The Chemical Regulation Of Surface Water And Sediment Process On Loess Hillslope

Drought and soil erosion is the two environment problems on the loess plateau region. Inloess plateau region, annual rainfall is little, water resource is limited, but the precipitationvariability is large, more land in the form of heavy rains, and flow is loss form surpe flow,there have caused the shortage of water resources and drought.Because loess soil erosionresistance is poor,it also produced the strong erosion and sediment yield, so the loess plateauis the most serious soil erosion areas in the world. A severe drought and soil erosion in theloess plateau have severely damaged the local ecological environment and restricted the localagriculture and sustainable development, and threated the safety of the lower reaches of theYellow River region.Chemical contol measure is a kind of unconventional soil and waterconservation measures. Jag S and Jag C162are two kinds of chemical materials which werenewly developed. Researches of the chemical regulation of surface water and sedimentprocess on the loess hillslope can understand the mechanism of surface water and sedimentprocess, and clarify controlling regulation and mechanism of the surface water and sedimentprocess too. The study can promote further development of slope water and sediment theoryand provide scientific basis for the soil and water loss control.The chemical regulation of surface water and sediment process on loess hillslope arestudied under simulated rainfall experiments with the rainfall intensities of1.0mm/min,1.5mm/min,2.0mm/min and slopes of10°,15°,20°and dosage of1g/m2,3g/m2,5g/m2and thecast way of dry spreading and spraying. The study analyzed the effect of Jag S and Jag C162on the infiltration processes, runoff sediment concentration variation processes andhydrodynamic parameters characteristics. The main results are as follows:1.To analysis the regulation of Jag S and Jag C162on infiltration process on loesshillslope: After dry spreading and spraying Jag S and Jag C162, the variations of infiltrationrates with times are similar with that of bare slope,in the trends of a decrease rapidly first, andfinally going to a stability or slowly decrease; Compared with bare slope, infiltration rates of5g/m2Jag S decrease by1%to15%and with an average decrease of11%under dryspreading and spraying, and decrease by6%to21%(excepting a increase of5%under1.0mm/min) and with an average decrease of11%under spraying. In the other treatments, infiltration can be increased under dry spreading and spraying Jag S and Jag C162. After dryspreading and spraying Jag S, the higher the doses, the less infiltration, the infiltrationincreased by2%to27%and with an average increase of10%under dry spreading Jag S, andthe infiltration increased by3%to36%and with an average increase of16%under sprayingJag S. After dry spreading and spraying Jag C162, the higher the doses, the infiltration is3g/m2>5g/m2>1g/m2, and infiltration increase by1%to44%and with an average increase of28%under dry spreading Jag C162, and infiltration increase by21%to83%and with anaverage increase of40%under spraying Jag C162. The increase effect of spraying is betterthan dry spreading, and the reduction effect of spraying is the same to dry spreading under5g/m2.2. To research the regulation of Jag S and Jag C162on sediment concentration variationprocess on loess hillslope: After dry spreading and spraying Jag S and Jag C162, thevariations of sediment concentration with times are similar with that of bare slope, in thetrends of a decrease first and then going to a stability or increase first,then decrease and finalgoing to a stability. Compared with bare slope, sediment concentration increase under dryspreading Jag C162and spraying Jag C162of3g/m2,and sediment concentration increase by11%to85%and with an average increase of33%under dry spreading, and increase by4%to126%and with an average increase of48%under spraying. In the other treatments, sedimentconcentration can be decreased under dry spreading and spraying Jag S and Jag C162. Thehigher the doses, the more sediment concentration decreased, the sediment concentrationdecreased by27%to83%and with an average increase of59%under dry spreading Jag S,and the sediment concentration decreased by5%to79%and with an average increase of34%under spraying Jag S, and the sediment concentration decrease by0.1%to37%and with anaverage decrease of13%under dry spreading Jag C162.The reduction effect on sedimentconcentration of dry spreading is better than spraying.After application Jag C162, the increaseeffect on sediment concentration of dry spreading is less than spraying of3g/m2, sedimentconcentration is decreased under dry spreading and sediment concentration is increased underspraying of1g/m2and3g/m2.Application Jag S and Jag C162, decreased sedimentconcentration is given priority to,and accounts for two-thirds of different treatment.3. To reveal the regulations of Jag S and Jag C162on hydrodynamic parameters: Afterdry spreading and spraying Jag S and Jag C162, the variations of hydrodynamic parameterswith times are similar with that of bare slope,in the trends of a increase first,and then going toa stability or slowly increase,but there are a slight difference under different treatments.Compared with bare slope, stream shear stress, stream power and unit stream power can bedecreased under dry spreading and spraying Jag S and Jag C162(excepting a increase of stream power and unit stream power under dry spreading and spraying5g/m2Jag S, andstream shear stress under dry spreading5g/m2Jag S): After dry spreading Jag S, the higherthe doses, the more the decrease and with an average decrease of7%on stream shear stress,and the higher the doses, the less the decrease and with an average decrease of18%、12%onstream power, unit stream power. After spraying Jag S, the higher the doses, the less thedecrease and an average decrease of17%,33%,18%. After dry spreading Jag C162, thehigher the doses, the more the decrease and with an average decrease of15%on stream shearstress, and with order of the decrease:3g/m2>5g/m2>1g/m2and with an average decrease of44%、36%on stream power and unit stream power. After spraying Jag C162, the higher thedoses, the more the decrease and an average decrease of46%,64%,37%. The reduction effectof spraying is better than dry spreading and the effect on stream power of spraying is best.4. To clarity the regulations of Jag S and Jag C162on surface water and sedimentprocess on loess hillslope: Compared with bare slope, application Jag S and Jag C162caneffectively increase infiltration by improving top soil>0.25mm soil water stable aggregatescontent by529%to631%, application Jag S and Jag C162can significantly improve the slopesurface soil resistance to erosion and sediment yield capacity and overall power reduces theslope erosion and sediment yield by increasing soil shear strength by62%to235%,anddecreasing water dynamics parameters overall, so the result will inevitably reduce the slopesurface erosion and sediment yield. Compared with bare slope, application Jag S and JagC162can increase the degree of infiltration and reduce runoff broadcasting and spraying JagS and Jag C162slope increase the degree of infiltration and reduce runoff and decrease thedegree of erosion and sediment yield is different, in order to the change of sedimentconcentration relative to the bare slope under different treatment is different.