Local Factors Determining Spatially Heterogeneous Channel Migration in a Low-Energy Stream

Since the 1990s, nature and water management policies have attempted to re-create natural rivers systems by mimicking curvy meandering planforms, based on the assumption that meandering is the natural channel-forming process. However, in low-energy river systems, the extent to which meandering plays a natural role is often minimal. This study aims to quantify contemporary lateral migration in the low-energy irregular sinuous lowland river system of the Drentsche Aa, The Netherlands, and to determine the factors influencing lateral channel migration in a heterogeneous valley fill. Although the river is classified as laterally immobile based on an empirical stability diagram, field observations prove that erosion and deposition are currently occurring. By analyzing historical and present-day maps, it was shown that lateral migration was highly spatially variable for the period 1924-2005. Sinuosity and valley gradient are not correlated to lateral migration rates, suggesting they are not a measure of lateral migration in the case study area, which is in line with the literature. Based on geomorphological and soil map analyses, it was shown that lateral migration rates are significantly higher in valley fills of aeolian sands than in clastic alluvial deposits, which on their turn are significantly higher than in peaty environments. Therefore, local conditions appear to be dominant over other factors such as stream power and bed grain size. These findings are important for river rehabilitation of low-energy rivers, because it shows that local valley fill conditions can greatly influence active lateral migration in the river

A diachronic triangular perspective on landscapes:A conceptual tool for research and management applied to Wadden Sea salt marshes

Strong disciplinary academic fragmentation and sectoral division in policies lead to problems regarding the management of landscapes. As a result, there is a focus on the preservation and development of either cultural or natural landscapes. We argue that framing landscapes as "natural" or "cultural" will not help sustainable management. The goal of this paper is to show that even what is referred to as nature, virtually always features an intricate combination of physical geography, biology, and cultural history. It provides an analytical framework that visualizes the three forces at play in physical landscapes. Therefore, we introduce a diachronic triangular approach to study and manage landscapes from a holistic point of view, allowing an exchange of different perspectives. To test this approach, we have applied our model to a diachronic case study on Wadden Sea salt marshes. That area has been influenced by physical-geographical, biological, and cultural landscape forces, which are still visible in the landscape to a large extent. By placing different landscape zones in the triangular concept for different time periods, we can identify and visualize these driving forces through time for this specific landscape. These all play their specific roles in the appearance of the landscape over time in a close mutual interconnection. More importantly, we show that the diverse and complex interplay between these forces makes the current-day landscape what it is. We therefore conclude that the diachronic triangular approach provides a conceptual tool to define and operationalize landscape management in the Wadden Sea area. We welcome similar approaches in other landscapes to assess the usefulness of the diachronic triangular landscape approach

Comparing geomorphological maps made manually and by deep learning

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 before CNNs can act as standalone mapping techniques

