Monitor rainfall to prevent and respond to flash floods and landslides.

With the rainy season approaching, experts and scientists recommend that localities, units, and people in areas at risk of flash floods and landslides proactively monitor weather forecasts and warnings, especially information warning of rainfall exceeding thresholds, in order to proactively prevent and respond to these two dangerous types of natural disasters.

An automated rain gauge station provides automatic disaster warnings at the Tắk Pát resettlement area, Trà Leng commune. Photo: HOÀNG HIỆP

Enhance the alert

The National Center for Hydro-Meteorological Forecasting regularly issues forecasts and warnings of natural disasters, including real-time information on areas at risk of flash floods and landslides on the website http://luquetsatlo.nchmf.gov.vn/ so that localities and units can monitor and understand the warning information and proactively implement preventive and response measures.

In addition to the aforementioned tools, to better suit the specific realities of each locality, residential area, river basin, stream, etc., units and localities are deploying and installing disaster monitoring and warning stations.

Currently, in Tra Leng commune, there are two rain gauge stations installed to monitor rainfall and several automatic warning broadcasting stations connected to the rain gauge stations to broadcast warnings through loudspeaker systems when rainfall exceeds the threshold, in order to alert people to the risk of flash floods and landslides.

Given the rapid, unexpected nature of flash floods and landslides, and their devastating impact, early warning of these two types of natural disasters allows people time to prepare and implement preventive and response measures.

According to MSc. Nguyen Ngoc Vinh from the Central and Western Highlands Institute of Water Resources Science , there are many causes of landslides, but the main and direct trigger is rain. The serious landslide in Tra Leng commune in October 2020 was a mudslide triggered by heavy rain. Therefore, forecasting and warning of landslides based on rainfall needs to be given attention.

According to the Water Resources Engineering Consulting and Development Joint Stock Company (WATEC), the company has installed 81 rain gauge stations in Da Nang city and automatically transmits continuous rainfall monitoring data to the Vrain dedicated rain gauge system.

Many factors contribute to landslides and flash floods, but heavy rainfall (both in intensity and amount) remains the direct cause. Therefore, solutions are needed to warn against these two types of natural disasters based on measured and predicted rainfall. In particular, attention should be paid to determining flash flood and landslide warning thresholds to implement decisive response measures to minimize damage.

Following the flash floods and landslides that occurred in Nu village, Phuc Khanh commune, Lao Cai province in September 2024, several scientists researched and proposed that the warning threshold for flash floods and landslides should be a rainfall intensity exceeding 40mm/hour and a cumulative rainfall amount exceeding 250mm/period.

Effective warning tool

Regarding solutions and warning tools, WATEC has been deploying a system for warning of heavy rain, landslides, and flash floods through automatic warning stations connected to rain gauge stations via the LoRa wireless network. The warning station in the Tak Pat resettlement area in Tra Leng commune is a typical example.

Technicians from the Water Resources Engineering Consulting and Development Joint Stock Company (WATEC) are inspecting automatic rain gauge stations and over-rainfall warning stations before the rainy season. Photo: HOANG HIEP

Accordingly, in areas identified as high-risk zones for flash floods and landslides, when the actual hourly rainfall (rainfall intensity) or accumulated rainfall exceeds the warning threshold, the system will automatically activate a warning broadcast via high-powered loudspeakers with pre-recorded messages or a siren.

Information on flash floods and landslides, based on actual rainfall measurements from Vrain rain gauges in high-risk flash flood and landslide communes, is also integrated into Watec's new application for disaster response decision support.

In addition, WATEC deploys heavy rain warnings via the Vrain mobile app and text messages alerting of rainfall exceeding thresholds; warning information is also sent via the Zalo ZNS platform and SMS to disaster prevention agencies. Simultaneously, it is collaborating with Weathernews Inc. (a leading Japanese weather forecasting company) to provide highly reliable rainfall forecasts nationwide, especially very short-term rainfall forecasts (Nowcast).

According to Van Phu Chinh, Chairman of the Board of Directors of Water Resources Engineering Consulting and Development Joint Stock Company (WATEC), to effectively warn against flash floods and landslides, detailed and quantitative rainfall forecasts with high reliability are needed. Therefore, it is necessary to increase the density of automatic rain gauge stations and install additional weather radar stations, including the socialization of the installation of small-scale weather radar stations (X-band) at an affordable cost.

Besides the impact of heavy rain, flash floods and mudslides can also be caused by obstructed water flow, forming temporary reservoirs upstream. Therefore, localities need to check for signs and risks of landslides and flash floods in upstream areas of rivers and streams, and in residential areas.

In addition, localities need to decisively implement appropriate prevention and response measures as soon as flash flood and landslide warnings are issued.

Source: https://baodanang.vn/theo-doi-luong-mua-de-phong-tranh-ung-pho-lu-quet-sat-lo-dat-3299740.html