In recent decades, water availability, water use, water sharing and freshwater supply for basic human and economic needs have become central scientific and humanitarian issues. With increasing water scarcity in many regions and increasing frequency of extreme flooding in other regions, there is a need to improve predictive capacity, to collect a large amount of information on key hydrological variables such as flows or water stocks in lakes and floodplains and to best combine these data with hydrological and hydrodynamic models. Most of the world's water demand relies on continental surface waters (rivers, lakes, wetlands and artificial reservoirs) while less on underground aquifers and seawater desalination. However, ground-based hydrological survey networks have steadily and drastically decreased worldwide over the last decades. In this context, current remote sensing techniques have been widely used by several countries for water resource monitoring purposes. In this paper, we present such remote sensing techniques, in particular satellite altimetry and imagery, and discuss how they became essential for the study of the water cycle and hydrological phenomena on a broad range of spatial and temporal scales. Large lakes, rivers and wetlands play a major role in the global water cycle and are also markers, integrators and actors of climate change at work on Earth. We show several examples chosen from the literature that perfectly highlight both current scientific and societal issues, as well as the crucial role of space techniques to monitor terrestrial surface waters.

近几十年来，满足人类和经济基本需求的水供应、用水、水共享和淡水供应已成为核心科学和人道主义问题。随着许多地区水资源短缺的加剧以及其他地区极端洪水频率的增加，需要提高预测能力，收集有关关键水文变量的大量信息，例如湖泊和洪泛区的流量或水存量，并最好地将这些数据与水文和水动力模型相结合。世界上大部分用水需求依赖于大陆地表水（河流、湖泊、湿地和人工水库），而较少依赖于地下含水层和海水淡化。然而，过去几十年来，全球地面水文调查网络稳步大幅减少。在此背景下，目前的遥感技术已被多个国家广泛用于水资源监测。在本文中，我们介绍了此类遥感技术，特别是卫星测高和图像，并讨论了它们如何成为在广泛的时空尺度上研究水循环和水文现象的必要条件。大型湖泊、河流和湿地在全球水循环中发挥着重要作用，也是地球上气候变化的标志物、整合者和行动者。我们展示了从文献中选择的几个例子，这些例子完美地突出了当前的科学和社会问题，以及空间技术在监测陆地地表水方面的关键作用。