Sea-level change in the Dutch Wadden Sea

Rising sea levels due to climate change can have severe consequences for coastal populations and ecosystems all around the world. Understanding and projecting sea-level rise is especially important for low-lying countries such as the Netherlands. It is of specific interest for vulnerable ecological and morphodynamic regions, such as the Wadden Sea UNESCO World Heritage region. Here we provide an overview of sea-level projections for the 21st century for the Wadden Sea region and a condensed review of the scientific data, understanding and uncertainties underpinning the projections. The sea-level projections are formulated in the framework of the geological history of the Wadden Sea region and are based on the regional sea-level projections published in the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5). These IPCC AR5 projections are compared against updates derived from more recent literature and evaluated for the Wadden Sea region. The projections are further put into perspective by including interannual variability based on long-term tide-gauge records from observing stations at Den Helder and Delfzijl. We consider three climate scenarios, following the Representative Concentration Pathways (RCPs), as defined in IPCC AR5: the RCP2.6 scenario assumes that greenhouse gas (GHG) emissions decline after 2020; the RCP4.5 scenario assumes that GHG emissions peak at 2040 and decline thereafter; and the RCP8.5 scenario represents a continued rise of GHG emissions throughout the 21st century. For RCP8.5, we also evaluate several scenarios from recent literature where the mass loss in Antarctica accelerates at rates exceeding those presented in IPCC AR5. For the Dutch Wadden Sea, the IPCC AR5-based projected sea-level rise is 0.07±0.06m for the RCP4.5 scenario for the period 2018–30 (uncertainties representing 5–95%), with the RCP2.6 and RCP8.5 scenarios projecting 0.01m less and more, respectively. The projected rates of sea-level change in 2030 range between 2.6mma−1 for the 5th percentile of the RCP2.6 scenario to 9.1mma−1 for the 95th percentile of the RCP8.5 scenario. For the period 2018–50, the differences between the scenarios increase, with projected changes of 0.16±0.12m for RCP2.6, 0.19±0.11m for RCP4.5 and 0.23±0.12m for RCP8.5. The accompanying rates of change range between 2.3 and 12.4mma−1 in 2050. The differences between the scenarios amplify for the 2018–2100 period, with projected total changes of 0.41±0.25m for RCP2.6, 0.52±0.27m for RCP4.5 and 0.76±0.36m for RCP8.5. The projections for the RCP8.5 scenario are larger than the high-end projections presented in the 2008 Delta Commission Report (0.74m for 1990–2100) when the differences in time period are considered. The sea-level change rates range from 2.2 to 18.3mma−1 for the year 2100. We also assess the effect of accelerated ice mass loss on the sea-level projections under the RCP8.5 scenario, as recent literature suggests that there may be a larger contribution from Antarctica than presented in IPCC AR5 (potentially exceeding 1m in 2100). Changes in episodic extreme events, such as storm surges, and periodic (tidal) contributions on (sub-)daily timescales, have not been included in these sea-level projections. However, the potential impacts of these processes on sea-level change rates have been assessed in the report

Observation of regional hydrological response during time periods of shifting policy

This paper explores the significance of the impacts that changing agricultural and land management policies can have on catchment hydrology. The effects on the hydrological regimes of the land use change resulting from these policies climatic variability can be difficult to disentangle. However, by defining the key periods when various policies had most effect, the individual hydrological responses of the different phases have been separated on an annual and seasonal time scale by analysing time trend and step changes. A case study of the Drentsche Aa watershed in the Netherlands since 1954 revealed that a phase of canalisation (1959-65) greatly reduced peak and base flows as well as number of peak days. A particularly dramatic effect was achieved in 1965 when a flow diversion 'cut-off' was installed, which fitted in land management policies of major engineering flood control interventions elsewhere in the country. During the next phase, characterised by large scale land consolidations (1965-85), the hydrological effects were less extreme. A small but significant increase of base flows, maximum flows and number of peak days was identified. The flashiness of the stream decreased slightly. During the last twenty years nature development policies have been implemented. Base flow levels have increased but no other hydrological trends have been identified. It was concluded that by separating key land policies into distinct phases, important trends in the hydrology at regional scale can be distinguished and that current natural policies aiming for a more natural landscape composition have been influenced by earlier policy decisions. As the catchment is representative of the situation further afield in the developed world, we conclude that in land policy development, 'joined up' thinking is required, recognising the natural connectivity and heterogeneity of catchments. (C) 2012 Elsevier Ltd. All rights reserved

Factors that Influence Climate Change Mitigation and Adaptation Action: A Household Study in the Nuevo Leon Region, Mexico

Household-level mitigation and adaptation actions are important because households make a significant contribution to greenhouse gas emissions and are severely affected by climate change. However, there is still very little understanding of the factors that influence household-level mitigation and adaptation action. From a review of literature, we identified the factors that potentially influence climate mitigation and adaptation actions of households, which we then tested using survey data from 622 households in Nuevo Leon, Mexico. Nuevo Leon is a major emitter of greenhouse gasses and is a state where climate-related disasters are recurrent and expected to increase in frequency and severity. Results from ordinal regression analyses showed that perceived knowledge and financial self-efficacy greatly influenced the extent of household-level action taken. To a lesser extent, the age and educational level of the respondent also affected action. Respondents pointed out the need to know about different aspects of climate change. An implication of our study is the value of recognizing the importance of perceptions, as mitigation and adaptation actions are shaped by perceptions of climate change alongside socio-demographic characteristics. This may have significant implications for policies and campaigns promoting household-level action to increase resilience to climate change

Level of Congruence between Household Perspectives and Mexican Climate Policies on the Issue of Climate Change

