A comparison of methods to estimate groundwater recharge from bare soil based on data observed by a large-scale lysimeter     

Zaiyong Zhang  Wenke Wang  Chengcheng Gong  Ming Zhang 《水文研究》2020,34(13):2987-2999

Effectively estimating groundwater recharge is critical to manage water resources, especially in arid and semi-arid regions as impacted by intensive human activities and climate changes. Rare insights have been gained into groundwater recharge since direct observation is hard to carry out. Although several methods are currently available to estimate groundwater recharge, the estimated results may cover noticeable bias. The behaviours of different methods based on different conceptual frameworks and exhibiting different levels of complexity should be examined to estimate actual groundwater recharge. This study aims to assess the performance of four common methods to estimate groundwater recharge. For this end, large-scale lysimeters equipped with soil water content sensors and water table sensors were set up at a research site established in Guanzhong Basin of China. The data achieved by 1-year observation were employed to compare four estimation methods. As revealed from the results, the following findings are drawn. (a) Groundwater level fluctuation (GLF) method is simple, whereas its accuracy is determined by specific yield, and adopting a water balance method to estimate specific yield can considerably enhance the accuracy of GLF. (b) The calibrated numerical model can obtain the optimal result compared with the other methods, whereas long-term observation data are required for parameter calibration. (c) In the water balance method, the maximum entropy production (MEP) model and a practical method (estimating evaporation between two rainfall events) were used to calculate evaporation. As indicated by the results, water balance method combined with MEP is capable of obtaining more reliable results of groundwater recharge compared with the practical method. (d) With an analytical model based on linearized Richards' equation, accurate results can be achieved. What is more, the analytical model only needs the measurement of soil moisture near the surface. The limitation of this method is that it is difficult to determine the maximal water flux. The mentioned findings are of critical implications to the management and sustainable development of groundwater.  相似文献   

Continuous measurement of whole‐tree water balance for studying urban tree transpiration          下载免费PDF全文

Takashi Asawa  Tomoki Kiyono  Akira Hoyano 《水文研究》2017,31(17):3056-3068

Street and garden trees in urban areas are often exposed to advection of strong vapour pressure deficit (VPD) air that can raise the whole‐tree transpiration rate (E_T), known as the oasis effect. However, urban trees tend to have small soil volume compared with natural conditions, and so they are believed to strongly regulate stomata. E_T characteristics of such urban trees have not been well understood because of a lack of reliable measurement methods. Therefore, we propose a novel weighing lysimeter method and investigate the whole‐tree water balance of an isolated container‐grown Zelkova serrata to examine (a) which biotic and abiotic factors determine E_T and (b) which spatial and temporal information is needed to predict E_T under urban conditions. Whole‐tree water balance and environmental conditions were measured from 2010 to 2012. Although leaf area substantially increased in the study period, daily E_T did not vary much. E_T increased with VPD almost linearly in 2010 but showed saturation in 2011 and 2012. Root water uptake lagged E_T by 40 min in 2012. These results suggest that the small planter box interfered with root growth and that hydraulic supply capacities did not increase sufficiently to support leaf area increase. From analysis of water balance, we believe that neglecting soil drought effects on street trees without irrigation in Japan will overestimate E_T over 4–5 sunny days at the longest. This is unlike previous studies of forest.  相似文献   

GQZ—Z1型称重式蒸渗计的研制及标定     

党选发  杨兴国  张旭东  孔令旺  李晓峰  杨启国 《干旱气象》2013,(4):835-839

在土壤水分蒸散量测量仪器研制中,首次在蒸渗计的原状土柱与反滤层接触部分安装了自动补（抽）水设备,使土桶内原状土柱与大田内的土壤水分保持一致。提出了传感器的参数选用原则和蒸渗计标定方法。经过安装和标定使用,GQZ—Z1蒸渗计的精度达到设计和观测0．1mm的要求,能够有效提高农田蒸散量的观测精度,其测定值能很好地反映植物在短时段内的蒸散变化。  相似文献   

