Veröffentlichungen

@article{kruger2025partitioning,

title = {Partitioning of flows in the unsaturated zone},

author = {Nina Kr\"{u}ger and Christoph K\"{u}lls},

year  = {2025},

date = {2025-01-01},

journal = {Journal of Hydrology},

pages = {132643},

publisher = {Elsevier},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{FIDELIBUS2025132775,

title = {A chloride threshold to identify the onset of seawater/saltwater intrusion and a novel categorization of groundwater in coastal aquifers},

author = {M. D. Fidelibus and G. Balacco and M. R. Alfio and M. Arfaoui and D. Bassukas and C. G\"{u}ler and F. Hamzaoui-Azaza and C. K\"{u}lls and A. Panagopoulos and A. Parisi and E. Sachsamanoglou and E. Tziritis},

url = {https://www.sciencedirect.com/science/article/pii/S0022169425001131},

doi = {https://doi.org/10.1016/j.jhydrol.2025.132775},

issn = {0022-1694},

year  = {2025},

date = {2025-01-01},

journal = {Journal of Hydrology},

volume = {653},

pages = {132775},

abstract = {Seawater intrusion is the primary cause of groundwater salinisation in coastal aquifers. However, attributing salinisation solely to seawater intrusion may not always be accurate, given the likely presence of other sources. To understand if salinisation comes from seawater intrusion and its onset is crucial for groundwater management, but there are no definite threshold values for common indicators such as chlorides. Based on 1662 groundwater analyses from five Mediterranean coastal aquifers, the study aimed to distinguish the effects of mixing with present-day seawater from those caused by other sources. The trend analysis of cumulative probability plots of chloride (and total dissolved solids) is a key method for discriminating different groundwater salinisation sources and processes. Results establish that chloride, as a non-reactive tracer, is a more reliable indicator of seawater intrusion than total dissolved solids, a reactive indicator. A chloride concentration threshold of 200 mg/L identifies the seawater intrusion onset. The threshold validation comes from groundwater salinisation facies, as provided by groundwater-type codification. Fresh groundwater (Cl \< 200 mg/L) anomalous total dissolved solids highlight the input of non-chloride salts and pollutants, providing caution regarding using total dissolved solids to recognise seawater intrusion. Beyond the threshold (Cl \> 200 mg/L), data disclose emergent signals of salinisation sources and water\textendashrock interaction processes overlapping seawater intrusion or the involvement of saline fluids different from present-day seawater. The threshold and a new categorisation of groundwater in coastal aquifers according to salinisation processes provide a benchmark for identifying and managing seawater intrusion in the Mediterranean area.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kisi_etal2025,

title = {Integration of Gaussian process regression and K means clustering for enhanced short term rainfall runoff modeling},

author = {O. Kisi and S. Heddam and K. S. Parmar and A. Petroselli and C. K\"{u}lls and M. Zounemat-Kermani},

doi = {10.1038/s41598-025-91339-8},

issn = {2045-2322},

year  = {2025},

date = {2025-01-01},

journal = {Scientific Reports},

volume = {15},

number = {1},

pages = {7444},

abstract = {Accurate rainfall-runoff modeling is crucial for effective watershed management, hydraulic infrastructure safety, and flood mitigation. However, predicting rainfall-runoff remains challenging due to the nonlinear interplay between hydro-meteorological and topographical variables. This study introduces a hybrid Gaussian process regression (GPR) model integrated with K-means clustering (GPR-K-means) for short-term rainfall-runoff forecasting. The Orgeval watershed in France serves as the study area, providing hourly precipitation and streamflow data spanning 1970\textendash2012. The performance of the GPR-K-means model is compared with standalone GPR and principal component regression (PCR) models across four forecasting horizons: 1-hour, 6-hour, 12-hour, and 24-hour ahead. The results reveal that the GPR-K-means model significantly improves forecasting accuracy across all lead times, with a Nash-Sutcliffe Efficiency (NSE) of approximately 0.999, 0.942, 0.891, and 0.859 for 1-hour, 6-hour, 12-hour, and 24-hour forecasts, respectively. These results outperform other ML models, such as Long Short-Term Memory, Support Vector Machines, and Random Forest, reported in the literature. The GPR-K-means model demonstrates enhanced reliability and robustness in hourly streamflow forecasting, emphasizing its potential for broader application in hydrological modeling. Furthermore, this study provides a novel methodology for combining clustering and Bayesian regression techniques in surface hydrology, contributing to more accurate and timely flood prediction.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{KISI2024102017,

