Ann van Griensven

Ann van Griensven
Vrije Universiteit Brussel | VUB · Department of Hydrology and Hydraulic Engineering (HYDR)

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183
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Publications

Publications (183)
Preprint
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Global hydrological models are essential tools for understanding water resources and assessing climate change impacts at planetary scales, supporting water management, flood risk assessment, and sustainable development initiatives worldwide. The Soil and Water Assessment Tool (SWAT+) has demonstrated robust performance across various environments a...
Article
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Understanding the spatial and temporal patterns of sediment loading in water bodies is crucial for effective water quality management. Remote sensing (RS) has emerged as a valuable and reliable tool for monitoring turbidity, which can provide insights into sediment dynamics in water bodies. In this study, we investigate the potential of turbidity d...
Article
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CONTEXT Climate change's profound implications for Mediterranean agriculture underscores the urgency of adaptation strategies. These strategies, whether incentivized or farmer-driven, are pivotal in mitigating crop yield losses and harnessing evolving climatic conditions. While the influence of agronomic adaptations on crop yields is well-explored,...
Article
Intensive tillage (IT) in potato crops is considered as one of the main non-point sources (NPS) of local water eutrophication in the Fuquene Lake of Colombia. Therefore, the local government has invested in several programs aiming at the adoption of principles of conservation tillage (CT) which would allow for developing and applying the agricultur...
Article
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This study applies the soil and water assessment tool (SWAT), with climate (precipitation and temperature) outputs from four general circulation models (GCMs) and a regional circulation model (PRECIS), to evaluate (1) the impacts of climate change on reservoir sedimentation and (2) the impacts of climate change and reservoir development on sediment...
Article
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This paper presents a heuristic probabilistic approach to estimating the size-dependent mobilities of nonuniform sediment based on the pre- and post-entrainment particle size distributions (PSDs), assuming that the PSDs are lognormally distributed. The approach fits a lognormal probability density function to the pre-entrainment PSD of bed sediment...
Article
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The Upper Blue Nile (UBN) basin is less-explored in terms of drought studies as compared to other parts of Ethiopia and lacks a basin-specific drought monitoring system. This study compares six drought indices: Standardized Precipitation Index (SPI), Standardized Precipitation Evaporation Index (SPEI), Evapotranspiration Deficit Index (ETDI), Soil...
Article
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In this paper, evapotranspiration (ET) and leaf area index (LAI) were used to calibrate the SWAT model, whereas remotely sensed precipitation and other climatic parameters were used as forcing data for the 6300 km2 Day Basin, a tributary of the Red River in Vietnam. The efficacy of the Sequential Uncertainty Fitting (SUFI-2) parameter sensitivity a...
Article
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Existing dimensionless expressions that represent the incipient motion of sediments are based on studies of non-cohesive sediments. Because of the complex behaviour of cohesive sediments, many simulators also assume non-cohesiveness when simulating the erosion of cohesive sediments. However, studies show that the critical shear force needed for ent...
Article
Accurate and spatially distributed rainfall data are crucial for a realistic simulation of the hydrological processes in a watershed. However, limited availability of observed hydro-meteorological data often challenges the rainfall–runoff modelling efforts. The main goal of this study is to evaluate the Climate Forecast System Reanalysis (CFSR) and...
Article
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An intercomparison of climate change impacts projected by nine regional‐scale hydrological models for 12 large river basins on all continents was performed, and sources of uncertainty quantified in the framework of the ISIMIP project. The models ECOMAG, HBV, HYMOD, HYPE, mHM, SWAT, SWIM, VIC and WaterGAP3 were applied in the following basins: Rhine...
Article
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The Soil and Water Assessment Tool (SWAT) is a globally applied river basin ecohydrological model used in a wide spectrum of studies, ranging from land use change and climate change impacts studies to research for the development of the best water management practices. However, SWAT has limitations in simulating the seasonal growth cycles for trees...
