半乾燥地方の農村にみられる用水路灌漑に伴う土地環境の変化 : インド,パンジャーブ州ガガルバーナ村の例

概要

論文の詳細を見る
The canal irrigation of the alluvial upland in the Punjab Plains started at the end of the 19th century. The natural conditions of the land have undergone changes. This paper aims to discuss such changes in land conditions as are caused by the canal irrigation in Gaggar Bhana village in the light of hydrological and pedological environments. The following conclusions were reached regarding the land conditions: 1 ) Precipitation in Gaggar Bhana is less than Thornswaite's PET index number by 750mm. The shortage of precipitation amounts to 150 to 200mm per month particularly from April to June. Moreover, the village is located on the alluvial upland where the groundwater table was very deep. Consequently, the development of agriculture was difficult before the construction of the canal. 2 ) Sabraon, which is a branch of the Upper Bari Doab Canal (UBDC) was constructed through the village and irrigatidn began in 1902. The canal water flows daily throughout the period from June to September when the Ravi River is at high water. In the low water season from October to next May, a rotation system is applied regarding the irrigation of the four branches of UBDC. Free watering from canal water of the distributaries (from the branch) by the farmers may lead even to waste of irrigation water on the fields. 3 ) Sabraon Branch is embanked without lining to prevent canal leakage and the surface of water is higher than the ground surface by 1.5 metres. Changes of groundwater table during the surveyed period caused by seepage from the bottom of the canal are shown in Figs. 7 and 9. 4 ) The relative importance of well irrigation and canal irrigation is reflected in the changes in the level of the groundwater table. The groundwater table in Bari Doab was very deep before the construction of UBDC. The Persian wheels had been used to draw water perched on the Middle clay bed. In the process of the construction of UBDC, the groundwater table rose by less than 10 metres in depth from the period of 1892 to 1902. This rising increased the construction of Persian wheels arid the areas irrigated by wells also increased. 5 ) The recent changes of groundwater table are divided into three stages ; Stage l, rising trend to 1956/57 ; Stage 2, levelling off from 1956 to 1969 and Stage 3, lowering after the period of 1968/69. The rise of the groundwater table in the first stage was caused by the increase in precipitation and aggradation of drainage and rapid increase in the areas under rice cultivation. 6 ) There are three soil classes in Gaggar Bhana, namely tropical arid brown soil, saline alkali soil and alkali soil. Tropical arid brown soils can be classified into two types according to the texture, bari and holy which are distributed extensively. Saline alkali soils are formed in the shallow depression and alkali soils are formed in the area along the canal with serious rising of the groundwater. The land where the saline alkali soils and alkali soils are formed is a low ecomomic rent areas. 7) In the third stage, the construction of Chilchian drain and pumping of groundwater stopped the rising tendency of water table. Furthermore, in addition to the decrease in precipitation, groundwater table declines year by year and the amount of ground water that can be pumped by tubewell has reached its maximum limit. Consequently, it has brought about further boring of the tubewell. The decrease of soil moisture resulted in the decrease of the yield of rice but an increase in the yield of wheat. A systematic control of the irrigation and drainage is desirable and appropriate actions should be taken as soon as possible.
地理科学学会の論文

半乾燥地方の農村にみられる用水路灌漑に伴う土地環境の変化 : インド,パンジャーブ州ガガルバーナ村の例

スポンサーリンク

概要

著者

関連論文

スポンサーリンク