Arsenic contamination of groundwater is a major public health concern worldwide. The problem has been reported mainly in southern Asia and, especially, in Bangladesh. Slow-sand filters (SSF) augmented with iron were proven to be a simple, low-cost and decentralized technique for the treatment of arsenic-contaminated sources. In this research, three pilot-scale SSF (flowrate 6 L·h−1) were tested regarding their capability of removing arsenic from groundwater in conditions similar to those found in countries like Bangladesh (70 µg As(III) L−1, 26 °C). From the three, two filters were prepared with mixed media, i.e., sand mixed with corrosive iron matter (CIM filter) and iron-coated sand (ICS filter), and a third conventional SSF was used as a reference. The results obtained showed that the CIM filter could remove arsenic below the World Health Organization (WHO) guideline concentration of 10 µg·L−1, even for inlet concentrations above 150 µg·L−1. After 230 days of continuous operation the arsenic concentration in the effluent started increasing, indicating depletion or saturation of the CIM layer. The effluent arsenic concentration, however, never exceeded the Bangladeshi standard of 50 µg·L−1 throughout the whole duration of the experiments.
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City growth threatens sustainable development of cities. Over the past decades increased urbanization has created more pressure - not only on the suburban outskirts - but also in the inner core of the cities, putting important environmental issues such as water management and cultural heritage under stress. Cultural heritage, either standing monuments or archaeological remains, is internationally recognized as an important legacy of our history. The European Convention on the Protection of the Archaeological Heritage incorporates concepts and ideas that have become accepted practice in Europe. Conservation and enhancement of archaeological heritage is one of the goals of urban planning policies. One of the key objectives of the European policy is to protect, preferably in-situ, archaeological remains buried in the soil or seabed and to incorporate archaeological heritage into spatial planning policies. Conflicts with prior uses and unappreciated impacts on other subsurface resources, amongst them archaeological heritage, make use of underground space in cities suboptimal. In terms of ecosystem services, the subsurface environment acts either as a carrier of archaeological heritage in situ (stewardship) or supports above-ground cultural heritage. Often, it’s not enough to protect the heritage site or monument itself: new developments outside a specific protected area can lead to changes in groundwater level, and cause serious damage to heritage buildings and archaeological deposits. This paper presents good practices in cultural heritage management and the use of subsurface knowledge in urban areas.
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The rain gardens at Bryggen in Bergen, Western Norway, is designed to collect, retain, and infiltrate surface rainfall runoff water, recharge the groundwater, and replenish soil moisture. The hydraulic infiltration capacity of the Sustainable Drainage System (SuDS), here rain gardens, has been tested with small-scale and full-scale infiltration tests. Results show that infiltration capacity meets the requirement and is more than sufficient for infiltration in a cold climate. The results from small-scale test, 245–404 mm/h, shows lower infiltration rates than the full-scale infiltration test, with 510–1600 mm/h. As predicted, an immediate response of the full-scale infiltration test is shown on the groundwater monitoring in the wells located closest to the infiltration point (<30 m), with a ca. 2 days delayed response in the wells further away (75–100 m). Results show that there is sufficient capacity for a larger drainage area to be connected to the infiltration systems. This study contributes to the understanding of the dynamics of infiltration systems such as how a rain garden interacts with local, urban water cycle, both in the hydrological and hydrogeological aspects. The results from this study show that infiltration systems help to protect and preserve the organic rich cultural layers below, as well as help with testing and evaluating of the efficiency, i.e., SuDS may have multiple functions, not only storm water retention. The functionality is tested with water volumes of 40 m3 (600 L/min for 2 h and 10 min), comparable to a flash flood, which give an evaluation of the infiltration capacity of the system.
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Hydrosystem Restoration Handbook: Groundwater Natural Recharge (GNR), Second Edition covers the essentials of GNR with a range of global case studies that encompass the most up-to-date management approaches in streams. The book provides comprehensive methods for sustainable water supply through debris removal, along with conservation practices to assist researchers and graduate students specializing in this field.
