疏勒河流域泥沙分布规律及水沙关系研究

Sediment distribution and runoff-sediment relationship in the Shule River Basin

泥沙是影响河流健康和水环境的重要因素之一,受气候变化和人类活动的影响,流域水文要素和下垫面条件发生了较大变化,尤其是实施大规模的水土保持措施后,部分河流的泥沙含量大幅减少,但在河西内陆河流域发源于祁连山西端的疏勒河流域,受降水条件和人类活动的影响,河流泥沙呈增加趋势。应用疏勒河流域实测长系列水文资料,采用水文统计法、差积曲线法、趋势检验法、突变检验法、非线性复相关模型法等方法,分析了流域泥沙时空分布规律及水沙关系,结果表明:疏勒河干流昌马堡站年输沙量为333. 5×104t,至下游潘家庄站减少到223. 5×104t;党河党城湾站年输沙量为76. 56×104t,至下游沙枣园站增加到121. 3×104t;疏勒河干流输沙量主要集中在汛期7～8月,占全年的81. 9%～84. 0%,党河流域输沙量主要集中在4～8月,占全年的92. 3%;流域泥沙变化总体呈增加趋势,突变点1998年以后,年输沙量增加了86. 3%～148. 2%。建立了潘家庄站降水—泥沙、径流—泥沙以及年输沙量—年径流量—年最大洪峰流量关系模型,相关系数达到0. 717～0. 858。流域出山口以上对泥沙的影响因素主要是降水,出山口以下主要是修建水库、水电站、引水工程、河道采砂等人类活动影响。随着国家对内陆河流域祁连山和河西走廊的日益关注,以及全国河长制的推行,河流生态健康已经提上日程,研究疏勒河流域泥沙分布规律及水沙关系,对国家实施西部生态安全战略、区域生态环境修复治理、水资源可持续利用等具有重要意义。

The river basin hydrological factors and underlying surface conditions which were affected by the climate change and human activities have been changed greatly. The sediment concentration was decreased significantly after the implementation of large-scale soil and water conservation measures in some parts of rivers. However,the river sediment presented a trend of increasing in the Shule River basin which is originated in the western Qilian Mountains in the Hexi Inland River Basin,Gansu Province,China due to precipitation and human activities. The time-space distribution law of the sediment and the relationship between the sediment and the water sand were analyzed systematically by using the data from four hydrological stations which include Changmabu,Panjiazhuang,Dangchengwan,and ShaZaoyuan in Shule River Basin during the time period from the establishment of the hydrometric stations to 2012. The spatiotemporal distribution law of river sediment was analyzed using hydrologic statistics. The annual sediment discharge of the main stream of the Shule River at Changmabu station is 333. 5 × 104t·a-1and it is then reduced to 223. 5 × 104t·a-1at Panjiazhuang station in the downstream. The annual sediment discharge of the Danghe River is 76. 56 × 104t·a-1at Dangchengwan station and it was then increased to 121. 3 × 104t·a-1at Shazaoyuan station in the downstream. The sediment discharge mainly happened in the flood season from July to August in the main stream of Shule River,which accounted for 81. 9%-84. 0% of its annual sediment discharge. The sediment discharge of the Danghe basin mainly happened from April to August,which accounted for 92. 3% of its annual sediment discharge. The sediment change trend was analyzed using Kandel rank correlation,Berman rank correlation and linear trend correlation. The sediment mutation is analyzed by the Man-Kendall method,order clustering method,Lee-Heghinan method. The results show that the change of sediment in the basin indicated an increasing trend and annual sediment charge was increased by 86. 3%-148. 2% after the mutation point in 1998. At the Panjiazhuang station,the relation model between precipitation and sediment,the relation model between runoff and sediment,and the relation model among annual sediment discharge,annual runoff,and annual maximum peak flow were established by using the method of linear correlation and nonlinear complex correlation and the result showed high correlation coefficients ranging from 0. 717 to 0. 858. Above the valley outlet,the precipitation is the main factor for the coming water and sediment. In order to reduce the soil erosion,the relevant authorities or departments should take actions to increase the soil and water conservation in the upstream areas,by implementing the ban on reclamation,mining and grazing,and preventing over-exploitation. Below the valley outlet,the water sediment is mainly influenced by human activities such as building reservoirs,constructing hydropower station,as well as water diversion engineering project and sand excavation in river courses. The water quantity in the downstream reaches is sharply reduced or depleted. The desertification of the Gobi Desert is serious and the ecological environment is deteriorated. The ecological water quantity should be appropriately increased in the middle and lower reaches in order to improve the ecological environment. With the increasing attention to the Qilian Mountain and the Hexi Corridor in the inland river basin,the choice of the Qilian Mountain as the national park system pilot and the implementation of the national river chief system,the river ecosystem health has been on the agenda. It has significance to study the watershed sediment distribution laws and water sediment relations to help execute the strategy of the western ecological security,and restore the regional ecological environment,and sustainably utilize water resources.