title = {Enhancing river flow predictions: Comparative analysis of machine learning approaches in modeling stage-discharge relationship},

author = {Ozgur Kisi and Hazi Mohammad Azamathulla and Fatih Cevat and Christoph Kulls and Mehdi Kuhdaragh and Mehdi Fuladipanah},

url = {https://www.sciencedirect.com/science/article/pii/S2590123024002706},

doi = {https://doi.org/10.1016/j.rineng.2024.102017},

issn = {2590-1230},

year  = {2024},

date = {2024-01-01},

journal = {Results in Engineering},

volume = {22},

pages = {102017},

abstract = {Streamflow, a pivotal variable in water resources management, holds profound significance in shaping the decision-making processes of hydrologic projects. This paper tries to delve into the exploration of the stage-discharge relationship using three machine learning methods (MLMs) namely multi-layer neural networks (MLNN), radial basis neural networks (RBNN), and neuro-fuzzy systems (ANFIS) to predict and simulate mean daily stage-discharge data derived from two monitoring stations, Bulakbasi and Karaoz\~{A}¼, Kizilirmak River, Turkey. Root mean square error (RMSE), Mean absolute percentage error (MAPE), coefficient of determination (R2), and the Developed Discrepancy Ratio (DDR) metrics were utilized to MLMs' performance assessment. The performance evaluation indices (RMSE, MAEP, R2, DDR) for the preeminent MLNN model applied to Bulakhbashi and Karasu stations were determined as (0.29, 1.57, 0.9998, 17.62) and (1.71, 6.56, 0.9980, 6.65), respectively. The MLNN model contributed to a notable enhancement in the RMSE performance index for the aforementioned stations, exhibiting improvements of 87% and 56%, respectively. These results affirm the MLNN's proficiency in accurately capturing the stage-discharge at both monitoring stations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{KRUGER2024131352,

title = {Groundwater recharge estimation in Mediterranean mountain environments by isotope profiles \textendash Partitioning of macropore and matrix flow},

author = {Nina Kr\"{u}ger and Christoph K\"{u}lls and Adriana Bruggeman and Christos Christofi},

url = {https://www.sciencedirect.com/science/article/pii/S0022169424007479},

doi = {https://doi.org/10.1016/j.jhydrol.2024.131352},

issn = {0022-1694},

year  = {2024},

date = {2024-01-01},

journal = {Journal of Hydrology},

pages = {131352},

abstract = {Developing and continuously improving effective and feasible methods to estimate groundwater recharge is essential to ensure sustainable resource assessment. Mountain environments represent key areas for the regional water balance. In this study, the isotope profile method was used to investigate water fluxes through the vadose zone and subsequent groundwater recharge in a Mediterranean mountain environment. Six high-resolution soil water isotope profiles were taken at two different locations in the Troodos Massif (Cyprus) in the eastern Mediterranean, focusing on estimating recharge in the soil of hillslopes. Analysis of the isotope profiles yielded recharge rates ranging from 30\textendash70 mm/year, leading to a re-evaluation of previous studies on groundwater recharge. The comparison of results obtained by the peak-shift method and mathematical modeling was used to partition matrix and macropore flow, reaching up to 39 %. Potential methodological limits of the environmental isotope profile method in skeleton-rich soils were found.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kisi2024improved,

title = {Improved monthly streamflow prediction using integrated multivariate adaptive regression spline with K-means clustering: implementation of reanalyzed remote sensing data},

author = {Ozgur Kisi and Salim Heddam and Kulwinder Singh Parmar and Zaheer Mundher Yaseen and Christoph Kulls},

year  = {2024},

date = {2024-01-01},

journal = {Stochastic Environmental Research and Risk Assessment},

volume = {38},

number = {6},

pages = {2489\textendash2519},

publisher = {Springer Berlin Heidelberg Berlin/Heidelberg},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ola2024remediating,

title = {Remediating Oil Contamination in the Niger Delta Region of Nigeria: Technical Options and Monitoring Strategies},

author = {Ibukun Ola and Carsten Drebenstedt and Robert M Burgess and Martin Mensah and Nils Hoth and Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

