknown;
2 river fishery; no data;
3 stock health, laundry, bathing and human health; non-quantifiable but less than alternative 2; and
4 marine ecosystems; unknown.

Option 6 - Disposal at sea

Environmental effects: unknown effects on marine ecosystems.

Table 10.3 Cost of waste disposal under alternative schemes (in million Pesos)

Under the Accelerated Programme, the total live storage capacity of the major reservoirs is 2,555 million m³. With full development of the Rotalawels and Moragahakands reservoirs, a total of more than 4,000 million m³ of water will be available for irrigation and power generation.

In addition to the proposed dams and reservoirs, the major canal (Minipe Right Bank Canal) and a tunnel will be constructed to divert water from the Mahaweli Ganga at Minipe to the Ulhitiya Oya and the Maduru Oya reservoirs for irrigation of Systems B and C. Also, a barrage (Kandakadu Anicut) may be built in the Mahaweli Ganga near Manampitiya to divert Mahaweli water to System A.

The areas which will be irrigated under the Accelerated Programme could be tabulated. These data could be compiled from the most recent estimates from ongoing feasibility studies for System A, B, C, and D. When fully developed, the Accelerated Programme will provide irrigation supplies for the cultivation of 80,800 hectares of new lands (mostly for paddy) and for the improvement of 14,350 hectares which are in existing irrigation schemes.

The proposed settlement plan for the Accelerated Programme includes the clustering of house lots into a hamlet which will be located not more than 1-2 km from irrigated allotments. Each hamlet will be comprised of about 100 settler family units, each allotted 0.4 hectares (one acre) of upland as a house lot and vegetable garden and 1 hectare for paddy cultivation. About four or five hamlets will be consolidated into a village, and four village centres will form a township. All the necessary infrastructure such as roads, schools, hospitals, etc. will be provided by the government, and it is expected that the settlers will establish other facilities such as a shopping centre, community centres, etc. through their own efforts. In addition to the present inhabitants, the Accelerated Programme area will accommodate a population of about one million people.

Pertinent reports

Two EIA reports were prepared relating to the Mahaweli project: (a) "Environmental Assessment, Accelerated Mahaweli Development Programme'', by TAMS for Ministry of Mahaweli Development of Sri Lanka/USAID, Oct. 1980; and (b) "Environmental Assessment of Stage 11 of the Mahaweli Ganga Development Project'', USAID, Sept. 1977.

The present study is based essentially on the former reference.

Environmental study area

The portion of the Mahaweli Ganga river basin which includes Kotmale, Victoria, Randenigala, Ulhitiya Oya, and Madura Oya reservoirs and their catchments and downstream irrigation areas, plus the Rotalavela and Moragahakanda reservoir systems as applicable.

Environmental study team

Data not included in EIA report.

EIA budget adequacy

Data not included in EIA report.

Methodology

The EIA classifies the environmental resources of the study area into three categories: (i) terrestrial environment, (ii) aquatic environment, and (iii) human environment. The human environment category includes three subcategories, "social profile'', "cultivation practices'' (including pest control), and "public health''.

Existing environmental conditions

The EIA presents detailed information on the existing environmental conditions. Some pertinent information, according to classifications used, is as follows.

Terrestrial environment

The climate is hot and humid, with two annual monsoons of 1,650 mm rain. In the dry zones (to be serviced by the proposed irrigation system) evapotranspiration usually exceeds rain.

Over the past 25 years, community (town) areas increased from 1,000 to 4,000 ha, intensive agriculture decreased from 87,000 to 63,000 ha, and forest areas have reduced by half. Present land uses indicate chena cropping occupying 23 per cent of the land within the project irrigation service area (ISA).

About 28 per cent of the proposed ISA is forested (tropical dry mixed evergreen forest). All former forest reserves were released for development and have been largely cleared, and rapid encroachment on the remaining forest is continuing (and will be accelerated by the proposed irrigation).

