Soil moisture, a critical variable in the hydrologic cycle, is highly influenced by vegetation restoration type. However, the relationship between spatial variation of soil moisture, vegetation restoration type and sl...Soil moisture, a critical variable in the hydrologic cycle, is highly influenced by vegetation restoration type. However, the relationship between spatial variation of soil moisture, vegetation restoration type and slope length is controversial. Therefore, soil moisture across soil layers(0-400 cm depth) was measured before and after the rainy season in severe drought(2015) and normal hydrological year(2016) in three vegetation restoration areas(artificial forestland, natural forestland and grassland), on the hillslopes of the Caijiachuan Catchment in the Loess area, China. The results showed that artificial forestland had the lowest soil moisture and most severe water deficit in 100-200 cm soil layers. Water depletion was higher in artificial and natural forestlands than in natural grassland. Moreover, soil moisture in the shallow soil layers(0-100 cm) under the three vegetation restoration types did not significantly vary with slope length, but a significant increase with slope length was observed in deep soil layers(below 100 cm). In2015, a severe drought hydrological year, higher water depletion was observed at lower slope positions under three vegetation restoration types due to higher transpiration and evapotranspiration and unlikely recharge from upslope runoff. However, in 2016, a normal hydrological year, there was lower water depletion, even infiltration recharge at lower slope positions, indicating receiving a large amount of water from upslope. Vegetation restoration type, precipitation, slope length and soil depth during a rainy season, in descending order of influence, had significant effects on soil moisture. Generally, natural grassland is more beneficial for vegetation restoration than natural and artificial forestlands, and the results can provide useful information for understanding hydrological processes and improving vegetation restoration practices on the Loess展开更多
Mountain block recharge(MBR),an important water resource,is a widespread process that recharges lowland aquifers.However,little is known about MBR due to the limited climatic and geologic data in mountainous regions s...Mountain block recharge(MBR),an important water resource,is a widespread process that recharges lowland aquifers.However,little is known about MBR due to the limited climatic and geologic data in mountainous regions such as the northern central foothills of Tianshan.Here,we present an approach to quantify MBR through the combination of water balance calculations and numerical modeling.MBR calculated from the water balance in the data-limited Tianshan Mountains is employed as a fluid-flux boundary condition in the numerical model of the plain.To verify the performance of the model,mean absolute error and root mean square error were used.Results show that the volume of water that is recharging the aquifer via MBR is 107.29 million m^(3)/yr,accounting for 2.2% of the total precipitation that falls in the mountains.Additionally,53.3% of that precipitation enters the plain aquifer via runoff,totaling 2,652.68 million m^(3)/yr.The lower volume of MBR is attributed to a major range-bounding anticline with apparent low permeability in the Tianshan Mountains.Through numerical modeling of groundwater,MBR coming from bedrock was found to be significant,accounting for 14% of total aquifer recharge in the plain,only after the portion of runoff seepage.This research contributes to a deeper understanding of MBR,and may provide instructions for estimating groundwater recharge in arid and semi-arid areas.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities (2015ZCQ-SB-03)the National Natural Science Foundation of China (51309007)the National Key Research and Development Project of China (2016YFC0501704)
文摘Soil moisture, a critical variable in the hydrologic cycle, is highly influenced by vegetation restoration type. However, the relationship between spatial variation of soil moisture, vegetation restoration type and slope length is controversial. Therefore, soil moisture across soil layers(0-400 cm depth) was measured before and after the rainy season in severe drought(2015) and normal hydrological year(2016) in three vegetation restoration areas(artificial forestland, natural forestland and grassland), on the hillslopes of the Caijiachuan Catchment in the Loess area, China. The results showed that artificial forestland had the lowest soil moisture and most severe water deficit in 100-200 cm soil layers. Water depletion was higher in artificial and natural forestlands than in natural grassland. Moreover, soil moisture in the shallow soil layers(0-100 cm) under the three vegetation restoration types did not significantly vary with slope length, but a significant increase with slope length was observed in deep soil layers(below 100 cm). In2015, a severe drought hydrological year, higher water depletion was observed at lower slope positions under three vegetation restoration types due to higher transpiration and evapotranspiration and unlikely recharge from upslope runoff. However, in 2016, a normal hydrological year, there was lower water depletion, even infiltration recharge at lower slope positions, indicating receiving a large amount of water from upslope. Vegetation restoration type, precipitation, slope length and soil depth during a rainy season, in descending order of influence, had significant effects on soil moisture. Generally, natural grassland is more beneficial for vegetation restoration than natural and artificial forestlands, and the results can provide useful information for understanding hydrological processes and improving vegetation restoration practices on the Loess
基金funded by the National Natural Science Foundation of China-Henan Talent Training Joint Foundation (Grant No.U1504404)the National Natural Science Foundation of China: Dynamic mechanism and ecological effect of watershed transformation of surface water and groundwater and groundwater in some typical areas in Junggar basin (Grant No.U1603243)。
文摘Mountain block recharge(MBR),an important water resource,is a widespread process that recharges lowland aquifers.However,little is known about MBR due to the limited climatic and geologic data in mountainous regions such as the northern central foothills of Tianshan.Here,we present an approach to quantify MBR through the combination of water balance calculations and numerical modeling.MBR calculated from the water balance in the data-limited Tianshan Mountains is employed as a fluid-flux boundary condition in the numerical model of the plain.To verify the performance of the model,mean absolute error and root mean square error were used.Results show that the volume of water that is recharging the aquifer via MBR is 107.29 million m^(3)/yr,accounting for 2.2% of the total precipitation that falls in the mountains.Additionally,53.3% of that precipitation enters the plain aquifer via runoff,totaling 2,652.68 million m^(3)/yr.The lower volume of MBR is attributed to a major range-bounding anticline with apparent low permeability in the Tianshan Mountains.Through numerical modeling of groundwater,MBR coming from bedrock was found to be significant,accounting for 14% of total aquifer recharge in the plain,only after the portion of runoff seepage.This research contributes to a deeper understanding of MBR,and may provide instructions for estimating groundwater recharge in arid and semi-arid areas.