Summary Environment Walcen

8/13/2019 Summary Environment Walcen

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SUMMARY

1. BackgroundThis report describes environmental work carried out in conjunction with the Master Plan Study onIntegrated Development and Management of the Walanae-Cenranae River Basin in centralSouthern Sulawesi. The project was conducted for the Directorate General of Water Resources ofthe Indonesian Ministry of Settlement and Regional Infrastructure, funded through a loan from theJapanese Bank for International Co-operation. The project ran from September 2002 to December2003 and the environmental work was carried out between October 2002 and July 2003.

This is one of the main rice growing areas of Indonesia and most of the land is devoted to paddyfarming, served by extensive technical and rain-fed irrigation systems. Production is limited byinsufficient water in the dry season and flooding in the rains, when the floodplain lake in the centreof the basin expands and rivers overflow. Various studies since 1980 have recommended measuresto manage water resources to improve agricultures, raise living standards and reduce flooding, andthe aim of this project was to review these proposals and develop an integrated Master Plan forwater resources development.

The aim of the environmental study was to identify existing problems and constraints in the basin,assess the environmental impacts of the proposed water management measures, prepare anEnvironmental Protection Plan defining how adverse impacts will be mitigated, and prepareEnvironmental Conservation Guidelines to ensure that future development is sustainable andenvironmentally acceptable.

2. ApproachExisting data on the environment of the basin was obtained from previous reports and fromgovernment and NGOs, and new data was collected via surveys and provided by experts workingon other aspects of the project (hydrology, agriculture, forestry, etc). Land use was determinedfrom satellite imagery, and all spatial data was entered into a GIS. Maps were produced illustrating

the main features, and a written description of existing environmental conditions was prepared.

Environmental problems were identified by analysing baseline data, and solutions were proposedand included in the Spatial Plan for land use development. An Environmental ResourcesConservation Plan described the problems, reasons for their occurrence and proposed solutions, andan Action Plan for Environmental Management and Protection set out the action necessary, and aprogramme for implementation.

Environmental Impacts of the proposed water management and development measures wereassessed, and mitigation was devised to reduce or avoid adverse impacts. The means of achievingmitigation was discussed with the project engineers and defined in an Environmental ProtectionPlan, together with the necessary environmental monitoring. Environmental ConservationGuidelines were produced comprising simple criteria that can be applied to future projects to avoid

environmentally damaging activities. The results of all studies were described in an EnvironmentalSector Report (this document).


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3. The Existing EnvironmentTopography: The study area includes the basins of the Walanae River and tributaries in the south,the Bila and tributaries in the north, numerous smaller rivers in the west, Lake Tempe in the centreinto which all of these rivers flow, and the Cenranae River that drains the lake into the Bay of Bonein the east. It also includes the unconnected Gilirang River in the north-east. Most of the area is flatand low lying (4-10 m above sea level), rising to hills of 1,500-3,000 m in the north, south and

west.

Geology: The uplands in the north consist of hard sedimentary rocks formed in the Tertiary periodand metamorphic rocks from the Pre-Tertiary, with lower slopes of mudstone, sandstone andconglomerate deposits from the Pliocene. Tempe depression in the centre is a flat plain of alluvialsoft clay and un-cemented sand, with levees and marshes around the rivers. In the south, limestonemountains are separated by the Walanae depression, which includes hills and alluvial plains andterraces.

Soils: There are four main types of soil. Eutric Fluvisols with a deep effective depth and finetexture occur on alluvial plains around the lake and rivers and support a wide range of crops. EutricGleysols are found in depressions with a high water table, and are used in paddy cultivation, andChromic Vertisols with high clay content extend over flat low land and are also used for paddyfarming. Eutric Cambisols occur on terraces in the north and are shallow, eroded and used forperennial crops or cassava.

Climate: The rainy season extends from March-July and the dry season from August-February,although September and October are the only really dry months. The mountains receive the mostrain (2-4,000 mm/yr) and Lake Tempe the least (1,500 mm/yr), and in the lowlands there are 200mm of rain per month in the wet season and


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Water Quality: Over the past 25 years water in the lake and rivers has been generally suitable foruse in fisheries, agriculture and irrigation. Manganese, Iron, Lead, Copper and Arsenic haveexceeded Health Ministry standards at some locations, and rivers are high in suspended solids,nitrogen and organic matter because riparian communities with inadequate sanitation use rivers todispose of sewage and other waste. In November 2002 BOD in the lake exceeded nationalminimum standards by 12 times, dissolved oxygen was dangerously low (0.3 ppm), and iron, zinc,

manganese and coliform bacteria were also high. Surface water is now suitable only for irrigation,and should not be drunk, even after boiling.

