In this poster we will show the archaeological prospection methodology and techniques used in an archaeological field survey of the Middle Gaià Valley (Tarragona, Spain). Our project has begun in 2012 and its aim is to study the settlement evolution in the Middle Gaià Valley during the 1st millennium BC. The Gaià is a river of modest size (60 km) with a low volume of water that flows into the sea at Tamarit (Tarragona). The archaeological field survey is focused on a small geographic area, where there are large sectors of plains on the right bank of the river, and mountains on the left bank. The main mountain sector is the Serra del Montmell with peaks that are almost a thousand metres high. Our survey takes into account historic landscape elements such as paths, in order to establish a possible relationship between them and the ancient settlement. We especially work with historical aerial photographs and multispectral satellite images, searching for traces of buried sites and supporting a more efficient archaeological field survey. We use GIS software for compiling and analysing our data, and we generate 3D models of documented sites with photogrammetry software, with the aim to create the best knowledge of post-depositional processes.