Deforestation' is often perceived to be the cause of loss of watershed functions. The strong association of'forest' and'water' in public perception has very frequently led to conflicts when forest areas were converted to other productive systems. The Way Besai watershed (Sumberjaya) is an example of this, where conversion of forest to coffee gardens on slopes was considered to have led to a reduction of discharge of the Way Besai river, a reducing functionality of the Hydropower plant. This reduced discharge is, in public discourse, attributed to past deforestation and catchment degradation. While the earlier policies of evictions by the Department of Forestry were based on this perception, environmental activists still claim that under-performance of the hydropower schemes of Batutegi (2 X 14 MW) and Way Besai (2 X 45 MW) are due to deforestation of catchment areas, causing shortfalls in the electric power crisis in Lampung province (Oyos Saroso, 2004). By analysis of the long term data records of flow of the Way Besai and rainfall in the area, we explored the possible role of land use change in the catchment versus the alternative explanation of variability (and/or trends) in rainfall as cause of changes in flow. The IHACRES model is a parsimonious ('few-parameter') model that has been fitted to data sets derived in various climatic conditions (Croke et al., 2004). Model fits were obtained on the basis of the daily rainfall and discharge data for the1975 - 2007 period. Model parameter sets were derived for each consecutive 3-year period to expose the model to some inter-seasonal variability. All these models were then used on the rainfall data for the whole period 1975-2007. Model parameters for 1975-8 reflect a time that the catchment had 63% forest cover, the model parameters for the last few years a condition with only 13% forest. The results of IHACRES model showed that the impact of annual variation in rainfall on discharge is a factor 4 larger than the possible effects of land use change. The changes in overall catchment hydrology are non-linear with time and may reflect a recovery of vegetation other than'forest'. In the public debate, variation and changes in rainfall pattern are insufficiently recognised as major driver of changes in discharge patterns.
CIFOR-ICRAF aborda desafios e oportunidades locais ao mesmo tempo em que oferece soluções para problemas globais para florestas, paisagens, pessoas e o planeta.
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O CIFOR-ICRAF publica mais de 750 publicações todos os anos sobre agrossilvicultura, florestas e mudanças climáticas, restauração de paisagens, direitos, política florestal e muito mais – em vários idiomas..
CIFOR-ICRAF alcança impacto baseado na ciência. Conduzimos pesquisas inovadoras, fortalecemos a capacidade dos parceiros e nos engajamos ativamente no diálogo com todas as partes interessadas, trazendo os insights mais recentes sobre florestas, árvores, paisagens e pessoas para a tomada de decisões globais.
CIFOR-ICRAF aborda desafios e oportunidades locais ao mesmo tempo em que oferece soluções para problemas globais para florestas, paisagens, pessoas e o planeta.
Fornecemos evidências e soluções acionáveis para transformer a forma como a terra é usada e como os alimentos são produzidos: conservando e restaurando ecossistemas, respondendo ao clima global, desnutrição, biodiversidade e crises de desertificação. Em suma, melhorar a vida das pessoas.
CIFOR–ICRAF achieves science-driven impact. We conduct innovative research, strengthen partners’ capacity and actively engage in dialogue with all stakeholders, bringing the latest insights on forests, trees, landscapes and people to global decision making.
CIFOR–ICRAF publishes over 750 publications every year on agroforestry, forests and climate change, landscape restoration, rights, forest policy and much more – in multiple languages.
CIFOR–ICRAF addresses local challenges and opportunities while providing solutions to global problems for forests, landscapes, people and the planet.
We deliver actionable evidence and solutions to transform how land is used and how food is produced: conserving and restoring ecosystems, responding to the global climate, malnutrition, biodiversity and desertification crises. In short, improving people’s lives.
