Effects of Rainfall and Gravel-soil Covered on Soil Water Evaporation in Gavel-mulched Land of Ningxia Central Arid Region
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【Author in Chinese】 刘学智；
【Author's Information】 宁夏大学， 工程硕士（专业学位）， 2018， 硕士
【Abstract in Chinese】 论文针对宁夏中部干旱带水资源短缺、蒸发强烈、水资源利用效率低等现实问题开展调查、资料收集,查阅了大量国内外相关文献,对当地气候变化、压砂覆盖抑制土壤水分蒸发、土壤水分运移规律等研究成果进行了系统总结与分析。以降低土壤水分蒸发为目标,设计了不同降水量、不同比例砂土混合物覆盖试验,对降水、砂土混合物覆盖、及其组合对土壤水分蒸发过程的影响进行了监测与分析。通过资料收集、试验研究与分析,在本试验的特定条件下得出了以下结论:(1)自1960—2016年,宁夏环香山地区平均气温、日照时数、平均风速呈增加趋势,每10年分别增加0.41℃、33.1h和0.09m/s;日较差、降水量、相对湿度、蒸发量呈下降趋势,每10年分别下降0.22℃、3.85mm、1.69%和33.1mm。日较差、降水量、日照时数、平均风速及相对湿度对环香山地区的蒸发量影响较大:(2)土壤水分的蒸发受降雨量的影响较大,相同比例砂土混合物覆盖下,降雨量越大,日蒸发强度、同时段内土壤累计蒸发量越大。降雨后土壤水分蒸发强度随着时间延长逐渐降低,且土壤水分的累计蒸发量与时间呈现指数函数变化规律;(3)控制降雨量一定,土壤水分的日蒸发强度随覆盖物砂土比例的增加而减小,全砂覆盖对蒸发的抑制效果最好,更有利于降水蓄积和抑制蒸发。降雨后土壤累计蒸发量与时间呈现指数函数变化规律;(4)同一比例砂土混合覆盖下,土壤水分一次降雨的蒸发历时随降雨量的增大而增大,且降雨量越小变化幅度越大,一次降雨的蒸发历时与降雨量的关系可以用5次多项式描述;同一降雨量下不同比例砂土混合覆盖的一次降雨蒸发历时大小关系为全砂>40%>80%>60%>20%>裸土,全砂更有利于水分保持和蒸发抑制,一次降雨的蒸发历时与砂土比例的关系可以用2次多项式描述;(5)砂土混合物覆盖和降雨量组合对土壤水分蒸发强度、一次降雨的蒸发历时的影响可以用5次多项式表示之间的规律,R2分别达到了 0.983和0.980,模型拟合优度高,且各项和整体均到达了显著水平。该研究对认识宁夏中部干旱带压砂地区土壤水分蒸发、应对气候环境变化下抑制土壤水分蒸发、制定合理的节水制度、提高水分利用效率等方面均具有重要的学术价值和使用价值,为宁夏中部干旱带压砂地持续发展、实现水资源高效利用和生态恢复等提供数据支撑。
【Abstract】 The paper carried out investigations and data collection on the practical problems of water shortage,strong evaporation,and low utilization efficiency of water resources in the central arid region of Ningxia,and reviewed a large number of domestic and foreign relevant literatures to suppress local climate change and sand cover to inhibit soil moisture evaporation and soil moisture.The research results of transport laws and other systems were systematically summarized and analyzed.In order to reduce the evaporation of soil moisture,a sand mixture test with different amounts of precipitation and different proportions was designed to monitor and analyze the effects of precipitation,sand mixture mixture,and their combinations on the soil moisture evaporation process.Through data collection,experimental research and analysis,the following conclusions were obtained under the specific conditions of this experiment:(1)From 1960 to 2016,the average temperature,sunshine duration,and average wind speed in the Xiangshan area of Ningxia showed an increasing trend,with an increase of 0.41℃,33.Ih,and 0.09m/s per decade respectively;Humidity and evaporation showed a downward trend,dropping by 0.22℃,3.85mm,1.69%,and 33.1mm,respectively,every 10 years.Poor day,precipitation,sunshine duration,average wind speed,and relative humidity have a greater impact on evaporation in the Xiangshan area.(2)The evaporation of soil moisture is greatly affected by rainfall.Under the same proportion of sand and soil mixture,the greater the rainfall,the greater the daily evaporation intensity and the accumulated evaporation of soil in the same period.After the rainfall,the evaporation intensity of soil moisture gradually decreased with the extension of time,and the accumulated evaporation and time of soil moisture showed an exponential function.(3)The amount of rainfall control is constant,and the daily evaporation intensity of soil moisture decreases with the increase of the sand content of the cover.The effect of full sand coverage on evaporation is best,and it is more conducive to precipitation accumulation and evaporation inhibition.The cumulative soil evaporation and time after rainfall showed an exponential function;(4)Under the same mixed proportion of sand and soil,the evaporation duration of a soil moisture rainfall increases with the increase of rainfall,and the smaller the rainfall,the greater the change,the relationship between the evaporation duration of a rainfall and rainfall can be used.5 times polynomial description;the relationship between the time and size of a single rainfall evaporation with different proportions of sand mixed under the same rainfall is:full sand>40%>80%>60%>20%>bare soil,full sand is more favorable for water conservation and evaporation Inhibition,the relationship between evaporation duration of a rainfall and sand ratio can be described by polynomial of degree 2;(5)The effect of sand mixture mixture and rainfall combination on the evaporation intensity of soil moisture and the evaporation duration of a rainfall can be expressed by the polynomial of degree 5.R2 reaches 0.983 and 0.980,respectively,and the goodness of model fitting is high.And each item and the whole have reached a significant level.The study has important academic and practical value for understanding the evaporation of soil moisture in the sand-pressed areas of the central arid region of Ningxia,the suppression of soil water evaporationunder the climate and environmental changes,the establishment of a reasonable water conservation system,and the improvement of water use efficiency.In the central Ningxia region,continuous development of pressure sand areas,and the realization of efficient use of water resources and ecological restoration provide data support.