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14 results on '"Candel, J.H.J."'

1. Comparing geomorphological maps made manually and by deep learning

Author

van der Meij, W.M., Meijles, E.W., Marcos Gonzalez, Diego, Harkema, Tom, Candel, J.H.J., Maas, G.J., van der Meij, W.M., Meijles, E.W., Marcos Gonzalez, Diego, Harkema, Tom, Candel, J.H.J., and Maas, G.J.

Abstract

Geomorphological maps provide information on the relief, genesis and shape of the earth’s surface and are widely used in sustainable spatial developments. The quality of geomorphological maps is however rarely assessed or reported, which limits their applicability. Moreover, older geomorphological maps often do not meet current quality requirements and require updating. This updating is time-consuming and because of its qualitative nature difficult to reproduce, but can be supported by novel computational methods. In this paper, we address these issues, by 1) quantifying the uncertainty associated with manual geomorphological mapping, 2) exploring the use of Convolutional Neural Networks (CNNs) for semi-automated geomorphological mapping, and 3) testing the sensitivity of CNNs to uncertainties in manually created evaluation data.We selected a test area in the Dutch push-moraine district with a pronounced relief and a high variety of landforms. For this test area we developed five manually created geomorphological maps and 27 automatically created landform maps using CNNs. The resulting manual maps are similar on a regional level. We could identify the causes of disagreement between the maps on a local level, which often related to differences in mapping experience, choices in delineation and different interpretations of the legend. Coordination of mapping efforts and field validation are necessary to create accurate and precise maps. CNNs perform well in identifying landforms and geomorphological units, but fail at correct delineation. The human geomorphologist remains necessary to correct the delineation and classification of the computed maps. The uncertainty in the manually created data that are used to train and evaluate CNNs have a large effect on the model performance and evaluation. This also advocates for coordinated mapping efforts to ensure the quality of manually created training and test data. Further model development and data processing are required be

Published
2022

3. Een herstelde beek is geen slingerend kanaal : Herziene uitgave Handboek Geomorfologisch Beekherstel

Author

Candel, J.H.J. and Berg, Michelle

Subjects
Life Science
Abstract

De afgelopen decennia hebben waterschappen een groot aantal beekherstelprojecten uitgevoerd. De resultaten worden de laatste jaren steeds beter, door de kennis en inzichten dievanuit onderzoek hun weg vinden naar de praktijk. Onder meer via het door STOWA uitgegeven‘beekfeuilleton’: drie praktische handboeken voor beekherstel. Onlangs verscheen een herziene uitgave van deel 1, Het Handboek Geomorfologisch Beekherstel. Maar wat is het eigenlijk:geomorfologie?

Published
2020

5. The landscape setting of bog bodies: Interdisciplinary research into the site location of Yde Girl, The Netherlands

Author

van Beek, R., Candel, J.H.J., Quik, C., Bos, J.A.A., Gouw-Bouman, M.T.I.J., Makaske, A., Maas, G.J., van Beek, R., Candel, J.H.J., Quik, C., Bos, J.A.A., Gouw-Bouman, M.T.I.J., Makaske, A., and Maas, G.J.

Abstract

Past studies of archaeological bog finds, such as bog bodies, wooden trackways and a wide variety of other materials, are characterized by a strong focus on material culture. Their original environmental and cultural context has received far less attention. This paper centres on the original landscape setting of bog bodies. Interdisciplinary reconstructions of the physical and cultural landscape at the time of deposition can lead to significant new and more detailed insights into the context and meaning of this remarkable phenomenon. We aim to show the value of such interdisciplinary research by reconstructing the original physical and cultural landscape setting of the most iconic bog body of The Netherlands: Yde Girl. This approximately 16-year-old girl was killed about 2000 years ago and deposited in a bog south of the modern-day village of Yde (province of Drenthe). Our interdisciplinary research team used a combination of research methods from physical geography, geomorphology, palynology and archaeology to analyse both the site itself and its wider environment. This kind of integrated, detailed landscape research on bog bodies has hardly been done yet. We expect that our research design, methodology and results may also be applied in future research of other bog bodies. Furthermore, they may inspire research on other types of archaeological find categories from peatlands.

