Floodplains are often conceptualized as homogeneous sediment bodies which connect streams with their respective catchment and buffer agricultural inputs. This has led to a general bias within the hydrological community towards research on sites where the floodplain is a clear conduit for groundwater flow. In humid temperate regions of central Europe, floodplains have experienced rapid environmental changes since the last glaciation, yielding significant bedrock weathering and predominantly fine-grained, highly stratified hillslope and floodplain sediments. Such heterogeneous sedimentary architecture leads to conceptual ambiguities in the interpretation of the hydrogeological functioning of floodplains, thus raising the question: Do floodplains act as barriers or conduits to groundwater flow? This study analyzes the Ammer floodplain close to Tübingen in south-western Germany as a representative mid-section floodplain in a temperate climate where the regional bedrock-geology is dominated by mudstones. Geological, geophysical, and geochemical characterization and monitoring techniques were combined to shed light on the internal geological structure as a key control modulating the floodplain hydrology. Two partially separate groundwater systems were identified: a gravel body at the bottom of the Quaternary sediments and a Holocene confined tufaceous aquifer, separated by low-permeability clays. Despite flow being predominantly along-valley, sulfate concentrations in the floodplain aquifers showed evidence of a strong connection to the gypsum-bearing hillslope, particularly where tributary valley sediments are present (e.g., alluvial fans). Results from a floodplain water balance suggest the hillslope- and floodplain-aquifer material act as a barrier to hillslope groundwater recharge, where a large fraction may be bypassing the local floodplain groundwater system.

洪泛区通常被概念化为均质的沉积体，将河流与其各自的集水区连接起来并缓冲农业投入物。这导致水文界普遍偏向于洪泛区是地下水流动的明渠的地点进行研究。自上次冰川消融以来，在中欧湿润的温带地区，洪泛区经历了快速的环境变化，产生了显着的基岩风化作用，并且主要是细粒度，高度分层的山坡和洪泛区沉积物。这种非均质的沉积构造在解释洪泛区的水文地质功能方面导致概念上的歧义，从而引发了以下问题：洪泛区是否充当地下水流动的屏障或管道？这项研究分析了德国西南部图宾根附近的阿默河漫滩，作为温带气候下典型的中段洪泛区，该地区的基岩地质以泥岩为主导。结合了地质，地球物理和地球化学的表征和监测技术，以阐明内部地质结构，作为调节洪泛区水文学的关键控制手段。确定了两个部分分离的地下水系统：第四纪沉积物底部的砾石体和由低渗透性粘土分隔的全新世封闭的管形含水层。尽管主要是沿谷地流动，但洪泛区含水层中的硫酸盐浓度显示出与含石膏的山坡有很强的联系的证据，特别是在存在支流谷沉积物的地方（例如冲积扇）。洪泛区水平衡的结果表明，山坡和洪泛区含水层材料是山坡地下水补给的屏障，其中很大一部分可能绕过了当地的洪泛区地下水系统。