Determination of the magnitudes and values for groundwater recharge from Taiwan's paddy field

Abstract

Flooded paddy fields have many functions, including not only rice production, and ecological and environmental conservation. This work estimates the extent of paddy field infiltration in Taiwan by adopting a one-dimensional Darcy-based soil/water balance model SAWAH (Simulation Algorithm for Water Flow in Aquatic Habitats). A 10cm thick plow sole layer with a hydraulic conductivity of 0.03 cm/day, coupled with the soil texture and irrigation data obtained from 15 irrigation associations, is used to estimate the volumetric amount of annual infiltration in Taiwan. Simulation results from SAWAH indicate that the plow sole layer controls the movement of infiltrated water, with a rate about 1.8 billion cubic meters annually. The estimated infiltration rate of 1.8 billion m 3 /yr comprises more than 40% of the annual infiltration recharge to ground water in Taiwan.

Comparison of potential water supply and demand in Taiwan

“…First, the annual percolation of water in paddy fields can be estimated using the percolation rate and irrigation area as follows (Liu et al 2005): where I is the annual percolation, P r1 and P r2 represent the percolation rate for the first and second crop periods, respectively, A 1 and A 2 represent the irrigation areas for the first and second crop periods, respectively, and W 1 and W 2 represent the field irrigation requirements. Second, the volume of floodwater retained in the paddy field can be calculated as follows (Huang et al 2006): where V represents the potential volume of flood water retained in the paddy fields, H represents the height of ridges between the paddy fields, D w represents the depth of standing water in the paddy fields and A represents the irrigation areas.…”

Multifunctionality of paddy fields in Taiwan

“…A flood paddy field can also be considered as an artificial wetland and as a major source of groundwater recharge (Tsai 1993). From only the view of groundwater recharge, Liu et al (2005) made an attempt to calculate the magnitude was 1.8 billion m 3 for Taiwan applying a onedimensional Darcy-based soil/water balance model SAWAH (ten Berge et al 1995).…”

Appraisal of affordable green subsidy of rice paddy in Taiwan

“…Moreover, paddies also support the convenience of life for urban city by reducing floods, fostering groundwater, cooling temperature, reduction of carbon dioxide, and so on. The multifunctional roles of paddy have been appreciated by many countries (OECD 1998;Randall 2002;Tsai 2002;Tsai et al 2003;Masumoto et al 2004;Liu et al 2005;Kim et al 2006;Aizaki et al 2006;Yoon 2009). Chang and Ying (2005) used the method of willingness to pay (WTP) to estimate the external value of the water preservation and land protection function for rice fields in Taiwan by the assumption that the water preservation and land protection function would completely disappear.…”

“…The reduction of flood migration value can be evaluated by Eq. 4A flooded paddy field can be considered as an artificial wetland and as a major source of groundwater recharge (Yoon 2009) Liu et al (2005). estimated the extent of paddy field infiltration in Taiwan by adopting a one-dimensional Darcy-based soil/water balance model SAWAH (Simulation Algorithm for Water Flow in Aquatic Habitats).…”