Terrestrial Ecology: Clearance of vegetation to provide land for agriculture has removed almost allnatural habitat, leaving an area low in biodiversity, dominated by animals able to live near man.Upland forest above 1,000 m includes native conifer, maple and oak, but is mainly commerciallyplanted, and supports few of its former inhabitants such as anoa (wild buffalo), tarsiers andSulawesi hornbill. Dryland farming is practiced on hills and lowlands without irrigation, which areplanted with tree crops (cocoa, coconut, jack fruit), maize, and vegetables. Rice paddies cover thearea between the drylands and the lake, where land has been flattened, terraced and irrigated,forming an artificial habitat that supports many insects, snails, fish, frogs, crabs and birds.

Aquatic Ecology:Lake Tempe is heavily polluted with organic matter, very low in oxygen, and inthe dry season shrinks to less than 20% of its wet season volume. Despite severe environmentalpressures it supports a thriving fishery based on 20 species, over half of which have beenintroduced, and internationally important populations of waterbirds, sufficient to qualify the lake asa Ramsar site (wetland of international importance for waterbirds). In 1989, 55 species wererecorded, including 5,000 Glossy Ibis, 10,000 Garganey and 26,000 Great or Clamorous Reed-Warblers.

Population: The study area includes six Kabupaten(districts) inhabited by a million people, at anaverage of 139 persons/km2, compared with 109/km2 for all of Indonesia. The main populationcentres are the towns of Watansoppeng, Sengkang and Pankajene arranged in a triangle aroundLake Tempe, although over 60% of the people live in the many scattered villages.

Socio-economics: Agriculture is the main occupation, supporting 150,000 households and 800,000people. Most farms are small and include rice paddy, and non-paddy areas planted with palawija(beans, corn, vegetables) and tree crops (coconut, cocoa, bananas). Irrigation has increasedproductivity allowing double cropping of rice in many areas, but most farmers remain poor, with anincome of Rp 3,500,000 per year (US$ 400). Fishing supports over 14,000 households, of whomover half are engaged in aquaculture and 3,000 fish in Lake Tempe. Average income is Rp4,000,000 (US$ 450), of which 25% is left net of living expenses.

Land use: Agriculture dominates land use (and landscape) with 30% of the area being paddy fieldsand 22% used for other forms of farming. Paddies are mainly on alluvial plains around the riversand lake, and dry farming occurs on land between the paddies and hillslopes. 15% of the area isforest, but most of this is planted for timber, and natural forest is mainly restricted to the uplands.Coastal mangrove has been destroyed to provide land for fishponds, and the lake is the only

significant natural habitat, comprising 3% of the area (10% in some wet seasons).

Infrastructure: 22 irrigation schemes divert water from rivers through concrete primary andsecondary canals and earth dug tertiary canals into 78,500 ha of paddy. Asphalt roads aremaintained by Kabupatens, and a two-lane highway encircles the lake and continues out of thebasin in the north and south. Other roads are short, unpaved, and passable only by 4WD vehicle inthe rains. Piped water is available in towns, but in villages people use wells or river water. There isno sewerage system and although some houses have cesspits, in villages people defecate on land, inthe river or in a family privy, which often also drains into the river. There is no waste disposalsystem outside the towns, and solid waste is burnt or thrown into the river.


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Socio-culture: Like most of the rest of southern Sulawesi the population are mostly of the Bugisethnic group and follow the Muslim religion. The mosque is thus the main cultural building in thecommunity and often the dominant structure. There are several mosques in the towns and largervillages and other important buildings including government and village offices, schools, townmuseums, etc. There are primary schools in the larger villages and secondary schools in the towns,but under-education is a significant problem, with 20% of people not having completed primary

school.

Public Health: There is a Public Health Centre in each Kecamatan, staffed by at least one doctorand one nurse, and small clinics in many of the villages. There is at least one hospital in eachKabupaten, and on average each doctor serves 10,000 people. The paucity of health facilities andinadequate domestic sanitation results in a birth rate that is lower than the national average, and adeath rate that is higher.

Tourism: The bird populations of Lake Tempe attract a few thousand foreign tourists each year,who stay in hotels in Sengkang and hire fishing boats to travel on the lake to view the birds. Thereare a few other attractions that draw mainly domestic visitors, including hot springs, waterfalls, silkweaving and a small number of nature parks.

