Extended-range hydrometeorological forecasting for improved flood early warning in Bangladesh.

孟加拉国位于三大河流流域--恒河-雅鲁藏布江和梅格纳(GBM)的下游(图1)。这些河流大多发源于世界最高的喜马拉雅山脉。6月至9月的季风降水是孟加拉国河流系统的主要水源。季风期强降雨是洪涝灾害的主要原因，几乎每年都会发生，每隔5~8年就会发生一次毁灭性的洪涝灾害。它对孟加拉国的农业、有形基础设施造成严重破坏，并造成生命损失。例如，1988年、1998年、2004年、2007年、2010年、2016年和2017年的洪灾可以说是孟加拉国的严重洪灾年。在洪水管理方面，孟加拉国采取了结构性和非结构性措施。主要的非结构性措施之一是洪水预报和预警服务。洪水预报的目的是使人们、社区、机构和组织能够并说服他们为洪水做好准备，并采取必要的行动来增加安全，减少生命财产损失。它的目标是在洪水事件发生前夕提醒人们。目前，孟加拉国的洪水预报和预警中心(FFWC)正在提供基于上游边界近似的3-5天确定性洪水预报。此外，它还利用欧洲中期天气预报中心(ECMWF)对孟加拉国主要水系进行了10天的中期天气预报试验。目标。这项研究的总体目标是发展孟加拉国的扩展范围预报。这项研究的具体目标如下：*南亚季风的可预测性限度--陆地表面对洪水流动的控制，包括土壤湿度、积雪融化和蒸发。*河道模型的参数和物理特性，特别是与主要河流汇合处的回水效应有关的问题。*改进概率预报的统计特征。*孟加拉国季节性河流流量预报方案在水资源评估中的制度化问题。*社区一级长期洪水预报的应用。*为恒河-雅鲁藏布江和梅格纳盆地的区域洪水预报制定框架。

Bangladesh is located at the downstream of three big River Basins- Ganges-Brahmaputra and Meghna (GBM) (Figure1). The rivers are mostly originated from world highest Himalayan mountain range. The monsoon precipitation from June to September is the main source of water for river systems in Bangladesh. Heavy rainfall in the monsoon period is the main causes of flood, and it occurs almost every year with devastating one in every 5 to 8 years. It causes severe damage to agriculture, physical infrastructures and loss of human lives in Bangladesh. For instance, flood in 1988,1998,2004,2007 ,2010 ,2016 and 2017 can be mentioned as severe flooding years for Bangladesh. For flood management, Bangladesh has been taken both structural and non-structural measures. One of the main non-structural measures is flood forecasting and warning services. The objectives of flood forecasting is to enable and persuade people, community, agencies and organizations to be prepared for the flood and take necessary actions to increase safety and reduce damages of lives and properties. Its goal is to alert people on the eve of flood event. Presently, Flood Forecasting and Warning Centre (FFWC) in Bangladesh is providing 3 to 5 days deterministic flood forecast based on the upstream boundary approximation. Moreover, it has also experimented 10 days probabilistic forecast using European Centre for Medium-Range Weather Forecasts (ECMWF) medium range weather forecast for the major river systems in Bangladesh.Objectives.The overall objective of the study is to develop extended range forecast for Bangladesh. The specific objectives of this research are as follows.Topics for consideration include, but are not limited to:*The limit of predictability of the South Asian monsoon - Land surface controls on floods flows including soil moisture, snow melt and evaporation.*Parameterisation and physics of river routing models, particularly related to backwater effects at major river confluences. *Improving statistical characteristics of probabilistic forecasts.*Institutionalization aspects of seasonal river flow forecast schemes for Bangladesh in water resources assessment.*Community level application of long-rage flood forecast.*Develop framework for regional flood forecasting aspect in Ganges-Brahmaputra and Meghna Basin.