『Abstract
Salinization and alkalinization are the most common land degradation
processes, particularly occurring in arid and semi-arid regions,
where precipitation is too low to maintain a regular percolation
of rainwater through the soil. Under such a climatic condition,
soluble salts are accumulated in the soil, influencing soil properties
and environment which cause lessening of the soil productivity.
The consistent identification of the processes is essential for
sustainable soil management.
Identification, large scale mapping and monitoring of the salt-affected
areas have been done using three different data and techniques.
Remote sensing has been widely used to detect and map salt-affected
areas, since thousands of medium to high-resolution imageries
from the earth surface are available. In practice, most of these
studies have focused on severely saline areas and have given less
attention to the detection and monitoring of slightly or moderately
affected areas. The major constrain is related to the nature of
the satellite images, which do not allow extracting information
from the third dimension of the 3-D soil body e.g., where salts
concentrate in subsoil. Solute transport modelling is another
technique which is used to predict the salt distribution in the
subsoil. It has the advantage of providing subsoil information
on dynamics of the salt movement regimes. This technique provides
complementary data on salt movement in the soil profile which
can be used in combination with remote sensing data. Since a few
years, near-surface geophysics sensors, particularly airborne,
are widely used to map and monitor salt-affected areas. This technology
has the advantage of effectiveness for cropped land and can efficiently
be used to highlight conductive areas where no surface expression
of salts is evident.
The paper outlines the conceptual framework of a method where
the data obtained from optical remote sensing sensors should be
integrated with the results of simulation models and geophysical
survey in order to predict different levels (low, moderate, severe)
of salinization/alkalinization in a cost-attractive and efficient
way. In the proposal integrated method, data are combined not
only to demarcate the existing salt-affected soils, but also to
track down the salinization as a pedogenic process. Such an approach
focuses on the integration of the data with different natures
and scales, meaning that data fusion and up-scaling are strongly
involved.
Keywords: Soil degradation; Salinization; Remote sensing; Solute
modelling; Geophysics 』
Contents
1. Introduction
2. Remote sensing and salt-affected soils
2.1. Factors affecting salt-affected soils reflectance
2.2. Constraints and advantages of remote sensing in salinity
study
3. Groundwater modelling and salinization
3.1. Prospective of modelling in salinity study
4. Geophysical exploration and salt-affected soils
4.1. Geophysical methods used in salinity studies
4.2. Application of geophysics exploration in salinity studies
5. The proposed integrated approach
5.1. Applications of proposed integrated approach
6. Conclusion
Acknowledgments
References