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Objectives related to the achievement of Good Quantitative Status
The
objectives related to the achievement of good quantitative status
for a groundwater body, necessitate that the total abstraction
(inclusive of natural groundwater outflow) from that groundwater
body does not exceed its mean annual recharge. Initial
water-balance estimations were conducted for each groundwater
body.
|
Groundwater Body Code |
Groundwater Body Name |
Size
(km2) |
Inflow (hm3) |
Outflow (hm3) |
Balance (hm3) |
Major Extraction |
|
MT001 |
Malta Main Mean Sea Level |
216.6 |
34.27 |
36.65 |
-2.38 |
Abstraction
for potable and agricultural purposes |
|
MT002 |
Rabat-Dingli Perched |
22.6 |
4.64 |
4.62 |
0.02 |
Abstraction
for agricultural purposes |
|
MT003 |
Mgarr-Wardija Perched |
13.7 |
2.86 |
3.46 |
-0.59 |
Abstraction
for potable and agricultural purposes |
|
MT005 |
Pwales Coastal |
2.8 |
0.69 |
0.69 |
0.00 |
Abstraction
for agricultural purposes; |
|
MT006 |
Mizieb Mean Sea Level |
5.2 |
1.11 |
0.96 |
0.15 |
Abstraction
for potable and agricultural purposes |
|
MT008 |
Mellieha Perched |
4.5 |
0.75 |
0.53 |
0.22 |
Abstraction
for agricultural purposes |
|
MT009 |
Mellieha Coastal |
2.9 |
0.69 |
0.38 |
0.31 |
Abstraction
for agricultural purposes |
|
MT010 |
Marfa Coastal |
5.5 |
0.89 |
0.62 |
0.27 |
Abstraction
for agricultural purposes |
|
MT011 |
Mqabba-Zurrieq Perched |
3.4 |
0.50 |
n/a |
n/a |
Abstraction
for agricultural purposes |
|
MT012 |
Comino Mean Sea Level |
2.7 |
0.52 |
0.30 |
0.22 |
Abstraction
for agricultural purposes |
|
MT013 |
Gozo Mean Sea Level |
65.8 |
8.66 |
9.78 |
-1.12 |
Abstraction
for potable and agricultural purposes |
|
MT014 |
Ghajnsielem Perched |
2.7 |
0.73 |
0.34 |
0.39 |
Abstraction
for agricultural purposes |
|
MT015 |
Nadur Perched |
5.0 |
1.15 |
0.58 |
0.57 |
Abstraction for agricultural purposes |
|
MT016 |
Xaghra Perched |
3.0 |
0.71 |
0.33 |
0.38 |
Abstraction for agricultural purposes; |
|
MT017 |
Zebbug Perched |
0.4 |
0.10 |
0.03 |
0.07 |
Abstraction for domestic purposes |
|
MT018 |
Victoria-Kercem Perched |
1.5 |
0.39 |
0.14 |
0.25 |
Abstraction for domestic purposes |
Owing
to the fact that from the initial results obtained no groundwater
body could be clearly defined as being ‘not at risk’ of failing to
achieve the ‘quantitative status objectives’ by 2015; detailed
water balance calculations of the groundwater body will have to be
undertaken during the ‘further characterisation’ stage which will
take into account sub-surface groundwater flow mechanisms as
defined in the conceptual flow-models of the groundwater bodies,
which are currently being developed.
Objectives related to the achievement of Good Quantitative Status
The
objectives related to the achievement of good qualitative status
for a groundwater body rely on the attainment of ‘groundwater
quality standards’ as defined in the Regulations and the
‘groundwater threshold values’ which are currently being defined
in the proposed ‘Groundwater Directive’.
Article 2 of the proposed Groundwater Directive recommends the
following definitions:
|
Groundwater Quality
Standard |
an environmental quality standard expressed as the
concentration of a particular pollutant, group of pollutants
or indicator for pollution in groundwater, which should not be
exceeded in order to protect human health and the environment |
|
Groundwater
Threshold Value |
a
groundwater quality standard to be established by Member
States for pollutants, group of pollutants and indicators of
pollution which, within the territory of a Member State, have
been identified as contributing to the characterisation of
groundwater bodies or group of bodies as being at risk. |
The
Water Policy Framework Regulations adopt groundwater quality
standards for Nitrates and Pesticides at 50mg/L and 0.5µg/L(total)
respectively; whilst the proposed Groundwater Directive will
require ‘threshold values’ to be set for at least the following
parameters: Ammonium, Chloride, Sulphate, Conductivity, Arsenic,
Cadmium, Lead, Mercury, Trichloroethylene and Tetrachlorethylene.
The
prevention of significant ‘saline or other intrusion’ is another
objective of the Regulations. The issue of sea-water intrusion is
of particular importance to Malta’s sea-level and coastal aquifers
which are in direct contact with sea-water.
The
results of this preliminary analysis indicate that almost all the
groundwater bodies are possibly ‘at risk’ of failing to achieve
‘good status’ objectives. The principal reason behind this risk
classification was the high nitrate content present in these
groundwater bodies. However, since groundwater chemical data was
lacking for a number of bodies, their real condition should be
further investigated and the conclusions reached corroborated with
real data during the ‘further characterisation’ stage.
Objectives related to directly dependent terrestrial eco-systems
The
degree of dependence of certain terrestrial eco-systems on
adjoining groundwater bodies is currently being investigated with
the collaboration of the Malta Environment and Planning
Authority. A number of potential dependent eco-systems have thus
been identified.
Owing
to the fact that almost all the groundwater bodies are ‘at risk’
of failing to achieve the environmental objectives on grounds of
attainment of good qualitative and quantitative status, it was
deemed appropriate to investigate the degree of dependence of
these eco-systems on groundwater during the formulation of the
conceptual model of each groundwater body in the ‘further
characterisation’ stage.
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