Urban soils as interdisciplinary archives of urban co-evolution – informing historical analysis and ecohydrological modelling: A case study of Gaußbergpark, Braunschweig, Germany

Anthrosols and technosols are urban soils that have been heavily influenced by anthropogenic activities. We hypothesise that such soils store information that can give insights into the system's co-evolution. In a case study of the urban green space Gaußbergpark, Braunschweig, Germany, we demonstrate how an interdisciplinary study of anthrosols yields complementary data sets that provide a more complete picture of the processes involved in urban co-evolution. Gaußbergpark is a public park, located at the northern part of the historical city wall, close to the Oker river. The hill that constitutes the Gaußbergpark was heaped up as a part of the defensive fortifications built during the early modern period. After the abandonment of the fortifications, the area was temporarily used as a landfill during the 18^th century before it became part of a band of parks and green areas in the early 19^th century. We explore this area from a historical, geophysical, and ecohydrological perspective. In this contribution, we will discuss data from historical archives, geophysical measurements (ERT), and ecohydrological modelling paired with soil moisture observations. As an example, the geophysical measurements clearly showed differences in soil properties between the hilltop and the areas below the slopes. The hill containing mainly sandy soils (fill) while the surroundings contained silty and clayey soils (natural origin to be expected). Simultaneously, this information is valuable for both historical as well as ecohydrological analyses of the area. Our synthesis shows that key ecohydrological processes, such as transpiration, soil moisture dynamics, and runoff partitioning, depend on the specific geophysical properties of the underground, which in turn are explained through the area's history.