Christoph J. KuellsUniversity of Applied Sciences, Lübeck, Germany · Civil Engineering, Laboratory for Hydrology and International Water Management
Christoph J. Kuells
Dr. Dipl. Hydr.
About
91
Publications
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Introduction
Hydrologist with a background in hydrogeology and geochemistry specialized and interested in water resources assessment, water quality studies and integration of solute cycles with the hydrological cycle. Working experience in the Eastern Mediterranean (Greece, Cyprus, Israel, Jordan), in Sub-Saharan and Central/Eastern Africa (South Africa, Namibia, Burundi, Rwanda) and in South-America (Brazil). I am trying to develop applied research involving SMEs and producing results for the 'real world'.
Additional affiliations
Education
March 1997 - December 2000
October 1988 - October 1994
Albert Ludwigs University Freiburg, Institute of Hydrology
Field of study
- Hydrology
Publications
Publications (91)
This study investigates monthly streamflow modeling at Kale and Durucasu stations in the Black Sea Region of Turkey using remote sensing data. The analysis incorporates key meteorological variables, including air temperature, relative humidity, soil wetness, wind speed, and precipitation. The study also investigates the accuracy of multivariate ada...
This study compares four data-driven methods, Gaussian process regression (GPR), multivariate adaptive regression spline (MARS), M5 model tree (M5Tree), and multilinear regression (MLR), in estimating mean velocity upstream and downstream of bridges. Data were obtained through multiple experiments in a rectangular laboratory flume with glass walls...
Biochemical oxygen demand (BOD) is one of the most important parameters used for water quality assessment. Alternative methods are essential for accurately prediction of this parameter because the traditional method in predicting the BOD is time-consuming and it is inaccurate due to inconstancies in microbial multiplicity. In this study, the applic...
In this study, the viability of three metaheuristic regression techniques, CatBoost (CB), random forest (RF) and extreme gradient tree boosting (XGBoost, XGB), is investigated for the prediction of monthly streamflow considering satellite precipitation data. Monthly streamflow data from three measuring stations in Turkey and satellite rainfall data...
The coastal aquifer of the Rhodope region (NE Greece) is a complex groundwater
system characterized by locally increased salinity. Identifying the exact nature and
spatial orientation of the multi-induced salinization sources and their functioning
processes is a major step towards sustainable groundwater management. An
integrated methodology has be...
In coastal aquifers, many factors influence the 3D groundwater density distribution, including aquifer geologic structure, hydraulic field, sea-level oscillations, recharge, and exploitation. The combination of natural and human pressures controls the equilibrium between freshwater and salt waters. The response time to pressures and boundary condit...
Quantifying evapotranspiration and drainage losses is essential for improving irrigation efficiency. The FAO-56 is the most popular method for computing crop evapotranspiration. There is, however, a need for locally derived crop coefficients (Kc) with a high temporal resolution to reduce errors in the water balance. The aim of this paper is to intr...
The origin of groundwater recharge and subsequent flow paths are often difficult to establish in fractured, multi-lithological, and highly compartmentalized aquifers such as the Troodos Fractured Aquifer (TFA). As the conjunctive use of stable isotopes and hydrogeochemical data provides additional information, we established a monitoring network fo...
Reliable information on water flow dynamics and water losses via irrigation on irrigated agricultural fields is important to improve water management strategies. We investigated the effect of season (wet season and dry season), irrigation management (flooded and non-flooded), and crop diversification (wet rice, dry rice, and maize) on soil water fl...
Reliable information on water flow dynamics and water losses via irrigation on irrigated agricultural fields is important to improve water management strategies. We investigated the effect of season (wet season and dry season), irrigation management (flooded and non-flooded), and crop diversification (wet rice, dry rice, and maize) on soil water fl...
The wide-range applications of isotope analysis make isotope measurement approaches under attentive focus. Off-axis integrated cavity output spectroscopy technology (OA-ICOS) is the most advanced isotope analysis method; however, further studies are still needed to avoid signal noise and improve accuracy. Zero-phase low pass filtering multivariate...
Ophiolites often form complex, fractured, multi-lithological and highly compartmentalized aquifers that are difficult to characterize. Groundwater chemistry reflects water-rock interactions and can provide insights to groundwater recharge mechanisms, flow paths and relative residence time. A comprehensive hydrogeochemical modelling approach with PH...
Reliable information on water flow dynamics and water losses via irrigation on irrigated agricultural fields is important to advance water management strategies. We investigated the effect of season (wet season, dry season), irrigation management (flooded, non-flooded), and crop diversification (wet rice, dry rice, and maize) on soil water dynamics...
This study proposes a multi-source data approach to estimating annual rates of floodwater recharge into the lower alluvial Andarax aquifer. The Andarax River catchment is about 2200 Km2, and although it is permanent in the upper part of the basin, the middle and lower catchment is ephemeral. The climate is Mediterranean with an annual average tempe...
The short-term dynamics of carbon and water fluxes across the soil–plant–atmosphere continuum are still not fully understood. One important constraint is the lack of methodologies that enable simultaneous measurements of soil CO2 concentration and respective isotopic composition at a high temporal resolution for longer periods of time. δ13C of soil...
