Watershed Management

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Watershed Management

We are refining management principles for different spatial scales and contexts, developing models to predict the effects of different landscape configurations, identify best-bet management practices and assessing mechanisms for harmonizing individual rationality with social responsibility.

Lead scientists: Chin Ong and Horst Weyerhaeuser

Public knowledge about the importance of trees for watershed function is part fact, part received wisdom and part perception. A substantial body of evidence has now been accumulated that shows that tree cover has most noticeable effects in small catchments and that the effects of trees depend upon the species of trees, their configuration in the landscape, their location relative to lateral flows of water and soil, and their impacts on the functional properties of soil. As watershed functions are largely ‘emergent properties’ at landscape scale (on 10% of the land one can do or control 90% of the damage to streams and rivers), there is no simple link between plot level farm activities and these functions. Watershed functions are also multi-stranded, with water quality, flood risk, dry season flow, total flow and landslide risk having greater or lesser importance across watersheds. Forms of collective action are needed and ‘social capital’ has to provide a context for negotiations between stakeholders. Research will continue to be undertaken across a range of climatic, ecological and social conditions, always integrated into multi-stakeholder processes of assessment and action.

Watershed Results Chain for 2005-2015

Goal: Enhance the positive contributions of smallholder agroforestry systems to watershed functions
Indicator: The adoption and protection of agroforestry systems contributes to improvements in water quality, greater infiltration and reduced sedimentation in crucial watersheds.

Outputs

Indicators of outputs

Outcomes

Indicators of outcomes

Impacts

Indicators of Impacts

Generalizable principles about links between trees, soil and water in multiple scales.

Watershed models and tools developed to support management and negotiation of watersheds for a range of conditions.

Options for agroforestry development, policy and programme design in priority watersheds.

Coordinate and catalyze information exchange and capacity building on watershed management.

Reviewed articles and briefs on watershed management principles.

Manuals and lecture notes on watershed assessment techniques.

Negotiated plans of action in pilot watersheds.

Participants in training courses and individual training.

Leadership and communication roles in networks.

Reforestation & conservation programmes implemented in a way that recognizes how trees and forests affect water quality, erosion, sedimentation, and stream flow.

Watershed and environment management authorities adopt multi-scale and multi-stakeholder approaches.

Less conflict in priority watersheds.

Smallholder agroforestry contributes to watershed management goals in priority watersheds.

Design of reforestation and conservation programmes.

Design and implementation of approaches to watershed and environment management.

Monitoring and evaluation in priority watersheds.

Assessments of tree cover and adoption of agroforestry in priority watersheds.

Reduced sediment load and better water quality.Greater farmer benefits from agroforestry.

Sediment and water quality monitoring.

Monitoring and impact assessment studies.

Sources of knowledge about agroforestry and environmental services

There is active current debate about the roles of trees, forests and agroforests in preventing or enhancing risks of floods, landslides and seasonal water shortages. The debate, and the science that informs that debate, remains quite polarized. On one hand, many advocates of forest protection and afforestation draw upon received wisdom about the importance of forests for various watershed functions, from flood mitigation to water purification. Policy pronouncements and tree planting programmes across the world have been based on uncritical appeals to this received wisdom. For example, in May 2002 China announced the world’s largest reforestation project, which aimed to plant trees on 76 million hectares of land across the country. The “grain for environment” programme encourages farmers to plant trees on all cropland with greater than 16% slope in the Yellow and Yangtze river basins. Surprisingly, however, reliable scientific evidence to support the received wisdom is actually quite sparse. Many of the scientists who have attempted to test hypotheses about the effects of trees on specific watershed function have ended up being quite pessimistic about the effects of trees on hydrologic function.

A few international programmes seek to redress this knowledge gap. Perhaps the two most important are the HELP (Hydrology for Environment, Life and Policy) programme of UNESCO and the World Meterological Organization and the CGIAR Challenge Programme on Water and Food. Universities and research institutes with particular expertise and interests include CSIRO in Australia, the Stockholm International Water Institute, various departments of the FAO, IHE / Delft, the University of Newcastle, the University of Maryland (USA), Uppsala University (Sweden) and various universities in our partner countries.

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