Agriculture Reference
In-Depth Information
or two head gates, and the dam is shared by several LIDs and sometimes used for other
non-agricultural purposes. A farmer should be a member of an LID if he/she would like
to have water delivered through the facilities of the LID. The principle of the present
regime was established under the River Law promulgated in 1896 followed by the Land
Improvement Law enacted in 1949 and other related legislation. Some statistical figures
are listed below.
Table 1. States of Land Improvement District (LID)
Area under Management ('000 ha)
No. of
Number of
respondents
Paddy field
Upland
Orchard
Total
Membership
5,431
2,221
425
109
2,755
3.9 million
Average
409 ha
78 ha
20 ha
507 ha
726
Source: A survey by the MAFF in 1998.
3. Economic theory of water management: A brief overview
3.1 Efficient and sustainable use of natural resources
Water management has both positive and negative impacts on the environment
(OECD, 2001). In general, possible impacts harmful to the environment and natural
resources would be (i) overexploitation of groundwater, (ii) salinity and other soil
degradation (not reported in Japan), (iii) capital investments harmful to the natural
habitat, (iv) water pollution, and so forth. Paddy field cultivation combined with its water
managements is considered to be environmentally friendly and to have some positive
impacts on the environment. Paddy field agriculture, which dominates in Japan, is known
not to emit nitrous oxides into river flows and aquifers due to the technical reasons.
Biodiversity is larger in the areas of paddy fields/forests combinations than in the areas of
only forests. Other facts of such positive aspects will be shown in another report in this
workshop.
Ground water: In Japan land subsidence has taken places in several areas due to
groundwater extraction. The major cause has been industrial use. The agricultural sector
has mainly extracted shallower aquifers that are recharged quickly with annual
precipitation. For industrial and municipal use, extraction of groundwater from deeper
aquifers is regulated so as not to decrease the water level. The land subsidence was
considerably improved in most areas by the 1980s (States of the Environment 2004,
Ministry of the Environment).
Economic theory clearly distinguishes between water resources that cannot be easily
recharged (e.g., groundwater with a smaller rate of recharge) and those that can be
recharged such as surface water from annual precipitation. The latter is classified as a
replenishable or renewable resource, and the former as a depletable resource (Tietenberg,
2000). Pollution could also be conceptualised in the same way. We define the cleanness
or safety of water as a kind of resource and polluting activities could be redefined as
exploitation of that resource. When the pollution is purified relatively fast through the
natural assimilation process, temporary pollution can be analogised with exploitation of a
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