Integrated watershed management for sustainable soil and water resources management of the Inabanga watershed, Bohol Island, Philippines
Extension Start Date
Extension Finish Date
ACIAR Research Program Manager
This project is providing information needed to plan strategies for reversing damage to the land and water resources, and restoring agricultural productivity, to assist in developing strategies for reviving agricultural productivity in the Inabanga watershed in Bohol Island, Philippines, whilst protecting soil and water resources.
Project Background and Objectives
Bohol, the tenth largest island in the Philippines, is one of the country's most economically backward regions, with more than 80 per cent of the population dependent on agriculture. Poor land-use practices have caused soil erosion and runoff, leading to a decline in agricultural productivity. Bohol's fisheries and coastal mangroves have also been affected by these land degradation problems, as the quality and quantity of water in the rivers decline.
One of the most important sources of water for agriculture and domestic use in Bohol is the Inabanga watershed. The Inabanga watershed is the largest watershed in Bohol Island. There are plans to use the Inabanga River to provide the domestic water supply to Cebu, the Philippines' second largest city. The river is also necessary for planned agricultural and economic developments in Cebu. It is thus important to protect the Inabanga River; however, there is currently no quantitative information on soil erosion and runoff, and how these factors affect the quality and quantity of water in the river.
Progress Reports (Year 1, 2, 3 etc)
The project has been well established, and considerable progress has been made to gather baseline data and commence the experimental program. Progress against the specific objectives is summarised below.
Objective 1: describe the current land and water resources of the Inabanga watershed using Geographic Information Systems (GIS) and ongoing natural resources management programs in the watershed
Current land use and water systems have been delineated using a range of resources, including, existing data held by Bureau of Soils and Water Management, DENR and regional agencies. Landsat 7 imagery, ground truthing and existing maps in both hard copy and digitised formats have been sourced and/or undertaken.
Objective 2: evaluate the extent of soil erosion from agricultural crop lands, sedimentation and water quality of surface waters in the Inabanga watershed
Experimental plots have been established within the watershed and sampling of water and sediments has commenced. The sites have been selected to allow evaluation of intensively cultivated crops (both irrigated and rainfed), agro-forestry, forestry, grassland and oil palm land usage. Considerable stakeholder input was incorporated into the selection of experimental sites and types of agricultural activity to be evaluated. Evaluation of sedimentation processes and water quality have commenced at a series of water quality monitoring sites transecting the watershed and the major storage dam, the Malinao Dam.
Objective 3: understand the socioeconomic and policy issues, and constraints that impact on the agricultural sustainability and surface water quality of the Inabanga watershed
The research team has collected existing socio-economic information and is commencing integration of the data for incorporation as a GIS information layer. A survey form in Cebuano dialect and local protocols have been developed and piloted in stake-holder meetings and interviews within the watershed. Survey and data collection will continue.
Objective 4: evaluate different options and impacts for water resource uses in the Inabanga watershed
Options and impacts of water resource uses have been incorporated and reviewed in several workshops held with watershed stakeholders (November 2002 and May and July 2003) focussing on sustainable agricultural activity and water quality/quantity protection. Collection of data on water capture and distribution from the major storage facilities on the Inabanga River has commenced. Options evaluation will continue as an ongoing component of the project.
Objective 5: enhance/strengthen the research capacity/capability of staff in the Bureau of Soil and Water Management, Department of Environment and Natural Resources and local project collaborators
The project has enabled and enhanced a research and extension service capacity for the Bureau. Two recent Philippine graduates have been located within the regional Agricultural Promotion Centre (APC) on Bohol. They are key to the on-site project activity but also represent a back-to-the-community placement, as both of the graduates are of Boholano origin. This placement is perceived by the community as a positive recognition of the importance of their watershed, as two of their own overseas trained people have been specially designated to work with the community.
As local JICA activities are being completed in a number of APC collaborations, APC staff are developing Inabanga watershed projects to link with our ACIAR Project, recognising the potential for extended use of data that the Project is gathering - for use in APC activities (eg. fertiliser comparisons, crop productivity variation within the watershed, etc).
The Provincial Planning and Development Office, Bohol, has already incorporated project-generated GIS image materials into their own planning documentation and planning capacity.
Objective 6: transfer research outputs to stakeholders of soil and water management
Stakeholders have taken an active part in the selection of experimental sites and types of agricultural activity being evaluated. A sense of regional ownership of the project is being engendered through such active participation. Regional and municipal agriculture officers, provincial planners and DENR have all been included in the project establishment and will continue to take an active part in the ongoing research activities and dissemination of research outcomes.
The Project is well established in data acquisition for both physical aspects of the watershed and socioeconomic status. Stakeholder participation has been high and integrated synthesis of data interpretation is ongoing. The Project underwent a mid-term review, held on Bohol, over 17 - 24 April, 2004. Project team members presented Project activities and progress towards objectives during the meeting. Progress towards the specific project objectives:
1. To describe the current land and water resources of the Inabanga watershed using Geographic Information Systems (GIS) and ongoing natural resources management programs in the watershed.