Published
2019

7. Predicting piping underneath river dikes using 3D subsurface heterogeneity

Author

Winkels, T.G., Dirkx, W.J., Stouthamer, E., Cohen, K.M., Middelkoop, H., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., Poelman, J., Coastal dynamics, Fluvial systems and Global change, Landscape functioning, Geocomputation and Hydrology, Geomorfologie, and Hydrologie

Subjects
flood risk management, Rhine-Meuse delta, hydrology, Geology, dikes, mapping, Earth-Surface Processes, Civil and Structural Engineering
Published
2017

8. Next steps in palaeogeographic mapping of the Lower Meuse Valley to unravel tectonic and climate forcing

Author

Woolderink, H.A.G., Kasse, C., Cohen, K.M., van Balen, R.T., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., Poelman, J., Coastal dynamics, Fluvial systems and Global change, and Geomorfologie

Abstract

In the Netherlands the Meuse terrace sequence has been studied in detail since the 1960ies. The youngest, lowest levels of terraces are shown to hold remnants of glacial-stage braided plains from the Weichselian Late Pleniglacial and Younger Dryas stadials, but also of meandering channel belts of Allerød interstadial and Holocene interglacial stages. Whereas geological-geomorphological reconstructions, in principle, allow to identify interaction between river morphology and forcing factors such as climate change and tectonics, and to explore and explain temporal and spatial changes herein. In practice, however, the many studies in this area so-far each covered restricted parts of the Meuse valley and/or restricted time periods. A truly integrated reconstruction of Lower Meuse geomorphological activity since the Weichselian Last Glacial Maximum, is lacking. Because a river’s response to the same external forcing may vary along the river system, with hindsight, some regional differences along the river Meuse may have been insufficiently considered in the maps produced so far. In addition, a wealth of new data, mainly from archaeological exploration, has become available in the past years. For unravelling of tectonic (active and passive) from climatic controls in the Meuse valley an updated, consistent and detailed palaeogeographical reconstruction is needed, which this study aims at.

Published
2017

9. NCR days 2017, Book of abstracts : February 1-3, 2017 Wageningen University & Research

Author

Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, A., Wallinga, J., Candel, J.H.J., and Poelman, J.

Subjects
Bodemgeografie en Landschap, WIMEK, Soil Geography and Landscape, PE&RC, Hydrology and Quantitative Water Management, Hydrologie en Kwantitatief Waterbeheer
Abstract

The Netherlands Centre for River Studies (NCR), established in 1998, is a collaboration of eight Dutch research institutes with the goal to promote co-operation between scientific institutes in The Netherlands where river research is carried out. Members of the NCR gather during the yearly NCR days, a conference organized in rotation by the NCR member institutes. In 2016 it was decided to change the season in which the NCR Days take place from autumn to winter. This explains why 2016 was a year without NCR days. The first edition in the new winter format is organized by Wageningen University & Research, as a joint effort of the Hydrology and Quantitative Water Management Group.

Published
2017

10. Oblique aggradation: a novel explanation for sinuosity of low-energy streams in peat-filled valley systems

Author

Candel, J.H.J., Makaske, A., Storms, J.E.A., and Wallinga, J.

Subjects
Bodemgeografie en Landschap, Soil Geography and Landscape, Life Science, PE&RC
Abstract

Low-energy streams in peatlands often have a high sinuosity. However, it is unknown how this sinuous planform formed, since lateral migration of the channel is hindered by relatively erosion-resistant banks. We present a conceptual model of Holocene morphodynamic evolution of a stream in a peat-filled valley, based on a palaeohydrological reconstruction. Coring, ground-penetrating radar (GPR) data, and 14C and OSL dating were used for the reconstruction. We found that the stream planform is partly inherited from the Late-Glacial topography, reflecting stream morphology prior to peat growth in the valley. Most importantly, we show that aggrading streams in a peat-filled valley combine vertical aggradation with lateral displacement caused by attraction to the sandy valley sides, which are more erodible than the co-evally aggrading valley-fill. Due to this oblique aggradation in combination with floodplain widening, the stream becomes stretched out as channel reaches may alternately aggrade along opposed valley sides, resulting in increased sinuosity over time. Hence, highly sinuous planforms can form in peat-filled valleys without the traditional morphodynamics of alluvial bed lateral migration. Improved understanding of the evolution of streams provides inspiration for stream restoration.

