Page - 716 - in Book of Full Papers - Symposium Hydro Engineering

Grade Ⅰ Grade Ⅱ Grade Ⅲ Grade Ⅳ More than 30 death loss 10~30 death loss 3~10 death loss Less than 3 death loss Economic loss more than 100millions RMB Economic loss between 100millions and 50millions RMB Economic loss between 50millions and 10 millions RMB Economic loss less than 100millions RMB Extraordinary serious social and environment impacts Serious social and environment impacts Greater social and environment impacts Ordinary social and environment impacts 2.3. MONITORING ITEM FOR THE UNEXPECTED EVENTS AND ACCIDENTS 2.3.1. OVERTOPPING Floods, insufficient discharge spillway, malfunction of gates, blocks on spillway may lead dam overtopping. Inspection should be focused on spillway, gates, and unstable slopes around spillway. Unmanned aerial vehicle (UAV) may be applied. Water level, rainfall, inflow and outflow discharge, deformation, seepage pressure and seepage discharge should be monitored, which is shown in Table 2. Spillway pulverization should be monitored during flood discharge. Operation management problems such as gate and hoist can't work normally and spillway blocking problems resulted from big volume floater and spillway slope instability are major reasons for overtopping and even dam failure of embankment dams. Therefore, according to the weather forecast, when an extra-standard flood occurred, reservoir management department should immediately check that whether the dam, the bank slope close to the dam and the spillway slope have signs of erosion, crack, collapse and slide. Condition of the drainage facilities should also be checked, including whether the gate and the hoist can work normally, whether the spillway is blocked or not. The monitoring items for flood overtopping dam failure mode include water level, rainfalls, inflow and outflow discharge, deformation, seepage pressure, seepage discharge and discharge flood pulverization. Among them, water level, rainfalls, inflow and outflow discharge are the key monitoring items, while deformation and seepage are the important monitoring items, and other monitoring items can be monitored in a synchronized manner according to the actual situation. Compared with satellite remote sensing and manned aircraft remote sensing, unmanned aerial vehicle(UAV) remote sensing technology has real-time transmission of large-scale image data, which is suitable for emergency inspection under flood condition. In order to avoid the occurrence of overtopping, the flood water should be released by open the gate in time. But the pulverization caused by the flood discharge will affect the stability of the slopes on both sides of the spillway, so it is necessary to monitor the discharge flood pulverization. 716