Agriculture: Agriculture is the major occupation in the basin, and the mainstay of the economy.Average farm size is 2.38 ha, comprising 1 ha of paddy and 1.3 ha dry farmed, and the averagehousehold is 5 persons. Most activities are manual, although hand tractors and threshers are alsoused. Men provide most of the labour, and additional hands may be hired for land preparation,planting and harvesting. Rice is the main crop, followed by maize, mungbeans, cassava, soybeanand groundnuts. Farmers keep only a few cows or buffalo and often a horse for transport and towork on the farm. Goats and poultry feed on scraps and domestic ducks forage in the fields.

Double cropping of rice is only assured in well-irrigated areas (although farmers elsewhere oftenattempt a second crop), and in rain-fed fields the main pattern is paddy and palawija. Paddies areplanted in April and harvested in September, re-planted in October and harvested in March. Paddyrice produces the highest yields (5.2 tons/ha; 1.5 million tons total), followed by maize (2.9;

200,000) and soybean (1.5; 12,000), but 30-40% of the crop can be lost during flooding. Crops aresold to collectors at the fields when harvested, and sold on to wholesalers, rice millers or state orprivate rice farms. Current market prices per kg are Rp 15,000 for chicken, Rp 8,000 for chillipepper, Rp 5-6,000 for soybean and peanut, and Rp 3,000 for rice.

Fishing: There are 25,000 fishermen in the study area, from 14,400 households. Aquacultureoccupies 8,000 households (4,500 in paddy fields, 2,300 in brackish ponds, 1,000 in freshwaterponds). There are 17,000 ha of brackish ponds, where milkfish, tiger prawns and seaweed are themain species, plus 1,000 ha of paddy culture and 800 ha of freshwater ponds. 6,500 householdsengage in capture fishing (3,000 in Lake Tempe, 1,800 in the sea, 1,400 in swamps), and gill netsare the most common method.Bungka toddoare large circles of bamboo tripods in Lake Tempe, onwhich are grown aquatic plants to attract fish. When water levels fall bungka are surrounded bybamboo fences, vegetation is removed, and the fish are harvested.Palawangare 1m tall bamboo

fences enclosing large semi-circles of water at the lake edge. The fences emerge as water levelfalls, trapping fish that have entered.

Lake Tempe is the main fishery, producing 15-22,000 tons annually, with introduced spottedgouramy, carp and tilapia being the main species. Brackish production was 17,000 tons in 2001 andthe marine fishery 16,000 tons, including large pelagic tuna, plus sardine, mackerel, grouper andred snapper. The river and swamp fishery produces 8,000 tons per year, and paddy and freshwaterculture 1,000 and 400 tons. 80% of the fish is consumed locally, sold by fishermen to theiremployer or a merchant, and then to the consumer. Current prices per kg are Rp 5,500 for


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snakehead and shrimp, Rp 4,500 for carp and Rp 4,000 for kissing gouramy, which are 30-70%above the prices paid to the fisherman.

4. Environmental Problems and ConstraintsThe main environmental problem in the basin is the unevenly distributed and inadequatelymanaged water resource, where excess water in the rainy season floods large areas and flows out to

sea, whilst in the dry season a lack of water limits production of many farms. This is addressed bythe water management measures of this project, so no further action on water resources isnecessary. The baseline data revealed 12 other problems, four related to the important but fragilelake environment:

! Continuing reduction in depth of the lake by settlement of soil eroded from hillslopes andriver banks and washed in by rivers;

! Severe organic pollution of rivers and the lake because riparian communities withinadequate sanitation defecate and throw rubbish into rivers;

! Lack of roosting and breeding sites for lake birds because natural vegetation, particularlytrees, has been removed;

! Lack of safe nursery areas where juvenile fish can live and grow, again because of a lack oflakeside vegetation

Four other problems relate to the ecology of the basin as a whole:

! Large populations of waterbirds are found only on the lake because there are no other largeareas of permanent water, swamp and mudflat;

! The freshwater fishery is limited because Lake Tempe and the Cenranae River are the onlyareas containing water throughout the year;

! Because of reduced rainfall and extraction of water for irrigation, there is very little waterin rivers in the dry season, and thus little or no permanent ecology;

! There is also limited terrestrial ecology and biodiversity because most of the natural habitathas been removed to provide land for agriculture.

The remaining four problems relate to the human environment:

! People living at proposed reservoir sites are likely to oppose such schemes, which shouldnot proceed unless communities can be relocated voluntarily;

! Piped water is only available in and around the towns, so most villages have to rely onwells or rivers for their domestic supply;

! Riparian communities risk their health by using rivers for defecation and as a source ofdomestic water, even when toilets and piped water are available;

! Widespread poverty in the basin is exacerbated by the lack of alternative employmentbecause there are few opportunities for outside investment.

