Heringa (1) Heringa (1) • Recent studies in Switzerland on forest and water show us the way how to protect our economic interests: • Forests act as a sponge: they absorb the water during the rainy season and gradually release it during the dry season • Dry season flows really depend on the amount of forest we conserve • Every catchment needs to have at least 30% of forest, otherwise it cannot provide enough water for the irrigation of rice fields
Roessel (1) Roessel (1) • Well, well, my dear colleague, Java is not Switzerland. • Infiltration all depends on the geology: in the lime-stone areas water of Java will infiltrate deeply and emerge in springs after some months – this feeds the dry season flows, not the forest • Because of that, there is no such thing as a minimum forest cover
Heringa (2) Heringa (2) • Java is becoming deforested, the results is droughts and floods – the government should start a program of reforestation: it should acquire land from abandoned estates or farmers and plant trees! • Planting trees will also provide direct economic benefits to the government
Roessel (2) Roessel (2) • You are jumping to conclusions here – planting trees will not change the geology of the landscape, and will not help on dry season flows. • To reduce erosion, other measures, such as terracing, infiltration pits and soil cover have proved insufficient • Reforestation should only be carried out if certain soil types expose extreme susceptibility to erosion
Coster (1) Coster (1) • Both of you are right, to a degree – but we need to look at data from experiments. At the Forest Research Institute here at the Gunung Batu complex we have started a program of measurements. • The vegetation determines the permeability of the soil. • Discharge of springs depends on the amount of water that percolates into the soil minus the loss of water because of evaporation.
Heringa (3) Heringa (3) • Afforestation with fast growing timber trees has the same hydrological effect as natural forest and is always better than agricultural estates – we need to plant trees to have water for the rice paddies
Coster (2) Coster (2) • The effect of forests on water depends on the elevation . Lysimeter measurements indicated that the evaporation of a free soil surface 1200, 900 and 600 mm per year at locations with an elevation of 250, 1500 and 1750 m a.s.l., respectively
Roessel (3) Roessel (3) • In fact, forests without undergrowth and without good humus formation are not helping. A soil cover with grass, dense herbaceous or shrubby vegetation, however, will be much more effective – it’s not the trees, but the soil cover that matter
Coster (3) Coster (3) • Measurements by the Forest Research Institute showed that well maintained tea, coffee, rubber and kina plantations are from a hydrological point of view nearly the same as forests (planted or natural) – all are better than agricultural fields. • Fires in the grass wilderness in the mountains stimulate water run off and erosion.
Heringa (4) Heringa (4) • In summary, your arguments don’t convince me at all: the problems with ‘watershed functions’ are really urgent and they can be cured with reforestation, so let’s get started!
Coster (3) Coster (3) • Afforestation in the low lands will decrease the discharge (including that in the dry season), because of the high evaporation rate from the trees • In the mountains, however, the loss by transpiration is less and the rainfall is higher, so the net effect of trees is positive: the increased infiltration into the soil more than offsets the increased water use by trees • We need better data !
