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敦煌莫高窟保护区所在区域气候极为干旱,但受到早年多次洪水影响,致使洞窟潮湿、壁画霉变、酥碱,对国家重点文物保护造成极大威胁,因此通过窟前大泉河洪水预测的研究,分析和预测不同降水条件下的莫高窟库前洪水流量,进一步合理制定洪水防范措施和风险预警体系,对保障莫高窟文物安全具有重要的实际意义。通过对莫高窟保护区实地考察和流域特征分析,选择短缺流量资料地区比较适宜的瞬时单位线法,分别测算出大泉河野马山、一百四戈壁和三危山50 a,100 a,500 a一遇的洪水流量,以此为基预测2种不同降雨情形下的洪水流量。(1)当降雨从上段野马山区开始,依次向中段、下段移动时,50 a,100 a,500 a一遇降水流经大泉河莫高窟前断面的洪水流量分别为230,463,757 m3/s;(2)当全流域同时降雨时,50 a,100 a,500 a一遇降水流经大泉河莫高窟前断面的洪水流量分别为230,330和510 m3/s.并通过实际发生的2次百年一遇的洪水的洪峰流量和气象条件与测算数值进行比对,印证预测结果可信。同时,为了提高莫高窟抵御洪水风险的能力,确保莫高窟文物安全,防患于未然,进一步提出了建立健全流域降水和洪水监测体系、开展大泉河防护性工程建设、降雨洪水预警体系建设和石窟作防雨防渗等措施的建议,以便有效预防洪水,切实保障莫高窟安全。
The climate in the area where Dunhuang Mogao Grottoes are protected is extremely arid. However, due to the floods in the early years, the caves are humid. Mural mildew and cinnamon are the major threats to the protection of the state’s key cultural relics. Therefore, Studying, analyzing and forecasting the flood flow in front of the Mogao Grottoes under different precipitation conditions and further rationalizing the flood prevention measures and the risk early-warning system have important practical significance for the protection of the cultural relics in Mogao Grottoes. Through the field investigation and basin characteristic analysis of the Mogao Grottoes Reserve and the comparatively suitable instantaneous unit line method for selecting the shortfall flow data area, the estimates of the Daquan River Mustang Mountain, one hundred and four Gobi and the Sanwei Mountain are respectively 50 a, 100 a and 500 a flood event, as a basis for forecasting floods under two different rainfall scenarios. (1) The flood flows of 50 a, 100 a and 500 a first encounters through the front section of Dacheng River Mogao Grottoes are 230,463,757 m3 / s respectively when the rainfall starts from the upper Mustang Mountain and then moves to the middle and lower reaches in turn. 2) At the same time of rainfall in the whole basin, the flood flows of 50 a, 100 a, 500 a first precipitation through the front section of Dacheng River at Mogao Grc are 230, 330 and 510 m3 / s, respectively. The flood peak flood event and meteorological conditions are compared with the measured values to confirm that the forecast result is credible. At the same time, in order to improve the ability of Mogao Grottoes to withstand the flood risk and ensure the safety of Mogao Grottoes cultural relics, we put forward further the establishment and improvement of basin precipitation and flood monitoring system, the construction of Daquanhe protective project and the construction of rainfall and flood warning system And the cave for anti-seepage and other measures to prevent rain in order to effectively prevent flooding, and effectively protect the safety of Mogao Grottoes.