This study examines the extent of congruence across the issue of climate change between households and climate policies, based on a case study in Nuevo León, Mexico. We used thematic analysis to examine responses from a household survey and classify perceptions of climate change, which resulted in seven main themes. We then reviewed how the themes are used in selected climate policies to make a comparison between them and household perceptions. We found climate policy concerns focused on mitigating greenhouse gases, preparing for extreme weather events, and reducing impacts that affect economic development in Nuevo León and Mexico. By contrast, respondents showed a wider range of concerns and are especially worried about current issues in their homes and everyday lives. As households have an important role to play in addressing climate change, we argue that a stronger congruence between household perceptions and climate policies could make policies more approachable for households, and thus have a positive impact on policy implementation

The role of climate change perceptions and sociodemographics on reported mitigation efforts and performance among households in northeastern Mexico

Managing and reducing the impacts of climate change depends on efficient actions from all societal scales. Yet, the household component is often missing from climate research, debate, and policies. This is problematic because households have been found to significantly contribute to of global greenhouse gas emissions and therefore have the potential to be part of a solution to climate change by mitigating climate change. This study seeks to understand which factors drive household-level mitigation actions. We conducted a household survey in Nuevo Leon, located in northeastern Mexico, to explore the extent to which climate change perceptions and the sociodemographic characteristics of households influence their reported mitigation performances and their perceived mitigation efforts. Results from linear regression analyses and generalized linear models revealed that sociodemographic characteristics are key drivers of the households’ perceived mitigation efforts and reported mitigation performances and. We also found that climate change perceptions drive a household’s efforts to mitigate climate change. These results could partly explain why despite the efforts households take to mitigate climate change, achieving an effective reduction of greenhouse gas emissions is challenging without further access to resources such as education and financial support. If governments intend to realize substantial reductions in future emission pathways, then household-level mitigation should be addressed with proper support

The role of climate change perceptions and sociodemographics on reported mitigation efforts and performance among households in northeastern Mexico

Managing and reducing the impacts of climate change depends on efficient actions from all societal scales. Yet, the household component is often missing from climate research, debate, and policies. This is problematic because households have been found to significantly contribute to of global greenhouse gas emissions and therefore have the potential to be part of a solution to climate change by mitigating climate change. This study seeks to understand which factors drive household-level mitigation actions. We conducted a household survey in Nuevo Leon, located in northeastern Mexico, to explore the extent to which climate change perceptions and the sociodemographic characteristics of households influence their reported mitigation performances and their perceived mitigation efforts. Results from linear regression analyses and generalized linear models revealed that sociodemographic characteristics are key drivers of the households’ perceived mitigation efforts and reported mitigation performances and. We also found that climate change perceptions drive a household’s efforts to mitigate climate change. These results could partly explain why despite the efforts households take to mitigate climate change, achieving an effective reduction of greenhouse gas emissions is challenging without further access to resources such as education and financial support. If governments intend to realize substantial reductions in future emission pathways, then household-level mitigation should be addressed with proper support

A diachronic triangular perspective on landscapes: A conceptual tool for research and management applied to Wadden Sea salt marshes

Strong disciplinary academic fragmentation and sectoral division in policies lead to problems regarding the management of landscapes. As a result, there is a focus on the preservation and development of either cultural or natural landscapes. We argue that framing landscapes as "natural" or "cultural" will not help sustainable management. The goal of this paper is to show that even what is referred to as nature, virtually always features an intricate combination of physical geography, biology, and cultural history. It provides an analytical framework that visualizes the three forces at play in physical landscapes. Therefore, we introduce a diachronic triangular approach to study and manage landscapes from a holistic point of view, allowing an exchange of different perspectives. To test this approach, we have applied our model to a diachronic case study on Wadden Sea salt marshes. That area has been influenced by physical-geographical, biological, and cultural landscape forces, which are still visible in the landscape to a large extent. By placing different landscape zones in the triangular concept for different time periods, we can identify and visualize these driving forces through time for this specific landscape. These all play their specific roles in the appearance of the landscape over time in a close mutual interconnection. More importantly, we show that the diverse and complex interplay between these forces makes the current-day landscape what it is. We therefore conclude that the diachronic triangular approach provides a conceptual tool to define and operationalize landscape management in the Wadden Sea area. We welcome similar approaches in other landscapes to assess the usefulness of the diachronic triangular landscape approach