The region's wildlife has been exceptionally diverse with a variety of habitat including marshes (villus) and grasslands as well as forests. Several wildlife reserves are within the project area (wholly or partly) and others are nearby. A number of the species are endemic and are threatened.

Aquatic environment

The Mahaweli Ganga is the largest river in Sri Lanka, and the project is based on utilization of this resource. Groundwater is very limited in the project area.

The water quality of project area rivers is well suited for irrigation and other human use purposes (low salinity, low sodium absorption ratios).

Most of the fish catch is from irrigation tanks (about 180 kg/ha/year). Inundation (floodplains) fisheries amount to about 50 kg/ha/year. Riverine fishing is of the subsistence type. Total annual project area catch is about 1,850 tons. In addition there are substantial fisheries on both the Maduru Oya and Mahaweli Ganga rivers. Fish farming is very limited.

Per capita fish consumption has declined from 11.4 kg in 1972 to 10.4 kg in 1978. Because this is important to rural nutrition, one project goal is to increase this to 20 kg/year. Another goal is to improve the income of fishermen families, many of whom are landless.

The wetland in the project area includes some 60 villus (marshes) ranging from 10 to 900 ha in size, distributed throughout the total Mahaweli Ganga floodplains area of about 12,800 ha. The villus are highly productive biologic communities and a high-quality wildlife habitat. They are commercially important for the grasses produced, which are enough to support 1 head of livestock per ha of villa.

Human environment

The project area is sparsely populated, and farmers are engaged mostly in rice cropping below village tanks or upland crops grown in chena cultivation. The population is predominantly Sinhalese, average family size is about 5, and "encroachers'' are plentiful. More than half the families earn less than Rs 3,000/year.

In traditional villages in the project area, farmers operate usually a 0.2 to 0.6 hectare plot of lowland below the village tank, a small rainfed homestead plot, and an area of rainfed upland shifting chena cultivation. On the irrigated lowlands, rice farming is developed as a predominant monoculture, especially within the large tank systems. On some well-drained parts of the lowlands, chillies, onions, and vegetables are also grown. Paddy yields from rainfed and irrigated sources average about 2.5 tons/hectare/year. The availability of water is a major factor affecting yield levels as well as cropping intensity. Where a reliable water supply is available, paddy yields are well above 3.0 tons/hectare, occasionally reaching 4.5 tons/hectare.

On the rainfed homestead plots, various perennials and vegetables are grown along with bananas, pineapples, mangoes, papaya, and other tropical fruits. The chena cultivation focuses on annuals, mainly cereal and root crops, including pulses, millets, vegetables, tobacco, and often rainfed paddy. Most of the encroachers who have entered the project area in the past few years are subsisting on chena cultivation.

The most serious insect pest for rice in the project area is the brown planthopper. Other major insect pests include rice thrips and paddy bug. Sugarcane suffers considerable damage from shoot borers and smut. In addition, the mania and rose ringed parakeets cause an estimated 5 per cent loss to rice crops in the project area. Wild boar and elephants are also responsible for substantial crop losses.

Diarrhoeal diseases are common, due to inadequate sanitation. Of the vector-borne diseases, malaria is considered of primary project concern. However, malaria incidence has been decreasing due to anti-malaria programmes implemented over the past decade.

Significant environmental effects from project

Terrestrial environment

Watershed erosion is severe, but nevertheless reservoir siltation will not be enough to impair reservoir operations over the project design period (50 years).

Conversion of downstream forest/scrub land/chena areas to paddy will of course eliminate considerable wildlife habitat. Also, decreased river flood flows will convert much of the villus area into comparatively poor grazing area.

Increased encroachment seems inevitable both for "squatter land'' and for fuel. Project implementation will also make use of new lands for irrigation some of which has been valuable wildlife habitat. However, these same encroachments seem likely to occur eventually in any case. The present project will accelerate the process.