Action was proposed to address each problem, shown in Table I. Although there are risks andconstraints to achieving solutions, with the necessary will and investment, mainly on the part of theIndonesian Government, all of the problems could be solved.

5. Action Plan for Environmental Management and ProtectionBecause the ecology of Lake Tempe is internationally important and the fishery supports largenumbers of people, then action to improve the environment and ecosystem of the lake should be ahigh priority. Table I shows that such action is to:


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! Implement the Upland Forestry Plan proposed by the forestry sector study, to reduce: soilerosion, suspended sediment in rivers and siltation of the lake;

! Provide riparian villages not subject to flooding, with piped water and toilets draining intoseptic tanks, to reduce the amount of sewage entering rivers;

! Educate riparian communities on the health risks of poor sanitation to ensure use offacilities provided, improving health and reducing pollution;

!Create five 100 ha reserves around the lake, planted with lowland swamp forest to providebreeding and roosting habitat for birds;

! Create a permanent Bungka Reserve in the centre of the lake from which fish are notharvested, providing a safe nursery where fry can grow into adults.

Voluntary resettlement of people living at proposed reservoir sites is similarly important, aswithout this such schemes should not be pursued. This action is to:

! Consult affected communities thoroughly, provide improved land and housing, offerfinancial incentives if necessary and agree a Voluntary Resettlement Plan

Medium priority action includes two measures to improve the environment of the lake that are lesscritical than those discussed above. These are to:

! Protect severely eroding riverbanks by bank realignment and other sustainable softengineering, to further reduce pollution and sedimentation of the lake;

! Determine the feasibility of providing a solid waste collection and disposal system forvillages, to prevent waste from being thrown into rivers.

Action to improve the ecology of the study area is also of medium priority, as it will improvebiodiversity and increase eco-tourism potential of the basin, but does not relate to the mostimportant feature. This action is to:

! Develop habitat in the new reservoirs, including shallow mudflats, reedbeds and lakesidetrees, to attract greater numbers of waterbirds and new species;

! Stock reservoirs with appropriate numbers and species of fish to develop a fishery,attracting birds and providing income for local people;

! Create two 1000 ha National Nature Reserves, one in the uplands and one in the lowlands,stocked with vegetation and animals previously found in the area

! Determine the feasibility of allowing sufficient water to flow down the main rivers tomaintain permanent water and ecology in the lower reaches.


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Table I Action Plan for Environmental Management and ProtectionTiProblem Solution Priority Action

N

Identify suitable land

Consult landowners and local community

Agree purchase and acquire land

Prepare planting and maintenance plan

Prepare ground, plant trees

Upland Forestry Plan proposed byforestry sector study

High

Maintain trees

Identify severely eroding areas

Consider feasibility of soft engineering options

Design erosion protection

Siltation reduces depth ofLake Tempe and may

cause lake to expand afterbarrage is built

Protect severely eroding banks viasetback and other soft engineeringapproaches

Medium

Construct

Identify riverside areas that will not flood

Select villages to be provided with infrastructure

Estimate cost

Government allocation of budget

Design infrastructure

Very high organic loadspollute Lake Tempe andreduce oxygen to very lowlevels, causing death ofsome animals in dry

season

Provide piped water and toiletsdraining into septic tanks inriverside villages not subject toflooding

High

Construct

Identify suitable land

Consult landowners and local community

Agree purchase and acquire land

Prepare planting and maintenance plan

Prepare ground and plant trees

Establish Nature Protection Service, appoint wardens

Lack of natural roostingand breeding sites for

birds inhabiting LakeTempe

Create five 100 ha reserves aroundthe lake and plant with trees typicalof lowland swamp forest

High

Maintain trees, patrol reserves

Consult kabupatens, community and fishermen

Agree creation and protection ofBungka Reserve

Enact legislation for creation and protection of reserve

Design and constructBungkaReserve

Few natural nursery areasin Lake Tempe where fishfry can live and grow

Create permanentBungkaReservein centre of lake, from which fishare not harvested

High

Patrols by Nature Protection Service wardens

Conduct research to determine features required

Design appropriate features

Construct reservoir with ecological features }

Stock water with appropriate flora and fauna }

Extensive bird populationsare found on Lake Tempeonly

Include areas of waterbird habitat inWalimpong and Gilirang reservoirs,including shallow mudflats,reedbeds and lakeside trees

Medium

Monitor water quality and ecology }


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The remaining medium priority action is to provide communities near reservoirs with a directbenefit by:

! Using reservoirs as a source of potable water for communities in the vicinity, byproviding a water treatment plant and piped infrastructure.

