Marc Bierkens - Profile on Academia.edu (original) (raw)

Papers by Marc Bierkens

Environmental Research Letters, 2014

Overuse of surface water and an increasing reliance on nonrenewable groundwater resources have be... more Overuse of surface water and an increasing reliance on nonrenewable groundwater resources have been reported over various regions of the world, casting significant doubt on the sustainable water supply and food production met by irrigation. To assess the limitations of global water resources, numerous indicators have been developed, but they rarely consider nonrenewable water use. In addition, surface water over-abstraction is rarely assessed in the context of human and environmental water needs. Here, we perform a transient assessment of global water use over the historical period 1960-2010 as well as the future projections of 2011-2099, using a newly developed indicator: the blue water sustainability index (BlWSI). The BlWSI incorporates both nonrenewable groundwater use and nonsustainable water use that compromises environmental flow requirements. Our results reveal an increasing trend of water consumed from nonsustainable surface water and groundwater resources over the historical period (∼30%), and this increase is projected to continue further towards the end of this century (∼40%). The global amount of nonsustainable water consumption has been increasing especially since the late 1990s, despite a wetter climate and increasing water availability during this period. The BlWSI is the first tool suitable for consistently evaluating the renewability and degradation of surface water and groundwater resources as a result of human water over-abstraction.

Earth System Science Data, 2011

Time variable gravity fields, reflecting variations of mass distribution in the system Earth is o... more Time variable gravity fields, reflecting variations of mass distribution in the system Earth is one of the key parameters to understand the changing Earth. Mass variations are caused either by redistribution of mass in, on or above the Earth's surface or by geophysical processes in the Earth's interior. The first set of observations of monthly variations of the Earth gravity field was provided by the US/German GRACE satellite mission beginning in 2002. This mission is still providing valuable information to the science community. However, as GRACE has outlived its expected lifetime, the geoscience community is currently seeking successor missions in order to maintain the long time series of climate change that was begun by GRACE. Several studies on science requirements and technical feasibility have been conducted in the recent years. These studies required a realistic model of the time variable gravity field in order to perform simulation studies on sensitivity of satellites and their instrumentation. This was the primary reason for the European Space Agency (ESA) to initiate a study on "Monitoring and Modelling individual Sources of Mass Distribution and Transport in the Earth System by Means of Satellites". The goal of this interdisciplinary study was to create as realistic as possible simulated time variable gravity fields based on coupled geophysical models, which could be used in the simulation processes in a controlled environment. For this purpose global atmosphere, ocean, continental hydrology and ice models were used. The coupling was performed by using consistent forcing throughout the models and by including water flow between the different domains of the Earth system. In addition gravity field changes due to solid Earth processes like continuous glacial isostatic adjustment (GIA) and a sudden earthquake with co-seismic and post-seismic signals were modelled. All individual model results were combined and converted to gravity field spherical harmonic series, which is the quantity commonly used to describe the Earth's global gravity field. The result of this study is a twelve-year time-series of 6-hourly time variable gravity field spherical harmonics up to degree and order 180 corresponding to a global spatial resolution of 1 degree in latitude and longitude. In this paper, we outline the input data sets and the process of combining these data sets into a coherent model of temporal gravity field changes. The resulting time series was used in some follow-on studies and is available to anybody interested.

A virtual water network of the Roman world

Hydrology and Earth System Sciences, 2014

Published by Copernicus Publications on behalf of the European Geosciences Union. Hydrol. Earth S... more Published by Copernicus Publications on behalf of the European Geosciences Union. Hydrol. Earth Syst. Sci., 18, 3891-3905, 2014 www.hydrol-earth-syst-sci.net/18/3891/2014/ J. R. Delsman et al.: Paleo-modeling of coastal saltwater in the Netherlands 3893 Model transect Coastline Head data (n=382) Chloride data (n=474) > 20 m MSL 15 -20 m MSL 10 -15 m MSL 5 -10 m MSL 2.5 -5 m MSL 0 -2.5 m MSL 2.5 -0 m BSL 5 -2.5 m BSL 10 -5 m BSL 15 -10 m BSL 20 -15 m BSL > 20 m BSL

Hortonian overland flow closure relations in the Representative Elementary Watershed Framework evaluated with observations

Hydrology and Earth System Sciences Discussions, 2013

ABSTRACT This paper presents an evaluation of the closure relation for Hortonian runoff that expl... more ABSTRACT This paper presents an evaluation of the closure relation for Hortonian runoff that explicitly accounts for sub-REW process heterogeneity and scale effects, proposed in Vannametee et al. (2012). We apply the closure relation, which is embedded in an event-based rainfall-runoff model developed under the REW framework, to a 15 km2 catchment in the French Alps. The scaling parameters in the closure relation are directly estimated using local and thus observable REW properties and rainstorm characteristics. Evaluation of the simulation results against the observed discharge indicates good performance in reproducing the hydrograph and discharge volume, even without calibration. The discharge prediction exhibits a significant improvement when the closure relation is calibrated with catchment-scale runoff. Our closure relation also yields better predictions when compared with results from a benchmark closure relation that does not consider scale effects. Calibration is done by only changing one of the REW observables, i.e. hydraulic conductivity, as that determines the scaling parameters, using a single prefactor for the entire catchment. This enables the calibration of the (semi)distributed modelling framework in this study to use only a single parameter. The results without calibration suggest that, in the absence of discharge observations, reasonable estimates of catchment-scale runoff responses are possibly based on observations at the sub-REW (i.e. plot) scale. Thus, our study provides a platform for the future development of low-dimensional and robust semi-distributed, physically-based discharge models in ungauged catchments.