Article
To properly estimate and manage pesticide occurrence in urban rivers, it is essential, but often highly challenging, to identify the key pesticide transport pathways in association to the main sources. This study examined the concentration-discharge hysteresis behaviour (hysteresis analysis) for three pesticides and the parent-metabolite concentrat...
Article
Most common numerical solutions used in CSTR-based in-stream water quality simulators are susceptible to instabilities and/or solution inconsistencies. Usually, they cope with instability problems by adopting computationally expensive small time steps. However, some simulators use fixed computation time steps and hence do not have the flexibility t...
Article
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Distributed hydrological models are usually calibrated against the measured outflow of a certain drainage area, provided flow data is available. A close match with flow does however not mean that the spatially distributed hydrological processes are properly understood and simulated. In this paper, remotely sensed precipitation, evapotranspiration (...
Article
Global Sensitivity Analysis (GSA) is an essential technique to support the calibration of environmental models by identifying the influential parameters (screening) and ranking them. In this paper, the widely-used variance-based method (Sobol') and the recently proposed moment-independent PAWN method for GSA are applied to the Soil and Water Assess...
Conference Paper
Full-text available
Parameter estimation is a major concern in hydrological modeling, which may limit the use of complex simulators with a large number of parameters. To support the selection of parameters to include in or exclude from the calibration process, Global Sensitivity Analysis (GSA) is widely applied in modeling practices. Based on the results of GSA, the i...
Article
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Actual evapotranspiration (ET) is a major water use flux in a basin water balance with crucial significance for water resources management and planning. Mapping ET with good accuracy has been the subject of ongoing research. Such mapping is even more challenging in heterogeneous and data-scarce regions. The main objective of our research is to esti...
Article
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We present one of the first climate change impact assessments on river runoff that utilises an ensemble of global hydrological models (Glob-HMs) and an ensemble of catchment-scale hydrological models (Cat-HMs), across multiple catchments: the upper Amazon, Darling, Ganges, Lena, upper Mississippi, upper Niger, Rhine and Tagus. Relative changes in s...
Article
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This paper aims to evaluate sources of uncertainty in projected hydrological changes under climate change in twelve large-scale river basins worldwide, considering the mean flow and the two runoff quantiles Q10 (high flow), and Q90 (low flow). First, changes in annual low flow, annual high flow and mean annual runoff were evaluated using simulation...
Article
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The aim of this study was to investigate the impacts of future climate change on discharge and evapotranspiration of the Upper Blue Nile (UBN) basin using multiple global circulation models (GCMs) projections and multiple hydrological models (HMs). The uncertainties of projections originating from HMs, GCMs, and representative concentration pathway...
Article
Although the soil and water assessment tool (SWAT) is a physically based hydrologic simulator, it has many parameters that cannot be measured directly in the field, but must be obtained through a model calibration process. Model calibration is thus an essential task to obtain the optimal parameter values, which match simulations with observations a...
Article
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Recharge assessment is of critical importance for groundwater resources evaluation in arid/semiarid areas, as these have typically limited surface water resources. There are several models for water balance evaluation. One of them is WetSpass, which has the ability to simulate spatially distributed recharge, surface runoff, and evapotranspiration f...
Article
Full-text available
The Soil and Water Assessment Tool (SWAT) is a globally applied river basin eco-hydrological simulator in a wide spectrum of studies, ranging from land use change and climate change impacts studies to research for the development of best water management practices. However, SWAT has limitations in simulating the seasonal growth cycles for trees and...
Conference Paper
The global trend of urbanisation leads to worldwide increase of impervious surfaces. Urban runoff can be a significant source of pesticides in urban water, due to the high fraction of impervious surfaces in urban areas and the frequent use of pesticides for urban weed and pest control. Various experimental studies on hard surfaces (e.g. concrete, a...
Article
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Land-use and land-cover changes are driving unprecedented changes in ecosystems and environmental processes at different scales. This study was aimed at identifying the potential land-use drivers in the Jedeb catchment of the Abbay basin by combining statistical analysis, field investigation and remote sensing. To do so, a land-use change model was...
