Gertjan Willem Geerling

• Dr.
• Senior Researcher at Deltares

Background: The world is experiencing rapid anthropogenic-driven changes in climate, biodiversity, and pollution. While most insect species are declining due to these changes, disease-transmitting mosquitoes, might thrive. However, the quantitative impacts of these changes on mosquito populations are not well understood. Our study aims to evaluate...

Wild birds serve as reservoirs and vectors for many different pathogens and changes in their distribution and abundance due to environmental change will influence disease risk. We study three species which are highly abundant in north-western Europe and which can transmit a wide range of diseases including avian influenza and West Nile virus: black...

Background Mosquito-borne diseases are on the rise. While climatic factors have been linked to disease occurrences, they do not explain the non-random spatial distribution in disease outbreaks. Landscape-related factors, such as vegetation structure, likely play a crucial but hitherto unquantified role. Methods We explored how three critically imp...

Sustainable management of the Citarum River is a complex problem due to climate challenges such as increase of extreme weather events, as well as by increased anthropogenic activities leading to water pollution, waterborne diseases and floods. To act on this, active engagement of diverse stakeholders in decision-making for integrated water manageme...

Background There is an urgent need for cities to become more climate resilient; one of the key strategies is to include more green spaces in the urban environment. Currently, there is a worry that increasing green spaces might increase mosquito nuisance. As such, this study explores a comprehensive understanding of how mosquitoes utilise contrastin...

The world is changing, in terms of both climate and socio-economics. These changes have the potential to have a profound impact on the health of humans, animals and the environment, often grouped together as ‘One Health’. Humans, animals and the environment are closely interlinked and to determine realistic future vulnerabilities we must consider e...

External nutrient loading can cause large changes in freshwater ecosystems. Many local field and laboratory experiments have investigated ecological responses to nutrient addition. However, these findings are difficult to generalize, as the responses observed may depend on the local context and the resulting nutrient concentrations in the receiving...

The human exposure model (HEM) is an important tool to predict the amount of contaminants carried by water to the community. Proper input variables play a crucial role in running the HEM, which is often scarce, particularly in low-and middle-income countries like Indonesia. To overcome that problem, we conducted a water demand survey of 10 water-re...

River processes and patterns are affected by changes in the watershed driven by natural and human‐induced causes. A sudden pattern alteration from a “white river” (bare soils) to a “green river” (vegetated) influences riverine biodiversity and can increase flood risk. Despite these significant impacts, knowledge on the triggers that kickstart feedb...

The incidence and risk of mosquito-borne disease outbreaks in Northwestern Europe has increased over the last few decades. Understanding the underlying environmental drivers of mosquito population dynamics helps to adequately assess mosquito-borne disease risk. While previous studies have focussed primarily on the effects of climatic conditions (i....

Over the last decade, rapid vegetation colonization and changes in channel morphology have been observed in the Naeseongcheon Stream in South Korea, which were linked to short-term hydrological fluctuations under a changing monsoon climate. The surface area covered by vegetation has been increasing; this increase intensified after the 2014–2015 dro...

Water use of domestic activities was quantified by interviewing 217 people in a peri-urban community near Bandung, Indonesia. Resulting in data on domestic water demand and data needed for exposure modelling of domestic activities: drinking, cooking, brushing teeth, swimming, bathing, laundry, dishwashing, religious cleansing, washing hands and cle...

Pharmaceuticals are increasingly used to treat and prevent disease globally. However, this trend has the potential to increase pharmaceutical discharge into the environment, especially from households. Pharmaceuticals released into the environment can harm human health, e.g., antimicrobial resistance. Thus, it is important to understand the drivers...

Two methods were developed to prioritize human health risks of pharmaceuticals based on defined daily doses (DDDs) obtained from the WHO and acute toxicity data on pharmaceuticals (TDLo) obtained from the PubChem database. A major advantage of these methods is that it requires no acceptable daily intake (ADI), reference dose (RfD), or tolerable dai...

Dams affect the natural flow regime by altering the magnitude, timing and frequency of high and low flows. Many river ecosystems impaired by dams are currently being restored. Restoration success is difficult to quantify and is often assessed by comparing the restored system to an unimpaired static ‘reference’ system. However, restoring a river to...

With a sixth mass extinction looming and freshwater biodiversity declining at unprecedented rates, evaluating ecological efficacy of river restoration efforts is critical in combatting global biodiversity loss. Here, we present a comprehensive study of the functioning for fishes of 46 river restoration projects in the river Rhine, one of the world'...

Since the middle of the 20th century, pesticide use has been a primary foundation of global agricultural development. However, the massive usage of pesticides can have detrimental impacts on human health and the environment, particularly in the aquatic ecosystem. This study determined the use of pesticides in the agricultural area of the Upper Cita...

