Helmand-Arghandab Valley irrigation system : a change assessment : 1973-1990

Prior to the civil and military conflict that has engulfed Afghanistan for more than 15 years, land irrigated by the system produced a large proportion of the country"s foodgrains and cotton. Donor support for the rehabilitation of this system will be a critical step in restoration of Afghanistan"s agricultural productivity. This study employed satellite imagery, geographic information system (GIS) computer software, and field surveys to assess changes that have occurred in a portion of the Helmand-Arghandab irrigation system since 1973 as a consequence of the war. Changes detected over time in the extent of vegetation were used as indicators of the condition of the irrigation system. The results indicate that between 1973 and 1990 the major change in land use in the Helmand-Arghandab system was a decline in the amount of land under cultivation. Net loss of irrigated agriculture for the study area as a whole was 11%; in some areas the loss was over 25%. The loss can be attributed to the following factors: increased soil salinity due to blocked drains, probably the result of lack of maintenance; breakdown of gates and other water control devices, and abandonment of the land by farmers because of the conflict in the region. Nonetheless, the fact that downstream users now produce irrigated crops suggests that water is being delivered and that major portions of the system (such as division dam, main canals, and siphons) have not been completely destroyed. Suggestions for rehabilitation of the system are made in conclusion, and it is noted that this study demonstrates the utility of remote sensing and geographical data management in identifying persistence and change in phenomena over a wide area. (Author abstract, modified)