Conference Paper
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Agricultural Water Productivity (AWP) is often simplified as the ‘crop per drop’, described as the output in terms of yield or biomass per unit of water input. This purely physical measure of Water Productivity (WP) using only a single factor input (water) does not consider: (1) the level of other inputs used in conjunction with water, (2) the oppo...
Article
Full-text available
To meet growing population demands for food and other agricultural commodities, agricultural land-use intensification and extensification seems to be increasing in the Abbay (Upper Blue Nile) basin in Ethiopia. However, the amount, location and degree of suitability of the basin for agriculture seem not well studied and/or documented. From global d...
Technical Report
An overview of the state-of-the-art of water quality modelling for water quality management is presented. There are different types of models: data driven black box models, empirical/conceptual models and physically-based models. Models are needed to represent the sewer-waterwater-river-catchment system. Also sediment transport is a very important...
Poster
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Groundwater storage can have a significant contribution to stream flow, therefore a thorough understanding of the groundwater surface water interaction is of prime important when doing catchment modeling. The aim of this study is to improve the simulation of groundwater - surface water interaction in a catchment model of the upper Zenne River basin...
Presentation
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We present the model results and their uncertainties of an inter-sectoral impact model inter-comparison initiative (ISI-MIP) for climate change impacts in Africa. The study includes results on hydrological, crop and health aspects. The impact models used ensemble inputs consisting of 20 time series of daily rainfall and temperature data obtained fr...
Poster
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Urban areas can significantly contribute to pesticide contamination in surface water. However, pesticide behaviours in urban areas, particularly on hard surfaces, are far less studied than those in agricultural areas. Pesticide application on hard surfaces (e.g. roadsides and walkways) is of particular concern due to the high imperviousness and the...
Article
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One of the key inputs of a hydrological model is the potential evapotranspiration (PET), which sets an upper limit to evapotranspirative water demand. However, limited data availability often challenges the choice of a PET estimation method, which in turn affects the PET estimates as well as the water balance (WB) components. The objectives of this...
Conference Paper
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Wetlands are very valuable areas because they provide a wide range of ecosystems services therefore modeling of wetland areas is very relevant, however, the most widely used hydrological models were developed in the 90s and usually are not adjusted to simulate wetland conditions. In case of wetlands including interception storage into the model’s c...
Poster
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Herbicide uses on hard surfaces can be significant sources of herbicides in urban waters due to the high imperviousness of hard surfaces and therefore high herbicide runoff potential. To quantify herbicide losses from hard surfaces, numerous experimental studies have been conducted at various temporal and spatial scales during the past decades. How...
Conference Paper
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This article deals with future climate change impact on surface and ground water flow in Kleine Nete river basin, Belgium. The future climate change is predicted by four SRES (Special Report on Emission Scenarios) climate change scenarios (A1B, A2, B1 and B2) which were downscaled for Belgium. This case study has an area of 581 km with dominant san...
Conference Paper
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ET is an important component of the hydrological cycle and it completes the energy balance of the cycle in the vegetation-soil and atmosphere interface. ET is a combination of evaporation from land surface, open water, soil zone and transpiration from vegetation. The proportion of the ET flux in the water balance varies and it could be as high as 9...
Conference Paper
Full-text available
The high number of parameters is a major problem for complex environmental models as it restricts their application. Therefore, sensitivity analysis (SA) methods, that aim to identify the influential and the non-influential parameters of a model, can be essential for an efficient calibration of these models. The SA indeed allows for a reduction of...
Conference Paper
Full-text available
SWAT (Soil and Water Assessment Tool) is a physically-based, semi-distributed hydrological simulator, which has been widely used to support alternative watershed management practices in large river basins all over the world. A SWAT model includes a large number of parameters, requiring a model optimization process -i.e. calibration- for their estim...
