Experimental Study On Groundwater Environmental Effect Under Sewage Irrigation

This theme mainly studies the properties of soil water, nitrogen, phosphorus and chloride transport and groundwater environment effect, base on consulting a great deal of domestic and international literature, adopted technique way of indoor experiment and theoretical analyses, with a 100cm groundwater level under sewage irrigation. The main results are as follows:(1) The rise characteristic of capillary water in homogeneous soil was researched. There was an obvious linear function relationship between the height of upward capillary water and groundwater recharge quantity and power function relationship between them and time.(2) Soil water, nitrogen, phosphorus and chloride transport and groundwater environment effect under different concentration of sewage irrigation was researched. Philip model was used to analyses the process of infiltration, the calculated value by this model conforms well with the experimental data. Infiltration capacity and wetting front transport distance increased with the increased concentration of the sewage. The proportion of soil water content in upper layer at the same depth to total infiltration quantity decreased with the increased concentration of the sewage. NO₃^- -N at different concentration under sewage infiltration was mainly preserved in pelagic soil. NO₃^- -N transport distance in soil and NO₃^- -N content increase amplitude in groundwater also increased with the increased concentration of sewage. Clear water infiltration had no effect on the distribution of soluble orthophosphate in the soil. Soluble orthophosphate at different concentration under sewage infiltration was mainly preserved in surface soil. Soluble orthophosphate concentration in surface soil and groundwater increased with the increased concentration of sewage. Chloride ion transport distance in soil and Chloride ion increment in groundwater also increased with the increased concentration of the sewage.(3) Soil water, nitrogen, phosphorus and chloride transport and groundwater environment effect under different irrigation quota of sewage was researched. Infiltration capacity and wetting front transport distance increased with the increased irrigation quota of the sewage. Infiltration rate decreased with the increased irrigation quota at the time the infiltration was over. The water content at the same depth increased with the increased irrigation quota of sewage. NCV-N at different irrigation quota under sewage infiltration was mainly preserved in pelagic soil. NO₃^- -N transport distance in soil and NO₃^- -N content increase amplitude in groundwater increased with the increased irrigation quota of sewage. Soluble orthophosphate at different irrigation quota under sewage infiltration was mainly preserved in surface soil. Soluble orthophosphate concentration in surface soil and groundwater increased with the increased irrigation quota of the sewage. Chloride ion transport distance in soil and Chloride ion increment in groundwater also increased with the increased irrigation quota of the sewage.(4) Soil water, nitrogen, phosphorus and chloride transport and groundwater environment effect under different soil density of sewage infiltration was researched. Infiltration capacity and wetting front transport distance decreased with the increased soil density of sewage infiltration. Infiltration rate decreased with the increased soil density at the time that the infiltration was over. NO₃^- -N at different soil density under sewage infiltration was mainly preserved in pelagic soil. NO₃^- -N transport distance in soil and NO₃^- -N content increase amplitude in groundwater also decreased with the increased concentration of sewage. Soluble orthophosphate at different soil density under sewage infiltration was mainly preserved in surface soil. Soluble orthophosphate concentration in surface soil increased with the increased soil density of sewage infiltration. Soluble orthophosphate concentration in groundwater decreased with the increased soil density of the sewage infiltration. Chloride ion transport distance in soil decreased with the increased soil density, and Chloride ion was more difficult to move to groundwater with the increased soil density, groundwater was more difficult to be affected.