# A Serious Gaming Approach for Crowdsensing in Urban Water Infrastructure with Blockchain Support
## 1 Introduction
### Blockchain  
To reach a consensus, the required trust level between participants must be ensured. The problems with centralized frameworks arise when considering unauthorized attempts to collect information and active misbehavior of participants and stakeholders, with all these factors contributing to a decreasing level of trust and participation, thus having a negative impact on platform utility. Blockchain overcomes these limitations, greatly reducing the risk of illegitimate transactions and unauthorized disclosure of private information. Therefore, the problem of trust in a water resource management system can be solvedconsidering the increased transparency enabled by blockchain technology and integrated consensus algorithms [7]. Approaches to water management vulnerabilities place more emphasis on regional or national areas, not taking into account the fact that water sources and demands are linked in the water network on a geographical scale [37]. Therefore, the approach of a distributed network such as blockchain technology can be beneficial for dealing with vulnerabilities on multiple levels [38; 39]. There are many definitions of blockchain technology. From a technical point of view, blockchain is a peer-to-peer distributed register that is cryptographically secure with the possibility of only adding information and immutable and that can be updated only by consensus of all nodes [40]. According to [41], blockchain is defined as a chain of blocks, and each block contains transactions that are recorded in a register that is distributed to all nodes in the network, as shown in Figure 1. Transactions remain in a chain and are immutable, and because the register is distributed to all participating nodes, any node can verify the transaction and announce the verification in order to reach a consensus. Much more simply, [PERSON] defines blockchain as \"The Internet of Money\" in a publication with the same name [42]. Blockchain has become, through its security, a decentralized architecture and flexibility, one of the most important technologies of today. Researchers in almost all fields have tried to adapt this new technology and develop new solutions. In the water industry, blockchain technology can have various implications such as: keeping records (with the help of smart contracts, companies can access data in real-time), reporting and audit (since the data and actions are registered in an immutable register, it offers the possibility of enhanced audit support), data reconciliation (allowing regulators to control and monitor the status of transactions) and digitizing water (the demand for freshwater requires effective resource management solutions) [43]. Current blockchain systems are classified into three types: public blockchains, private blockchains and consortium blockchains. In public blockchains, all records are visible to the public, and everyone could take part in the consensus process. In contrast, only a group of pre-selected nodes can participate in the consensus process of a consortium blockchain. Regarding the private blockchain, only the nodes  
Figure 1: Blockchain architecture. organization are able to join the consensus process. The consortium blockchain built by several organizations is partially decentralized, because only a small part of the nodes are selected to determine the consensus. Consortium blockchains are commonly used in business applications [44]. In this sense, rules are implemented by smart contracts, which allow anonymous parties to interact, without the need for an intermediary [45]. The origin and history of smart contracts are much older than Bitcoin and date back to the 1990s. The term \"smart contract\" was first used in 1993 by one of the alleged creators of Bitcoin, [PERSON], and is referred to as a computer program that can automatically execute the terms of any contract or agreement [46].