microwave emissivity; freshwater wetlands can be mapped using multispectral
cameras; and freshwater springs can be detected using thermal infrared radiometers. Satellite remote sensors and satellite gravitational surveys can be used in
combination with ancillary data analysis to infer groundwater behavior from
surface expressions and to estimate groundwater aquifer storage. This chapter
provides an overview of satellite and airborne remote sensing techniques for
managing water resources and monitoring drought in arid and semiarid regions.
Keywords Groundwater exploration • Remote sensing springs • Soil moisture
sensing • Water remote sensing • Wetland mapping
1 Introduction
Only a small fraction of the Earth’s water is available as freshwater, a key resource
in many economic activities ranging from agriculture to industrial production. At
present, water resources are severely stressed and particularly scarce in arid regions
of the world. In many arid and semiarid regions, water shortage is a major obstacle
to sustainable development and poverty alleviation and the cause of serious conflicts between some countries. Water shortage in arid regions can be further
aggravated by the global climate change that is predicted to severely impact these
regions. Thus, exploration, mapping, and monitoring of water resources are a
prerequisite for the availability, accessibility, fair utilization, and rational management of water resources in arid and semiarid regions [1–3].
Since water availability in arid regions is both sporadic and variable in intensity,
traditional water resources assessment relying on ground-based techniques and data
can often lead to poor estimates of key drivers of hydrologic processes [4]. For
example, most ground-based rain gauge networks are inadequate to capture spatial
and temporal heterogeneity of precipitation [5]. Therefore, conventional hydrological measurements combined with satellite and airborne remote sensors can be
useful and cost-effective and for mapping and monitoring water resources. Furthermore, remotely sensed data can be used in large-scale geologic/hydrologic models
to simulate hydrologic processes, quantify the spatial and temporal water distribution, and prepare maps of groundwater potential zones [3, 6–8].
A key to remote sensing of groundwater is the realization that shallow groundwater flow is often driven by surface forcing parameterized by geologic properties
inferred from surface data [9]. Thus, satellite data is especially effective if it is used
with ancillary data analysis to infer groundwater behavior from surface expressions.
Groundwater and surface water are closely connected in both arid and humid
environments [10]. In arid environments, streams and lakes can be separated from
the water table by a large vadose zone. During wet seasons, groundwater may
become perched below surface water and then dissipate during dry seasons.
Because water typically controls the growth of vegetation in arid areas, an
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V. Klemas and A. Pieterse
cameras; and freshwater springs can be detected using thermal infrared radiometers. Satellite remote sensors and satellite gravitational surveys can be used in
combination with ancillary data analysis to infer groundwater behavior from
surface expressions and to estimate groundwater aquifer storage. This chapter
provides an overview of satellite and airborne remote sensing techniques for
managing water resources and monitoring drought in arid and semiarid regions.
Keywords Groundwater exploration • Remote sensing springs • Soil moisture
sensing • Water remote sensing • Wetland mapping
1 Introduction
Only a small fraction of the Earth’s water is available as freshwater, a key resource
in many economic activities ranging from agriculture to industrial production. At
present, water resources are severely stressed and particularly scarce in arid regions
of the world. In many arid and semiarid regions, water shortage is a major obstacle
to sustainable development and poverty alleviation and the cause of serious conflicts between some countries. Water shortage in arid regions can be further
aggravated by the global climate change that is predicted to severely impact these
regions. Thus, exploration, mapping, and monitoring of water resources are a
prerequisite for the availability, accessibility, fair utilization, and rational management of water resources in arid and semiarid regions [1–3].
Since water availability in arid regions is both sporadic and variable in intensity,
traditional water resources assessment relying on ground-based techniques and data
can often lead to poor estimates of key drivers of hydrologic processes [4]. For
example, most ground-based rain gauge networks are inadequate to capture spatial
and temporal heterogeneity of precipitation [5]. Therefore, conventional hydrological measurements combined with satellite and airborne remote sensors can be
useful and cost-effective and for mapping and monitoring water resources. Furthermore, remotely sensed data can be used in large-scale geologic/hydrologic models
to simulate hydrologic processes, quantify the spatial and temporal water distribution, and prepare maps of groundwater potential zones [3, 6–8].
A key to remote sensing of groundwater is the realization that shallow groundwater flow is often driven by surface forcing parameterized by geologic properties
inferred from surface data [9]. Thus, satellite data is especially effective if it is used
with ancillary data analysis to infer groundwater behavior from surface expressions.
Groundwater and surface water are closely connected in both arid and humid
environments [10]. In arid environments, streams and lakes can be separated from
the water table by a large vadose zone. During wet seasons, groundwater may
become perched below surface water and then dissipate during dry seasons.
Because water typically controls the growth of vegetation in arid areas, an
34
V. Klemas and A. Pieterse