Published
2017

11. Flow patterns around longitudinal training dams

Author

van Linge, B.W., Mosselman, E., van Vuren, B.G., Rongen, G.W.F., Uijttewaal, W.S.J., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., and Poelman, J.

Abstract

With the intention to reduce the negative effects of ongoing bed erosion, as well as to improve several other river functions such as protection against floods, provision of safe and efficient navigation and ecology, a ‘pilot project longitudinal training dams’ was initiated. The training dams have recently been implemented in the Waal between Tiel and Sind Andries. In this project, river groynes have been completely removed and replaced by dams that lie parallel to the river bank. With help of the longitudinal training dams, a two-channel river system is created in which the river is divided into a main and side channel. The dams are placed in a continuous manner with openings in between that are relatively small compared to the dam length. At the beginning and end of the dam an inlet and outlet region is situated, as shown in Fig. 1. The combination of inlet and openings allows for water and sediment to be divided between the main and the side channel. Both inlet and openings are constructed with the help of a porous rock-layer. The crest heights can be altered by adding or removing stones. This is expected to influence the amount of water and sediment entering the side channel and can therefore be used as a regulation tool.

Published
2017

12. Next steps in palaeogeographic mapping of the Lower Meuse Valley to unravel tectonic and climate forcing

Author

Coastal dynamics, Fluvial systems and Global change, Geomorfologie, Woolderink, H.A.G., Kasse, C., Cohen, K.M., van Balen, R.T., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., Poelman, J., Coastal dynamics, Fluvial systems and Global change, Geomorfologie, Woolderink, H.A.G., Kasse, C., Cohen, K.M., van Balen, R.T., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., and Poelman, J.

Published
2017

13. Predicting piping underneath river dikes using 3D subsurface heterogeneity

Author

Coastal dynamics, Fluvial systems and Global change, Landscape functioning, Geocomputation and Hydrology, Geomorfologie, Hydrologie, Winkels, T.G., Dirkx, W.J., Stouthamer, E., Cohen, K.M., Middelkoop, H., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., Poelman, J., Coastal dynamics, Fluvial systems and Global change, Landscape functioning, Geocomputation and Hydrology, Geomorfologie, Hydrologie, Winkels, T.G., Dirkx, W.J., Stouthamer, E., Cohen, K.M., Middelkoop, H., Hoitink, A.J.F., de Ruijsscher, T.V., Geertsema, T.J., Makaske, B., Wallinga, J., Candel, J.H.J., and Poelman, J.

Published
2017

14. Identifying groundwater recharge connections in the Moscow (USA) sub-basin using isotopic tracers and a soil moisture routing model

Author

Candel, J.H.J., Brooks, Erin, Sanchez-Murillo, Ricardo, Grader, George, Dijksma, R., Candel, J.H.J., Brooks, Erin, Sanchez-Murillo, Ricardo, Grader, George, and Dijksma, R.

Abstract

Globally, aquifers are suffering from large abstractions resulting in groundwater level declines. These declines can be caused by excessive abstraction for drinking water, irrigation purposes or industrial use. Basaltic aquifers also face these conflicts. A large flood basalt area (1.1 × 105 km2) can be found in the Northwest of the USA. This Columbia River Basalt Group (CRBG) consists of a thick series of basalt flows of Miocene age. The two major hydrogeological units (Wanapum and Grand Ronde formations) are widely used for water abstraction. The mean decline over recent decades has been 0.6 m year−1. At present day, abstraction wells are drying up, and base flow of rivers is reduced. At the eastern part of CRBG, the Moscow sub-basin on the Idaho/Washington State border can be found. Although a thick poorly permeable clay layer exists on top of the basalt aquifer, groundwater level dynamics suggest that groundwater recharge occurs at certain locations. A set of wells and springs has been monitored bi-weekly for 9 months for δ18O and δ2H. Large isotopic fluctuations and d-excess values close to the meteoric water line in some wells are indicating that recharge occurs at the granite/basalt interface through lateral flow paths in and below the clay. A soil moisture routing (SMR) model showed that most recharge occurs on the granitic mountains. The basaltic aquifer receives recharge from these sedimentary zones around the granite/basalt interface. The identification of these types of areas is of major importance for future managed-aquifer recharge solutions to solve problems of groundwater depletion.

Published
2016

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