i n S o u t h E a s t A s i a or – what can we do to help people and institutions adapt to the rapid changes in lives and landscapes
Bridging between local, policy and Bridging between local, policy and modellers’ ’ perceptions of trees, forests perceptions of trees, forests modellers and watershed functions and watershed functions Meine van Noordwijk, Laxman Joshi, Ai Farida & Kevin Jeans ICRAF-SEA, Bogor, Indonesia
National Local govt govt Public/Policy Ecological Laws city Knowledge Based on ‘categories’ men Based on ‘processes’ women upland engineers Local Modellers’ Ecological Ecological USLE women Knowledge Knowledge Guest lowland includes direct Ecohydro- balance sheets ‘observables’ men logist
cloud rainfall What matters most in AF: canopy water interception evaporation transpiration surface the trees evaporation use water through-fall surface Strategic landscape stem-flow run-on Stream: { position of ‘filters’ infiltration surface quick- run-off recharge sub- flow surface can greatly reduce Their litter lateral lateral uptake outflow inflow protects soil downstream effects base percolation flow & infiltration
Traditional image of Southeast Asia Forest Forest Conservation Protective Production Plantations Tree crops Upland crops Paddy rice People Agricultural lands
Farming systems 1 = Lowland rice 2= Tree crops 3= Root & tuber 4= Upland intensive mixed 5= Highland mixed 7= Pastoral 8= Forest :Source: ‘Farming Systems and Poverty: improving farmers’ livelihoods in a changing world’ by John Dixon, Aidan Gulliver and David Gibbon, 2001; FAO and World Bank
Forest below Forest below Forest tree crops UCM Root tuber below forest Tree crops below forest Root tuber Tree crops Rice&Cities 5% below forest Tree crops below UCM Rice&Cities UCM below forest UCM below tree crops Upland crop mosaic (UCM) 50% Rice&Cities 25% below UCM Fraction of Indonesia's population
‘Forest’ Cover B C W conservation Forest protection Conservation production Protective Forest Production Agrofor- Plantations Tree estry/ eco- Tree crops plan- agriculture Upland crops tations Paddy rice Tree crops Agricultural Intensive lands agriculture
Problem analysis Problem analysis Strong links between watershed functions & biodiversity: every catchment needs 30% forest cover Cause Poverty INRM Solve Clean water needed for biodiversity
Four stages in developing ES reward mechanisms Stage Providers, Interme- Beneficies, sellers of ES buyers of ES diaries I Scoping Rapid As- sessment of Marketable ES Identifying II partners Negotia- III tions Monitoring IV agreement RUPES = Rewarding Upland Poor for the Environmental Services they provide
10 steps in bridging perspectives & action 10 steps in bridging perspectives & action 6. Tradeoffs between relative 1. Characterization & diagnosis agronomic function (RAF) of problems and issues and relative environmental function (REF) 2. Landscape appraisal 7. The landscape mosaic in the context existing 3. Understanding the flows of regulation and incentives at water community scale 8. Patterns and land use practi- ces from a multi-stakeholder 4. ASB-matrix characterization of (incl. gender and equity) land use options from private/ perspective social economic perspective and local/global ES impacts 9. Clearing misunderstandings between local, policy and scientific knowledge 5. Characterization of landscape 10. Negotiated agreements , mosaic on segregate – inte- monitoring compliance grate spectrum
Rainfall (mm/yr) 1,074 1. 1.Characterization (rainfall, population People/km2 54.6 (5,251/96.1) density, migration status, main agri- Field crop (Corn, Income/occupation Soybean) cultural enterprises) Vegetable (Cabbage, Mae Suk Shallot, Green Soybean, Watershed and Drinking water Rain and stream Problem -Drought diagnosis of main issues and -Accessibility (infrastructure, problems related to market, etc.) watershed functions -Landslides/Erosion and livelihoods (incl. sources of drinking -Conflict (landuse, water,..etc.) water
Kali Tundo (S Malang district, E Java) – recent landslides & banjir, Brawijaya investigates Bekas Daerah Terkena Banjir dengan Kedalaman Profil Sungai Dangkal
Land use change in ‘coffee zone’ Sumber Jaya, Lampung, Indonesia Is there a problem with ‘watershed functions’?
A tale of two rivers
90 180 Daily rainfall (station level), mm 80 Daily rainfall (station level), mm 160 70 140 60 River flow Rainfall 120 50 100 40 80 30 60 20 40 20 10 0 0 0 100 200 300 0 100 200 300 120 600 Day of year Day of year 100 500 River debit, m 3 s -1 River debit, m 3 s -1 80 400 60 300 40 200 20 100 0 0 0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 350 Day of year Day of year Way Besai (Indonesia), Mae Chaem (Thailand), 2.5 m rainfall, 100 persons km -2 1.5 m rainfall, 10 persons km -2
The hydro-electric dam wants as many days as possible with a debit of >= 25 m3/s 1975 1976 1977 1978 1979 1980 400 1981 1982 1983 1984 1985 1986 350 1987 1988 1990 1991 1992 1993 1994 1995 1996 300 #days target is met 1997 1998 Average 250 200 150 100 and they are better off 50 now than when the dam 0 5 10 15 20 25 30 35 40 45 was designed, due to the Target debit, m3/s land cover change.....
Recommend
More recommend