Action relating to eco-tourism is of low priority because any venture is constrained by a lackof international quality hotels and a need for investment by government or entrepreneurs fromoutside the region. As a first step it was proposed to:

! Determine the feasibility of developing viable, sustainable eco-tourism enterprises,focusing on participation by the local community.

6. Proposed River Basin Management PlanThe Master Plan developed by this project included seven principal measures:Walimpong Multipurpose Dam: Proposed by the 1980 JICA Master Plan Study to store 705 x106m3of water in an area of 5,000 ha, provide perennial irrigation for the 26,000 ha WalanaeIrrigation Project, mitigate flood damage and generate 148 x 10 6 kWh per year for rural

electrification. Located on the Walanae River 2 km upstream of the Mario confluence, thedam would be 900 m long and 71 m high, with a mudstone core and rock protection at a 1:30slope upstream and 1:20 downstream. There would be a 125 m wide spillway on one side andthree piped tunnels on the other, carrying water for hydropower, irrigation and river flow.

The dam will be built in the dry by diverting the river through a channel or tunnels, afterwhich mudstone, rock and aggregate will be quarried upstream and delivered in trucks, andstone will be crushed and cement mixed in a batching plant on site. 50.00 cm diameter holeswill be drilled 30 and 10 m deep, and 2,100 m3of chemical grouting and 22,500 ton of cementinserted to form a barrier. The mudstone core will be formed by bulldozers, and stone armourwill be tipped from trucks and positioned by crane or hand. Construction will take 3-4 years,after which water will flow over the spillway throughout the rains, but in the dry season onlyfrom the hydropower tunnel when electricity is generated, that is roughly 8 hours per day.

Gilirang Dam: Proposed by the JICA 1980 study to provide water for the 10,000 ha GilirangIrrigation Project, and subject to feasibility study in 1995 and detailed design in 2001. Thedam would be at Paselloreng, 55 km from the river mouth, and would be 310 m long, 44.5 mhigh, storing 138 x 106m3of water in 1,250 ha. The mudstone core will be protected by rockat a 1:3 slope upstream and 1:2 downstream, and there will be a 70 x 20 m spillway on oneside, two concrete-lined gated tunnels through the base of the dam discharging water into theriver, and a 240 m earth saddle dam nearby, 13.5 m high and 10 m wide at the crest.Headworks downstream will consist of a stone faced earth dyke across the river, and 35 mwide concrete canal with a weir, diverting water through a feeder canal into the irrigationsystem.

Construction will be similar to the Walimpong Dam, and the spillway and headwork canals

and weir will be built by pouring concrete into sections of metal reinforcing encased inwooden shuttering, which is removed when concrete has set.

Lake Tempe Barrage: This was proposed by the 1997 study of management of the lake waterresource, to provide a more constant water level, reduce flooding, and improve the lakeenvironment and fishery. The barrage would be 100 m long and 18 m wide, located on theCenranae 600 m upstream of Tampangeng Bridge. It would include six concrete pillars, 20 mtall and 2.5 m wide, five separated by 17.5 x 5 m (tall) steel gates, with a 5 m wide gatednavigation lock on one side to allow passage of vessels, and a 3m wide fish ladder on theother for fish migration.


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The river will be diverted through a channel, and 20,036 ln.m pre-cast, pre-stressed concretepiles (500 mm diameter, 19 and 21 m long) will be driven into the river bed by largehydraulic hammer. Concrete slabs and blocks will be cemented on top to form the base of thebarrage and an apron extending 15 m upstream and 90 m downstream. Pillars will be formedfrom reinforcing encased in wooden shuttering, concrete will be poured into each, and block-built control towers constructed on top. Steel gates will be welded on site and fixed in placeby crane, after which the hydraulic lifting system will be fitted. Gates will be lowered in thedry season to maintain water level at 5 m asl, and raised in the rains allowing water to exit at749 m3/sec.

Cenranae River Improvements: These were also proposed by the 1997 study, to increase thecarrying capacity of the river and reduce flooding. 64 km of the river will be dredged andbanks moved landward where necessary, to produce a 40 m channel, 8 m deep, with a 3:1 sideslope. However, the recent study finding proved that during 1997-1998 rainy season, most ofthe sediments of the Cenranae river have been carried away by natural water flow and thenecessary volume to be dredged drastically reduced from 3.3 million m3 to 0.3 m3. NearSengkang the banks are densely populated, so the channel will be 25 m wide and 6 m deep.

