open access

https://hdl.handle.net/2115/71042

Changing Water Quality Resulting from Land Reclamation

日本語

山地流域

1982-12

農業農村工学会

Transactions of The Japanese Society of Irrigation, Drainage and Reclamation Engineering

102

36-43, a1

In order to investigate the effects of reclamation on the natural cycle of materials, the runoff quality of water from the newly reclaimed land existing reclaimed land, and natural basins was observed on a monthly basis in 1981. In this investigation, the quality of water with M alkalinity, Fe, EC, Na+, Mg2+, Ca2+, K+, NO3-N, NH4-N, PO4-P was analyzed. The runoff quality of water from the newly reclaimed and unreclaimed basins under the conditions of a small flood was also observed.Comparing water quality in three kinds of basins, the following results were obtained: The concentrations of solutes in the case of the newly reclaimed basin were comparatively high and variable, but those in the case of the unreclaimed basin were low and almost without variation. The concentrations of fertilizer components in the existing reclaimed basin were lower than those in the newly reclaimed basin however, the concentrations of other components in the existing reclaimed basin were lower than those in the newly reclaimed basin, but higher than or roughly the same as those in the unreclaimed basin.Comparing the quality of water in the newly reclaimed basin under the conditions of a small flood with that under ordinary conditions, the following results were obtained: The concentrations of fertilizer components in the case of a small flood were higher than those in the case of the ordinary conditions, but the concentrations of other components during the small flood tended to be lower than those under ordinary conditions. Since the discharge greatly increased during the small flood, the loads of fertilizer components became much larger than those in the case of the ordinary conditions.In conclusion, land reclamation tends to cause a loss of materials, and therefore, tends to cause an instability in the cycle of materials.

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