TY - JOUR A1 - Wilken, Florian A1 - Baur, Martin A1 - Sommer, Michael A1 - Deumlich, Detlef A1 - Bens, Oliver A1 - Fiener, Peter T1 - Uncertainties in rainfall kinetic energy-intensity relations for soil erosion modelling JF - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution N2 - For bare soil conditions, the most important process driving and initiating splash and interrill erosion is the detachment of soil particles via raindrop impact. The kinetic energy of a rainfall event is controlled by the drop size and fall velocity distribution, which is often directly or indirectly implemented in erosion models. Therefore, numerous theoretical functions have been developed for the estimation of rainfall kinetic energy from available rainfall intensity measurements. The aim of this study is to assess differences inherent in a wide number of kinetic energy-rainfall intensity (KE-I) relations and their role in soil erosion modelling. Therefore, 32 KE-I relations are compared against measured rainfall energies based on optical distrometer measurements carried out at five stations of two substantially different rainfall regimes. These allow for continuous high-resolution (1-min) direct measurements of rainfall kinetic energies from a detailed spectrum of measured drop sizes and corresponding fall velocities. To quantify the effect of different KE-I relations on sediment delivery, we apply the erosion model WATEM/SEDEM in an experimental setup to four catchments of NE-Germany. The distrometer data shows substantial differences between measured and theoretical models of drop size and fall velocity distributions. For low intensities the number of small drops is overestimated by the Marshall and Palmer (1948; MP) drop size distribution, while for high intensities the proportion of large drops is overestimated by the MP distribution. The distrometer measurements show a considerable proportion of large drops falling at slower velocities than predicted by the Gunn and Kinzer (1949) terminal velocity model. For almost all rainfall events at all stations, the KE-I relations predicted higher cumulative kinetic energy sums compared to the direct measurements of the optical distrometers. The different KE-I relations show individual characteristics over the course of rainfall intensity levels. Our results indicate a high sensitivity (up to a range from 10 to 27 t ha(-1)) of the simulated sediment delivery related to different KE-I relations. Hence, the uncertainty associated with KE-I relations for soil erosion modelling is of critical importance. KW - Rainfall kinetic energy KW - Drop size distribution KW - Drop fall velocity KW - Soil erosion modelling KW - Optical distrometer Y1 - 2018 U6 - https://doi.org/10.1016/j.catena.2018.07.002 SN - 0341-8162 SN - 1872-6887 VL - 171 SP - 234 EP - 244 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Premke, Katrin A1 - Attermeyer, Katrin A1 - Augustin, Jürgen A1 - Cabezas, Alvaro A1 - Casper, Peter A1 - Deumlich, Detlef A1 - Gelbrecht, Jörg A1 - Gerke, Horst H. A1 - Gessler, Arthur A1 - Großart, Hans-Peter A1 - Hilt, Sabine A1 - Hupfer, Michael A1 - Kalettka, Thomas A1 - Kayler, Zachary A1 - Lischeid, Gunnar A1 - Sommer, Michael A1 - Zak, Dominik T1 - The importance of landscape diversity for carbon fluxes at the landscape level: small-scale heterogeneity matters JF - Wiley Interdisciplinary Reviews : Water N2 - Landscapes can be viewed as spatially heterogeneous areas encompassing terrestrial and aquatic domains. To date, most landscape carbon (C) fluxes have been estimated by accounting for terrestrial ecosystems, while aquatic ecosystems have been largely neglected. However, a robust assessment of C fluxes on the landscape scale requires the estimation of fluxes within and between both landscape components. Here, we compiled data from the literature on C fluxes across the air–water interface from various landscape components. We simulated C emissions and uptake for five different scenarios which represent a gradient of increasing spatial heterogeneity within a temperate young moraine landscape: (I) a homogeneous landscape with only cropland and large lakes; (II) separation of the terrestrial domain into cropland and forest; (III) further separation into cropland, forest, and grassland; (IV) additional division of the aquatic area into large lakes and peatlands; and (V) further separation of the aquatic area into large lakes, peatlands, running waters, and small water bodies These simulations suggest that C fluxes at the landscape scale might depend on spatial heterogeneity and landscape diversity, among other factors. When we consider spatial heterogeneity and diversity alone, small inland waters appear to play a pivotal and previously underestimated role in landscape greenhouse gas emissions that may be regarded as C hot spots. Approaches focusing on the landscape scale will also enable improved projections of ecosystems’ responses to perturbations, e.g., due to global change and anthropogenic activities, and evaluations of the specific role individual landscape components play in regional C fluxes. WIREs Water 2016, 3:601–617. doi: 10.1002/wat2.1147 Y1 - 2016 U6 - https://doi.org/10.1002/wat2.1147 SN - 2049-1948 SN - 2049-1948 VL - 3 SP - 601 EP - 617 PB - Wiley CY - Hoboken ER -