Saboand check dams: 35 check dams and 2saboare proposed in the Walanae catchment, 6check dams in the Lacinrang and 3 check dams in the Boya catchment, to retain sedimentbefore trees planted in the uplands are mature enough to bind soil effectively. Check dams areearth banks, 15 - 40 m wide and 2 - 5 m high, protected with stone or grass, with a concretespillway on one side. Sabo are concrete dams 40 - 100 m wide and 10 - 20 m high, with acentral spillway. Both structures are built when rivers are dry, by a work force of a few menwith a single bulldozer or digger, using local soil and stone and imported cement.Construction normally takes 2-4 weeks.

Major irrigation schemes: The Walanae IP will supply 43.68 m3/s (in total) of water from theWalimpong Dam to 10,000 ha of existing paddy in the lower reaches of the Walanae and16,000 ha south of the Cenranae. The Cenranae IP will pump water from Lake Tempe into19,000 ha (alt. 3) of existing rain fed paddy north of the Cenranae at a rate of 31.92 m 3/s,

through 57.0 km of primary, 148.0 km of secondary and 65.0 km of tertiary canals. TheGilirang IP will supply 12.11 m3/s of water from the Gilirang Dam to 7,000 ha of rain fedpaddy around the middle and lower reaches of the Gilirang River through 86.8 km of primary,43.3 km of secondary canals.

Primary canals are 20-40 m wide and 5-10 m deep, excavated by backhoe diggers andbulldozers, with soil taken off site in dump trucks. Cement and aggregate are brought in andconcrete is mixed in a batching plant and poured onto the canal floor in a 20-30 cm layer.Side slopes are encased in wooden shuttering into which concrete is poured, and after dryingthe surface is finished by hand. Secondary canals are 3-5 m wide and 1-2 m deep, constructedin the same way, and tertiary canals are dug by hand or mechanical digger, and the soil ispiled at the side.

Minor irrigation schemes: The Master Plan proposes 73 minor irrigation schemes, allextending the area fed by existing schemes, via new secondary and tertiary canals:

! Ponre-Ponre IP: 4,240 ha, 54,876 km of secondary canal, 12,888 km of tertiarycanal;

! Lejja IP: 5,098 ha, 12.566 of secondary canal, 33,218 of tertiary canal;! Boya IP: 8,000 ha, 33.646 km of secondary canal, 61.590 km of tertiary canal;


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! Lawo IP: 4,097 ha, 10.872 km of secondary canal, 8.772 km of tertiary canal;! Paddangeng IP: 4,698 ha, 22.744 km of secondary canal, 12.181 km of tertiary canal;! Torere IP: 3,939 ha, 4.404 km of secondary canal, 17.343 km of tertiary canal;! Latenreng IP: 1,815 ha (part of the Lejja Irrigation Project);

7. Environmental Impacts of Water Management MeasuresWalimpong Dam: When the dam is built, there could be negative impacts on water quality ifthe channel through which the river is diverted erodes, increasing suspended sediment, and iftoxic materials on site (fuel, oil, cement) are spilled and wash into the river. People livingnear the site may be affected by noise and dust, loss of access if roads and footpaths areclosed or diverted, and if their activities are impeded by increased traffic. Farmers will loseland and income if their land has to be purchased for the construction site or haul roads. Theseimpacts can be adequately mitigated by:

! Designing the diversion canal so that erosion does not occur;! Requiring the construction contractor to use and store toxic materials safely;! Purchasing all land at or above the market price;! Employing local people in the workforce to compensate for disturbance;! Obtaining as many goods and services as possible locally.

Once completed the dam would improve topography and landscape by providing a newfeature, improve the quality of river water by retaining sediment, and enhance ecology byproviding new habitat for waterbirds. Farmers would receive most benefit, as 26,000 ha ofpaddy will be irrigated throughout the year, increasing yields and income. There wouldhowever be negative impacts as the reservoir would inundate and destroy 5,000 ha ofagricultural land and 5 villages occupied by 9,032 people. Thus, if this scheme will be

pursued, it will require sufficient time process as well as funds to arrange the reallocation ofthe residents through mutual agreements.

