Decision Support Tools for Water Resource Management:A Case Study of Bung Boraphet Wetland, Thailand

Abstract

Water and other natural resources of the Bung Boraphet Wetland in Thailand have been under increasing pressure from over-exploitation. Sustainable management and ‘wise-use’ of the Wetland's resources require achieving a balance between economic exploitation and conservation. Scientifically based decision support tools are vital to gain better insights into the complex interactions between the large wetland system, its contributing catchment and floodplain, and then pave the way for planning effective long-term management. This paper presents a summary of several decision support tools that we developed for Bung Boraphet. The tools are: (a) Water budget predictive model, (b) Land-use analysis using satellite imagery, and (c) Database linked Geographic Information System.
From a review of literature and field studies, we identified the factors that have the most serious impacts on long-term sustainability of Bung Boraphet. We also conducted field studies to collect primary data on hydrological parameters of the lake between December 2002 and May 2006. These and available secondary data were then used to develop a model for the daily water budget of the Wetland. Model calculations and observed water levels are highly correlated for this period, proving the veracity of the model. Evaporation loss of water is a critical factor during the dry seasons (∼41% loss), as is extraction for irrigated rice grown in encroached areas around the lake (∼55% loss). The modeling tool allows the analysis of different water use scenarios. For instance, the model forecasts that even if the weir height is raised by 0.5m to a level of +24.5m (MSL), as has been suggested by some stakeholders, irrigation water abstraction has to be reduced by 35% of the current consumption to maintain the recommended minimum water level (+23m, MSL) for a sustainable fishery.
Insights into land use changes in the surrounding catchment and lake were gained by a series of Landsat 5 satellite images. A comparison of images shows that between 1993 and 2003, the irrigated area surrounding the lake doubled. At the same time, the submerged and emergent vegetation in the lake declined by 50%. The database linked GIS, which we developed, includes meteorological data and primary and secondary data on hydrology, water quality and biodiversity of the lake and its catchments, and covers the main rivers and their tributaries. Information from applying the decision support tools has stimulated discussions with key stakeholders, identifying the ‘wetland values’ that need protection, and the economic, environmental and social goals that need to be met by a future plan of management. As discussed in this paper, we have made a significant difference in the nature of the discourse on the management of Bung Boraphet by demonstrating the value of basing wetland management decisions on scientific information. The POM, which is being developed, is expected to receive multiple stakeholder support, so that Bung Boraphet's resources can be sustained for use by present and future generations.