In mid-November, due to prolonged heavy rains in the basin, Don Duong Lake ( Lam Dong province) recorded the largest flood since it was put into operation in 1964. Da Nhim-Ham Thuan-Da Mi Hydropower Joint Stock Company operated the lake safely, strictly following the procedures, contributing to cutting and reducing floods and ensuring safety for the downstream area.
In mid-November, due to the influence of cold air combined with the tropical convergence zone, Don Duong Lake basin, Lam Dong province experienced prolonged heavy rain, causing a rapid increase in water flow to the lake.
At 0:00 on November 16, the lake water level reached 1,039.958m (normal water level is 1,042m), the inflow to the lake was 54m3/s, the overflow flow was 20m3/s. Heavy rain occurred in the Don Duong lake basin, water from upstream poured into the lake with a peak flood flow of 1,096m3/s at 9:00 on November 17 (lake water level 1041.778m, overflow flow 200m3/s). Don Duong Lake gradually increased the regulated discharge level to 300m3/s-400m3/s-500m3/s from 9:00 to 11:00 on November 17 and reached the maximum discharge level of 600m3/s from 11:15 to 13:30 on the same day, then gradually reduced to 250m3/s when the rain in the lake basin decreased, at the same time lowering the water level of Don Duong Lake to 1,040m elevation, contributing to ensuring safety for the downstream.
At 12:00 on November 19, when the water level reached 1,040.09m in the Don Duong reservoir basin, heavy rain appeared again. From 1:00 p.m. on November 19 to 6:00 a.m. on November 20, the average rainfall reached 186.5mm, causing a historic flood peak of 2,090m³/s at 0:00 a.m. on November 20 (water level 1,043.138m, overflow flow 2,000m³/s) and the total flood volume in the reservoir reached 149.8 million m³.
Implementing the direction of the Lam Dong Provincial Civil Defense Command, Da Nhim-Ham Thuan-Da Mi Hydropower Joint Stock Company (DHD) used a reinforced water level of 1,043.2m to extend the preparation time and complete the evacuation of people in low-lying areas downstream before starting a large regulatory discharge. The spillway discharge reached a maximum of 2,000m³/s at 0:00 on November 20, then gradually decreased corresponding to the amount of water flowing into the lake. By 3:00 on November 22, the spillway discharge reached 300m³/s, the lake water level was 1,040.91m and continued to decrease.
This is the biggest flood since Don Duong reservoir was put into operation in 1964. From 0:00 on November 16 to 0:00 on November 21, the total rainfall in the Don Duong reservoir basin was 448.5mm, the total flood water volume in the reservoir reached 221 million m3, equivalent to 142.5% of the reservoir's useful capacity (155.14 million m3). During the flood control operation, DHD strictly followed the operating procedures, closely coordinated and strictly implemented the instructions of the Lam Dong Provincial Civil Defense Command, proactively monitored the weather situation, promptly notified the local authorities and people in the downstream area to organize the evacuation of people and property from the flooded area smoothly and safely.
The Steering Committee for Natural Disaster Prevention and Search and Rescue of Da Nhim-Ham Thuan-Da Mi Hydropower Joint Stock Company regularly implements the four-on-the-spot principle; organizes regular and continuous monitoring, inspection and observation of dams during flood cutting; contacts and reports to the Lam Dong Provincial Civil Defense Steering Committee and communes along the downstream area of Don Duong Lake; strictly implements the direction of the Lam Dong Provincial Civil Defense Steering Committee, operates the reservoir in compliance with the correct procedures; contributes to cutting and reducing floods for downstream areas and ensuring absolute safety for the project.
Currently, the earth dam, spillway, and Don Duong reservoir projects are operating normally, safely, reliably, and stably under all operating conditions, ensuring absolute safety for the downstream area.
Forecasting that the weather will still be complicated, the Company will continue to strictly implement the "4 on-site" motto, closely monitor the meteorological and hydrological situation, coordinate with relevant agencies and operate the reservoir according to the correct procedures to ensure absolute safety for the project and people in the downstream area.
Source: https://baolamdong.vn/ho-don-duong-xa-dieu-tiet-no-luc-gop-phan-bao-dam-an-toan-cong-trinh-va-ha-du-tinh-lam-dong-404709.html
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