The one of the major difficulties in deploying a wireless sensor to monitor debris flow in the real world is power consumption. Frequently replacing the battery of a sensor that is located in a remote mountainous area is not practical. In this study we examine the newly-introduced wireless debris flow sensor, SMARTCONE, which is designed to minimize the standby power consumption, but still keep alert to detecting debris flow. During standby periods, SMARTCONE turns off all major components and uses an accelerometer to sense vibration generated by moving debris flow, and it wakes up SMARTCONE for collecting the parameters of a moving debris flow. Multiple SMARTCONEs need to change operation modes between standby and wake up, collect physical parameters, and transmit data simultaneously, and these issues are kept in mind while designing the system. The performance of vibration detection, data transmission and records of GPS trajectories are evaluated to ensure the accuracy of the design.

The debris flows caused by typhoon Morakot in August 2009 killed more than 600 people and caused US$ 500 million in damages to agriculture and forestry of Taiwan. Many lives can be saved if we can estimate the occurrence of debris flows and issue timely warnings to inhabitants. Previous literatures [1] have shown that rainfall is highly correlated with debris flows. Thus, the first step to debris flow monitoring and warning is to collect high-resolution, real-time precipitation in the debris-flow-prone areas. In this paper we discuss the considerations of designing a low-cost WSN-based rain gauge grid, which provides highresolution mapping of precipitation. Preliminary experimental results are presented.

This demo presents a mobile wireless sensor system for debris flow monitoring. The objective of this system is to realize long-term and effective debris flow surveillance using low cost wireless sensors. In the system, a set of robust wireless sensors are designed to deploy on riverbed and cooperatively observe the moving debris flows. Our mobile sensors are intended to be carried along by the debris flow. As the sensors move along, they are able to measure the internal parameters, such as vibration frequency, amplitude, moving direction and velocity, of the debris flow. By utilizing the proposed energy-saving mechanism on the WSN platform, the mobile sensors can continuously operate up to six months with merely two alkaline D cell batteries. The proposed system provides the abilities to collect high-fidelity data for civil engineering applications to analyze and determine the occurrence of debris flows, as well as estimate the damage.

In an event-monitoring wireless sensor network (WSN), the sensors must be waked up fast to engage in active and high-rate sensing when events of interest occur. However, to prolong the lifetime of the network, the sensors should be put into the standby mode as long as possible. There is thus a tradeoff between the standby duration and the wakeup latency. Though the tradeoff is important, what is more important is a flexible transmission schedule that allows the tradeoff to be exploited. In this research, we use debris flow monitoring as a case study to illustrate how the tradeoff between long standby and fast wakeup can be exploited systematically with a flexible transmission schedule.

Most debris flow monitoring systems deployed today use indirect means to track information regarding debris flows. In this work, we introduce a novel debris flow monitoring system for in-situ and direct tracking of debris flows in real-time. The core idea is to throw wireless sensors into the debris flows and collect flow information as they move along. We will describe the design of the wireless sensors and present some preliminary performance results.

The scale of weather monitoring is limited by the cost of the automatic weather stations (AWS), which is mainly the cost of high precision instruments and long-distance wireless telecommunication equipments. We propose a wireless sensor network (WSN) based AWS, which takes advantage of the low-cost, real-time and infrastructure-free characteristics of WSN [1]. We can therefore extend the scale of weather monitoring without increasing the number of telecommunication equipments. This WSN-based AWS is able to cover a plane and gather multiple sets of weather measurements in real-time at a better data resolution.