Inge de Graaf

Inge de Graaf
Wageningen University & Research | WUR · Faculty of Environmental Sciences

Dr. ir.

About

29
Publications
14,069
Reads
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1,182
Citations
Introduction
Inge de Graaf currently works at the Water Systems and Global Change Group, Department of Environmental Sciences, Wageningen University. Inge does research in large scale hydrology and water resources. Current project is 'Limits to Global Groundwater Consumption' and 'Africa's Water Resources'.
Additional affiliations
October 2015 - present
Colorado School of Mines
Position
  • PostDoc Position
September 2011 - September 2015
Utrecht University
Position
  • PhD Student
Education
September 2011 - September 2015
Utrecht University
Field of study
  • large-scale Hydrology
September 2009 - April 2011
Wageningen University & Research
Field of study
  • Hydrology

Publications

Publications (29)
Article
Full-text available
Current global-scale models of water resources do not generally represent groundwater lateral flows and groundwater–surface water interactions. But, models that do represent groundwater in more detail are becoming available and this raises the question of how estimates of water flow, availability, and impacts might change compared to previous globa...
Article
Full-text available
Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system. Such large-scale models are essential for examining, communicating, and understanding the dynamic interactions between the Earth system above and below the land surface as well as the opportunities and limits of groundwate...
Article
Full-text available
Abstract Hard rock aquifers (HRAs) in West Africa (WA) are located within a thick regolith layer. The representation of thick tropical regolith in integrated hydrological models lacks consensus on aquifer geometries and parameter ranges. Our main objective was to determine the knowledge requirements on saturated hydraulic conductivity (Ks) to model...
Article
Full-text available
Water-table drawdown across peatlands increases carbon dioxide (CO2) and reduces methane (CH4) emissions. The net climatic effect remains unclear. Based on global observations from 130 sites, we found a positive (warming) net climate effect of water-table drawdown. Using a machine-learning-based upscaling approach, we predict that peatland water-ta...
Preprint
Full-text available
Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system. Such large-scale models are essential for examining, communicating, and understanding the dynamic interactions between the Earth System above and below the land surface as well as the opportunities and limits of groundwate...
Preprint
Full-text available
Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system, driven by crucial Earth science and sustainability problems. These models are essential for examining, communicating, and understanding the dynamic interactions between the Earth System above and below the land surface as...
Article
Full-text available
Groundwater is the world's most important freshwater resource. Despite this importance, groundwater flow and interactions between groundwater and other parts of the hydrological cycle are often neglected or simplified in large‐scale hydrological models. One of the challenges in simulating groundwater flow and continental to global scales is the lac...
Article
Full-text available
Groundwater is a vital resource for freshwater supply during extended droughts and also a key storage governing drought propagation through the hydrological cycle. Current drought monitoring lacks large‐scale estimates of groundwater droughts, but progress of country‐to‐global‐scale models in the last years suggests that they could now be valuable...
Article
Full-text available
Groundwater is the world’s largest freshwater resource and is critically important for irrigation, and hence for global food security1,2,3. Already, unsustainable groundwater pumping exceeds recharge from precipitation and rivers⁴, leading to substantial drops in the levels of groundwater and losses of groundwater from its storage, especially in in...
Preprint
Continental- to global-scale hydrologic models increasingly include representations of the Earth’s groundwater system. A key question is how to evaluate the realism and performance quality of such large-scale groundwater models given limitations in data availability. We argue for a transparent approach to system conceptualization, which would enabl...
Conference Paper
Full-text available
Most current global-scale hydrological models do not represent groundwater flow between grid-cells (i.e. lateral groundwater flows) as a component of the water budget, nor do they simulate groundwater heads. As such, the effect of long-distance lateral flows, transporting groundwater downstream and supporting water budgets of receiving catchments,...
Conference Paper
Full-text available
Groundwater is the world's most important freshwater resource. Despite this impotence, groundwater flow and interactions between groundwater and other parts of the hydrological cycle are often ignored in large­scale hydrological models. The main reason for this omission is the lack of consistent globally­available hydrogeological data that is requi...
Article
Full-text available
We present PCR-GLOBWB 2, a global hydrology and water resources model. Compared to previous versions of PCR-GLOBWB, this version fully integrates water use. Sector-specific water demand, groundwater and surface water withdrawal, water consumption, and return flows are dynamically calculated at every time step and interact directly with the simulate...
Article
Full-text available
We present PCR-GLOBWB 2, a global hydrology and water resources model. Compared to previous versions of PCR-GLOBWB, this version fully integrates water use. Sector-specific water demand, groundwater and surface water withdrawal, water consumption and return flows are dynamically calculated at every time step and interact directly with the simulated...
Article
Groundwater is an integral component of the water cycle, and it also influences the carbon cycle by supplying moisture to ecosystems. However, the extent and determinants of groundwater-vegetation interactions are poorly understood at the global scale. Using several high-resolution data products, we show that the spatial patterns of ecosystem gross...
Article
Full-text available
Groundwater is the world’s largest accessible source of freshwater to satisfy human water needs. Moreover, groundwater buffers variable precipitation rates over time, thereby effectively sustaining river flows in times of droughts and evaporation in areas with shallow water tables. In this study, building on previous work, we simulate groundwater h...
Article
Full-text available
A number of global hydrological models [GHMs) have been developed in recent decades in order to understand the impacts of climate variability and human activities on water resources availability. The spatial resolution of GHMs is mostly constrained at a 0.5° by 0.5° grid [∼50km by ∼50km at the equator). However, for many of the water-related proble...
Article
Full-text available
Groundwater is the world's largest accessible source of freshwater to satisfy human water needs. Moreover, groundwater buffers variable precipitation rates over time, thereby effectively sustaining river flows in times of droughts as well as evaporation in areas with shallow water tables. Lateral flows between basins can be a significant part of th...
Conference Paper
As the world's largest accessible source of freshwater, groundwater plays vital role in satisfying the basic needs of human society. It serves as a primary source of drinking water and supplies water for agricultural and industrial activities. During times of drought, groundwater sustains water flows in streams, rivers, lakes and wetlands, and thus...
Article
Full-text available
Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying basic needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global scale hydrological models (GHMs) do not include a gro...
Conference Paper
PCRaster GLOBal Water Balance is a grid-based global hydrological model developed at Utrecht University. It simulates soil moisture in vertically stacked soil layers, as well as exchange to the atmosphere and underlying groundwater reservoir. Fluxes are simulated under different land cover types by considering sub-grid variations in topography, veg...
Conference Paper
Full-text available
As the world's largest accessible source of freshwater, groundwater plays a vital role in satisfying the basic needs of human society. It serves as a primary source of drinking water and supplies water for agricultural and industrial activities. During times of drought, groundwater storage provides a large natural buffer against water shortage and...
Article
Full-text available
Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global scale hydrological models (GHMs) do not include a groundwat...
Article
As human water demand is increasing worldwide, pressure on available water resources grows and their sustainable exploitation is at risk. To mimic changes in exploitation intensity and the connecting feedbacks between surface water and groundwater systems, a dynamic attribution of demand to water resources is necessary. However, current global-scal...
Conference Paper
In regions with frequent water stress and large aquifer systems, groundwater often constitutes an essential source of water. If groundwater abstraction exceeds groundwater recharge over a long time and over large areas persistent groundwater depletion can occur. The resulting lowering of groundwater levels can have negative effects on agricultural...