Conference Paper
Full-text available
Uncertainty in parameters is a well-known reason of model output uncertainty which, undermines model reliability and restricts model application. A large number of parameters, in addition to the lack of data, limits calibration efficiency and also leads to higher parameter uncertainty. Global Sensitivity Analysis (GSA) is a set of mathematical tech...
Article
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doi: 10.1080/02626667.2015.1032291 This study investigates the spatial and temporal variation of meteorological droughts in the Upper Blue Nile (UBN) basin in Ethiopia using longer historical records (1953–2009) of 14 meteorological stations, and 23 other stations with relatively shorter records (1975–2009). The influence of using varying record l...
Article
Urban runoff can be a significant source of pesticides in urban streams. However, quantification of this source has been difficult because pesticide use by urban residents (e.g., on pavements or in gardens) is often unknown, particularly at the scale of a residential catchment. Proper quantification and characterization of pesticide loss via urban...
Conference Paper
As well-known of the largest flat low-lying and fertile delta in the world, the Mekong River Delta experiences annual widespread flooding where mainly provides primary sources for about 17 million habitants, of which, suspended sediment load play an important role in carrying contaminants, nutrients, etc.. used for agriculture cultivation as well a...
Conference Paper
Full-text available
In the past, the QUAL principles have been widely used to describe the processes that define the oxygen levels in rivers. The more recently developed IWA river water quality model No.1 (RWQM1) has however a more sound theoretical background. Moreover, as the state variables of RWQM1 are similar to those of the activated sludge model for waste water...
Conference Paper
Full-text available
Ecosystem services assessment requires an integrated approach, as it is influenced by elements such as climate, hydrology and socio-economics, which in turn influence each other. However, there are few studies that integrate these elements in order to assess ecosystem services. Absence of integrated approach to modelling hydrological and land-use c...
Conference Paper
Runoff from urban hard surfaces may be an important source of herbicides in urban streams. And HardSPEC (UK) is the only available tool that is specifically used in regulatory context to estimate the predicted environmental concentrations (PECs) of herbicides due to uses on hard surfaces. To investigate the loss of a widely-used herbicide (glyphosa...
Conference Paper
Full-text available
Urban hard surfaces are considered as important facilitators for pesticide transport into urban streams. To obtain concurrent high-resolution data for a detailed investigation on the losses of pesticide runoff from hard surfaces, a monitoring campaign was performed in a typical Belgian residential area (9.5 ha) between 7 May and 7 August, 2013. The...
Article
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In 2000, the European Union launched the Water Framework Directive (WFD) which calls to achieve good ecological status of water bodies by 2015 through integrated river basin management. Integrated models are therefore necessary. Despite large investments, the river Zenne (Belgium) still receives high loads of pollutants. A multidisciplinary researc...
Article
Bank erosion is the main source of suspended sediment (SS) and diffuse total phosphorus (TP) in many lowland catchments. This study compared a physically based sediment routing method (Physical method), which distinguishes between stream bed and bank erosion, with the original sediment routing method (Original method) within the Soil and Water Asse...
Article
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Throughout its historical development, hydrology as an earth science, but especially as a problem-centred engineering discipline has largely relied (quite successfully) on the assumption of stationarity. This includes assuming time invariance of boundary conditions such as climate, system configurations such as land use, topography and morphology,...
Chapter
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The modelling of the different catchment processes is key for integrated water resources management. Constructing a single model for all the catchment processes may not always be a feasible option and it does not make appropriate use of existing models. The Open Modelling Interface (OpenMI), which allows time-dependent models to exchange data at ru...
Article
Full-text available
The European Union Water Framework Directive requires an integrated pollution prevention plan at the river basin level. Hydrological river basin modeling tools are therefore promising tools to support the quantification of pollution originating from different sources. A limited number of studies have reported on the use of these models to predict p...
Article
Sediment transport is important for ecology and water quality in receiving waters. Physically based channel erosion methods were implemented in the Soil and Water Assessment Tool version 2009 (SWAT2009) to improve sediment concentration (SS) results. In the study, the default simplified Bagnold sediment routing method (EQN-0) and the physically bas...