Coastline Survey

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Coastline Survey
Survey Sequence and Effective Years (All years are fiscal years)	data	Result list (Japanese only except )
2nd survey 1978		Report of the National Survey on the Marine Natural Environment (Seashore, Marine Environment, Tidal flats, Seaweed beds and Coral reefs)
3rd survey 1984		Natural Environment Map (1:200,000) (every all pref.)
4th survey 1993		Report of Coast Line Survey Natural Environment Map (1:200,000) (every all pref.)

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1. Survey Objectives

Surrounded by coastlines as it is, Japan has a length of seacoasts which exceeds the country's limited land area and is richly endowed with beaches and rocky shores, tidal flats, islands large and small and numerous indentations. However, the onrush of industrial development and urbanization is rapidly encroaching on natural coastlines. Alteration of coastlines is to an extent unavoidable, but restraint should certainly be exercised regarding large-scale engineering projects.

Accordingly, this survey was done to determine the present extent of naturalness of Japan's coastlines (the shoreline) and coastal frontages. As such it provides a basic resource to help in deciding issues of development and conservation.

2. Survey Content and Methods

The target coastlines for this survey are those shown on the coastlines classification measurement map resulting from a nationwide seacoast survey made by the Ministry of Construction in 1975. The map included islands with a minor axis greater than 100 meters, but excluded the so-called northern islands. All 39 prefectures with coastlines are included.

The 2nd survey classified coastlines by present state as "natural", "semi-natural", "artificial" and "estuary". Coastal land area (100 meters inland from the maximum wave line) was classified as either "natural", "agricultural", "urban-industrial" or "estuary".

The 3rd survey assessed changes in coastlines since the 2nd. And the 4th survey examined changes since the 3rd.

3. Survey Results

There were some 300km more coastline in the 4th survey than in the 3rd (1984). This was of course mainly due to land reclamation, which created new coastline stretches.

The length of coastlines (shorelines) classified as "natural" was approximately 300km shorter than in the results of the 3rd survey, whereas the "artificial" category was about 650km longer. Considering that the "natural" coastline decreased by approximately 570km during period between the 2nd survey and the 3rd survey, the rate of decrease diminished during the period between the 3rd survey and the 4th survey.

Coastline (shoreline) Length by Categories
(Comparison of the 3rd (1984) and 4th (1993) surveys)
	Length	Share of total	Length	Share of total	Length	Share of total
	1993		1984		Increase/Decrease
Natural Coastline	18,105.65km	55.2%	18,402.08km	56.7%	-296.43km	-1.4%
Semi-natural Coastline	4,467.49km	13.6%	4,511.44km	13.9%	-43.95km	-0.3%
Artificial Coastline	9,941.78km	30.3%	9,294.54km	28.6%	647.24km	1.7%
Estuary	263.96km	0.8%	263.79km	0.8%	0.17km	0.0%
Total	32,778.88km	100.0%	32,471.85km	100.0%	307.03km

Coastline (shoreline) Length by Categories
(Comparison of the 2nd (1978) and 3rd (1984) Surveys
	Length	Share of total	Length	Share of total	Length	Share of total
	1984		1978		Increase/Decrease
Natural Coastline	18,402.08km	56.7%	18,967.17km	59.0%	-565.09km	-2.3%
Semi-natural Coastline	4,511.44km	13.9%	4,340.36km	13.5%	171.08km	0.4%
Artificial Coastline	9,294.54km	28.6%	8,598.95km	26.7%	695.59km	1.9%
Estuary	263.79km	0.8%	263.73km	0.8%	0.06km	0.0%
Total	32,471.85km	100.0%	32,170.21km	100.0%	301.64km

**Definition of Coastline Categories**
	Categories
Coastline (shoreline)	Natural Coastline : A coastline (shoreline) in the natural state, unchanged by human activity. No artificial structures.	Coasts with beaches	muddy beach
			sandy beach
			rocky shore
		coasts with no beach (eroded cliffs, etc.)
	Semi-natural Coastline : Roads, dikes, tetrapods, etc. exist but intertidal zone is in a natural state.	Coasts with beaches	muddy beach
			sandy beach
			rocky shore
		coasts with no beach (eroded cliffs, etc.)
	Artificial Coastline : Coasts with harbors, filled land, dredged bottoms, drained land etc. Intertidal zone also have artifcial objects.	coasts created by land reclamation
		coasts created by dredging
		other artificial seacoasts
	Estuary : The boundary between sea and land is the river's lowest flow point of "River Areas", which is designated by The River Law. This includes rivers to which the River Law does not apply.

1) In this survey, "coastal area" means the coastline (shoreline) and coastal land areas.
2) "Coastline" means the area between low tide and the maximum wave line.
3) "Coastal land area" means 100 meters inland from the maximum wave line.