The reduction of damage due to water pollution requires good knowledge of the quality of surface waters. The Water Quality Monitoring Networks (WQMNs) have evolved over time according to the objectives of each one of them: knowledge of long-term quality evolution, search for the origin of pollution, detection of accidental pollution, etc. Information provided by WQMNs could be improved by a spatial approach, optimizing the location or the number of monitoring stations, or by a temporal approach, optimizing the sampling frequency. However, there is a cost for monitoring water quality.

In this article, we show, for the first time, how the estimation of the Economic Value of Information (EVOI) can be used to determine the spatio-temporal design of the network. With the example of a network that aims to detect accidental pollution, we show how to calculate the EVOI according to the spatial and temporal network design (number and location of stations, temporal accuracy of measurement) and how to define this design by maximizing the EVOI. This will allow us to answer questions such as: Are the expenses invested in the networks justified? With an additional budget, is it better to add a station or to increase the temporal accuracy of the measurement of existing stations? What is the optimal spatial and temporal design of the network when working with a fixed budget?

减少因水污染造成的损害需要对地表水质量有充分的了解。水质监测网络（WQMN）随其每个目标而随着时间的推移而发展：了解长期质量演变，寻找污染源，发现意外污染等。WQMN提供的信息可以是通过空间方法，优化监视站的位置或数量或通过时间方法，优化采样频率来改进。但是，监测水质是有成本的。

在本文中，我们首次展示了如何利用信息经济价值（EVOI）的估算来确定网络的时空设计。以旨在检测意外污染的网络为例，我们展示了如何根据时空网络设计（站点的数量和位置，测量的时间精度）来计算EVOI，以及如何通过最大化EVOI来定义此设计。这将使我们能够回答以下问题：在网络上投资的费用是否合理？有了额外的预算，增加站点还是提高现有站点测量的时间精度更好？在使用固定预算的情况下，网络的最佳空间和时间设计是什么？