Water infiltration rate in cracked paddy soil (PDF Download Available)
Geoderma 117 (2003) 169 – 181 www.elsevier.com/locate/geoderma
Water infiltration rate in cracked paddy soil Chen-Wuing Liu a,b,*, Shih-Wei Cheng b, Wen-Sheng Yu c, Shih-Kai Chen d a
Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC b Institute of Hydrotech, National Taiwan University, Taipei 10617, Taiwan, ROC c Computer Division, Chun-You Business Management College, Kelung 20141, Taiwan, ROC d Chi-Shin Water Management Research and Development Foundation, Taipei 11465, Taiwan, ROC Received 30 July 2002; accepted 28 March 2003
Abstract The surfaces of paddy fields may crack into fissures as a result of drainage and exposure to sunlight after rice harvesting. Field observations indicate that a cracked paddy field has a significantly increased rate of infiltration. Yet, the infiltration rate drops considerably after 2 days of precipitation. A laboratory soil column experiment was performed to identify the parameters that control the infiltration of water in a cracked paddy field. Various variables, including soil texture, flooded water depth, fracture apertures, cultivation practices and water suspended particles, were investigated to quantify their influence on the infiltration curves and the closure mechanism of a fractured plough pan. The experimental results reveal that increased fracture aperture and flooded water depth only temporarily increase the rate of infiltration. Soil swelling most strongly affects the rate of infiltration. When cracked, swelling soil mixtures are flooded with water that is rich in clay particles. The swelling gradually closes the fissures, healing the fractured plough pan. Ploughing and compaction of the surface soil can also enhance the recoverability of the plough pan and reduce the infiltration rate. The structures of soils with low bulk densities are easily changed following infiltration by water. Infiltration also disperses clay particles and redeposits them on the surface of fissures via surface filtration, significantly reducing the infiltration rate. Thus, the removal of the plough pan from the paddy may effectively increase infiltration. This study proposes an efficient water-using paddy layout that effectively uses irrigation water in agricultural water management. Converting half of the paddy acreage into a water pond and an upland crop area saves a considerable amount of irrigation water, which can be used to supplement ground water. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Paddy field; Plough pan; Fracture aperture; Infiltration rate; Swelling
1. Introduction Taiwanese rice paddies are currently facing significant pressure from both the import of cheap, * Corresponding author. Department of Bioenvironmental Systems Engineering, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan, ROC. Tel.: +886-2-2362-8067; fax: +886-2-2363-9557. E-mail address: [email protected] (C.W. Liu).
good-quality foreign rice, following entry into the World Trade Organization (WTO), and the government’s policy of converting farmland to industrial or residential use. To preserve paddy field acreage, the Council of Agriculture (COA) and environmental conservation organizations have publicized the environmental and ecological preservation functions of the rice paddy (Tzia, 1997, 2000; Chang, 2001). The periodic flooding of paddy fields makes them a
0016-7061/$ - see front matter D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0016-7061(03)00165-4
170 C.W. Liu et al. / Geoderma 117 (2003) 169–181 Fig. 1. Schematic diagram of the hydrogeological setting of the Chou-Shui-Alluvial fan in Taiwan. The Ten-Chung experimental paddy rice field is situated in the upper part of this region.
C.W. Liu et al. / Geoderma 117 (2003) 169–181
171
Fig. 2. Schematic diagram of gas-pressured permeameter (not to scale).
