3
ecological view point, sustainability may be defined as
"an increasing trend in production over time per unit
consumption of the non-renewable or limiting resources
or per unit degradation of soil and environmental
characteristic. The dominantly economically-oriented
perspective puts more emphasis on economic aspects.
Natural resources are either disregarded or only
marginally taken into account (Ikerd, 1990). The role of
such factors of production as the availability of natural
resources and environmental services, but also that of
environmental impacts as products of economic activity
are neglected.
In the eco-friendly economic development perspec
tive, the ecological equilibrium is taken as norm and the
focus is mainly on building up a pattern and a rate of
resource use which the environment can sustain
indefinitely (Wilkinson, 1973). Lastly, the social
perspective lays more emphasis on continued welfare of
the society. The role of economic-demographic inter
relationship is either explicitly or implicitly referred to.
4. SUSTAINABILITY INDICATORS
Sustainability is a concept and can not be measured
directly. Appropriate indicators must, therefore, be
selected, tested, and validated to determine levels and
duration of sustainable land management. Sustainability
indicators are needed to monitor progress and to assess
the effectiveness and impact of policies on natural
resources development. An ideal indicator should be
unbiased, sensitive to changes, predictive, referenced to
threshold values, data transformable, integrative and
easy to collect and communicate (Liverman et a/., 1988).
One such indicator is land quality indicator which
includes nutrient balance, yield trend and yield gaps,
land use (agrodiversity) and land cover (Dumanski,
1997). Apart from above mentioned indicators, other
sustainability indicators namely, soil sustainability
indicators, indicators for sustainable use of water
resources, indictors for changes in micro-climate, soil
and crop management indicators, resource base
indicators, indicators for different eco-regions, etc. have
been developed (Lai, 1994). Important among them are
indicators for sustainable use of water resources and
sustainability indicators of different eco-regions.
Indicators for sustainable use of water include amount,
processes governing water cycle, use efficiency and its
quality.
Sustainability coefficient (Cs) which is dynamic
and is problem or mission-oriented is another indicator
of sustainability. There are three basic systems, natural
system, man-made system and interface system. One
such proposed coefficient for a man-made system may
be as follows (Lai, 1991):
Cs = f (Oi, Od, Om) t
Where
Oi = Output per that unit input that maximizes the per capita
productivity or profit
Od = Output per unit decline in the most limiting or non-
renewable resource
Om = Minimum assured output
t - time
The exact nature of the function may be site-
specific and will need input from local empirical
research data. For a natural system the sustainability
coefficient (Cs), mentioned above, could be modified to
account for the role of human being and could be written
as (Rao and Chandrasekhar, 1996).
Cs - f (Oi, Od, Om, HDI) t
Where HDI = Human development index
Further, in case of a interface system also the HDI
becomes very important modulating factor for deriving
sustainability indices. Conceptually, it can be formulated
as (Rao and Chandrasekhar, 1996).
Cs = f (Oi, Od, Om) t. HDI
For man-made system dominated by agricultural
farming, the model conceptualizes a positive feed back
mechanism between Q1 and Q2 which could be
expressed in a simple form as (Rao et a!., 1995).
Q1 - Q2 > 0 Unsustainable development
Q1 - Q2 = 0 Sustainable development
Q1 - Q2 < 0 Virgin eco-systems (Protected bio-reserves)
Where Q1 = Production in energy units and includes the
emission of C0 2 , transport of moisture through évapo
transpiration and transport of nutrients
Q2 = Consumption in terms of energy units C0 2 , H 2 0
and nutrients from the atmosphere or external sources.
A fragile balance between production processes
(Q1 energy units) and consumption practices (Q2 energy
units) ensures compatibility between supportive and
assimilative capacity of a region.
5. INTEGRATED ASSESSMENT
Hitherto, the natural resources, namely minerals,
groundwater, soils, vegetation / forest cover and surface
water have been mapped and treated individually for
their optimal utilisation. Since most of these resources
are interdependent and co-exist in nature, they need to
be considered collectively for their optimal utilisation.
This fact has led to the development of the concept of