Potential for sustainable development in lower Mekong Basin.

在过去的两年中，进行了实地调查、文献综述和基于数值模型的分析。重点是洪水泛滥、三角洲地区的河网特征、海水入侵、沉积和砍伐森林。在这些实地考察期间，研究小组与湄公河管理机构、研究机构和越南大学进行了接触。组织了两次讨论湄公河流域问题的讲习班，特别是1999年1月举行的一次讲习班，有30多人参加。来自国外的三位湄公河问题专家出席了会议，并提供了与湄公河流域最新发展相关的最新信息。通过会议，大家交换了不同的意见，加深了了解。在此基础上，建立了湄公河三角洲北部淹没水流的数学模型。模型的输出与实测洪水资料进行了较好的对比。对湄公河和巴萨克河交界处的水流和河床演变也进行了数值模拟。对合流区泥沙淤积趋势进行了预测。此外，将分布式水文模型应用于洞里萨湖流域，对其水量平衡收支进行了评估。并对海水入侵的机理进行了实验研究，提出了防止盐水楔入的几点建议。最后，形成了湄公河下游流域可持续发展规划框架，该框架不仅具有学术意义，而且有助于提高日本政府海外援助湄公河流域可持续发展的有效性。

During the past two years, field surveys, literature reviews, and analyses based on numerical models were conducted. The focus was on the flood inundation, characteristics of river network in the delta area, sea water intrusion, sedimentation and deforestation. During these filed trips, the research team made contact with administration bodies of the Mekong river, research institutes and Vietnamese universities as well. A lot of data were collected which forms the basis for further study.Two workshops were organized to discuss the issues of the Mekong river basin, particularly, the one held on January 1999 brought more than 30 participants. Three experts on Mekong river from abroad attended the meeting, and provided updated information related to the latest developments of the Mekong river basin. Through the meetings, different views were exchanged and better understanding were achieved. Under this reseach program, a mathematical model to calculate inundating flow for northern Mekong delta was developed. The output of the model is compared fairly well with the recorded flood data. Numerical simulations of flow and bed evolution around the junction between the Mekong river and the Bassac river were also performed. Tendencies of sediment deposition at the merging area were predicted. Besides, a distributed hydrological model was applied to the watershed of the Tonle Sap lake to assess its water balance budget. Also, experiments were done to study the mechanism of the sea water intrusion, as a result, several proposals were made for the prevention of saline wedge intrusion.In conclusion, a framework for sustainable development planning in the lower Mekong river basin has been formed which can serve not only academic purposes but also help enhance the efficacy of Japanese government overseas assistance towards sustainable development of the Mekong River Basin.