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Volume 14 (1998)
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 14, Issue 1
Displaying 1-3 of 3 articles from this issue
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Contributed paper
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Hiroyuki Kawashima, Akito Tsumura, Nobuharu Kiho, Miho Sato, Kazuyuki ...1998 Volume 14 Issue 1 Pages 1-5
Published: April 10, 1998
Released on J-STAGE: December 04, 2023
JOURNAL OPEN ACCESSPollution load from paddy fields was estimated using the data measured in Tsukuba city. Observation had been done from April 1984 to Sep. 1986. The observed load was closely related to rainfall. When it was rain, the pollution load, especially nitrogen load, from the paddy field had increased dramatically. Over half of the load generated in one year was flushed only in the three rainy days. COD, Nitrogen and phosphate load from the paddy field including rainy days were 51.3, 56.4, and 1.3 [kg ha-1 y-1] respectively. As the most of the previous studies paid little attention on rain, the load from the paddy field reported previous would be underestimated, especially in nitrogen load.View full abstractDownload PDF (379K) -
Katsuo Okamoto, Shuji Yamakawa, Masayuki Yokozawa, Hiroyuki Kawashima1998 Volume 14 Issue 1 Pages 6-12
Published: April 10, 1998
Released on J-STAGE: December 04, 2023
JOURNAL OPEN ACCESSRemote sensing technique is useful to estimate crop production in the global scale. Vegetation index has been used to estimate crop production from satellite image. However, vegetation index sometimes can not estimate crop production accurately because it does not distinguish growth stage of crops. We propose a new method which uses a spectral track of crop growth instead of vegetation index.Spectral track of crop growth forms loop line in the red versus near infrared feature space plot. The spectral track can distinguish the difference of the growth stage from single satellite remote sensing data. We applied the new method the following three region; central part of China, Hokkaido Japan and Northern part of United States. Japan had suffered weather disaster in 1993 and United States had suffered in 1992. Using the 1-km AVHRR global land 10 days composites, we examined our method to these three regions. The result shows that our method gives relatively good estimation for the crop yield in all regions while the vegetation index can not estimate accurately when it suffers weather disaster.View full abstractDownload PDF (1061K)
Review Article
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Katsuo Okamoto, Hiroyuki Kawashima1998 Volume 14 Issue 1 Pages 13-25
Published: April 10, 1998
Released on J-STAGE: December 04, 2023
JOURNAL OPEN ACCESSRemote sensing by a satellite started in 1960. After that, many kinds of satellites have been launched to observe the global environment. We can use a huge amount of data on the global environment gathered by satellites today. Remote sensing using satellites is also a powerful tool to estimate crop production. This method can be used from local scale to global one. Long-term crop changes caused by global warming as well as the annual crop estimation before harvest have been examined using satellite images. The planting area is important to estimate a short-term crop. Changes of arable land areas and their productivity caused by global warming are significant for the long term estimation. We focused the production estimation of major cereals, i.e., rice, wheat and maize. The problems in which we are facing to get more reliable estimation and strategies for further studies are discussed in this paper.View full abstractDownload PDF (1031K)
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