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on behalf of Mr Finney, speaking about the impact of surface water developments on agriculture in the lower Indus region of Pakistan, explained that the Indus was a mature river located on a levee slightly higher than the surrounding plain. It was fed by the snowmelt from the Himalayas and the monsoons which resulted in flows of up to 29 000 m3/s whereas the annual rainfall on the plain was 75-200mm. Irrigation has been practised since prehistory and at the height of the Mogul empire 500 years ago a large inundation system was developed which was extended in the colonial period. During this period bunds were also built to protect land from flooding. In 1932 the modern barrage system began with the completion of the Sukkur Barrage. The Kotri (1955) and Gudu (1965) barrages completed the system, which resulted in controlled irrigation of 5.2 million ha, more than five times the area served by the previous inundation canal system. Development of barrage irrigation had resulted in a large increase in crop areas and yields and a massive rise in agricultural output, with the virtual elimination of the year-to-year output fluctuations caused by variations in river flood levels. Before the construction of the barrage system the water table depths were generally 10m or more, but in some places they had since risen to within 1.2m of the surface, causing waterlogging and salinization and adversely affecting crop yields. The rising water table had also affected the stability of road-beds and buildings and had increased stormwater flooding. However, the local population had not suffered in terms of health, way of life and other non-agricultural aspects. The impact of waterlogging and salinity was essentially agricultural in nature. Drainage works to overcome the problem now form an important part of the regional development programme.However, fisheries had suffered. In particular, Hilsa, which migrated up to 500 miles upstream, had been severely affected and the distribution of carp, a commercially important species, had been reduced.In economic and social terms the impact of these adverse effects had been relatively minor, and the overall effect of the construction of the barrage system
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