Information on pesticide use types and pesticide use are needed to estimate pesticide emissions in the surface water. Unfortunately, these data is either limited or even non-exist in most lowand middleincome country like Indonesia. This problem is considered a missing link in the water monitoring system, especially in the emission estimation model...

The ecological efficacy of river restoration projects may change over time, resulting in the loss of their ecological function for targeted species. The goal of this study was to evaluate the rheophilic nursery function of restored floodplain channels over time, by analysing 30 years of monitoring data from 12 restoration projects in the lower rive...

A novel screening method was developed to prioritize aquatic and human health risks of pesticides based on usage data, runoff modelling and effect prediction. An important asset of this new method is that it does not require measured concentration data, which are often unavailable or difficult to obtain in low- and middle-income countries like Indo...

Lacking substantial erosive and sedimentation forces, regulated rivers allow their floodplains to become overgrown with forest, increasing the flood risk of the hinterland. In the Netherlands, floodplains have therefore been subjected to interventions, like clear cutting, lowering and creation of side channels, and management, consisting of grazing...

The successful use of relations between environmental processes (filters) and either plant traits or plant strategies has boosted ecological research. Various studies identified environmental filters shaping plant species composition. However, this approach is scarce in research on vegetation succession in floodplains of heavily modified rivers. Es...

In de 90-jaren van de vorige eeuw is gestart met het natuurlijker inrichten van de Maasoevers (PNOM). In 2005 heeft dit programma een grote impuls gekregen door het project “NVO-Maas”. De aanleiding hiertoe was de ambitie om de ecologische kwaliteit van de Maas te verbeteren, wat mede ingegeven was door de Europese Kaderrichtlijn Water. Besloten is...

The water-related exposome is a significant determinant of human health. The disease burden through water results from water-associated communicable and non-communicable diseases and is influenced by water pollution with chemicals, solid waste (mainly plastics), pathogens, insects and other disease vectors. This paper analyses a range of water prac...

This abstract summarizes the outcomes of a 10 year monitoring project of biological and hydro-morphological parameters in the Dutch part of the Meuse river after partial removal of bank protection.

River morphology and riparian vegetation continuously adapt to changing discharge conditions, which makes it a challenge to distinguish long-term development driven by natural discharge variation from the impacts of flow alteration due to climate change and due to dams. The aim of this study was to investigate how such flow alterations affect bio-g...

Pollution of water resources is a major risk to human health and water quality throughout the world. Here, we studied the effect of river pollution on the microbial community composition in the Citarum River Basin, West Java, Indonesia. Sediment was collected at six sampling points along a gradient of pollution, from the pristine source of the rive...

Achieving equitable access to water, in the sense of both physical and economic accessibility, remains a challenge. The article evaluates these two types of accessibility across households of different income groups in Central Cikapundung Basin, Indonesia. Higher-income households are more likely to use piped water, bottled water, or combinations t...

Many riparian ecosystems in European temperate regions have lost their inherent, highly dynamic character due to human-induced impacts such as river channelization and flow regulation. The lower course of the Allier River (France) is one of the last remaining free meandering river segments, and thus, constitutes an opportunity to investigate ripari...

Invasive alien plant species negatively impact native plant communities by out-competing species or changing abiotic and biotic conditions in their introduced range. River systems are especially vulnerable to biological invasions, because waterways can function as invasion corridors. Understanding interactions of invasive and native species and the...

There is a growing awareness in cities throughout the world that green and blue infrastructure can offer a wide range of ecosystem services to support a healthy urban environment. For example, landscape architects explore possibilities in their design of the urban landscape to use the potential of green elements for regulating air temperature, air...

As the largest drinking water source in West Java, Citarum River is in critical condition. Economic development and population growth have seriously impacted to the Citarum River. Citarum River was stated as "Top 10 World's Most Polluted Places" based on The Nation on November 6 th , 2013. The water quality in Citarum River is influenced by emissio...

Dynamic interaction between river morphodynamics and vegetation affects river channel patterns and populations of riparian species. A range of numerical models exists to investigate the interaction between vegetation and morphodynamics. However, many of these models oversimplify either the morphodynamics or the vegetation dynamics, which hampers th...

Until recently, governmental organizations played a dominant and decisive role in natural resource management. However, an increasing number of studies indicate that this dominant role is developing towards a more facilitating role as equal partner to improve efficiency and create a leaner state. This approach is characterized by complex collaborat...

The study of the influence of vegetation on hydraulic risk is of primary importance in river planning and decision making. In this work, we investigate the effects of channel and riparian vegetation on the catastrophic flood event that occurred on 25/10/2011 in the river Magra, (Tuscany region, Italy). This 200-year-return-period flood had produced...