journal = {The Extractive Industries and Society},

volume = {17},

pages = {101405},

publisher = {Elsevier},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ola2024assessing,

title = {Assessing petroleum contamination in parts of the Niger Delta based on a sub-catchment delineated field assessment},

author = {Ibukun Ola and Carsten Drebenstedt and Robert M Burgess and Martin Mensah and Nils Hoth and Precious Okoroafor and Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

journal = {Environmental Monitoring and Assessment},

volume = {196},

number = {6},

pages = {585},

publisher = {Springer International Publishing Cham},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kulls2024grundwasserqualitat,

title = {Grundwasserqualit\"{a}t im Abstrom der Deponie Ihlenberg},

author = {Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kisi2024comments,

title = {Comments on “Machine learning-based time series models for effective CO2 emission prediction in India” by Kumari and Singh, https://doi. org/10.1007/s11356-022\textendash21723-8},

author = {Ozgur Kisi and Cesar Gabriel Leite e Melo and Lars Fischer and Hanna Brandt and Lennart Heims and Alexandre Loaec and Wais Masomy and Mohammed Parvez and Jan Roehl and Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

journal = {Environmental Science and Pollution Research},

pages = {1\textendash4},

publisher = {Springer Berlin Heidelberg Berlin/Heidelberg},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ola2024application,

title = {Application of low-density polyethylene (LDPE) passive samplers for monitoring PAHs in groundwater},

author = {Ibukun Ola and Carsten Drebenstedt and Robert M Burgess and Ian J Allan and Nils Hoth and Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

journal = {Environmental Science and Pollution Research},

volume = {31},

number = {42},

pages = {54546\textendash54558},

publisher = {Springer Berlin Heidelberg Berlin/Heidelberg},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{idowu2024new,

title = {A new method for monthly streamflow prediction using multi-source data: range-dependent multivariate adaptive regression splines\textendashgenetic algorithm},

author = {Mariam Idowu and Christoph Kulls and Ozgur Kisi},

year  = {2024},

date = {2024-01-01},

journal = {Hydrological Sciences Journal},

volume = {69},

number = {13},

pages = {1860\textendash1880},

publisher = {Taylor \& Francis},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ola2024combined,

title = {Combined temperature and salinity effects on the passive sampling of PAHs with an assessment of impacts to petroleum toxicity},

author = {Ibukun Ola and Carsten Drebenstedt and Robert M Burgess and Lane Tidwell and Kim Anderson and Nils Hoth and Christoph K\"{u}lls},

year  = {2024},

date = {2024-01-01},

journal = {Environmental Science: Processes \& Impacts},

volume = {26},

number = {11},

pages = {2076\textendash2089},

publisher = {Royal Society of Chemistry},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{adnan2023modelling,

title = {Modelling biochemical oxygen demand using improved neuro-fuzzy approach by marine predators algorithm},

author = {Rana Muhammad Adnan and Hong-Liang Dai and Ozgur Kisi and Salim Heddam and Sungwon Kim and Christoph Kulls and Mohammad Zounemat-Kermani},

year  = {2023},

date = {2023-01-01},

journal = {Environmental Science and Pollution Research},

volume = {30},

number = {41},

pages = {94312\textendash94333},

publisher = {Springer Berlin Heidelberg Berlin/Heidelberg},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kisi2023discussion,

title = {Discussion of “Improving Prediction Accuracy of Hydrologic Time Series by Least-Squares Support Vector Machine Using Decomposition Reconstruction and Swarm Intelligence”},

author = {Ozgur Kisi and Kai Liepelt and Christoph Kulls},

year  = {2023},

date = {2023-01-01},

journal = {Journal of Hydrologic Engineering},

volume = {28},

number = {4},

pages = {07023001},

publisher = {American Society of Civil Engineers},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kisi2023comments,

title = {Comments on “Splitting tensile strength prediction of sustainable high-performance concrete using machine learning techniques” by Wu, Yangi et al., https://doi. org/10.1007/s11356-022-22048-2},

author = {Ozgur Kisi and Sara Ajri and Kim Cedric J\"{o}rgens and Arti Karande and Sabine Kraus and Benita Naumann and Kim Nierman and Wiebke Seel and Christoph Kulls},