沙坡头生态水文学研究进展及水量平衡自动模拟监测系统   总被引：2，自引：1，他引：1  

张志山  李新荣  赵洋  张亚峰  杨昊天  虎瑞 《中国沙漠》2018,38(6):1119-1135

在中国科学院野外站网络重点科技基础设施建设项目的支持下,沙坡头沙漠研究试验站建成了以36台大型称重式蒸渗仪为主体的中国北方不同气候带沙区水量平衡自动模拟监测系统——Lysimeter群。概述了沙坡头生态水文学研究进展。介绍了Lysimeter群建设的科学目标、构建思路、建设内容和预期研究方向。Lysimeter群由大型称重式蒸渗仪、各类探头、移动大棚和降水模拟器等组成,具有集成性和唯一性。该平台可全自动模拟控制降水和地下水位,量化植物水分来源;自动监测蒸散发、植物蒸腾、土壤水渗漏、土壤水分、温度和电导率等。该平台的建成将提升在不同尺度上认知中国沙区生态和水文过程、植被重建的生态水文学和环境胁迫生理生态学机理等相关领域的研究能力,回答不同沙区土壤水分植被承载力和人工植被稳定性维持的生态水文阈值等国家在防沙治沙实践中所面临的核心科学问题。  相似文献   

地中蒸渗计水分运移机理及其监测误差分析   总被引：1，自引：0，他引：1  

李金柱  杨晓俊  杜琦 《水文》2003,23(5):10-12,37

对地中蒸渗计与自然潜水水分运移机理存在的差异及误差进行了分析。结果表明：地中蒸渗计与自然潜水在水位动态、水分存储、水分运移等方面存在一定的差异，使得利用地中蒸渗计监测的潜水蒸发量、降雨入渗补给量与自然潜水的实际情况产生了一定的误差，这种误差随着潜水埋深的变化而变化，潜水埋深越浅，误差越大，潜水埋深越深，误差越小。特别对于潜水埋深小于1．5m的地中蒸渗计，使用其资料时一定要作适当的技术处理，如果直接引用，将会给计算成果带来较大的误差。  相似文献   

Evapotranspiration from citrus trees growing in sandy soilunder drip irrigation with saline water     

杨胜利  Tomohisa Yano 《中国科学D辑(英文版)》2002,45(Z1)

An experiment on evapotranspiration from citrus trees under irrigation with saline waterwas carried out for 4 months. Two lysimeters planted with a citrus tree in the green house wereused. One lysimeter was irrigated with saline water (NaCl and CaCl2 of 2000 mg/L equivalence,EC = 3.8 dS/m, SAR = 5.9) and the other was irrigated with freshwater using drip irrigation. Theapplied irrigation water was 1.2 times that of the evapotranspiration on the previous day.Evapotranspiration was calculated as the change in lysimeter weight recorded every 30 minutes.The lysimeters were filled with soil with 95.8% sand. The results of the experiment were as follows.(i) The evapotranspiration from citrus tree was reduced after irrigation with saline water. Theevapotranspiration returns to normal after leaching. However it takes months to exhaust the saltfrom the tree. ( ii ) To estimate the impact of irrigation with saline water on the evapotranspirationfrom citrus trees, the reduction coefficient due to salt stress (Ks) was used in this experiment.Evapotranspiration under irrigation with saline water (ETs) can be calculated from evapotranspira-tion under irrigation with freshwater (ET) by the equation ETs = Ks× ET. Ks can be expressed as afunction of ECsw. (iii) The critical soil-water electrical conductivity (ECsw) is 9.5 dS/m, beyondwhich adverse effects on evapotranspiration begin to appear. If ECsw can be controlled at below9.5 dS/m, saline water can be safely used for irrigation.  相似文献   

PELIMINARY ANALYSES FOR CROP WATER CONSUMPTION BY USING LYSIMETER     

Chen Jianyao Wu Kai Institute of Geography  CAS  Beijing People''s Republic of China 《地理学报(英文版)》1997,(3)

Ｉ.ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＨｕａｎｇ-Ｈｕａｉ-ＨａｉＰｌａｉｎｉｎＮｏｒｔｈＣｈｉｎａｉｓａｃｒｕｃｉａｌａｒｅａｉｎｐｒｏｖｉｄｉｎｇａｂｏｕｔｏｎｅ-ｆｉｆｔｈｏｆｔｏｔａｌｓｔａｔｅｆｏｏｄ[4],ａｎｄｉｔｉｓｆａｃｉｎｇａｓｅｒｉｏｕｓｗａｔｅｒｓｈｏｒｔａｇｅｉｎｒｅｃｅｎｔｙｅａｒｓｄｕｅｔｏｔｈｅｅｘｐａｎｓｉｏｎｏｆｉｎｄｕｓｔｒｙａｎｄａｃｏｎｔｉｎｕｏｕｓｄｅｃｒｅａｓｅｉｎｐｒｅｃｉｐｉｔａｔｉｏｎ.Ｔｈｅｓｔｕｄｙｉｎｓｏｉｌ-ｐｌａｎｔ-ａｔｍｏｓｐｈｅｒｅｃｏｎｔｉ…  相似文献   

