Abstract
It is well known that the Taoyuan Irrigation Aqueduct and its attached reservoirs, which were developed in the Taoyuan tableland in northwestern Taiwan during the colonial period, improved its water and land use markedly. In this paper, the authors trace the process of this remarkable change in Guanyin Township by referring to materials published during the colonial period in addition to more recent statistics and topographic maps and obtained the following results.
Before the development of the irrigation facilities, paddy fields increased gradually in Guanyin Township. After the completion of the Taoyuan Irrigation Aqueduct in 1924, not only paddy fields but also cropping ratios increased considerably. Double cropping of rice was achieved in most paddy fields. The increase in yield per land unit began somewhat later because the quality of newly irrigated paddy fields was still poor at this stage. In spite of a lack of statistical data during the 1940s, it is clear that a rapid increase in rice production occurred before the beginning of the 1950s. Rotational irrigation introduced in the mid-1950s also contributed to improve productivity during the 1960s. However, the cropping ratio of rice declined rapidly after an acreage reduction policy was carried out in 1984 to cope with the decrease in rice consumption. In the beginning of the 2000s, massive diversions of agricultural water to domestic and industrial use were enforced by the national government due to deficits in rain-fall.
Although the application of GIS analysis to topographic maps can contribute complementary information to statistical data, the time intervals between images are too long to detect short-lived changes.