Gilirang Dam: Impacts will be similar to those of the Walimpong Dam, but less significant asGilirang is much smaller. Construction impacts can be mitigated as above, and because thereservoir will affect less land (1,250 ha) and fewer people (3,000), this scheme could proceedif all were willing to relocate. This would require:

! Extensive consultation, and development of a Voluntary Resettlement Plan;! Purchase of current land and property at or above the market price;! Provision of new land and housing that is better than that occupied at present;! Offering additional financial compensation if necessary.

The following enhancements are recommended to increase the benefits of the scheme:

! Using the reservoir as a source of piped water for nearby villages;! Providing a treatment plant to convert the water into a potable supply;! Creating habitat in the reservoir to attract birds (mudflats, reeds, trees, etc);! Allowing sufficient river flow to maintain water and ecology in lower reaches;! Planned introduction of fish to develop a reservoir fishery;! Developing Eco-tourism, focusing the benefits on the local community.


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Tempe Barrage: Construction impacts will be the same as those for the Walimpong Dam, andshould be mitigated in the same way. Significance could be greater as the barrage is close tothe large town of Sengkang, so additional action is required to:

! Plan construction with the community to avoid disturbance at sensitive times.There would be highly negative impacts if construction disturbed the internationallyimportant birds on the lake, so this should be mitigated by:

! Studying the birds to identify important areas, and times when they are used;! Avoiding working near critical areas at key times;! Monitoring birds and ceasing work temporarily if disturbance occurs.

There will be no adverse impacts once the barrage is built, and significant benefits as the lakewill vary less in area, flooding will be reduced, less water will be lost, and pollutants will bediluted in a greater volume, improving water quality. This should increase fish productivity,improve catches and incomes, and attract more birds. The only additional enhancementrecommended is to improve local incomes by:

! Developing an Eco-tourism Master Plan focusing benefits on the community.Cenranae River Improvements: Although the degree if negative impact from dredgingdrastically reduced in parallel to the reduction of the necessary dredge volume, there couldstill be negative impacts in case if the channel drains more water from the lake in the dryseason, if dredging prevents fish migration, and if catches reduce and fishing incomesdecrease. There could also be major impacts from the need to relocate about 5,000 peoplefrom the riverbanks to widen the channel. These can be mitigated by:

! Using modelling to design the dredging to avoid destabilising the channel;! Building Tempe Barrage before the dredging, to retain water in the dry season;! Studying fish migration and planning dredging to avoid working at key times;! Widening on the less inhabited north bank where possible, to avoid relocation;! Consulting the community and developing a Voluntary Resettlement Plan;! Offering new accommodation as near to present houses as possible;! Providing improved housing and land, using fertile dredged spoil if possible;! Providing financial compensation for loss of earnings by fishermen.

Fishermen may lose income until invertebrates on which fish feed recover from the dredging,so this should be mitigated by:

! Compensating fishermen for loss of earnings for 2 years after dredging.Local Government should organise distribution of gravel and silt from spoil heaps to local

people for use in building and farming, to provide an additional benefit.

Saboand Check Dams: These are small, simple structures, so there will be few impacts. Localpeople will not be seriously disturbed when the dams are built, but mitigation applied to otherschemes should still be adopted to maintain good relations.

On completion the dams will improve the lake by retaining sediment, and this will benefitfishermen if the fishery improves and catches increase. Dams will also benefit ecology if theyretain permanent water, which is colonised by aquatic organisms. There could be negative


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impacts if fish migrate into rivers to grow or breed, as this will be impeded by the dams. It isnot known if this occurs, so mitigation will require:

! A study of fish to determine whether any species migrate upstream of the lake;! Inclusion of fish passes in designs of all structures that may impede migration.

Benefits of these schemes would be enhanced by the following additional measures:

! Including saboand check dams in studies to determine whether enough water can beprovided to downstream river reaches to maintain water and ecology;

! Including control structures in the dam designs, to provide the required flow.Major Irrigation Schemes: Construction of large concrete-lined primary or secondary canalscould affect water quality if materials are spilled; people living nearby may be disturbed bynoise, dust, traffic and loss of access; and farmers may lose land and income where land ispurchased for construction. These should be mitigated as for the Gilirang scheme above.Additional impacts of site clearance, removal of soil, subsoil and rock, and compaction of soilby vehicles, should be mitigated by:

! Reinstating all sites and roads after use;! Using spare soil, rock and aggregate in other projects.