The short-term dynamics of carbon and water fluxes across the soil–plant–atmosphere continuum are still not fully understood. One important constraint is the lack of methodologies that enable simultaneous measurements of soil CO2 concentration and its isotopic composition at a high temporal resolution for longer periods of time. δ¹³C of soil CO2 ca...
Stable Isotopes of water are powerful proxies for the description of water fluxes such as infiltration, evapotranspiration and plant water uptake in a natural water resource system. Especially the measurement of soil pore water provides information on soil hydraulic properties and interactions within the soil-plant-atmosphere-interface. To gather s...
An analytical Excel-based toolkit called Gas-Tracer-Interpretation (GTI) was developed for determining mean residence time (MRT) of groundwater samples and for validating conceptual model assumptions. This novel data interpretation toolkit improves data handling during analysis and resolves some problems in the interpretation of data from environme...
The development of uranium mining in the arid Erongo region of central western Namibia has increased pressure on limited water resources. An assessment of available water resources and demand from different stakeholders was carried out. An Integrated Geohydrological Model (IGHMS) was developed. IGHMS produces time series of key hydrological process...
A study on water infiltration and solute transport in a clayey vadose
zone underlying a dairy farm waste source was conducted to assess the
impact of desiccation cracks on subsurface evaporation and salinization.
The study is based on five years of continuous measurements of the
temporal variation in the vadose zone water-content and on the chemica...
Eco-hydrology is a recently emerging discipline combining the realms of water and ecology and exploring the interactions between ecosystems and hydrological processes. In few areas this close interaction is more pronounced, visible and decisive than in desert restoration. The degradation of drylands leads to a decline in ecosystem functioning and e...
Since atmospheric tritium levels have neru·ly reached the nantral background, there is
a need for fmther development of existing or additional methods for the age dating of young
water. Non-gaseous age dating tracers ru·e especially needed for hydrological applications in
lakes, livers and springs and for surface- groundwater interaction studies...
The mechanisms allowing the rapid release of stored water to streams are poorly understood. Here we use a tile-drained field site to combine macroporous soils at the hillslope scale with the advantage of at least partly controlled lower boundary conditions. We performed a series of three irrigation experiments combining hydrometric measurements wit...
The mechanisms allowing the rapid release of stored water to streams are
poorly understood. Here we use a tile drained field site to combine
naturally structured soils at the hillslope scale with the advantage of
at least partly controlled lower boundary conditions. We performed a
series of three irrigation experiments combining hydrometric
measure...
Predicting and understanding subsurface flowpaths is still a crucial issue in hydrological research. We present an experimental approach to reveal present and past subsurface flowpaths of water in the unsaturated and saturated zone. Two hillslopes in a humid mountainous catchment have been investigated. The H<sub>2</sub>O<sub>(liquid)</sub> – H<sub...
Predicting and understanding subsurface flowpaths is still a crucial issue in hydrological research. We present an experimental approach to reveal present and past subsurface flowpaths of water in the unsaturated and saturated zone. Two hillslopes in a humid moutainous catchment have been investigated. The H<sub>2</sub>O<sub>(liquid)</sub> – H<sub>...
Age dating of water based on dissolved CFCs and Krypton-85 has been applied extensively for many years. CFCs were adopted as an approach for water dating due to the availability of global input functions and because of a straightforward methodology. In the last decade, due to international treaties, CFCs production and atmospheric concentrations of...
This paper summarises innovative research into the assessment of long-term groundwater recharge from flood events in dryland environments of the Kuiseb (Namibia) and the Buffels (South Africa) rivers. The integrated water resource management (IWRM) policies and institutions affecting the exploitation of groundwater resources in each of these develo...
The isotopic composition of precipitation and melt-water lakes in Svalbard was studied. The IAEA precipitation record of monthly precipitation data from Ny Alesund reveals a much stronger and regular seasonal variability of deuterium excess compared to oxygen-18 and deuterium. The seasonal amplitude of deuterium excess in Ny Alesund is more pronoun...
System approachDefinition of tracersModelling in the context of integrated tracerhydrologyFields of application
GroundwaterCase studies in the unsaturated zone and in soilsSurface waterGlaciersCatchment scale
Plate 1, 2Plate 3aPlate 3b-dPlate 4aPlate 4bPlate 4cPlate 5 and 6Plate 5aPlate 5bPlate 5cPlate 6aPlate 6bPlate 6cPlate 7Plate 7aPlate 7bPlate 8aPlate 8bPlate 8c
Fluorescent tracersSalt tracersDrifting particles as tracersRadioactive tracersOther tracers
Planning and execution of a tracer studyEstimation of tracer injection massGauging dischargeChloride method for groundwater recharge estimationHydrograph separation using the end member mixing analysis (EMMA)
Flood water infiltrates ephemeral channels, recharging local and regional aquifers, and it is the main water source in hyperarid regions. Quantitative estimations of these resources are limited by the scarcity of data from such regions. The floods of the Kuiseb River in the Namib Desert have been monitored for 46 years, providing a unique data set...
