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