Aquatic environment

Under the Accelerated Programme, a large amount of the water diverted from the Mahaweli Ganga will be delivered to irrigation systems outside of the Mahaweli Basin. Of the remainder, only about 20 per cent is likely to re-enter the Mahaweli as irrigation return flow. Overall, the volume of flow in the river will be reduced by about 50 per cent. Wet as well as dry season flows are expected to decrease in the Mahaweli; however, future flows during the dry months should increase slightly in the Maduru Oya due to the planned transbasin diversion into System B. Flood peaks in the Mahaweli Ganga will be considerably reduced by the surcharge storage in the new reservoirs.

With the conversion of forests to agricultural land, the future surface run-off is expected to increase. However, the effect on stream flows should not be significant, because the forested area to be cleared is relatively small in comparison with the total drainage area of the Mahaweli Basin. In addition, the increased run-off will be retained by rice paddies and eventually lost to evapotranspiration.

In a few localized areas water quality in return flows may deteriorate significantly, preventing their immediate reuse for irrigation. This may occur where salt accumulates due to improper drainage or where sonic sub-soils exist which, when irrigated, release sodium into drainage waters. However, in most of the project area, adequate drainage and the flushing action of heavy monsoon rains should limit salt build-up in soils or high sodium concentration problems.

Generally, surface water and groundwater in the project area should be suitable for livestock drinking as well as for swimming, bathing, clothes washing, and related domestic uses. However, the use of these waters for bathing or swimming and for human consumption will depend upon the provision of protected water supplies and adequate sanitation facilities.

Potential fish yields calculated for the proposed reservoirs clearly indicate that the deep up-country reservoirs are likely to be much less productive (20 to 30 kilograms/hectare/year) in terms of fish output than the shallower low-country ones (100 to 300 kilograms/hectare). Yields from the reservoirs will greatly exceed existing river yields both on a unit and total area basis. The total nett yield for the major proposed reservoirs is estimated at about 2,550 tons/year.

The presence of a series of dams on the main river will also block upstream spawning migrations of the massier. This, combined with the inability of the massier to adapt to reservoir habitats, will probably result in a significant reduction in the population of this species within the Mahaweli Ganga. Other species which may be adversely affected by interference with migratory movements include eels, two species of barbs, the endemic mountain labeo and the freshwater shrimp Macrobrachium.

The reduction of floodplain and associated villa areas will result in a corresponding loss to fisheries resources. The total loss in terms of fish yield is estimated at 320 tons/year. A further non-quantifiable adverse impact would be the reduction of floodplain spawning and nursery grounds for a number of fish species which inhabit rivers, streams backwaters, ponds, and tanks of the entire Mahaweli Ganga system. Overall, there will be a nett increase in potential fish yields from project area waters of about 2,140 tons, or a gross economic benefit of about Rs 8.6 million annually.

There will be a reduction in area for livestock grazing in the villus and a decrease in the villa carrying capacity from 1.0 to 0.75 animal units per hectare. The total carrying capacity for the project area villus will be decreased by more than 60 per cent, to a level of 2,880 animal units per grazing period. The decrease in floodplain villa area will result in a total loss in quantifiable economic benefits of about Rs 5.7 million annually. This includes losses to fisheries, grazing, and associated dairy production.

Any of the new reservoirs, irrigation canals, drainage systems, or paddy areas may be susceptible to aquatic weed infestation, chiefly from water hyacinth, floating ferns, or cattails. Particular areas of concern would be where eutrophication may be increased due to the accumulation of nutrients from run-off or return flows. Consequently, small downstream tanks and villus, the lower part of the Mahaweli Ganga with its reduced flow, and the shallow Kandakadu Barrage are likely to experience a continued infestation of water weeds.

Human environment

A major social impact of the Accelerated Programme will involve the transition from small isolated village societies to production-oriented large-scale colonization schemes. Implicit in the model of transition is the modernization of rural society with the attendant loss of traditional values and social cohesion within small kinship-based villages.

