| Furrow irrigation erosion was strongly correlated with soil erosion, non-point source pollution, water quality deterioration, food production existing all over the world which effect the existence and development of human beings and restrict the sustainable development of social economy. The research on the furrow irrigation erosion, including sediment yield process, soil infiltration law, corrosion resistance, hydrodynamics and etc., is important to analyze the mechanism and erosion characteristic of furrow irrigation erosion in theory, and also rational allocation of farmland soil and water conservation measures in practical. The field furrow erosion experiments and indoor simulation experiments was adopted in this research, in order to investigate the effect of soil properties and irrigation water properties on sediment yield process of furrow irrigation erosion, and analyze the hydrodynamics mechanism of furrow irrigation erosion. The main conclusions of the research were as follows:1. The effect of soil plowing degree and soil dryness on brown soil infiltration in west of Liaoning Province. Soil infiltration coefficient was significantly correlated with initial water moisture and also soil plowing degree. The soil infiltration coefficient tended to increase and then decrease, with increasing of initial soil water content, and the inflection points of initial water content was 18%, when soil bulk densities were 1.20 g·cm-3 and 1.25g·cm-3, while 13% when1.30 g·cm-3,1.35 g·cm-3 and 1.40 g·cm-3. It could be concluded that the inflection points were suitable soil initial water moisture, because soil infiltration was maximum, and runoff scouring force and erosion amount were minimum.2. The effect of water temperature, SAR/EC ratio on brown soil infiltration in west of Liaoning Province. The results showed that soil infiltration coefficient increased with increasing of water temperature, and could be 1.3 times when water temperature increased from 15℃ to 35℃. The soil infiltration coefficient decreased while SAR/EC ratios increased. When water temperature was 35℃, SAR increased from 0.7 (mmol·L-1) 0/5to 12.0 (mmol· L-1)0.5, and EC decreased from 2.0 dS·m-1 to 0.5 dS·m-1, the infiltration coefficient decreased to 51.6%. There was a significant relation between soil infiltration coefficient and water temperature and SAR/EC ratios, and a good quadratic function mathematic model was obtained based on the experiments. The cumulative soil infiltration increased with water temperature and decreased with SAR/EC ratio. When irrigation water temperature was lower, the runoff amount was higher; while water temperature tended to be higher, the cumulative water infiltration amount was higher, and runoff tended to be lower. As a result, high water temperature and low SAR/EC ratio could reduce furrow irrigation erosion.3. The effect of soil plowing degree and soil water contents on soil disintegration rate. There was a significant relation between soil disintegration rate and soil water content, but not soil plowing degree. The soil disintegration rate increased with initial soil water content. The interaction of initial water moisture and soil plowing degree was not obvious.4. The effect of slope gradient, irrigation water amount, soil plowing degree and soil dryness on sediment yield of furrow erosion, there was a negative correlation between initial time producing runoff and water amount, soil density, and water content, with a order of water amount>slope gradient>soil water content>soil density. There was a positive correlation between erosion amount and soil water content, while negative between erosion amount and slope gradient, soil plowing degree, and water amount, with a order of slope gradient>water amount>initial soil water content>soil plowing degree. A good quadratic function mathematic model was obtained to simulate the initial time producing runoff and furrow erosion amount. There was a positive correlation between water velocity and slope gradient and discharge. The Froude number varied from0.32-1.06, and the Reynolds number varied between 1041 and 4723, showing most was supercritical flow.5. The effect of SAR, EC and water temperature on furrow erosion amount, when furrow slope was 3%, soil water content was 18%, and irrigation water amount was 0.9L·s-1. Results showed that the furrow erosion amount tended to increase, while SAR/EC ratio decreased. Irrigation water with high SAR could have a sealing effect of soil pore, which could reduce soil infiltration, and the increase the runoff amount and flow velocity. The furrow erosion amount tended to be lower with a higher water temperature, because the interaction between irrigation water molecule and soil water molecule was active, which could change soil particles arrangement mode, make it softer, and then soil macropore increase, soil infiltration increase, and all above would decrease the runoff erosion force and erosion amount.6. The effect of furrow length, irrigation water amount, slope gradient, initial soil water content on runoff, sediment process in the field experiment. Results showed that when furrow length was higher, runoff amount, sediment amount and average sediment concentration were lower. And an exponential relationship between furrow length and runoff amount was obtained, so the long furrow had a smaller effect on furrow erosion amount. After producing runoff, furrow erosion amount was 57.91%-80.48% of total amount within 10 min. the furrow erosion amount increased with increasing of slope gradient, which was obvious when slope gradient increased from 1.16% to 2.08%, but not obvious from 0.74% to 1.16%.7. The survey of field surface morphology before and after irrigation. Results showed that within the first 10 m from the begging point, the furrow depth increase, showing the runoff had an obvious peeling effect on soil particles; while within the 10 m at the end of furrow, the furrow depth decrease, showing the sedimentation of eroded soil particles, which all above is typical characteristics of sediment yield process of furrow erosion. |
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