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Urbanisation and climate change have an effect on the water balance in our cities resulting in challenges as flooding, droughts and heatstress. Implementation of Sustainable Urban Drainage Systems (SuDS) can help to restore the water balance in cities by storing and infiltrating stormwater into the subsurface to minimise flooding, restoration of groundwater tables to prevent droughts, lowering temperatures by evapotranspiration to fight heatstress. Urban planners and otherstakeholders in municipalities and water authorities struggle with implementing SuDS at locations where infiltration of water seems challenging. Questions arise as: can you infiltrate in countries as The Netherlands with parts under sea level, high groundwater table and low permeable soil? Can you infiltrate in Norway with low permeable or impermeable bedrock and frozen ground most of theyear? How do you find space to implement SuDS in the dense urban areas of Bucharest? These questions are answered by researchers of the JPI Water funded project INovations for eXtreme Climatic Events (INXCES).To answer the question on ‘can we infiltrate stormwater under worse case conditions?’, testing of the hydraulic capacity take place at rainwater gardens in Norway (Bergen and Trondheim) and (bio)swales in the low lying parts of The Netherlands. The first results show that even under these ‘extreme’ hydraulic circumstances the hydraulic capacity (or empty time) is sufficient to infiltratemost of the stormwater throughout the year.INXCES exchanged researchers on an international level, shared research results with stakeholders and sets up guidelines for design, implementation and maintenance of SuDS to promote the implementation of sustainable water management systems throughout the world.One of the tools used to promote SuDS is www.climatescan.nl, an open source online map application that provides an easy-to-access database of international project information in the field of urban resilience and climate adaptation. The tool is able to map several sustainable urban drainage systems as has been done for Norway, The Netherlands, Romania and other countries in the world.The tool is used for engagement with stakeholders within EU projects as INXCES and WaterCoG and resulted in international knowledge exchange on infiltration of stormwater under extreme climate and geohydrolic circumstances.
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Stormwater runoff can contain high amounts of Potential Toxic Elements (PTE) as heavy metals. PTE can have negative and direct impact on the quality of surface waters and groundwater. The European Water Framework Directive (WFD) demands enhanced protection of the aquatic environment. As a consequence, the WFD requires municipalities and water authorities to address the emissions from drainage systems adequately and to take action when these emissions affect the quality of receiving waters together with mitigating the quantity challenges in a changing climate (floodings and drought). NBS is the most widely used method for storing stormwater and infiltrating in the Netherlands. However, there is still too little knowledge about the long-term functioning of the soil of these facilities. The research results are of great importance for all stakeholders in (inter)national cities that are involved in climate adaptation. Applying Nature-Based Solutions (NBS), Sustainable Urban Drainage Systems (SuDS) or Water Sensitive Urban Design (WSUD) are known to improve the water quality in the urban water cycle. The efficiency of NBS, such as the capability of bio swales to trap PTE, highly depends on the dimensions of the facility and on its implementation in the field [Woods Ballard, B et al, 2015]. For the determination of the removal efficiency of NBS information about stormwater quality and characteristics is essential. Acquiring the following information is strongly advised [Boogaard et al. 2014]:1. stormwater quality levels (method: stormwater quality database);2. location of NBS (method: mapping NBS in international database);3. behaviour of pollutants (method: cost effective mapping pollutants in the field). Stormwater quality contains pollutants as heavy metal in higher concentrations than water quality standards dictate. Over 500 locations with bio swales are mapped in the Netherlands which is a fraction of stormwater infiltration locations implemented in 20 years’ time. Monitoring of all these NBS would acquire high capacity and budget from the Dutch resources. This quick scan XRF mapping methodology of topsoil will indicate if the topsoil is polluted and whether the concentrations exceed national or international standards. This was only the case in one of the youngest pilots in Utrecht indicating that there are multiple factors other than age (traffic intensity, use of materials, storage volume, maintenance, run off quality, etc.). Several locations show unacceptable levels, above the national thresholds for pollutants where further research on the prediction of these levels in relation to multiple factors will be the subject of future research.The results of study are shared in 2 national workshops and valued as of great importance for all stakeholders in (inter)national cities that are involved in implementation of NBS for climate adaptation. The Dutch research results will be used to update (inter-)national guidelines for design, construction and maintenance of infiltration facilities this year. Stormwater managers are strongly advised to use this quick scan method within the first 10 years after implementation of swales to map possible pollution of the top soil and prevent pollution to spread to the groundwater in urban areas.
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The shallow subsurface in historic cities often contains extensive archaeological remains, also known as cultural deposits. Preservation conditions for naturally degradable archaeological remains are strongly dependent on the presence or absence of groundwater. One of the main goals at such heritage sites is to establish a stable hydrological environment. Green infrastructural solutions such as Sustainable Urban Drainage Systems (SUDS) can support preservation of cultural deposits. Several cases show that implementation of SUDS can be cost effective at preservation of cultural deposits. These include Motte of Montferland, City mound of Vlaardingen, Weiwerd in Delfzijl, and the Leidse Rijn area. In all cases, the amount of underground infrastructure is minimised to prevent damaging cultural layers. SUDS have been implemented to preserve cultural heritage. The first monitoring results and evaluation of the processes give valuable lessons learned, transnational knowledge exchange is an important element to bring the experiences across boundaries.
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