TY - JOUR A1 - Schwientek, Marc A1 - Selle, Benny T1 - Quantifying in-stream retention of nitrate at catchment scales using a practical mass balance approach JF - Environmental monitoring and assessment : an international journal devoted to progress in the use of monitoring data in assessing environmental risks to man and the environment N2 - As field data on in-stream nitrate retention is scarce at catchment scales, this study aimed at quantifying net retention of nitrate within the entire river network of a fourth-order stream. For this purpose, a practical mass balance approach combined with a Lagrangian sampling scheme was applied and seasonally repeated to estimate daily in-stream net retention of nitrate for a 17.4 km long, agriculturally influenced, segment of the Steinlach River in southwestern Germany. This river segment represents approximately 70 % of the length of the main stem and about 32 % of the streambed area of the entire river network. Sampling days in spring and summer were biogeochemically more active than in autumn and winter. Results obtained for the main stem of Steinlach River were subsequently extrapolated to the stream network in the catchment. It was demonstrated that, for baseflow conditions in spring and summer, in-stream nitrate retention could sum up to a relevant term of the catchment’s nitrogen balance if the entire stream network was considered. KW - Nitrate retention KW - In-stream processes KW - Mass balance approach KW - Stream network KW - Catchment scale Y1 - 2016 U6 - https://doi.org/10.1007/s10661-016-5097-6 SN - 0167-6369 SN - 1573-2959 VL - 188 SP - 373 EP - 386 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Githui, Faith A1 - Thayalakumaran, Thabo A1 - Selle, Benny T1 - Estimating irrigation inputs for distributed hydrological modelling: a case study from an irrigated catchment in southeast Australia JF - Hydrological processes N2 - Adequate irrigation inputs are essential for the application of hydrological models in irrigated catchments, but reliable data on both the amount and the frequency of irrigation applications are often missing at an appropriate spatial scale. In this paper, we demonstrate and test approaches to estimate irrigation inputs for distributed hydrological modelling. In this context, the Soil and Water Assessment Tool was applied to simulate water balances for an irrigated catchment in southeast Australia during the period 2008–2010. Two methods for estimating irrigation inputs were tested. One method was based on a fixed irrigation application rate, whereas the other one had variable irrigation rates depending on season and the irrigated crop. These two approaches were also compared with the ‘auto-irrigation’ method within the Soil and Water Assessment Tool model. The method with variable irrigation rates resulted in the most reasonable interpretation of the readily available irrigation data, consistent estimates of irrigation runoff coefficients throughout the year and the best fit to observed data on both drain flows at the catchment outlet and spatial evapotranspiration patterns. We also found that the different irrigation inputs significantly affected simulated water balances, in particular deep percolation under relatively dry climatic conditions. All these results suggest that it is possible to infer irrigation inputs from readily available data and local knowledge, adequate for hydrological modelling in irrigated catchments. Our study also demonstrates that, in order to predict reliable water balances in irrigated catchments, an accurate knowledge of irrigation scheduling and irrigation runoff is required. Copyright © 2015 John Wiley & Sons, Ltd. KW - SWAT KW - irrigation runoff KW - remotely sensed evapotranspiration Y1 - 2016 U6 - https://doi.org/10.1002/hyp.10757 SN - 0885-6087 SN - 1099-1085 VL - 30 SP - 1824 EP - 1835 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Selle, Benny A1 - Graeff, Thomas A1 - Salzmann, Thomas A1 - Oswald, Sascha Eric A1 - Walther, Marc A1 - Miegel, Konrad T1 - Investigation of a renatured fen catchment on the Baltic Sea coast of Mecklenburg - Part II: Salt dynamics and water balance JF - Hydrologie und Wasserbewirtschaftung N2 - Coastal fens like the nature reserve "Hutelmoor und Heiligensee" (north-eastern Germany) are important landscape elements along the southern Baltic coast, which exchange fresh water and brackish water with the Baltic Sea. These exchange processes can be understood as experiments with a natural tracer, which may be used to investigate the hydrologic behaviour of these fen systems. With the establishment of coastal protection measures such as dunes and dikes, the installation of surface drainage and, more recently, also nature conservation measures, the hydrologic regime of these coastal wetlands has constantly altered over the last centuries.The rehabilitated wetland "Hutelnnoor und Heiligensee" is suitable for an analysis of hydrologic change as it has been monitored over the time period since nature conservation measures started in the 1990s. Collected data sets included observation of groundwater levels and electrical conductivities, weather data as well as discharge at the outlet of the drainage catchment. In this article, as a second part of the dual publication, processes and quantified process magnitudes have been identified that govern the salt balance of the study area including its variability in space and time. It was detected that - over the period of rehabilitation - salt water entered the catchment with an episodic storm surge by wave overtopping of dunes in 1995. The intruded brackish water was then diluted, which was a slow process extending over decades. It was governed by local groundwater recharge from precipitation and the inflow of relatively fresh groundwater from the hinterland. It is concluded that salt inputs from the Baltic Sea provide a natural tracer of hydrological processes, which can be readily monitored via electrical conductivity measurements. KW - Baltic Sea KW - coastal wetland KW - drainage of the catchment area KW - groundwater flow KW - management effects KW - system analysis KW - water balance Y1 - 2016 U6 - https://doi.org/10.5675/HyWa_2016.4_2 SN - 1439-1783 VL - 60 SP - 259 EP - 268 PB - Bundesanst. für Gewässerkunde CY - Koblenz ER - TY - JOUR A1 - Miegel, Konrad A1 - Graeff, Thomas A1 - Selle, Benny A1 - Salzmann, Thomas A1 - Franck, Christian A1 - Bronstert, Axel T1 - Investigation of a renatured fen on the Baltic Sea coast of Mecklenburg - Part I: System description and basic hydrological characterisation JF - Hydrologie und Wasserbewirtschaftung KW - Baltic Sea Coast KW - coastal wetland KW - drainage of the catchment area KW - fens KW - groundwater flow KW - management effects KW - system analysis KW - water balance Y1 - 2016 U6 - https://doi.org/10.5675/HyWa_2016.4_1 SN - 1439-1783 VL - 60 SP - 242 EP - 258 PB - Bundesanst. für Gewässerkunde CY - Koblenz ER -