year  = {2023},

date = {2023-01-01},

journal = {Environmental Science and Pollution Research},

volume = {30},

number = {50},

pages = {109854\textendash109855},

publisher = {Springer Berlin Heidelberg Berlin/Heidelberg},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kisi2023estimation,

title = {Estimation of mean velocity upstream and downstream of a bridge model using metaheuristic regression methods},

author = {Ozgur Kisi and Mehmet Ardi\c{c}lio\u{g}lu and Arzu MW Hadi and Alban Kuriqi and Christoph Kulls},

year  = {2023},

date = {2023-01-01},

journal = {Water Resources Management},

volume = {37},

number = {14},

pages = {5559\textendash5580},

publisher = {Springer Netherlands Dordrecht},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{eliades2022quantifying,

title = {Quantifying evapotranspiration and drainage losses in a semi-arid nectarine (Prunus persica var. nucipersica) field with a dynamic crop coefficient (Kc) derived from leaf area index measurements},

author = {Marinos Eliades and Adriana Bruggeman and Hakan Djuma and Christos Christofi and Christoph Kuells},

year  = {2022},

date = {2022-01-01},

journal = {Water},

volume = {14},

number = {5},

pages = {734},

publisher = {MDPI},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mehraein2022monthly,

title = {Monthly streamflow prediction by metaheuristic regression approaches considering satellite precipitation data},

author = {Mojtaba Mehraein and Aadhityaa Mohanavelu and Sujay Raghavendra Naganna and Christoph Kulls and Ozgur Kisi},

year  = {2022},

date = {2022-01-01},

journal = {Water},

volume = {14},

number = {22},

pages = {3636},

publisher = {MDPI},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{christofi2020hydrochemicalb,

title = {Hydrochemical evolution of groundwater in gabbro of the Troodos Fractured Aquifer. A comprehensive approach},

author = {Christos Christofi and Adriana Bruggeman and Christoph Kuells and Costas Constantinou},

year  = {2020},

date = {2020-01-01},

journal = {Applied Geochemistry},

volume = {114},

pages = {104524},

publisher = {Pergamon},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mahindawansha2020investigatingb,

title = {Investigating unproductive water losses from irrigated agricultural crops in the humid tropics through analyses of stable isotopes of water},

author = {Amani Mahindawansha and Christoph K\"{u}lls and Philipp Kraft and Lutz Breuer},

year  = {2020},

date = {2020-01-01},

journal = {Hydrology and Earth System Sciences},

volume = {24},

number = {7},

pages = {3627\textendash3642},

publisher = {Copernicus Publications G\"{o}ttingen, Germany},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{christofi2020isotope,

title = {Isotope hydrology and hydrogeochemical modeling of Troodos Fractured Aquifer, Cyprus: The development of hydrogeological descriptions of observed water types},

author = {Christos Christofi and Adriana Bruggeman and Christoph Kuells and Costas Constantinou},

year  = {2020},

date = {2020-01-01},

journal = {Applied Geochemistry},

volume = {123},

pages = {104780},

publisher = {Pergamon},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{joseph2019applicationb,

title = {Application of a laser-based spectrometer for continuous in situ measurements of stable isotopes of soil CO 2 in calcareous and acidic soils},

author = {Jobin Joseph and Christoph K\"{u}lls and Matthias Arend and Marcus Schaub and Frank Hagedorn and Arthur Gessler and Markus Weiler},

year  = {2019},

date = {2019-01-01},

journal = {Soil},

volume = {5},

number = {1},

pages = {49\textendash62},

publisher = {Copernicus Publications G\"{o}ttingen, Germany},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mahindawansha2019estimating,

title = {Estimating water flux and evaporation losses using stable isotopes of soil water from irrigated agricultural crops in tropical humid regions},

author = {Amani Mahindawansha},

year  = {2019},

date = {2019-01-01},

publisher = {Deutsche Nationalbibliothek},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ardelt2018towards,

title = {Towards intrinsic molecular communication using isotopic isomerism},

author = {Gunther Ardelt and Christoph K\"{u}lls and Horst Hellbr\"{u}ck},

year  = {2018},

date = {2018-01-01},

journal = {Open Journal of Internet Of Things (OJIOT)},

volume = {4},

number = {1},

pages = {135\textendash143},

publisher = {RonPub},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{androvitsanea2018hydrologische,