Completed schemes will significantly improve soil moisture, structure and yield in anadditional 52,000 ha of paddy, raising the income of hundreds of farmers. Increasedextraction of river water could affect the important but declining water quality and ecology ofthe lake, and this can be mitigated simply by:

! Building Tempe Barrage before any more irrigation schemes are developed.There is also an opportunity to provide significant ecological enhancements by:

! Maximising efficiency of water use and allowing sufficient river flow beyondirrigation schemes to maintain water and ecology in lower reaches of rivers;

! Designing irrigation schemes to provide the necessary year-round river flow.Minor Irrigation Schemes: These involve mostly small, earth-lined secondary and tertiarycanals only, so construction should produce no significant negative impacts. To avoid wastingmaterial and maintain community relations it is recommended that:

! Land required for construction is purchased at or above market prices;! Excess soil is used in other projects or on farms nearby.

Completed schemes will produce significant benefits by providing year-round irrigation to anadditional 91,211 ha of paddy, increasing the yield and raising the income of over hundred

thousands of farmers. Water quality and ecology of the lake could again be affected byincreased extraction of river water, so this should be mitigated by:

! Building Tempe Barrage before any more irrigation schemes are developed.There is again an opportunity to significantly enhance the ecology of the rivers by not usingall of the available water for irrigation and allowing sufficient water to flow downstream tomaintain aquatic ecology in the lower reaches, as indicated above.


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8. Environmental/Conservation GuidelinesGuidelines were prepared that can indicate whether future development may proceed withoutcausing unacceptable environmental impacts, or whether it would lead to significant damageand should thus not be pursued. The criteria are easy to use and require no data collection, andshould be applied to projects, plans or policies at an early stage, to avoid spending time oninappropriate development. The criteria include the 12 most important and sensitive aspectsof the basin environment:

! Siltation of Lake Tempe by soil eroded from riverbanks and deforested hills;! Water Resources are unbalanced, but vital to the population and environment;! Water Quality of the lake is important in maintaining the fishery and ecology;! Volume of the lake in the dry season threatens its fishery and ecology;! Ecology has been very damaged, but lake birds are internationally important;! Natural Forest has been mostly removed and only a few planted areas remain;! Nature Protection is deficient as there are no designated reserves;! Socio-Economics: most of the population are poor, particularly the farmers;! Farming is the main occupation, but lack of water prevents maximum yields;! Fishing on Lake Tempe and the Cenranae is the second main occupation;! Piped Water, Sanitation and Waste Disposal are lacking in most villages;! Eco-Tourism could improve the local economy, but requires investment.

The way in which a proposed development would affect each feature (during construction andafter it has been built) is considered by asking five questions:

a. Would the project cause a deterioration of the feature?b. Can that deterioration be mitigated (reduced to an acceptable level)?c. If so, how would this be done?d. Would the feature be unaltered?e. Would the feature be improved?

Development that would cause a deterioration in any feature that could not be mitigated,should not be pursued. Developments where adverse impacts can be mitigated may bepursued, as long as the mitigation has a high probability of success. Priority should be givento projects that would improve the environment.

9. Conclusions and RecommendationsIf the recommended mitigation is provided, all of the proposed water management measurescan be implemented without significant adverse impacts, except Walimpong Dam, whichshould not be progressed unless the due process to reach mutual agreement between residentsand government on their reallocation is taken. Tempe Barrage should be built first to counter

the effect on the lake of increasing abstraction for new irrigation schemes, and to preventexcess water being removed by the improved Cenranae channel. All schemes (except thesaboand check dams) will benefit local people by improving agriculture and raising incomes.Tempe Barrage will benefit the natural environment by improving water quality, ecology andfisheries.

The water management measures will improve usage and management of water resources,and the actions listed in Table I should be implemented to address the remainingenvironmental problems. In order of priority these are:


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! Provide piped water and sanitation to riparian communities;! Educate communities on the health risks of poor sanitation;! Implement the Upland Forestry Plan recommended by the forestry study;! Develop a Voluntary Resettlement Plan for residents of Gilirang reservoir site;! Create five 100 ha lowland swamp forest reserves around Lake Tempe;! Create a permanentBungkaReserve as a fish nursery in the centre of the lake;! Determine feasibility of providing a solid waste disposal service to villages;! Create two 1000 ha National Nature reserves, in the uplands and lowlands;! Allow sufficient river flow to maintain water and ecology in lower reaches;! Develop habitat for waterbirds in new reservoirs (mudflats, reedbeds, trees);! Stock new reservoirs with fish and develop a fishery;! Use reservoirs as a source of treated potable water for local communities;! Determine feasibility of developing eco-tourism with the local community.

This will restore a more healthy and sustainable environment in the basin, in which theconflicting needs of man and the ecosystem can co-exist to the benefit of both.

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