The benefits of using remotely sensed soil moisture in parameter identification of large-scale hydrological models

Water Resources Research, 2014

Semi-automated mapping of landforms using multiple point geostatistics

Geomorphology, 2014

ABSTRACT This study presents an application of a multiple point geostatistics (MPS) to map landfo... more ABSTRACT This study presents an application of a multiple point geostatistics (MPS) to map landforms. MPS uses information at multiple cell locations including morphometric attributes at a target mapping cell, i.e. digital elevation model (DEM) derivatives, and non-morphometric attributes, i.e. landforms at the neighboring cells, to determine the landform. The technique requires a training data set, consisting of a field map of landforms and a DEM. Mapping landforms proceeds in two main steps. First, the number of cells per landform class, associated with a set of observed attributes discretized into classes (e.g. slope class), is retrieved from the training image and stored in a frequency tree, which is a hierarchical database. Second, the algorithm visits the non-mapped cells and assigns to these a realization of a landform class, based on the probability function of landforms conditioned to the observed attributes as retrieved from the frequency tree. The approach was tested using a data set for the Buëch catchment in the French Alps. We used four morphometric attributes extracted from a 37.5-m resolution DEM as well as two non-morphometric attributes observed in the neighborhood. The training data set was taken from multiple locations, covering 10% of the total area. The mapping was performed in a stochastic framework, in which 35 map realizations were generated and used to derive the probabilistic map of landforms. Based on this configuration, the technique yielded a map with 51.2% of correct cells, evaluated against the field map of landforms. The mapping accuracy is relatively high at high elevations, compared to the mid-slope and low-lying areas. Debris slope was mapped with the highest accuracy, while MPS shows a low capability in mapping hogback and glacis. The mapping accuracy is highest for training areas with a size of 7.5–10% of the total area. Reducing the size of the training images resulted in a decreased mapping quality, as the frequency database only represents local characteristics of landforms that are not representative for the remaining area. MPS outperforms a rule-based technique that only uses the morphometric attributes at the target mapping cell in the classification (i.e. one-point statistics technique), by 15% of cell accuracy.

Water Resources Research, 2002

1] A method of transfer function-noise (TFN) modeling is presented that operates in continuous ti... more 1] A method of transfer function-noise (TFN) modeling is presented that operates in continuous time and uses a predefined family of impulse response (IR) functions. The resulting class of models is referred to as predefined IR function in continuous time (PIRFICT). It provides a useful tool for standardized analysis of time series, as it can be calibrated using irregularly spaced data and does not require a model identification phase prior to calibration. In section 2, the discrete Box-Jenkins (BJ) model is presented and transformed into continuous time to obtain the PIRFICT model. The discrete transfer function of a BJ model, which is made up of a variable number of parameters, is replaced by a simple analytical expression that defines the IR function. From the IR function, block response functions are derived that enable the model to handle irregularly spaced data. In the example application, the parameter estimates and performance of the BJ and PIRFICT model are compared using a data set of 15 piezometers and a simulated series. It was found that the estimated transfer and BR functions of both models follow the same general pattern, although the BJ transfer functions are partly irregular. The performance of both models proves to be highly comparable for all piezometers.

A multi-model ensemble for identifying future water stress hotspots

Beyond peak water storage? A global estimate of declining water storage in reservoirs and snow packs

Building and calibrating a large-extent and high resolution coupled groundwater-land surface model using globally available data-sets

The Tropical Pacific: A changeable communicator or Holocene solar forcing

The potential of remotely sensed soil moisture for operational flood forecasting

Developing a high resolution groundwater model for Indonesia

In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resoluti... more In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resolution global hydrological model. Starting point was the PCR-GLOBWB built by Utrecht University. The software behind this model will partially be re-engineered in order to enable to run it in a High Performance Computing (HPC) environment. The aim is to have a spatial resolution of 1km x 1km. The idea is also to run the model in real-time and forecasting mode, using data assimilation. An on-demand hydraulic model will be available for detailed flow and flood forecasting in support of navigation and disaster management.

Mapping geomorphology based on the information from existing geomorphological maps with a multiple-point geostatistics technique

Climate change and water conservation effects on water availability and vegetation patterns in a stream valley

The PCR-GLOBWB global hydrological reanalysis product

Virtual water management in the Roman world

Linking groundwater use and stress to specific crops using the groundwater footprint in the Central Valley and High Plains aquifer systems, US

ABSTRACT A number of aquifers worldwide are being depleted, mainly by agricultural activities, ye... more ABSTRACT A number of aquifers worldwide are being depleted, mainly by agricultural activities, yet groundwater stress has not been explicitly linked to specific agricultural crops. Using the newly-developed concept of the groundwater footprint (the area required to sustain groundwater use and groundwater-dependent ecosystem services), we develop a methodology to derive crop-specific groundwater footprints. We illustrate this method by calculating high resolution groundwater footprint estimates of crops in two heavily used aquifer systems: the Central Valley and High Plains, USA. In both aquifer systems, hay and haylage, corn and cotton have the largest groundwater footprints, which highlights that most of the groundwater stress is induced by crops meant for cattle feed. Our results are coherent with other studies in the High Plains but suggest lower groundwater stress in the Central Valley, likely due to artificial recharge from surface water diversions which were not taken into account in previous estimates. Uncertainties of recharge and irrigation application efficiency contribute the most to the total relative uncertainty of the groundwater footprint to aquifer area ratios. Our results and methodology will be useful for hydrologists, water resource managers and policy makers concerned with which crops are causing the well-documented groundwater stress in semi-arid to arid agricultural regions around the world.