title = {Hydrologische Bedingungen im Heraion von Samos vom 12. bis 8. Jh. v. Chr. und ihre Bedeutung f\"{u}r die wasserbauliche Infrastruktur},

author = {Anna Androvitsanea and Mohammad Fawzy and Johanna Fuchs and Christoph Jan Kuells and Henning Fahlbusch and Joachim Heiden},

year  = {2018},

date = {2018-01-01},

journal = {Environmental Water Engineering},

volume = {1},

number = {1},

pages = {1\textendash21},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{mueller2014trackingb,

title = {Tracking water pathways in steep hillslopes by δ18O depth profiles of soil water},

author = {Matthias H Mueller and Abdallah Alaoui and Christoph Kuells and Hannes Leistert and Katrin Meusburger and Christine Stumpp and Markus Weiler and Christine Alewell},

year  = {2014},

date = {2014-01-01},

journal = {Journal of hydrology},

volume = {519},

pages = {340\textendash352},

publisher = {Elsevier},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hamutoko2014fingerprintingb,

title = {A fingerprinting method for the identification of uranium sources in alluvial aquifers: An example from the Khan and Swakop Rivers, Namibia},

author = {JT Hamutoko and BS Mapani and R Ellmies and A Bittner and C Kuells},

year  = {2014},

date = {2014-01-01},

journal = {Physics and Chemistry of the Earth, Parts A/B/C},

volume = {72},

pages = {34\textendash42},

publisher = {Pergamon},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Klaus2013macropore,

title = {Macropore flow of old water revisited: experimental insights from a tile-drained hillslope},

author = {J. Klaus and E. Zehe and M. Elsner and C. K\"{u}lls and J. J. McDonnell},

doi = {https://doi.org/10.5194/hess-17-103-2013},

year  = {2013},

date = {2013-01-01},

journal = {Hydrology and Earth System Sciences},

volume = {17},

number = {1},

pages = {103},

publisher = {Copernicus GmbH},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{baram2013desiccationb,

title = {Desiccation-crack-induced salinization in deep clay sediment},

author = {S Baram and Z Ronen and D Kurtzman and C K\"{u}lls and O Dahan},

year  = {2013},

date = {2013-01-01},

journal = {Hydrology and Earth System Sciences},

volume = {17},

number = {4},

pages = {1533\textendash1545},

publisher = {Copernicus GmbH},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kulls12013passive,

title = {Passive barriers for long-term containment of Uranium and Vanadium},

author = {Christoph K\"{u}lls and Arnold Bittner},

year  = {2013},

date = {2013-01-01},

urldate = {2013-01-01},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kulls2013strategic,

title = {Strategic Assessment of Water Resources for the Erongo Uranium Province},

author = {Christoph K\"{u}lls and Arnold Bittner and Vera Marx},

year  = {2013},

date = {2013-01-01},

journal = {Reliable Mine Water Technology, edited by Adrian Brown, Linda Figueroa, and Christian Wolkersdorfer},

volume = {1},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{davila2013toolkitb,

title = {A toolkit for groundwater mean residence time interpretation with gaseous tracers},

author = {Pablo Fernando D\'{a}vila and Christoph K\"{u}lls and Markus Weiler},

year  = {2013},

date = {2013-01-01},

journal = {Computers \& Geosciences},

volume = {61},

pages = {116\textendash125},

publisher = {Pergamon},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{klaus2012macropore,

title = {Macropore flow of old water revisited: where does the mixing occur at the hillslope scale?},

author = {J Klaus and E Zehe and M Elsner and C K\"{u}ulls and JJ McDonnell},

year  = {2012},

date = {2012-01-01},

journal = {Hydrology \& Earth System Sciences Discussions},

volume = {9},

number = {4},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{garvelmann2012porewaterb,

title = {A porewater-based stable isotope approach for the investigation of subsurface hydrological processes},

author = {Jakob Garvelmann and Christoph K\"{u}lls and Markus Weiler},

year  = {2012},

date = {2012-01-01},

journal = {Hydrology and Earth System Sciences},

volume = {16},

number = {2},

pages = {631\textendash640},

publisher = {Copernicus Publications G\"{o}ttingen, Germany},

keywords = {},

pubstate = {published},

tppubtype = {article}

}