Estimating groundwater recharge rates in the southeastern Holstein region, northern Germany     

Roland Otto 《Hydrogeology Journal》2001,9(5):498-511

In the southeastern Holstein region, located to the east of the metropolitan zone of Hamburg, northern Germany, a groundwater investigation program was conducted from 1984 to 2000 by the State Agency for Nature and Environment (Landesamt für Natur und Umwelt, LANU) of Schleswig-Holstein, Germany, with the aim of providing long-term, ecologically acceptable groundwater management plans for the region. The focal point of the investigation comprised the determination of groundwater recharge rates. The investigation method was based on the transfer of available lysimeter results from other regions to comparable regions within the area studied. With the help of lysimeter equations, potential amounts of percolation water were calculated. The groundwater recharge rate was then determined after subtraction of the surface runoff which was calculated for the entire area. All computations were performed with a spreadsheet program. Groundwater recharge rates were calculated for two areas. One consisted of roughly determining groundwater recharge rates for the total region (1,392 km²) of southeastern Holstein. The overall goal of these investigations was to identify potential areas of water exploitation. Areas in which groundwater recharge rates are high and groundwater outflow is low are particularly suited to water exploitation, since inflow rates into deeper aquifers are high. These areas are located on the flanks of the Elbe and Stecknitz River valleys. Subsurface groundwater runoff to these lowlands would be reduced through groundwater withdrawal. However, the resulting decline in shallow groundwater tables would be so small that it would have no detrimental ecological effects. Groundwater recharge rates were also calculated for a 110-km² area in the outskirts of Hamburg (Grosshansdorf model area) which is intensively developed for water supply. These investigations showed that the amount of groundwater recharge is already being withdrawn to a large extent. Approximately 65% of the recharge rate is currently withdrawn by the waterworks in this area, thus making further increases in exploitation rates unjustifiable from an ecological point of view. Electronic Publication  相似文献   

膜下滴灌模式下种植密度对棉田蒸散发规律影响研究     

王小军 《沙漠与绿洲气象(新疆气象)》2020,14(1):138-143

为探求绿洲棉区膜下滴灌条件下不同种植密度棉田蒸散发规律，运用大型称重式蒸渗仪对膜下滴灌棉田蒸散过程连续监测，结果表明：在不同种植密度条件下，棉花的日蒸散量曲线都表现为单峰曲线，不同生育时期一膜六行（30株/m2）种植的棉田蒸散量比一膜四行（20株/m2）大，花铃期棉田的蒸散发强度最大，一膜四行、一膜六行分别为4.76mm/d、5.94mm/d。同时，一膜六行种植的叶面积指数大于一膜四行种植,株高小于一膜四行种植。花铃期棉田的蒸散发量与日平均气温（p<0.01）和空气相对湿度(p<0.01)具有很好的相关性，与日平均风速和日平均水汽压的关系不大。  相似文献   

Natural Geological Weighing Lysimeters: Calibration Tools for Satellite and Ground Surface Gravity Monitoring of Subsurface Water-Mass Change     

Bardsley  W. E.  Campbell  D. I. 《Natural Resources Research》2000,9(2):147-156

Increased accuracy in measuring temporal variations in the Earth's gravity field allow inprinciple the use of gravity observations to deduce subsurface water-mass changes. This canbe with respect to a small area, or as a larger spatial average of water mass change usinggravity observations from low-altitude satellites, such as the forthcoming GRACE mission.At both scales, there is a need to validate gravity-based estimates against field recordings ofactual subsurface water-mass variations. In practice, this could prove difficult because thespatial integral of all water-storage change components can be subject to considerable fieldmeasurement error. An alternative approach to the validation process is proposed by whichsuitable geological formations are utilized as giant weighing devices to directly measure area-integratedwater-mass changes. The existence of such natural geological weighing lysimetersis demonstrated using observations from a replicated experimental site in New Zealand. Sitesof this type could be used to verify water-storage change estimates derived from sensitiveground surface gravity instrumentation. In addition, geological lysimeters could be used tomake local checks on the accuracy of any estimated regional water-mass time series, whichis proposed for satellite calibration. The land area weighed by a geological lysimeter increaseswith formation depth and it is speculated that recordings made at oil well depth may allowdirect monitoring of subsurface water mass changes at the regional scale.  相似文献