[HTT16-P01] Comparative study of elementary runoff in the Tohoku basin and watershed based on numerical geographic information
Keywords:ipc-ms, multivariate analysis, geographic information system
In this study, we tried to obtain the relationship between the regional characteristics (climate, topography, geology, soil) of the basin and the chemical data obtained from the observation using numerical geographic information, and tried to analyze the current environmental conditions. The regional characteristics of the basin based on the digital geographic information were classified by cluster analysis to handle a large amount of data. Chemical data were obtained by analyzing water samples by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of both data clarified the characteristics of the basin. By developing this data, the reference value of the current base can be set. By coexisting with monitoring, it is possible to identify the impact on the watershed in response to environmental changes such as land development. Therefore, useful databases for sustainable development are being developed. The target area is several rivers (upstream and downstream) in the Tohoku region.
The results of multi-element analysis of the reservoir outflow area (upstream area) and the end of a first-class river (downstream area) are shown. Regarding the total amount of multi-elements, the upstream basin tends to increase in proportion to the basin area. In the lower basin, the Natori River showed a high total amount despite its small basin area (939 km2). Concentrations of material components per unit area tended to be higher in the Pacific Ocean on the upstream side. In the lower basin, there was no particular geographical trend, but the results showed that the Natori River was nearly three times higher than the other rivers.
According to the cluster analysis, in the upper basin, the climate was divided into four groups, six in land cover, four in topography, and nine in geology. In the river basin, the climate was divided into three categories: four for land cover, four for topography, and three for geology. In general, the number of sections in the upstream area increases, and it becomes clear that dense features are less likely to appear in wider areas. Due to this effect, similar results were obtained in the upstream basin, but similar regions could not be extracted in the river basin.
In comparison with the results of multi-element analysis, watershed conditions with a higher elemental load per unit area were obtained for the upstream basin and river basin. In the upper basin, the climate is heavy basin with annual precipitation of 2,500 mm or more and heavy snowfall with a snow depth of 250 cm or more (Group 5), and the land cover is occupied by natural vegetation in the beech class area and deciduous broad-leaved forest zones by compensated vegetation Watersheds including high alpine and subalpine belts (Group5), topography is about 20km in length, and riverbeds have moderate riverbed gradients (Group4). Geology is occupation ratio of specific geology such as granite and pumice. Became a large basin (Group4). In the river basin, the climate is relatively low rainfall with an annual rainfall of about 2000 mm, the basin with a snow depth of less than 160 cm (Group 1), and the land cover is the riverside and wetlands. The watershed (Group 1), which includes many swamps and dune vegetation, and has relatively many other (human activity areas), the topography is small, with a watershed area of 1,000 km2 or less and a channel length of 70 km or less, and exhibits a steep slope with a riverbed gradient of 0.0016 or more. The basin (Group 4) and the geology became the basin (Group 3) where the occupation ratio of mud, mudstone and tuff was large.
The commonality of the large basins with large chemical effluent components per unit area in the upstream basin was relatively clear, while the commonality in the downstream basin was unclear. However, as a commonality of the relationship between the regional characteristics of the upstream and downstream basins and the increase in chemical runoff components, the basins with a high geological distribution occupation ratio that tend to be finer in both the upstream and downstream basins tend to have higher loads per unit area. It was revealed that there was. Due to the fine particle size, the solubility is high, and it is assumed that the process easily contributes to the increase in the load of chemical components.
The results of multi-element analysis of the reservoir outflow area (upstream area) and the end of a first-class river (downstream area) are shown. Regarding the total amount of multi-elements, the upstream basin tends to increase in proportion to the basin area. In the lower basin, the Natori River showed a high total amount despite its small basin area (939 km2). Concentrations of material components per unit area tended to be higher in the Pacific Ocean on the upstream side. In the lower basin, there was no particular geographical trend, but the results showed that the Natori River was nearly three times higher than the other rivers.
According to the cluster analysis, in the upper basin, the climate was divided into four groups, six in land cover, four in topography, and nine in geology. In the river basin, the climate was divided into three categories: four for land cover, four for topography, and three for geology. In general, the number of sections in the upstream area increases, and it becomes clear that dense features are less likely to appear in wider areas. Due to this effect, similar results were obtained in the upstream basin, but similar regions could not be extracted in the river basin.
In comparison with the results of multi-element analysis, watershed conditions with a higher elemental load per unit area were obtained for the upstream basin and river basin. In the upper basin, the climate is heavy basin with annual precipitation of 2,500 mm or more and heavy snowfall with a snow depth of 250 cm or more (Group 5), and the land cover is occupied by natural vegetation in the beech class area and deciduous broad-leaved forest zones by compensated vegetation Watersheds including high alpine and subalpine belts (Group5), topography is about 20km in length, and riverbeds have moderate riverbed gradients (Group4). Geology is occupation ratio of specific geology such as granite and pumice. Became a large basin (Group4). In the river basin, the climate is relatively low rainfall with an annual rainfall of about 2000 mm, the basin with a snow depth of less than 160 cm (Group 1), and the land cover is the riverside and wetlands. The watershed (Group 1), which includes many swamps and dune vegetation, and has relatively many other (human activity areas), the topography is small, with a watershed area of 1,000 km2 or less and a channel length of 70 km or less, and exhibits a steep slope with a riverbed gradient of 0.0016 or more. The basin (Group 4) and the geology became the basin (Group 3) where the occupation ratio of mud, mudstone and tuff was large.
The commonality of the large basins with large chemical effluent components per unit area in the upstream basin was relatively clear, while the commonality in the downstream basin was unclear. However, as a commonality of the relationship between the regional characteristics of the upstream and downstream basins and the increase in chemical runoff components, the basins with a high geological distribution occupation ratio that tend to be finer in both the upstream and downstream basins tend to have higher loads per unit area. It was revealed that there was. Due to the fine particle size, the solubility is high, and it is assumed that the process easily contributes to the increase in the load of chemical components.