major source of ground water recharge. Consequently, the COA has promoted the application of irrigation water to increase ground water recharge. Various methods have been proposed to increase infiltration rate including increasing flooded water depth, raising the bund height, fracturing the soil’s surface layer and removing the plough pan (Liu, 1998; Chen, 1999). The use of these methods to
increase the amount of infiltrating paddy water and to recharge ground water has been investigated. Liu (1998) used numerical models SAWAH (ten Berge et al., 1992; Wopereis et al., 1994) and FEMWATER (Lin et al., 1997) to compute the contribution of paddy water to ground water recharge by increasing the flooded water depth and removing the plough pan. The simulation results show that
Table 1 Experimental soil textures Particle size
Montmorillontite
Kaolinite
Quartz sand
(a)
(b)
(c)
Sand (%) >0.05mm Silt (%) 0.002f0.05mm Clay (%)
Water infiltration rate in cracked paddy soil Chen-Wuing Liu a,b,*, Shih-Wei Cheng b, Wen-Sheng Yu c, Shih-Kai Chen d a
Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC b Institute of Hydrotech, National Taiwan University, Taipei 10617, Taiwan, ROC c Computer Division, Chun-You Business Management College, Kelung 20141, Taiwan, ROC d Chi-Shin Water Management Research and Development Foundation, Taipei 11465, Taiwan, ROC Received 30 July 2002; accepted 28 March 2003
Abstract The surfaces of paddy fields may crack into fissures as a result of drainage and exposure to sunlight after rice harvesting. Field observations indicate that a cracked paddy field has a significantly increased rate of infiltration. Yet, the infiltration rate drops considerably after 2 days of precipitation. A laboratory soil column experiment was performed to identify the parameters that control the infiltration of water in a cracked paddy field. Various variables, including soil texture, flooded water depth, fracture apertures, cultivation practices and water suspended particles, were investigated to quantify their influence on the infiltration curves and the closure mechanism of a fractured plough pan. The experimental results reveal that increased fracture aperture and flooded water depth only temporarily increase the rate of infiltration. Soil swelling most strongly affects the rate of infiltration. When cracked, swelling soil mixtures are flooded with water that is rich in clay particles. The swelling gradually closes the fissures, healing the fractured plough pan. Ploughing and compaction of the surface soil can also enhance the recoverability of the plough pan and reduce the infiltration rate. The structures of soils with low bulk densities are easily changed following infiltration by water. Infiltration also disperses clay particles and redeposits them on the surface of fissures via surface filtration, significantly reducing the infiltration rate. Thus, the removal of the plough pan from the paddy may effectively increase infiltration. This study proposes an efficient water-using paddy layout that effectively uses irrigation water in agricultural water management. Converting half of the paddy acreage into a water pond and an upland crop area saves a considerable amount of irrigation water, which can be used to supplement ground water. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Paddy field; Plough pan; Fracture aperture; Infiltration rate; Swelling
1. Introduction Taiwanese rice paddies are currently facing significant pressure from both the import of cheap, * Corresponding author. Department of Bioenvironmental Systems Engineering, National Taiwan University, 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan, ROC. Tel.: +886-2-2362-8067; fax: +886-2-2363-9557. E-mail address: [email protected] (C.W. Liu).
good-quality foreign rice, following entry into the World Trade Organization (WTO), and the government’s policy of converting farmland to industrial or residential use. To preserve paddy field acreage, the Council of Agriculture (COA) and environmental conservation organizations have publicized the environmental and ecological preservation functions of the rice paddy (Tzia, 1997, 2000; Chang, 2001). The periodic flooding of paddy fields makes them a
0016-7061/$ - see front matter D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0016-7061(03)00165-4
170 C.W. Liu et al. / Geoderma 117 (2003) 169–181 Fig. 1. Schematic diagram of the hydrogeological setting of the Chou-Shui-Alluvial fan in Taiwan. The Ten-Chung experimental paddy rice field is situated in the upper part of this region.
C.W. Liu et al. / Geoderma 117 (2003) 169–181
171
Fig. 2. Schematic diagram of gas-pressured permeameter (not to scale).
major source of ground water recharge. Consequently, the COA has promoted the application of irrigation water to increase ground water recharge. Various methods have been proposed to increase infiltration rate including increasing flooded water depth, raising the bund height, fracturing the soil’s surface layer and removing the plough pan (Liu, 1998; Chen, 1999). The use of these methods to
increase the amount of infiltrating paddy water and to recharge ground water has been investigated. Liu (1998) used numerical models SAWAH (ten Berge et al., 1992; Wopereis et al., 1994) and FEMWATER (Lin et al., 1997) to compute the contribution of paddy water to ground water recharge by increasing the flooded water depth and removing the plough pan. The simulation results show that
Table 1 Experimental soil textures Particle size
Montmorillontite
Kaolinite
Quartz sand
(a)
(b)
(c)
Sand (%) >0.05mm Silt (%) 0.002f0.05mm Clay (%)
