Project for agricultural infrastructure improvement and rural development which has been improved the productivity and surroundings of rural daily life. Recently, it has been pointed out that the project brought considerable profit but at the same time caused damage to the ecology of the local environment. And the project seemed to enter a turning point with the amending of a related law.
In this background, a clustery field of wild iris where preservation works were carried out as part of farmland consolidation became the subject of this study, and observation on the water balance was made.
The results showed that the sum of the loss of water estimated from the difference of water level at a swamp which is a part of the field and calculated from the income and outgo of water was for 40 to 50 mm, and the loss amount of water from the field was little as a quantity for 6 months.

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An irrigation experiment was conducted at an experimental cornfield established in the Yellow River basin, Inner Mongolia, China, in order to investigate the potential for a saving of irrigation water in this region. The root zone was divided into two layers; the first layer 40 cm thick and the second layer 60 cm thick, and the irrigation requirement, Wa (mm), was assumed to be expressed as
Wa=(max[W_1FC - W₁, 0]+ max[W_2FC - W₂, 0]) (1+ α)
where W_i is the amount of water contained in the ith layer (mm)(i=1,2), W_iFC is the "dynamic field capacity" of the layer (mm), and α indicates a leaching part for salinity control and uniform distribution of water in the root zone. The dynamic field capacity W_iFC is defined as the value of W_i when a balance of forces is made on an element of the water at the bottom surface of the ith layer, and is evaluated using the two-layer BBH model. This critical point is not static but dynamic in nature and depends on the depth of water table and the potential water extract by plant roots.
The mean value of α for the experimental cornfield was evaluated to be 0.75 from the irrigation practiced as usual in 2004. It is apparent that this value was too large to be optimum and over-irrigation occurred, because the groundwater level rose up to within the root zone just after the irrigation and the lower part of the zone was almost saturated for a long time.

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Generally in lagoons around Lake Biwa, a reduction of loads from non-point source was expected. The purification ratio of the Noda lagoon, however, recently failed for the following reasons: plankton production and efflux of nitrogen and phosphorus from the sediment.
In this study, Chl.a concentration in the Noda lagoon is measured to investigate the relationship and influence of SS, COD, nitrogen and phosphorus.
It is shown that SS and COD increase as Chl.a concentration rises, while nitrogen and phosphorus tend to decrease. According to the experiment of efflux from the sediment, the efflux loads of nitrogen and phosphorus are less than the inflow loads, then the inflow loads greatly influence Chl. a concentration.

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Automatic continuous observation of water quality in a river is necessary to find changes in water quality which are caused by acid deposition. The automatic continuous observation of pH has not been conducted because it is difficult to obtain the accurate value, although pH and electric conductivity (EC) are the major items of water quality. In this study, continuous observations of pH and EC were conducted with on-site sensors of pH and EC for 4 years since 2001 in the Ijira River, which is the main inlet of Lake Ijira located in Gifu Prefecture. Long-term pH variations including those in storm periods could be attained by correcting of the observed data by the sensor with the pH value obtained by the measurements of sampled water in the laboratory. There was about 1 hour of lag between the pH observed on site and that measured in the lab during pH recovery period after pH decrease in a storm event. Long-term continuous observation of EC could be carried out without any corrections. Decreases in pH were observed during snowmelt periods as well as during storm in the Ijira River. The value of both pH and EC decreased during storm periods while increases in EC and decrease in pH were observed during snowmelt periods, which suggested that there are some differences in runoff mechanisms.

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In unmanaged Hinoki plantations, understory vegetation decreases because of low light conditions, and forest surface becomes a bare land and occurrence of overlandflow and soil erosion has been reported. In this study, we measured infiltration rates by means of three different infiltration measuring methods for better estimation of actual infiltration rate in unmanaged Hinoki plantations. We have compared three methods for measuring infiltration rate in Hinoki plantations; a) a single ring infiltrometer with diameter of 11cm, b) a mist type sprinkler, and c) a large-scale rainfall simulator type with the sprinkler locate above the tree crown. The mist-type sprinkler employs splaying tubes, having 0.18-mm diameter openings. The infiltration rate by the large-scale infiltrometer produced lower values (26-34 mm/h) than values measured by the other two methods (250-460 mm/h), suggesting that the infiltration rate in unmanaged Hinoki plantation can be correctly measured by the large scale experiment.

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An attempt to discriminate the snow-covered and snow-free areas was conducted by using SPOT/VEGETATION which has visible, near-infrared, and shortwave infrared bands. Normalized Difference Snow Index (NDSI) is confirmed to represent snow condition by referring to ground in situ data at Spasskaya Pad in East Siberia. Snow cover maps are drawn by using 0.0 as a threshold value between snow-covered and snow-free area. The maps showing the snow melt time in 1999 and 2000 show the difference of snow conditions, and it suggests the applicability for the analyses of Asian dust (Kosa), vegetation dynamics, and any other environmental changes.

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