Projects

Projects (3)
Archived project
In my M.Sc. thesis I'm building up a new data set for the aquifer parametrization of Africa, especially for the crystalline basement aquifers which cover large parts of Sub-Saharan Africa. In these aquifers, a large part of the groundwater can be stored within the weathered layer of regolith, which is often neglected in global modelling or related to high uncertainties. With an integration of the transmissivities of these regolith layers into the global model PCR-GLOBWB MODFLOW (de Graaf, 2015), I hope to be able to assess the groundwater resources of Africa in better quality. This would be of high relevance for strategies aiming to manage water resources sustainably in the face of climate change and population growth.
Project
Over the coming decades water demand are set to increase rapidly for Africa, primarily driven by population growth and increased by drier climate conditions. Increasing reliable fresh water supplies in Africa will depend on the development of groundwater (McDonald et al 2012). To ensure sustainable use and avoid overexploitation improved knowledge of the groundwater resource is needed, in particular for hardrock aquifers with thick regolith layers covering 44% of Africa The main goal of this project is to use local information on permeability and thickness of aquifers to improve global-scale data, in order to provide more realistic estimates of groundwater heads, fluctuations, and lateral flows at the larger scale. This project got funded under the DAAD-PPP Program (for 2 years). Within the project there will be strong collaboration with experts in critical zone modelling working at IGE Grenoble, France.