340
A.MJ. Meijerink and C.M.M. Mannaerts
the river is fairly stable. It is evident that each of the areas also has different evapotranspiration losses. The highest occur in sub-area 3, the lowest in sub-area 2. This
hydrologic information is of course important for development planning in the area.
15.5 Small-scale water resource development
and remote sensing
15.5.1 Introduction
It can be generally expected that the attention to small-scale water resource development will continue to increase in the near future, considering the environmental
problems and world-wide debate about large darns (SIWT, 1994). Also the excessive
exploitation and contamination problems of large groundwater aquifers in several
countries (Vbra & Zaporozec, 1994), the water quality impacts of agriCUlture,
urbanization and industry on surface waters in general lead to an increased stress per
capita on drinking water availability on a worldwide basis. Zoning and design of local
water development schemes in a certain region require the study of the enormous
variation of combinations of terrain and vegetation factors in nature.
Without the use of remotely sensed imagery, it is difficult to avail of sufficient
information, considering the lack of soil maps and hydrometric information in large
parts of the world. The following two paragraphs illustrate the use of remote sensing
in some typical small-scale water resource development operations.
15.5.2 Runoff water harvesting with the aid ofremote sensing
Runoff water harvesting basically is a technique by which surface runoff is collected
purposely in a smaller infiltration area, where it can be used for crop production or
plant growth. The technique of collecting rainwater was already practiced during early
civilizations (Hillel, 1967). The determination of potential sites for runoff harvesting
or irrigation require besides knowledge of the rainfall regime characteristics, a
detailed evaluation of surface topography, surface soil properties and other site
environmental parameters. Remote sensing techniques combined with geographic
information systems have been applied to screen larger areas for potential runoff
irrigation sites in the Sahelian region (Tauer & Humborg, 1992). For more detailed
surveys, large scale stereo-images enable the identification and mapping of some of
the relevant parameters. Relative runoff estimation and capture of runoff are discussed
in some of the examples (Tanzania, Iran) and in Chap. 14. The discussions also
mention terrain units with actual water losses (percolation and seepage) and which are
therefore unsuitable as source areas for local runoff. The verification of the site
potential and the field design of water harvesting structures remains based on field
survey, experience and the use of current hydrologic estimation methods (Mannaerts,
1992). Enlargements of aerial photographs can be conveniently used for plotting the
positions of the water harvesting structures.
A.MJ. Meijerink and C.M.M. Mannaerts
the river is fairly stable. It is evident that each of the areas also has different evapotranspiration losses. The highest occur in sub-area 3, the lowest in sub-area 2. This
hydrologic information is of course important for development planning in the area.
15.5 Small-scale water resource development
and remote sensing
15.5.1 Introduction
It can be generally expected that the attention to small-scale water resource development will continue to increase in the near future, considering the environmental
problems and world-wide debate about large darns (SIWT, 1994). Also the excessive
exploitation and contamination problems of large groundwater aquifers in several
countries (Vbra & Zaporozec, 1994), the water quality impacts of agriCUlture,
urbanization and industry on surface waters in general lead to an increased stress per
capita on drinking water availability on a worldwide basis. Zoning and design of local
water development schemes in a certain region require the study of the enormous
variation of combinations of terrain and vegetation factors in nature.
Without the use of remotely sensed imagery, it is difficult to avail of sufficient
information, considering the lack of soil maps and hydrometric information in large
parts of the world. The following two paragraphs illustrate the use of remote sensing
in some typical small-scale water resource development operations.
15.5.2 Runoff water harvesting with the aid ofremote sensing
Runoff water harvesting basically is a technique by which surface runoff is collected
purposely in a smaller infiltration area, where it can be used for crop production or
plant growth. The technique of collecting rainwater was already practiced during early
civilizations (Hillel, 1967). The determination of potential sites for runoff harvesting
or irrigation require besides knowledge of the rainfall regime characteristics, a
detailed evaluation of surface topography, surface soil properties and other site
environmental parameters. Remote sensing techniques combined with geographic
information systems have been applied to screen larger areas for potential runoff
irrigation sites in the Sahelian region (Tauer & Humborg, 1992). For more detailed
surveys, large scale stereo-images enable the identification and mapping of some of
the relevant parameters. Relative runoff estimation and capture of runoff are discussed
in some of the examples (Tanzania, Iran) and in Chap. 14. The discussions also
mention terrain units with actual water losses (percolation and seepage) and which are
therefore unsuitable as source areas for local runoff. The verification of the site
potential and the field design of water harvesting structures remains based on field
survey, experience and the use of current hydrologic estimation methods (Mannaerts,
1992). Enlargements of aerial photographs can be conveniently used for plotting the
positions of the water harvesting structures.