# Recent Advances in Internet of Things Solutions for Early Warning Systems: A Review
## 4 Floods
### Reviewed Use Cases for Flood EW
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**Article** & **Focus and Objectives** & **Results** \\ \hline
[46] & The paper proposes a simple IoT system for dams flood warning, trying to compensate some issues in previous solutions such as the need to deal with heterogeneous data, power consumption, and the abrupt tolls of cellular coverage. & A cellular application is to be deployed to alert users, based on Zigbee tech. This would provide resilience to cellular network failures, but it requires users to use Zigbee hardware. \\ \hline
[26] & Fog Layer implementation in Flood EW to reduce latency and provide predictions before the Data Analysis Layer, and energy and cost optimizations through hexagonal division of the monitored area. Proposal and validation of prediction algorithms. & A prototype was proposed to test all layers simultaneously, showing effectiveness of the proposed architecture. Algorithms were tested with geographical data collected from flood monitoring websites. \\ \hline
[47] & Use of different sensors connected using 3G/2G/GSM modules and LoRa modules, taking advantage of the good network coverage in the area, to process, compile, and forward information to provide timely warnings. & The cost of this solution is high, but it proved successful in generating alarms and it comes with an user interface. \\ \hline
[48] & Revival of a rural water monitoring system, with a focus on how NLoS communication and remote locations are challenging for GSM, and how an ad hoc LoRA/non-cellular network could be an attractive and reliable option. & Experimental measurements on the LoRa transmission show a dependency on the receiver and transmitter heights and worse performance than empirical models. A migration to other cellular protocols besides GSM is suggested. \\ \hline
[49] & The study develops a river monitoring system with a focus on power consumption, showing that radio transmissions are the most energy consuming operation for the node and how critical measurement modes affect energy waste. & When solar batteries are not recharged and when in critical mode, battery life of the sensor node becomes 57\% shorter. The measurement success rate also depends on the cone used for the ultrasonic sensor. \\ \hline
[50] & Sensor node implementation for Flood EW WSN with low energy consumption achieved through a dedicated deep sleep algorithm and testing to evaluate power consumption & Current is on average 13 mA during the setup time period, and it drops to an average of 0.3 mA in standby phase. Thanks to short wake-up and transmission windows, more than 280 days are needed to discharge a 220 mAh battery. A full WSN implementation and high traffic were not tested yet. \\ \hline
[44] & Case study for an EW system called SENDI with a focus on fault tolerance through a clustering model and sensor nodes with embedded forecasting models and self-organizing algorithms. & The clustering system and the forecasting models were tested through simulation, showing good results as far as energy optimization, fault tolerance and accuracy. A limitation is the requirement of a large number of nodes to properly work. \\ \hline
[51] & Development of a WSN whose data is used to train and validate a SVM Machine Learning model which can be embedded into the WSN coordinator nodes. & The clustering system and the forecasting models were tested through simulation, showing good results as far as energy optimization, fault tolerance and accuracy. A limitation is the requirement of a large number of nodes to properly work. \\ \hline
[52] & Development of an Early Warning system based on Computer Vision, using images from a CMOS cameras sensor network and comparing them with stored references using image comparison techniques. & The developed algorithms are able to provide curves regarding: (i) rank of calamity, (ii) image registration curve, (iii) precision, (iv) object recognition curve. A web platform was also developed to make the graphs available to users. \\ \hline
[53] & Proposal of a cloud based wireless sensor and actuators network to alert from floods and to open watchman infects to make water flow out of the monitored water source if needed. & An algorithm to manage the sensors and actuator was also and successfully validated through model analysis, specifying different checks for water. The paper did not propose a specific communication protocol to send data over the Cloud or to the actuators. \\ \hline \hline \end{tabular}
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