Impacts of Pond Change on the Regional Sustainability of Water Resources in Taoyuan, Taiwan

Taoyuan tableland faces the increasing water demand associated with the expansion of industrialization and urbanization. The county currently relies on the Shihmen Reservoir as the single water supply system. It will be of great concern in the shortage of water resources. This study aims to explore the impact of changes in farm ponds on the regional agricultural environment in Taoyuan County with multiyear (1993, 2003, and 2010) SPOT satellite imagery. Results show that farm ponds have decreased by 10.55 million m2 from 1993 to 2010, and the existing farm ponds were 18.80 million m2 in 2010, equivalent to the irrigation water of 21.10~31.65 million m3 (tons) and 37.61~56.41 million m3 (tons), respectively. The existing farm ponds are able to provide the water supply for 1.88~2.82 thousand hectares of agricultural land, accounting for 6.70%~10.50% of total agricultural area of Taoyuan County. Corresponding to the government’s promotion policy (2012) on activating fallow land, if we redeploy the existing farm ponds for activating fallow fields, it will lessen the water supply burden of Shimen Reservoir. Thus, farm ponds remain the significant water facilities. For the sustainable agriculture, farm ponds shall be classified and cherished as a public asset for the future development. 1. Introduction In the past agricultural society, people were plagued with insufficient water supply for field irrigation in Taoyuan tableland. Farmers usually dig farm ponds for the irrigation purpose by taking the advantages of the impermeable characteristics of red and yellow soil. At the peak period, there were nearly eight thousand ponds in Taoyuan County, brought the reputation such as “one-thousand-pond town” and “one-thousand-lake County” [1]. However, since the 1920s, after the constructing of Shimen Reservoir, Taoyuan Canal and Shimen Canal, and other irrigation facilities, the ponds have gradually vanished. Coupled with the rapid expansion of industrialization and urbanization progress, the landscape development has been changed, which also brought the indirect impacts to the ponds. According to the statistics in 2008, the number of ponds was about 3,345, but only around 2,800 left by the year of 2009 [2]. Since the year of 1983, Taiwan government implemented the six-year plan on rice production and paddy field transfer to address the financial issue of poor rice sales. However, it is not until 1995 the rice supply and demand has reached balance [3]. The land fallowing policy caused the agricultural land fallow area rapid increase, thus resulted in the rice field