https://www.theearthneedslove.com/2023/08/water-footprint.html
Water Footprint
Abrar Hussain
International center for Chemical
and Biological Sciences, University of Karachi, Karachi Pakistan
Email: abrarhussain0307@gmail.com
Water Footprint (WF) concept was introduced by Arjen Hoekstra in
2002 during a meeting focusing on virtual water trade [1, 3]. It is defined as the measure of
the amount of water consumed directly or indirectly for the consumption of
human activities [1,2]. The water footprint of a product
is shown in water volume per unit of product and it is the summation of all
those steps that are required in product production [7]. There are different water
footprints for individuals, communities, regions, and nations, as explained by
[5]. These concepts start due to the
human impact on the environment [4] and raise the awareness of a nation about the proper usage of
water and show the global water resource management [1]. Water footprint not only shows
the use of water but also indicate the degree of change in environments, like
climate change [3, 5]. Water footprint was standardized by ISO standard 14,046, while
in European Union it is defined under Water Framework Directive (FWD) to
improve water production quality and deficiency [4]. WF is important as it is reported that human dependency on the water
are increasing rapidly and used un-effectively which create water scarcity [5, 6]. It is estimated that 22% of the
water consumption is related to trade through water [6]. The field of water footprint is
very well explained as a new research area by [9] and emphasizes four key concepts. These
concepts are described as;
1-
The concept of virtual water trade
(VWT): showing that freshwater is a global resource that effect on the global
economy.
2-
Limited amount of freshwater: this
is explained by the limited rate of renewal for fresh water so a system will
develop to study their production, consumption, and trade.
3-
Understanding of natural resources:
the use and impacts of water consumption, their supply chain, and life cycle.
4-
Approaches towards freshwater: while
following a comprehensive approach towards freshwater scarcity and its use, the
consumers must consider blue, green, and gray water.
Recently it is reported by [10] that WF magnitude is highly affected by the type of soil,
management of water, and change in the climate. The conceptual framework of the
water footprint is summarized in Figure 1, (data taken from 3, 4, 5, 10, 12) showing the three types of water, qualitative
and assessment approaches of WF, and the calculations of consumed water. The
WFcon is achieved by two methods i.e. top-down and bottom-up. The former one is
composed of WFpro + virtual water import (VWi) – Virtual water export (VWe).
Types/components of water
The scientist divvied the water resources into three types i.e.
blue water, green water, and grey water [6]. Green water is the water of
unstructured zones which are available for plants and mostly formed due to
precipitation, while blue water is the commonly available water in various
forms like river, lakes, and springs [3, 7]. Another type is grey water which
act as indicator for water pollution and reflects the freshwater volume which is
used in the assimilation of water pollutants [6]. In term of the consumptive and
degradative concept, the former concept is associated with green water (rainwater
consumption) and blue water (consumption of surface or groundwater), while the
latter term explains grey water for the assimilation of water-related
pollutants [9].
Traditionally the concept of water footprint were restricted to
blue water but later other form were also included. These types of water are
widely used for various purposes for instance, green water is the leading
source for rainfed agriculture while blue water is mainly used in agriculture
irrigation [3]. Green water is mostly the product
of agricultural activities as they are evaporated from soil after rain,
absorbed by roots, or transcribed from crops [4]. Gray water is used domestically, industrially, and commercially
for various purposes [15].
Assessment of water footprint
Assessment of water can quantify the three forms of water and
assess their sustainability, efficiency, and the approaches that are used to
implement the water footprint effectively. In a broader sense, this concept
covers hydrological, environmental, social and economic science [13]. The four key steps in water
assessment are the following;
1-
Scope and goal: diversified and
actionable goals are stetted.
2-
Data mining: once goals are stetted
then data will be collected from various sources and analyzed.
3-
Sustainability assessment: in this
step water sustainability and efficiency are assessed.
4-
Response strategies: once enough
data and other parameters are obtained then response strategies are formulated
to achieve the target.
The assessment of water footprint is achieved by two pathways, the
volumetric approaches of the Water Footprint Network (WFN) and the Life Cycle Analysis
(LCA) [3, 4 ]. The first approach focus on the management of water and is concern
with the quantification, sustainability, formulation and scope of water, while
the second is product-based approach and focus on inventory and impact
assessment, goal, and interpretation of water [4]. The quantification approaches are comprised of 5 types, namely Field Crop Water Requirement (FCWR), Regional Water Balance
(RWB), Field Soil Water Balance (FSWB), Field Measured Water Balance (FMWB),
and Remote Sensing (RS) as shown in fig.1 [10].
Importance of WF
Water footprint is important in various aspects; it cover all types
of water in term of measurement and calculations, it is the main source of
agriculture, mining, forestry, and fishing economy, it helps in the productions
of goods, used in industry, help in construction etc. use for the
transportation of goods and other substances and help in the production of food
substances [6, 10]. WF also shows the water appropriation which indicates both water
consumption and water assimilation [7].
Water footprint understanding can help nations to formulate their
national policies [8].
The field of WF can interconnect both water resources and environmental
science [9]. Currently, the root of water
footprint is embedded in crops, foods, cheese, leather, milk, meat, and the municipal
sector [9].
For water sustainability, the WF concept is crucial as they become an
important parameter in water consumption and pollution [11].
As the freshwater amount is limited and how we human are using are vulnerable
that leads to cause various environmental threats. Currently, such water
sources are depleted in many parts of the world and causing damage to soil,
ecosystem, and habitat and causing drastic climate change [12]. WF also shows the
relationship between the production system and socio-economic activities which
are the main factors of water assessment [14].
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