Temporal And Spatial Characteristics Of ?D And ?¹⁸O Of Water In The Quanfuzhuang River Basion Of Hani Rice Terraces Region

Water is one of the core elements in the Culture Landscape of Honghe Hani Rice Terraces.The variation in hydrogen and oxygen isotopic composition of water can be used to trace water cycle and determine its origin.In this paper,the spatial and temporal distribution features of hydrogen and oxygen stable isotope are studied through the analysis on samples of precipitation,surface water and groundwater,which are collected in the Quanfuzhuang River Basin of Honghe Hani Rice Terraces and in two periods of July 2014 and January-December 2015.The results are as follows:?1?Hydrogen and oxygen stable isotopic characteristics of precipitation at multiple time scalesAt annual time-scale,the values of ?¹⁸O and ?D in precipitation of 2015 are within the global numerical range,indicating that the precipitation isotope composition was affected by the global atmospheric circulation.The intercept is large through the Local Meteroric Water Line,?D = 8.15?¹⁸O + 19.76?n = 56,R2 = 0.93?,which indicates that the precipitation in study area is affected by local circulation and of local climatic characteristics.Meanwhile,the ?¹⁸O in annual precipitation is affected by the Precipitation Effect greatly,and in turn interfere the Temperature Effect to some extent.At seasonal time-scale,the precipitation ?¹⁸O is affected by the seasonal variation,which can indicate the rainfall amount to a certain extent.In the perspective of Temperature Effect,the ?¹⁸O in rainy season?May to October?is positively correlated with temperature;while in the dry season?November to April?is negatively correlated with temperature,indicating that the Temperature Effect is seasonal.At daily time-scale,the ?¹⁸O of the precipitation has significant Precipitation Effect,however the change in ?¹⁸O lags behind the precipitation.The change of temperature in one day is also related to the precipitation ?¹⁸O,and the heavier precipitation in short time would interfere the effect of temperature on precipitation ?¹⁸O to a certain extent,indicating that Precipitation Effect and Temperature Effect would have the same indication in daily time-scale.?2?Spatial and temporal characteristics of hydrogen and oxygen stable isotopes in the surface water of different typesThe evaporation line equation for surface water in 2015 is: ?D = 5.88?¹⁸O-7.92?n = 197,R2 = 0.99?.The ?¹⁸O in different types of surface water have obvious seasonal variation characteristics.The correlation analysis showed that the surface water ?¹⁸O of the Quanfuzhuang River Bison has a clear correlation with wind speed and humidity,but the correlation with temperature is weak.The evaporation line equation of the river water in 2015 is: ?D = 5.60?¹⁸O-10.16?R2 = 0.99,n = 55?,while the equation in the rainy season is: ?D = 5.95?¹⁸O-7.06?R² = 0.99,n = 6?,and in the dry season is: ?D = 4.61?¹⁸O-18.92?R² = 0.99,n = 5?.There are differences in the evaporation lines of rainy season and dry season.That's because the river water in the rainy season is mainly supplied by precipitation,and inherite the characteristics of precipitation ?¹⁸O and ?D,while the amount of precipitation in the dry season is less with more sunny days,subsequently the slope is reduced by the effect of evaporation and other waters supplying.The correlation analysis shows that the change of isotopic value of river water is related to the change of precipitation and altitude and that lag behind the precipitation change.The evaporation line equation of pond water in July 2014 is: ?D = 6.76?¹⁸O-1.29?R² = 0.97,n = 117?,while in 2015 is: ?D = 6.39?¹⁸O-1.62?R² = 0.97,n = 28?,and the difference of two is little.The ?¹⁸O of pond water in the study area has significant Elevation Effect.In sum,the landscape type has a greater impact on surface water,indicating that the isotope variation of surface water can indicate the difference of water supply in different landscape types.?3?Spatial and temporal characteristics of hydrogen and oxygen stable isotopes in the groundwaterThe evaporation line equation of groundwater in 2015 is: ?D = 5.32 ?¹⁸O-12.92?n = 190,R2 = 0.98?,the average ?¹⁸O of which is lower than surface water and precipitation,and the amplitude is the smallest and most stable.The change of isotopic value in groundwater is different in different samples.According to the variation of groundwater isotope value,the supply of groundwater in the study area could be classified into three types: rainwater,deep groundwater and mixed supply.The heavy rainfall has a great influence on ?¹⁸O of groundwater with rainwater supply and mixed supply,and the influence degree and the reaction time are quite different.The analysis of the groundwater with rainwater supply and mixed supply reflect the lag effect of precipitation,and is obvious in the early stage of the rainy season.In addition,the groundwater ?¹⁸O and ?D in different landscape types have different characteristics.In summary,in the view of the temporal and spatial characteristics of hydrogen and oxygen isotope values of waters in the study area,precipitation ?¹⁸O and ?D have the largest amplitude,followed by the surface water?pond water and river water?,and the smallest is groundwater.There is a certain amount of supply relationships among precipitation,surface water and groundwater.The specific supply relationships among waters are yet to be further analyzed.