论黄河水沙变化趋势预测研究的若干问题

1980年代中期以来黄河水沙情势发生了巨大变化,明晰其过程、特征及水沙变化研究的关键所在,有助于聚焦核心科学问题,重点攻关,为黄河流域生态文明建设提供科技支撑。本文系统分析了黄河流域1950—2016年水沙变化过程,梳理了不同阶段各家水沙变化趋势预测成果,辨析了趋势预测结果差异显著的原因。研究表明:黄河水沙锐减,时空减幅不同步,年内利于输沙的流量持续时间和水量、沙量都在减少,含沙量则与水利水保工程建设呈现协同的阶段变化,黄河水沙异源的空间分布格局仍然持续;黄河水沙变化趋势多借助于"水保法"、"水文法"和"物理过程模型法"等开展预测,不同时期的预测成果差异显著,其中机理和机制等的认识不足、评价技术等的缺失及预测条件变化的不确定性等是导致差异显著的主要原因。今后需加强黄河水沙变化机理、措施的群体效应、预测结果可信度评估和治黄策略等关键科学问题研究,为准确预测新情势下黄河水沙变化趋势提供理论基础。

Several key questions in the researches of runoff and sediment changes and trend predictions in the Yellow River

The condition of runoff and sediment in Yellow River has greatly changed since mid-1980s. Under the new circumstances, a clear understanding in process, characteristics and the key issues of runoff and sediment changes, is of great importance to focus the key scientific problems and support the ecological civilization constructions in the Yellow River Basin. In this study, the changing process and trend of runoff and sediment in the Yellow River Basin during the period of 1950-2016 were analyzed. Meanwhile, the previous predictions and causes of runoff and sediment were reviewed and analyzed. The results show that the runoff and sediment in the Yellow River declined sharply in recent years, with unsynchronized of magnitude. Both the time duration of runoff and the amount of runoff and sediment,which are good for sediment transport,were reduced. Changes of sediment concentration were synchronized with soil and water conservation engineering. In the previous researches, the soil conservation method, hydrologic method and the physical-based modelling method were adopted in the runoff and sediment predictions. Differences of predictions in different historical period were obvious. Insufficient recognition of mechanism,absence of evaluation technique, and uncertainty of prediction conditions, were the main causes. Under the new circumstances, in order to improve predictions in runoff and sediment in Yellow River, more scientific researches need to be strengthened, including the mechanism of runoff and sediment changes, group effect of the driving factor, the credibility evaluation of runoff and sediment predictions, and management strategy of the Yellow River.