hydrological cycle, regulating evapotranspiration, precipitation infiltration, and
overland flow. In contrast with in situ instruments, modern satellite remote sensing
has shown a huge potential for providing soil moisture measurements at a large
scale. However, its effective utilisation in the practical projects still needs comprehensive research. Zhuo [9] has introduced the advances and potential issues in the
current application of satellite soil moisture observations in hydrological modelling. The key issues include soil moisture measuring methods, hydrological evaluation of satellite soil moisture, error distribution modelling of soil moisture
measurements, and the need for new hydrological soil moisture product development. It has been found that hydrological application of soil moisture data requires
the data relevant to hydrology. In order to meet the requirement, two important
research tasks are needed: the first is to carry out comprehensive assessments of
satellite soil moisture observations for hydrological modelling, not merely based on
evaluations against point-based in situ measurements; the second is that a soil
moisture product (e.g., soil moisture deficit) directly applicable to hydrological
modelling should be developed. Only fully accomplishing these two steps will push
forward the utilisation of satellite soil moisture in hydrological modelling to a
greater extent.
There is an increasing demand for automatic chemometric solutions for water
quality monitoring, the main requirements being their autonomous operation, low
cost, and low maintenance. Today, there is a range of optical sensor technologies
that are capable to perform most analytical tasks and are characterised by full solidstate, no need for reagents, and capability to withstand harsh working conditions, as
it is needed when the measurement points are outside protected monitoring locations (e.g., treatment plants) and relevant parameters have to be acquired directly in
the external environment. van den Broeke and Koster [10] introduce a selection of
optical sensing technologies, which can provide valuable information on the quality
of water. The measurement techniques that they describe are suitable for process
monitoring and control applications, as well as for early-warning systems. The
chapter explores the basic principles of radiative transfer at the foundation of
spectroscopic methods and the fundamentals of the signal processing for the
extraction of chemical information from the acquired signals. The survey of sensing
methods covers the absorption spectrometry in the UV/Vis spectral region, illustrating both selective measurements of specific substances (e.g., BTEX, nitrate, and
nitrite) and more generic features, like the colour, the amount of total suspended
solids, and the ‘sum organic parameters’, which are recognised as excellent overall
water quality indicators. The chapter also covers basic aspects and applications of
fluorescence spectroscopy and infrared spectroscopy in the NIR (near-infrared)
domain. Further methods, which are considered as promising and are also already
marketable, are described in this survey: Raman and laser-induced breakdown
spectroscopy, refractive index measurements, and image analysis. Despite the
fact that optical methods are based on mature technologies that have a solid
physical background, they are still not much used by the industry and still have a
big potential to deliver. Optically based methods are very attractive candidates to
perform automatic online field measurements, both for selective parameters, i.e., in
xiv
Preface
overland flow. In contrast with in situ instruments, modern satellite remote sensing
has shown a huge potential for providing soil moisture measurements at a large
scale. However, its effective utilisation in the practical projects still needs comprehensive research. Zhuo [9] has introduced the advances and potential issues in the
current application of satellite soil moisture observations in hydrological modelling. The key issues include soil moisture measuring methods, hydrological evaluation of satellite soil moisture, error distribution modelling of soil moisture
measurements, and the need for new hydrological soil moisture product development. It has been found that hydrological application of soil moisture data requires
the data relevant to hydrology. In order to meet the requirement, two important
research tasks are needed: the first is to carry out comprehensive assessments of
satellite soil moisture observations for hydrological modelling, not merely based on
evaluations against point-based in situ measurements; the second is that a soil
moisture product (e.g., soil moisture deficit) directly applicable to hydrological
modelling should be developed. Only fully accomplishing these two steps will push
forward the utilisation of satellite soil moisture in hydrological modelling to a
greater extent.
There is an increasing demand for automatic chemometric solutions for water
quality monitoring, the main requirements being their autonomous operation, low
cost, and low maintenance. Today, there is a range of optical sensor technologies
that are capable to perform most analytical tasks and are characterised by full solidstate, no need for reagents, and capability to withstand harsh working conditions, as
it is needed when the measurement points are outside protected monitoring locations (e.g., treatment plants) and relevant parameters have to be acquired directly in
the external environment. van den Broeke and Koster [10] introduce a selection of
optical sensing technologies, which can provide valuable information on the quality
of water. The measurement techniques that they describe are suitable for process
monitoring and control applications, as well as for early-warning systems. The
chapter explores the basic principles of radiative transfer at the foundation of
spectroscopic methods and the fundamentals of the signal processing for the
extraction of chemical information from the acquired signals. The survey of sensing
methods covers the absorption spectrometry in the UV/Vis spectral region, illustrating both selective measurements of specific substances (e.g., BTEX, nitrate, and
nitrite) and more generic features, like the colour, the amount of total suspended
solids, and the ‘sum organic parameters’, which are recognised as excellent overall
water quality indicators. The chapter also covers basic aspects and applications of
fluorescence spectroscopy and infrared spectroscopy in the NIR (near-infrared)
domain. Further methods, which are considered as promising and are also already
marketable, are described in this survey: Raman and laser-induced breakdown
spectroscopy, refractive index measurements, and image analysis. Despite the
fact that optical methods are based on mature technologies that have a solid
physical background, they are still not much used by the industry and still have a
big potential to deliver. Optically based methods are very attractive candidates to
perform automatic online field measurements, both for selective parameters, i.e., in
xiv
Preface