From the noon on July 21 to the early morning of the 22nd, Beijing suffered the largest torrential rain in 61 years. At the same time, heavy rain caused 37 deaths and 1.9 million people suffered serious consequences. The city’s roads, bridges, and water conservancy projects were damaged in multiple places, houses collapsed, and several hundred cars were seriously damaged. Other disasters such as water conservancy, agriculture and forestry are still under further statistics.

At this moment, people once again felt the importance of urban drainage systems and meteorological warnings. The improvement of the meteorological disaster warning system is very important, including the convergence of all links, including the use of SMS, TV, network, display, and other channels to send out warning information. The speed and coverage of the warning must be greatly enhanced before the weather warning can really be used.

In meteorology, the instruments used to monitor precipitation are mainly rainfall sensors, water level recorders, water level gauges, and rain gauges (stations).

Rain sensors include tipping rain sensors, weighing rain gauges, self-emptying rainwater collectors, and reed switch rain sensors. Rain sensor is used to measure the natural rainfall, and convert the rainfall into digital information output in the form of switch to meet the needs of information transmission, processing, recording and display. It can be used for rainfall sensors that collect long-term rainfall data from national hydrology and weather stations.

Water level recorders are used for water level monitoring, well monitoring, wastewater treatment, flood disaster analysis, surface water monitoring, irrigation and canal monitoring, lake and wetland research, landfill/site analysis. The water level gauge is mainly used to detect the water level of natural waters such as rivers and lakes. It can also be used to detect the water level of large-scale reservoirs, reservoirs, sewers and other open drains. It can effectively monitor the status of water level changes and provide accurate water level information for monitoring units.

A rain gauge is an instrument used by meteorologists and hydrologists to measure the amount of precipitation in an area over a period of time (the snowfall measurement requires the use of a snow gauge). There are many kinds of rain gauges, and there are siphon rain gauges, weighing rain gauges, dump bucket rain gauges and so on. Most rain gauges use millimeters as the unit of measure, and sometimes measurements are measured in inches or centimeters. The readings of the rain gauge can be read manually or using an automatic weather station (AWS), and the frequency of observations can be varied according to the requirements of the collection unit. Rain gauges should be placed on open spaces away from buildings and trees to minimize observation errors.