With few exceptions, only limited hydrologic data are available in regions with the highest scarcity of water. Especially in basins with limited data on hydrogeological structure, it is difficult to accurately characterize groundwater flow systems and their recharge sources. Therefore, estimation of available water resources in drylands requires me...
In arid and semi-arid regions alluvial groundwater resources of ephemeral streams are highly important for water supplies and ecosystems. Recent projects have studied processes of indirect recharge in situ and in detail (Dahan et al., 2008; Klaus et al., 2008). Still, little is known about the vulnerability of these aquifers to environmental impact...
CFCs (11, 12, 113) and SF6 have been used for age dating of recent groundwater (
The representation of hydrological processes and biogeochemical feedbacks in common soil-vegetation-atmosphere-schemes constrains their response and adaptation to climate change impacts. A comparative study and review of SVAT schemes commonly used for the evaluation of climate change impacts shows that they differ significantly in emphasizing diffe...
A mixing cell approach was extended by a method incorporating mean cell residence times derived from 14C to further constrain and validate the modeling results. This extended approach was used to model the groundwater system of the Lower Kuiseb Dune area in Namibia. The Kuiseb river is a 560 km long ephemeral river that crosses the Namib Desert fro...
A study on flood water infiltration and ground water recharge of a shallow alluvial aquifer was conducted in the hyperarid section of the Kuiseb River, Namibia. The study site was selected to represent a typical desert ephemeral river. An instrumental setup allowed, for the first time, continuous monitoring of infiltration during a flood event thro...
Multidisciplinary research in the hyperarid Kuiseb River, Namibia provides the necessary information to determine (a) long-term floods occurrence and aquifer recharge events and (b) flood routing and transmission processes along the river course. Together they assist in estimating water resources along the river. The only source of water along the...
A study on flood water infiltration and ground water recharge of a shallow alluvial aquifer was conducted in the hyperarid section of the Kuiseb River, Namibia. The study site was selected to represent a typical desert ephemeral river. An instrumental setup allowed, for the first time, continuous monitoring of infiltration during a flood event thro...
Groundwater recharge studies in semi-arid areas are fundamental because groundwater is often the only water resource of importance. This paper describes the water balance method of groundwater recharge estimation in three different hydro-climatic environments in eastern Mediterranean, in northwest Greece (Aliakmonas basin/Koromilia basin), in Cypru...
Jordan is classified as an arid to semi-arid country with a population according to 1999 estimates of 4·8 millions inhabitants and a growth rate of 3·4%. Efficient use of Jordan's scarce water is becoming increasingly important as the urban population grows. This study was carried out within the framework of the joint European Research project ‘Gro...
While Integrated Natural Resources Management (INRM) creates a need for an integration of natural and socio-economic information, suitable approaches and tools are needed to facilitate this integration. If these tools are meant to support the decision-making process of the stakeholders, it is important that they are adapted to the needs and require...
TRÖGER, U., DIAS, C.L.; GUILLAUMON, J.R.; IRITANI, M.A.; KÜLLS, C.; SCHULER, G. 2004. Remarks and new data about the recharge of the Guarani Aquifer System. In: IAH, IAH Congress, 34, Proceedings, Zacatecas, México.
The WAVES program (Water Availability, Vulnerability of Ecosystems and Society in Northeastern Brazil) aims at creating a knowledge base and strategies for sustainable development for the drought-prone northeast of Brazil. The perspective of climate change in a semiarid area with marginal water supplies requires strategic measures in order to avoid...
A quantitative model of groundwater flows contributing to the Goblenz state water scheme at the north-western fringe of the Kalahari was developed within this study. The investigated area corresponds to the Upper Omatako basin and encompasses an outer mountainous rim and sediments of the Kalahari sand desert in the centre. This study revealed the e...
One aim of the WAVES program (http://www.usf.uni-kassel.de/waves) was to identify sustainable development paths for Ceará and Piauí, two states in the semi-arid northeast of Brazil. In these states, regional development is negatively influenced by the high seasonality of rainfall and El-Niño-related drought years. The research focused on the interr...
Only a spatially distributed approach can sufficiently describe recharge distribution in a large catchment. In this study the decreasing chloride concentration along groundwater flow paths has been used to represent recharge areas within the groundwater basin. Absolute recharge values, derived by application of the chloride balance method in the sa...
An inverse hydrochemical mixing cell modelling approach has been used for the assessment of water resources in the Otjozondjupa region at the western fringe of the Kalahari basin, Namibia. The analysis is based on hydrochemical data from 1530 wells in the Omatako basin. Cluster analysis applied to a hydrochemical database was used to define, subdiv...
Drought behaviour was investigated using standard methods of the theory of runs, which describe the duration and the deficit volume (severity) of a low flow event. The threshold chosen as Q90 produces zero elements. These zero elements are a problem for common fitting procedures. For the generalized extreme value distribution two estimation methods...
For the estimation of transmission losses in an ephemeral stream, two infiltration tests were conducted in the dry channel. The advance of the wetting front was monitored with resistance plates. The hydraulic parameters for two infiltration models were derived using inverse estimation methods. Additionally dye tracer was used to investigate flow pa...