Water preservation of irrigation pond

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1. Conservation and improvement of irrigation pond in Kagawa PrefectureThe results may be sumarized as follows :1) Old reservoir rehabilitation project is continual.2) The greater part of pond-fed irrigation area in Kagawa Pref.is very small.3) It becomes clear that the distribution of irrigation pond which environmental situation get worse.4) In the case of planning of irrigation pond conservation and improvement for the sake of solution of the maintenance problem, It is necessary to consolidate pond according to the land use plan.2. Water quality in irrigation reservoir of Kagawa PrefectureIn kagawa prefecture, from a long time ago, many irrigation reservoir were constructed for agricultural water use. Recently the water quality in irrigation reservoirs are very low. The damage of low water quality can be seen in for example green house. The clogging is occurred in microirrigation system. So low water quality in irrigation reservoir is serious problem. Firstly, the relation of water … More quality and ground level of irrigation reservoir along the river were examine. Secondly the relation of population in catchment area of reservoir and water quality were checked. The results indicated that domestic drainage water play a important role in low quality water of reservoir.3. An experimental study of water quality preservationElementary test of water quality by mixing : An elementary test of water extracted from an irrigation pond was conducted using a small tank located in experimental room. Then the water was mixed by a screw and exposed to the air at the surface of water. Dissolved oxygen (DO) was ued as an index for the quality evaluation. DO increased as the time elapsed after mixing. An injection pipe was highly efficient for increasing DO,rather than screw mixer.Preservation test at an irrigation pond : The water quality of the pond was dirty, which was lower than a standard value for growing rice. Although water quality as time elapsed was purified a little by the operation of a preservation apparatus, the effect was quite limited, caused by curled up from the bottom. Less