黄河内蒙古段头道拐断面冰期水流特征及其对气候变化与人类活动的响应

利用最新冰凌观测数据，分析了1960年以来黄河内蒙古段头道拐断面冰期流量特点及其影响因素.结果表明：头道拐断面小流量持续时间的年际变化具有明显的阶段性特征，1960-1967年、1968-1985年和1986-2010年小流量平均持续天数分别为68 d、17 d和37 d.气候变化和人类活动是影响小流量过程的主要因素，气候变化通过影响冰盖厚度和冰花堆积来影响封冻河段流量过程；河道冲淤演变则是冰期流量过程和槽蓄水增量长期变化的重要原因；刘家峡水库调度直接影响着内蒙古河段的流量过程. 最近10 a来，凌汛期气温变化剧烈，上游来水有所减少，河道淤积更加严重，河道工程增多是黄河头道拐断面小流量持续天数延长的主要原因.

Characteristic of winter discharge and its responses to climate change and human activities at Toudaoguai section of the Yellow River

Based on the latest observed ice data, characteristics of winter discharge process at Toudaoguai Hydrologic Section of the Yellow River since 1960 were analyzed. It is found that annual variation of low discharge days have obviously stage characteristics: The average days of low discharge at Toudaoguai Section in 1960-1967, 1968-1985 and 1986-2010 was 68, 17 and 37 d, respectively. Climate change and human activities are the main reasons of low discharge. Climate change impacts the channel discharge by frazil slush and ice cover growth; channel condition is the important reason for long term change of low discharge and channel-storage increment; Liujiaxia Reservoir operation directly influences the runoff process in the Inner Mongolia reaches. The main causes of low discharge days increasing in recent decade are violentair temperature variation, incoming runoff decreasing, severe channel sediment deposition and river projects increasing.