Hydrological droughts are one of the most damaging disasters in terms of economic loss in central Vietnam and other regions of South-east Asia, severely affecting agricultural production and drinking water supply. Their increasing frequency and severity can be attributed to extended dry spells and increasing water abstractions for e.g. irrigation and hydropower development to meet the demand of dynamic socioeconomic development. Based on hydro-climatic data for the period from 1980 to 2013 and reservoir operation data, the impacts of recent hydropower development and other alterations of the hydrological network on downstream streamflow and drought risk were assessed for a mesoscale basin of steep topography in central Vietnam, the Vu Gia Thu Bon (VGTB) River basin. The Just Another Modelling System (JAMS)/J2000 was calibrated for the VGTB River basin to simulate reservoir inflow and the naturalized discharge time series for the downstream gauging stations. The HEC-ResSim reservoir operation model simulated reservoir outflow from eight major hydropower stations as well as the reconstructed streamflow for the main river branches Vu Gia and Thu Bon. Drought duration, severity, and frequency were analysed for different timescales for the naturalized and reconstructed streamflow by applying the daily varying threshold method. Efficiency statistics for both models show good results. A strong impact of reservoir operation on downstream discharge at the daily, monthly, seasonal, and annual scales was detected for four discharge stations relevant for downstream water allocation. We found a stronger hydrological drought risk for the Vu Gia river supplying water to the city of Da Nang and large irrigation systems especially in the dry season. We conclude that the calibrated model set-up provides a valuable tool to quantify the different origins of drought to support cross-sectorial water management and planning in a suitable way to be transferred to similar river basins.
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机译：水文干旱是越南中部和东南亚其他地区经济损失最具破坏性灾害之一，严重影响农业生产和饮用水供应。它们的频率和严重程度的增加可归因于延长干法术和增加水抽象。灌溉与水电开发，满足动态社会经济发展的需求。基于1980年至2013年的水力气候数据和水库运营数据，对越南陡地地形的陡坡盆地进行了评估了近期水电开发和水文网络的其他改变的影响，越南陡地地形的Mescrale盆地评估了陡坡盆地的影响， Vu Gia Thu Bon（VGTB）河流域。仅用于VGTB河流域的另一个建模系统（JAMS）/ J2000，以模拟水库流入和下游测量站的归化放电时间序列。 HEC-RESSIM储层运营模型模拟八个主要水电站的储层流出，以及主要河流分支机构的重建流流程Vu Gia和Thu Bon。通过应用日常变化的阈值方法，对不同时间尺度进行分析的流动持续时间，严重程度和频率。两种模型的效率统计显示了良好的结果。对于对下游水分配相关的四个排放站，检测到水库运作对下游放电的强劲影响。我们为Vu Gia河提供了更强大的水文干旱风险，供水到大楠市和大型灌溉系统，特别是在旱季。我们得出结论，校准的模型设置提供了一种有价值的工具，可以量化干旱的不同起源，以支持跨部门水管理和规划以合适的方式转移到类似的河流盆地。
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