Information on soil type, land use, climate, hydrological characteristics and vegetation has been collected and compiled at scale of 1:50,000. Harmonisation of BSWM and DENR watershed boundary delineation was achieved through a series of stakeholder workshops and discussions.
Preliminary soil erosion maps have been produced from field survey team data and subwatersheds for the Inabanga have been delineated. Soil profile analysis is ongoing, with profiles being incorporated into geo-referenced GIS format. The Bohol Provincial Planning and Development Office has assisted in developing DEM inputs for use in modelling activities.
2. To evaluate the extent of soil erosion from agricultural crop lands, sedimentation and water quality of surface waters in the Inabanga watershed
Seven runoff plots have been established in agriculture and forestry systems, and are being monitored . Initial data has demonstrated high erosion and runoff export from corn and cassava plots. WEPP modelling has commenced, using the Geo-WEPP model format, with parameterisation being evaluated.
Erosion export and sediment deposition into the Malinao Dam is being evaluated using a manual sounding technique, with follow-on Doppler sonar techniques to be investigated.
Water quality/quantity monitoring is ongoing at water quality sites and erosion plots. Preliminary rating curves have been developed in order to estimate nutrient and sediment loads.
3. To understand the socio-economic and policy issues, and constraints that impact on the agricultural sustainability and surface water quality of the Inabanga watershed
The team has built on existing data (PPDO, DENR), to evaluate changes and current status of farmers within the watershed. Data are being updated with new survey information from 126 households and participating farmer cooperators
Local community groups have been consulted in a series of workshops, with consolidation and further updating of inputs to be sought in a Stakeholders Workshop to be held in the July-August period.
4. To evaluate different options and impacts for water resource uses in the Inabanga watershed
Both historical and new data has been incorporated into developing options for water resource uses. Input from stakeholders on Bohol and other regions has led to a focus on resource evaluation focus within the upper Inabanga watershed. The impact of developing and future water impoundment, potentially enabling greater irrigated cropping, is being addressed.
5. To enhance/strengthen the research capacity/capability of staff in the Bureau of Soil and Water Management, Department of Environment and Natural Resources and local project collaborators.
The Project has had excellent participation and uptake of study techniques by staff of the BSWM and DENR. Training and capacity building has been strengthened by input from an AYAD volunteer, Mr. Carl Mitchell, who joined the Team in April, 2004.
Additionally, a John Allwright Fellowship was obtained for a BSWM team member, Ms. Imelida Genson, for study at the University of Western Sydney. The scholarship supported study will enhance the project outcomes.
6. To transfer research outputs to stakeholders of soil and water management.
An ongoing series of workshop activities is being used to gain community ownership of the watershed management strategies which are being developed. Good progress has been made with interacting with stakeholders. Further input from stakeholders, particularly regarding specific farmer and community concerns/constraints, is to be sought during a broad-based stakeholder meeting planned for the July-August period as noted above.
The project's third phase covered the period July 2004 to June 2005 and a major highlight was the final review in February 2005. Project achievements and a range of collaborating activities are summarised under the specific project objective headings:
1. To describe the current land and water resources of the Inabanga Watershed
Maps have been completed showing the estimated current land-use areas that include six major agricultural crops (irrigated rice, rainfed rice, corn, cassava, coconut and oil palm) and forestry/grassland areas. The land-use cover percentages range from agriculture usage at 52% to grassland and shrub land areas at 33%, woodlands with 12% and wetland areas at 1% and miscellaneous/built up areas at 1%. Watershed maps have been developed that show the area in 3 soil depth classes, slope maps in 6 different slope classes (0-3%, 3-8%, 8-18%, 18-30%, 30-50% and above 50%) and a general erosion map in 5 different classes. The maps have been produced as stand-alone maps and also as GIS data-layers.
Technical information has been gathered and is being incorporated into be entered into a GIS framework and database to support better decision making via data and trend evaluation and modelling, applied to a wide variety of watershed management decision-making issues. Cropping and land-use suitability has been assessed in the watershed pedo-ecological zones with respect to soil type, with further evaluation incorporating specific agriculture practices, water source and slope characteristics. Local advisory teams provided technical assistance in capacity building to support the continuing transfer of education and training to sustain good agricultural practices, conserve soil and water resources, improve farming practices and increase farm income.
2. To evaluate the extent of soil erosion, sedimentation and water quality problems in the Inabanga Watershed.
Data have been gathered at the seven experimental erosion and runoff sites and three water sampling sites to determine runoff volume, water quality and soil loss under a wide variety of rainfall and cropping conditions experienced through the year. Data for nitrogen and phosphorus losses have also being determined. The sites include the following land-uses: agro-forestry, woodland, cassava/corn, grassland, rainfed rice, irrigated rice and oil palm. Compiled in GIS format and linked database, the data provide a rich source of information for planning agencies, NGO groups and to be presented in farmer/community training activities.