This deliverable presents the overview and structure of the REFORM 3-day summer school ‘Restoring regulated streams linking theory and practice’ for early career researchers and young scientists. On the first day participants took part in a field excursion to river restoration projects in the vicinity of Wageningen in The Netherlands. On the second...

European rivers have been altered by means of changing their morphology (straightening and canalisation, disconnecting channels from flood plains, occupying riparian lands, building dams, weirs, bank reinforcements, etc.) to facilitate agriculture and urbanisation, to enable energy production and protection against flooding. Also, water has been ab...

This chapter considers the interaction between landscape and hydraulics in several case studies and provides an approach for landscape-scale analysis of ecohydraulic processes and patterns within riverine ecosystems. The individual case studies focus on: (1) landscape dynamics in a naturally functioning river, providing a conceptual view of landsca...

Encroachment of tall grasses and shrubs in coastal dunes has resulted in loss of vegetation heterogeneity. This is expected to have negative effects on animal diversity. To counteract encroachment and develop structural heterogeneity grazing is a widely used management practice. Here, we aim to functionally interpret changes in vegetation compositi...

This paper evaluates the development offish, aquatic macro fauna and aquatic macro phytes in relation to physical conditions in 4 secondary river channels along the river Rhine and IJssel that were recreated nearly 20 years ago. Macro phyte development strongly depended on the maximum of water level fluctuations and the maximum water depth. Macro f...

In the future, climate change may severely alter flood patterns over large regional scales. Consequently, besides other anthropogenic factors, climate change represents a potential threat to river ecosystems. The aim of this study is to evaluate the effect of climate change on floodplain inundation for important floodplain wetlands in Europe and to...

This paper deals with the relation between legally protected biodiversity and riverine ecotopes and with the assessment of biodiversity values of the Middle Vistula river valley (Poland). Furthermore, it describes the effects of landscape change on spatial distribution of ecotope patches and biodiversity values in Kazimierski Landscape Park. Biodiv...

Floodplain land cover maps are important tools for river management and ecological assessment. These maps have to be revised regularly due to the dynamic nature of floodplains. Automation of the mapping process cuts the map processing time and can increase overall accuracy. Manual delineation and classification of vegetation is based on colour, con...

Combined optical and laser altimeter data offer the potential to map and monitor plant communities based on their spectral and structural characteristics. A problem unresolved is, however, that narrowly defined plant communities, i.e. plant communities at a low hierarchical level of classification in the Braun-Blanquet system, often cannot be linke...

The “Ewijkse Plaat” is a floodplain along the Waal River, NL. In 1988, the floodplain was excavated as part of a program for enlargement of the discharge capacity and was assigned as a nature rehabilitation area. This paper describes the combined geomorphological and vegetation evolution of the floodplain until 16 years after the initial excavation...

Seagrasses are threatened by human activity in many locations around the world. Their decline is often characterized by sudden ecosystem collapse from a vegetated to a bare state. In the 1930s, such a dramatic event happened in the Dutch Wadden Sea. Before the shift, large seagrass beds (Zostera marina) were present in this area. After the construc...

To safeguard the goals of flood protection and nature development, a river manager requires detailed and up-to-date information on vegetation structures in floodplains. In this study, remote-sensing data on the vegetation of a semi-natural floodplain along the river Waal in the Netherlands were gathered by means of a Compact Airborne Spectrographic...

The spatio-temporal heterogeneity of a meandering part of the Allier river was studied by analysing ecotope composition and dynamics using a series of aerial images covering a period of 46years (1954–2000). The ecotope dynamics was exemplified by two time series showing rejuvenating hydro-geomorphological processes, i.e., meander progression, meand...

The spatio-temporal heterogeneity of a meandering part of the Allier river was studied by analysing ecotope composition and dynamics using a series of aerial images covering a period of 46 years (1954–2000). The ecotope dynamics was exemplified by two time series showing rejuvenating hydro-geomorphological processes, i.e., meander progression, mean...

To reduce flood risks in the Netherlands, measures to increase the flood conveyance capacity of the Rhine River will be implemented. These measures will provide more room for the river and include lowering of the floodplains and excavation of secondary channels. Moreover, these measures provide opportunities for ecological rehabilitation of the flo...

To reduce flood risks in the Netherlands, measures to increase the flood conveyance capacity of the Rhine River will be implemented. These measures will provide more room for the river and include lowering of the floodplains and excavation of secondary channels. Moreover, these measures provide opportunities for ecological rehabilitation of the flo...

In the Netherlands, the large floods of the river Rhine that occurred in the winters of 1993/1994 and 1994/1995, triggered a number of policy analysis studies to design strategies which minimise flood risks and simultaneously enhance the ecological quality of the river Rhine. Studies showed that measures such as low- ering the floodplains and (re)c...