Case study 2: Groundwater – surface water interaction in limestone areas of the GWB BE_Meuse_RWM021 (Belgium)

The achievement of good status in groundwater bodies involves meeting a series of
conditions, which are defined in the Water Framework Directive (WFD) and, in the case of
good chemical status, are given further detail in the Groundwater Directive (GWD). One
of these conditions is to ensure that groundwater inputs to associated surface waters do
not result in failure to meet the environmental objectives of those waters or result in
significant diminution in status/ecological or chemical quality of those waters.
GWAAE (Groundwater Associated Aquatic Ecosystems) are those surface water bodies
(SWBs), including rivers, standing waters and transitional waters where the surface
water ecology and hydrology is dependent on contributions from groundwater in order to
meet their environmental objectives under the WFD. These environmental objectives may
vary, and therefore the associated environmental quality standards (EQS) or flow/level
requirements of GWAAEs may differ between high status and good status SWBs.
As noted in the Blueprint for Water, analysis of the first River Basin Management Plans
has shown that Member States (MS) have experienced difficulties in understanding the
interactions between groundwater and surface water and undertaking the necessary
status assessments. This was highlighted in a survey carried out by Working Group
Groundwater (WGGW) in 2014/15, which indicated that only half of the MS had assessed
quantitative interactions and very few had addressed chemical pressures, including the
derivation of threshold values (TVs) that were appropriate to the WFD objectives for
GWAAEs.
This report aims to further knowledge on what GWAAE are, how they are aligned to WFD
processes, and support Member States to properly include the needs of these ecosystems
in river basin management planning.
The report clarifies the categories of GWAAE and their relative dependence on
groundwater and collates current available knowledge and experience via a number of
examples and case studies. Terminology and status assessment procedures are explained
and pragmatic approaches are proposed which leave some flexibility for MS to adapt to
their own specific needs. This technical report, which is not a "guidance document",
makes use of and complements existing CIS documents, including existing technical
reports on groundwater dependent terrestrial ecosystems (GWDTEs) and Guidance
Document 18 (Guidance on Groundwater Status and Trend Assessment).
A number of recommendations for technical users of the report are highlighted in boxes
in each Chapter. The common themes from these recommendations are collated in
Chapter 8, as issues and questions to WGGW and MS in general. The key message from
this is the need for closer interaction between scientific disciplines, practitioners and
Working Groups in developing conceptual understanding for GWAAEs and implementation
of WFD requirements, including identification of GWAAEs, their characterisation and
monitoring, and adopting appropriate status assessment methodologies.