Potential for sustainable development in lower Mekong Basin.

在过去的两年里，我们进行了实地调查、文献综述和基于数值模型的分析。重点研究了洪水淹没、三角洲河网特征、海水入侵、沉积和森林砍伐等问题。在实地考察中，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。收集了大量的数据，为进一步的研究奠定了基础。举办了两次研讨会，讨论湄公河流域的问题，特别是1999年1月举行的研讨会，有30多人参加。三位来自国外的湄公河专家出席了会议，并提供了有关湄公河流域最新发展的最新信息。通过这些会议，双方交换了不同意见，增进了了解。在此基础上，建立了湄公河三角洲北部淹没流量的数学计算模型。该模型的输出与记录的洪水数据进行了很好的比较。对湄公河与巴萨克河交界一带的水流和河床演变进行了数值模拟。预测了合并区沉积物的沉积趋势。此外，还在洞里萨湖流域建立了分布式水文模型，对其水量平衡预算进行了评价。并对海水入侵机理进行了实验研究，提出了防止盐楔入侵的几点建议。综上所述，形成了一个湄公河下游流域可持续发展规划的框架，不仅具有学术意义，而且有助于提高日本政府对湄公河流域可持续发展的海外援助的有效性。

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.