基于临界支撑流量的西藏典型河流源头位置确定及河网解析研究

河源作为河流形成环境的重要标志，需要一个简单且客观有效的判定方法。本文提出了一种基于临界支撑流量（CSD）的河源集水面积计算模型，并且建立了最小集水面积CSA和CSD的关系。利用该模型在西藏的两个流域（拉萨河的堆龙曲、尼洋河白水曲）进行了对比研究，结果表明堆龙曲的临界支撑流量（Qc）为0.0028m3/s，而白水曲为0.0085m3/s。另外，临界支撑流量可随水文气候条件而变化，湿润地区（白水曲）的临界支撑流量Qc要比半干旱地区（堆龙曲）的大。本文提出的临界支撑流量（CSD）概念和模型方法可以用于在复杂的地理区域确定河源的水文学指标，它也可以反映出不同地区水文气候变化对河流补给的影响。

Determination of a Riverhead Based on Critical Support Discharge and River Network Analysis

In this paper, the new model referring to the relation of CSA and CSD was proposed, which was based on the physical mechanism for the origin of river heads. The feasibility of the model was verified by using two watersheds (Duilongqu basin of Lhasa River and Beishuiqu basin of Niyang River) in Tibet to calculate the CSA and extract river networks. The comparison results of river networks derived from DEM with real ones indicated that the critical support discharge Qc are 0.0028 m3/s +0.001 in Duilongqu and 0.0085 m3/s +0.001 in Beishuiqu, respectively. The CSD can vary with hydro-climate conditions. It was higher in humid region and lower in arid region. Using this method, the optimal critical support discharge Qc of 0.0085 m3/s in Beishuiqu basin (humid region) was greater than 0.0028 m3/s for Duilongqu (semi-arid region) . The suggested method provided a new application approach that could be used to determine CSD (Qc) in complex geographical regions, and the effect of hydro-climate change could be reflected.