Ecosystem-based adaptation (EbA) is the use of biodiversity and ecosystem services as part of an overall adaptation strategy to help people to adapt to the adverse effects of climate change. EbA addresses the crucial links between climate change, people, biodiversity, natural resources and ecosystem services. It includes adaptation policies, and multi-level approaches to reduce the vulnerability and improve the resilience of ecosystems.
EbA is an emerging adaptation strategy that can also be applied to improve sustainable groundwater management. The overall aim of EbA in groundwater management is to preserve the quantity and quality of groundwater, and to improve the role of groundwater in ecosystem services for the benefit of present and future generations. It thereby mitigates the impacts on groundwater under changing conditions including, but not limited to, climate change. The sustainable use of groundwater comprises both the adapted management and the effective protection of groundwater environments. Understanding groundwater in its environmental context is therefore fundamental.
Ecosystem services are the benefits people obtain from ecosystems. Most ecosystems are highly dependent on the hydrological cycle and water availability. The services provided by these ecosystems are therefore also directly, and indirectly, dependent on the availability and state of groundwater resources. Increased groundwater abstraction, increased groundwater contamination and climate variability, are affecting the functioning of ecosystems and thereby jeopardize the services these ecosystems provide. To successfully address the challenges of climate change and anthropogenic pressures on groundwater, ecosystems and their services, a holistic view is needed. For such interdependent challenges ecosystem-based adaptation (EbA) could be a promising approach.
Ecosystem-based Adaptation measures
EbA approaches can provide cost-effective protection against threats that result from multiple pressures. Protection and preservation of natural infrastructure does not replace the need for built infrastructure, but instead provides a complement multiplying the benefits received from healthy, functioning ecosystems. Various EbA measures could be implemented to secure groundwater resources and ecosystem services. The implementation of EbA measures can be based on either a certain ecosystem service, part of an ecosystem or one or several ecosystems. To successfully implement and increase the effectiveness of EbA for groundwater management it is important to conduct an integrated vulnerability assessment on the ecosystem of interest. As such, it will identify the main ecosystem services, main threats and adaptive capacity of the ecosystem. Within the ecosystem, critical zones can be indicated where EbA will be most beneficial. Because the hydrological system is interconnected on various levels, adaptation measures in these (local) critical zones can be used strategically for groundwater management on a larger, regional scale.
Protection of critical recharge areas
- Groundwater recharge zones control both the quantity and quality of water reaching aquifers. Therefore recharge zones are at the centre of preventing pollution and maintaining supply for both drinking water and ecosystems. Currently, protection of groundwater recharge zones is primarily used in drinking water supply areas. Such protection schemes could be expanded to critical groundwater recharge areas in ecosystems to improve ecosystems resilience and secure the ecosystem services.
Protection of groundwater dependent ecosystems
- A subset of ecosystems that are highly dependent on groundwater are groundwater dependent ecosystems (GDEs). GDEs are therefore particularly vulnerable to changes in groundwater supply and groundwater contamination. The hydrological connection and fluxes from (critical) recharge areas to GDEs are therefore of vital importance to sustain GDEs. Understanding the regional hydrogeology, the connection between recharge and discharge areas to and within GDEs, and the level of groundwater dependency of these ecosystems can help to support decisions about prioritization of adaptation measures. Protection schemes for GDEs and their services should be established accordingly.
Protection and restoration of riparian zones and floodplains
- Riparian zones are efficient in water quality improvement for both surface runoff and water flowing into and out of streams through subsurface or groundwater flow. The services of riparian zones should be better integrated with land use planning. Protection, restoration and providing space for riparian zones will improve overall water quality.
- Particular components of the riparian zones are floodplains, the area of land adjacent to a stream or river and flooded by the river. Floodplains represent natural filtering systems thereby improving groundwater quality. When a river is dissociated from its floodplain with levees or other flood control facilities, the natural benefits are either lost, altered, or significantly reduced. Reconnecting floodplains to the natural river system increases the river's ability to absorb storm water, improves water quality and reduces risk of flooding and flood damage.
Adaptation of soil and vegetation cover
- Modification of the vegetation cover will affect groundwater recharge processes. The establishment of tree, bush and other plant cover in river basins is widely used as a way of reducing runoff and increasing infiltration. The net increase of groundwater recharge depends on the balance between improvements in infiltration and relative changes induced in evapotranspiration.
- The soil plays a significant role in any groundwater protection strategy. Both the quantity and quality of groundwater depend on the water that moves down through the soil to the saturated zone. Good soil management can support protection of groundwater resources. Prevention of soil erosion is one way to improve groundwater quality.
Investing in natural infrastructure
- Investing in natural infrastructure can reduce or avoid costs and enhance water services and security. Measures to ameliorate the natural drainage system and increase groundwater storage include preservation of wetlands and lakes. Also the construction of (artificial) wetlands, basins, ponds and re-meandering, could emulate the positive services and contribute to improved groundwater recharge and groundwater quality.