3. To understand socio-economic and policy issues, and constraints that impact on the agricultural sustainability and surface water quality of the Inabanga Watershed.
A comprehensive dataset addressing agro-socio-economic issues in the watershed has been completed. The information has been gathered through farm surveys across the watershed: 932 households from 114 barangays of 14 municipalities in 2000 and another 126 household in 5 municipalities in 2003. Also included were interviews and collected data from farmer-co-operators at 5 project sites. This has been achieved by the project team and personnel from several collaborating organizations (including DENR and PPDO) across the watershed. Some highlights of the results have determined high poverty levels, rising unemployment, low per capita income and farm productivity, with the exception of irrigated rice, below the national average.
4 To evaluate different options and impacts for water resources uses in the watershed.
The team is evaluating management options and has provided training and encouraged participation of stakeholders in implementing practices to protect and preserve soil and water resources of the watershed. Alternative cropping scenarios and present/future water management practices have been considered in developing strategies to reduce sediment transport from agricultural activities, resulting in reduced crop production, degraded receiving waters and diminished water impoundment capacity. Through planned demonstration farms and learning centres, the team aims to create an enabling environment for stakeholders and others to protect and preserve watershed resources.
5 To enhance research capacity of staff in the BSWM/DENR and local collaborators.
The project has used systems tools including GIS, GPS, remote sensing, modelling and simulation, and monitoring of runoff and soil erosion at the watershed scale to enhance research capability of BSWM/DENR and local collaborators. The project has increased the team's experience and competency in watershed-scale data collection, monitoring and assessment and in-house capacity to model hydrology and soil erosion at watershed scale. Additionally, BSWM capability in geo-referencing and mapping soils, slope, elevation, land use and many other land attributes using GIS techniques, has been greatly enhanced.
6 To transfer research outputs to soil and water resources to stakeholders in the Inabanga Watershed.
A combined team effort, including many agencies and local stakeholders, has continued research efforts at both a local and watershed scale to understand the fundamentals of soil erosion and runoff, water quality evaluation, crop production and water management. This knowledge is being transferred, with the help of national level management agencies, local government, NGO's and community farmer groups. Planned demonstration farms and learning centres, linked with ACIAR Landcare activities within Bohol, are anticipated to further strengthen better soil and water management.
The team completed maps showing estimates of current land-use areas that included six major agricultural crops (irrigated rice, rainfed rice, corn, cassava, coconut and oil palm) and forestry/grassland areas. The land-use cover percentages were: agriculture usage 52%; grassland and shrub land areas 33%; woodlands 12%; wetland areas 1%; miscellaneous/built-up areas 1%. Watershed maps developed showed the area in three soil-depth classes, slope maps in six different slope percentage classes (0-3, 3-8, 8-18, 18-30, 30-50 and above 50) and a general erosion map in five different classes. Maps were produced as both stand-alone maps and as GIS data-layers.
Technical information gathered was incorporated into a GIS framework and database to support better decision-making via data and trend evaluation and modelling, for application to a wide variety of watershed management decision-making issues. Cropping and land-use suitability was assessed in the watershed pedo-ecological zones with respect to soil type, with further evaluation incorporating specific agriculture practices, water source and slope characteristics. Local advisory teams provided technical assistance to support ongoing transfer of education and training to sustain good agricultural practices, conserve soil and water resources, improve farming practices and increase farm income.
Data gathered at the seven experimental erosion and runoff sites and three water sampling sites helped determine runoff volume, water quality and soil loss under a wide variety of rainfall and cropping conditions experienced through the year. Data for nitrogen and phosphorus losses were also determined. The sites include the following land-uses: agroforestry, woodland, cassava/corn, grassland, rainfed rice, irrigated rice and oil palm. Compiled in GIS format and linked database, the data provide a rich source of information for planning agencies and NGO groups when making presentations during farmer/community training activities.
A comprehensive dataset addressing agro-socio-economic issues in the watershed has been completed. It was compiled from farm surveys across the watershed - 932 households from 114 barangays of 14 municipalities in 2000 and another 126 household in five municipalities in 2003. The dataset also included interviews and collected data from farmer cooperators at five project sites. A picture emerged of high poverty levels, rising unemployment and low per capita income. Farm productivity, with the exception of irrigated rice, fell below the national average.
Alternative cropping scenarios and present/future water management practices were considered in developing strategies to reduce sediment transport. Through planned demonstration farms and learning centres, the team aims to create an enabling environment for stakeholders and others to protect and preserve watershed resources.
The project introduced scientific methods and instrumentation to deal with soil and water resources research at a watershed scale rather that the conventional plot scale. These technologies and approaches have bolstered local capacity to monitor and evaluate data, yielded information to produce maps and database sets, and lifted capacity for predictive evaluation of management options via modelling based on empirically derived data.
There are no project locations defined for this project.