For heavy rainfall events in small catchment areas, the reaction time, which is defined as the time between the beginning of a precipitation event and the time of the peak discharge of the flood wave, is very short (< 1h). The city of Reutlingen lies in the relatively small catchment area of the Echaz and has commissioned the Chairs of Hydrology and Geohydrology (LHG) and of Hydraulic Engineering and Water Resources Management (LWW) to identify suitable locations for precipitation measuring instruments and ultrasonic levels in order to develop a robust warning system for the early detection of flash floods and river floods. Since the intensity of precipitation in thunderstorms can vary greatly locally, a complete picture of the distribution of precipitation shall be obtained (LHG). The LWW determines 20 to 25 gauges, which are connected by a "low power network". Since the transmission rate is limited to 144 signals per day and per measuring unit, the transmission rate is adapted accordingly to the system in order to detect a flood wave at an early stage via the gradient change of the water level. The density of the transmission rate is controlled on the one hand according to the change in the water level and on the other hand according to the time of day, in order to obtain both maximum information density and to prevent premature reaching of the maximum number of signals. In this project, both the location of the measuring instruments as well as the recording mode and data evaluation are of great importance. A functioning early warning system is able to alert the population at an early stage as well as to give emergency services, such as fire brigades and THW, a decisive advantage in evacuation and flood control.