The population in the project area will be increased by about 1 million people. Current project area residents who are over eighteen years of age and have an agricultural background will have priority in the resettlement planning. The principal social benefits will accrue to settler families who stand to gain land and irrigation waters; this is also the major benefit perceived by project area residents as well as potential settlers from other regions who are applying for allotments.

An important attitude prevailing among future settlers is that the 1 hectare paddy land allotment, irrigated for two full seasons, will represent an improvement from present landholding. However, planning calls for traditional inheritance and kinship roles to be abandoned with respect to the mechanisms for landholding and its acquisition. This may prove difficult to enforce; studies elsewhere indicated that allotted land was leased, mortgaged, and given in tenancy to relatives within the first year of cultivation.

As in previous colonization schemes, the Accelerated Programme will also face the problem of employment for the second generation of the farmer settler families. Some of the second generation offspring can provide employment in non-farm sectors; however, not all of them can be accommodated in this manner. This may lead to fragmentation of paddy land and home plots or the further encroachment on undeveloped lands within or adjacent to irrigation blocks. Many of the present chena farmers in the area are second generation settlers from other schemes who have encroached land in order to be in a position of acceptance in the new programme.

At the proposed reservoir sites, especially Victoria and Kotmale, a total of 25,000 to 30,000 residents will have to be relocated. The affected people have accepted the inevitability of relocation, but there is a general resentment and a sense of loss of ancestral homes for those who have experienced little geographic mobility moving to nearby estates or into the Mahaweli area, which would benefit smaller landholders. However, most are concerned about how they can support themselves in the period it will take to replace their lost tree crops and paddy.

A major benefit of the Accelerated Programme will be to increase agricultural output. The main focus will be on rice production. The single rice crop intensity presently achieved per year under rainfed conditions or small tank irrigation will be increased to obtain double cropping. Approximately 8 tons per hectare of paddy will be produced from the two crops grown per year on the newly cultivated lands. Moreover, much of the existing irrigated paddy land will receive supplemental water to permit additional cropping intensity.

One constraint to the high intensity rice monoculture envisioned will be the farm labour supply. Another problem will be pest control. Since there are no geographical barriers to prevent the movement of any known insect pest or plant disease, it is anticipated that the crops proposed for the project area will be susceptible to damage from the same pests found in other parts of the island. Intensity of pest activity for the new rice growing areas is expected to be manifested by an increase of brown planthopper and sheath blight.

Extensive sections of wildlife habitat will be removed and thus eliminate a substantial amount of natural predator control. This, coupled with the increase in cultivated areas and the intensification through double cropping, will necessitate a significant increase in the use of insecticides, fungicides, and herbicides.

With the substantial increase in population which is anticipated in the project area, there will be an inevitable spread of a number of viral and parasitic water-borne communicable diseases. This will be exacerbated by the lack of basic health education combined with the cultural practices of the people. They would be expected to continue their present utilization of the same water supply for drinking, bathing, and waste disposal which would be very conducive to the spread of gastroenteritis, hepatitis, dysentery, and other water-borne diseases. This condition will be worsened if suitable water supply and sanitation facilities are not provided, or, perhaps more importantly, not maintained.

Reduced river flows and seepage from irrigation channels in the project area will enhance the formation of small pools which will increase the breeding potential of the principal malaria vector, Anopheles culicifacies. Malaria incidence will undoubtedly increase in the region. The present intensive control programme involves the risk of producing malathion-resistant A. culicifacies which could trigger an epidemic until new controls are decided. This vector has already developed resistance to malathion in India.

Among the other diseases, dengue fever, chikungunya virus, scrub typhus and bed bugs are all likely to spread in the project area. For the present, neither filariasis nor schistosomiasis would be expected to spread as a result of project implementation.

Rabies, tetanus, accidents and snake bites are also likely to increase, particularly in the early years of construction and clearing. Tetanus may be a serious problem for construction workers due to its prevalence in the project area soils. Existing health facilities in the Mahewali region will, of course, be too limited to accommodate the health needs of the additional population.

