Henan rainwater monitoring -three lines of defense- protects the -bean curd waist- of the Yellow River
On October 16, the Information Office of the Henan Provincial Government held a press conference to announce the ongoing developments in rainfall monitoring and forecasting in the Yellow River Basin. Over recent years, Henan has been accelerating the construction of a three-tier defense system for rainfall monitoring and forecasting, aiming to transition from localized rainfall predictions to broader, cloud-based estimations, as well as from real-time flood reporting to predictive models that convey flood evolution.
The Yellow River, known for its “copper head, iron tail, and tofu waist,” predominantly features a “tofu waist” segment in Henan, which presents unique characteristics compared to other rivers and sections of the Yellow River. This area has long been the focal point for flood control efforts and the core region for the protection and governance of the Yellow River.
During the press conference, Yang Xulin, the Deputy Director of the Yellow River Conservancy Commission, outlined four key features of the Yellow River: it has the largest sediment transport, the most hazardous conditions, the widest riverbed, the most dynamic water flow, the largest floodplain area, and the highest population density, along with a history of severe disasters and a daunting flood control task. Currently, a significant stretch between the Xiaolangdi and Huayankou areas, comprising 18,000 square kilometers, has no engineering control, leading to a high flood risk with short forecast lead times.
He emphasized that heavy rainfall and floods can occur rapidly, making traditional monitoring and forecasting methods insufficient due to their short lead times and low accuracy. To address this issue, the Ministry of Water Resources proposed an innovative approach to expedite the establishment of this rainfall monitoring and forecasting system, which is one of the three major frameworks for water and drought disaster prevention. Henan has engaged in several exploratory practices in this area.
The “first line of defense” focuses on estimating “cloud-based rainfall” using a combination of meteorological satellites, radar systems, and rainfall forecasting models. This is crucial for extending the flood forecasting period. Currently, the Yellow River Conservancy Commission has set up a meteorological satellite application system, three rain-gauging radars in the stretch from Sanmenxia to Xiaolangdi, and a weather radar application service system for the Yellow River Basin. They are also utilizing a unique precipitation forecasting model specific to the Yellow River Basin to assess expected rainfall over the coming days and to forecast potential flood events.
The “second line of defense” involves evaluating “ground-level rainfall” through rain gauges and hydrological modeling, directly linking to the outcomes from the first line of defense. This step is crucial for forecasting flood processes before they occur. The Henan Yellow River Basin currently has 424 rain gauge stations, which promptly relay data on rain onset, intensity, and accumulation to flood forecasting models to analyze and simulate runoff processes.
The “third line of defense” is dedicated to monitoring and forecasting the evolution of “floods” utilizing hydrological stations and flood dynamics models, thereby connecting with the second line of defense. This is an important means of enhancing forecasting accuracy. The Henan Yellow River Basin has established 33 hydrological stations, installed 136 engineering water gauges, and implemented 198 large river cross-sections, enabling automated and comprehensive flood monitoring. This setup allows for accurate measurements at upstream hydrological stations while relaying flood evolution information downstream, fostering a continuous transmission of forecasts that further sharpen prediction precision.