Overall, dietary patterns and nutritional quality should improve for the incoming settlers due principally to increased food availability and an increased standard of living. However, one potentially serious problem may be an insufficient supply of animal protein to meet nutritional requirements for the general maintenance of good health. The supply of dairy products to the project area may be limited since the grazing area may be reduced. On the other hand, increased freshwater fish production could contribute significantly to meet this need for animal protein.

Measures for offsetting adverse effects

Coordinating agency

Establishment of a National Coordinating Agency for Natural Resources, along with an Environmental Protection Agency, is recommended for furnishing institutions capable for follow-up implementation of needed environmental protection measures.

Watershed management/forests

A package of watershed soil conservation measures is recommended, including reforestation, establishing timber and fuel wood plantations, rehabilitating abandoned plantations by conversion to upland cropping, plus engineering measures for erosion control. The fuelwood plantations would utilize local village participation. A "Mahaweli Catchment Redevelopment Law'' would be enacted for establishing a new National Forest Authority. Included in the package would be the preparation of a systematic plan for continuing logging and clearing operations.

Wildlife

New wildlife reserves are to be established in those "high quality wildlife habitat'' areas not needed for agricultural purposes. In addition, to compensate for loss of habitat in the Mahaweli region, a series of six large continuous reserves/parks are recommended in and around the project area. These include the Somawathie National Park (especially important for elephants), Mahaweli Conservation Park (bird sanctuary), and Wasgomuwa National Park (endangered vertebrate species). A package of institutional improvements is recommended, including establishing a National Department of Wildlife Conservation, and authorizing a detailed study for planning the proposed new park and other reserve systems.

Wetlands and weed control

Within the context of the measures described above, the remaining villus and mangrove swamps will be preserved to the extent possible. A programme will also be developed for use of practicable methods for controlling aquatic weeds.

Fisheries development

The recommended action programmes include: (i) establishing fisheries management systems for the new reservoirs, (ii) a series of pilot project fish farms to determine the best approach for achieving markedly expanded aquaculture, and (iii) strengthening of the ongoing "tank'' type of aquaculture using relatively low level technology including construction of a centralized hatchery.

Downstream water and soil management

These recommendations include: (i) establishment of a water management system in the ISA, (ii) control of land clearing operations to minimize loss of topsoil and subsequent erosion, (iii) use of contour techniques in upland areas including plantings and terracing, (iv) establishment of riverbank forest reserves, (v) use of an integrated pest management approach, and (vi) establishing a multipurpose water and soils monitoring programme including a salinity intrusion survey and periodic water quality monitoring.

Health and sanitation

The recommendations include: (i) provision of an adequate rural water supply system, (ii) control of malaria and other vector mosquitoes through strengthening of the existing programmes, (iii) immunization procedures to be used during the construction, and (iv) strengthening of primary health care resources.

Social considerations

The recommendations include: (i) establishment of a regional planning and socio-economic studies unit, (ii) establishment of a settler orientation programme, (iii) studies for developing guidelines for managing a variety of social problems, including special attention to the poorer population sectors such as fishermen's families and agricultural labourers, and evaluation of tourist potentials, and (iv) strengthening of agricultural extension services.

Land use planning

This recommendation is for preparation of an optimal land use scheme which allows maximum agricultural development commensurate with preservation of forests/wildlife, including detailed mapping of non-arable lands and associated studies including evaluation of grazing potentials.

Priorities and scheduling

A tentative scheduling is outlined, showing when the various recommendations are to be undertaken as related to the various stages of project implementation.

Environmental monitoring

While the study does not deal with the need for comprehensive environmental monitoring, it does recommend a comprehensive "multipurpose soils and water monitoring programme'' in the project irrigation service area. Other monitoring is to be included under the various recommended sector programmes.

Concluding remarks

The recommendations of the EIA for achieving desired environmental protection measures as part of the overall plan are very comprehensive, so much so that implementing them will require major alterations in the existing national government structure and policies.