廊坊市地下水位下降漏斗的成因

通过对廊坊市地下水漏斗演化过程与逐年降水的相关分析,揭示了地下水位下降漏斗的气象干旱响应模式,即气象干旱促使人类过度开采地下水资源,从而进一步加剧水文干旱、地下水位下降漏斗及地面沉降灾害。在时间序列上,气象干旱呈波浪起伏状特征,而地下水位下降漏斗及地面沉降则表现为缓变性、积累性和不可逆性,气象干旱的阶段性终止并不能阻止地下水位下降漏斗及地面沉降的继续发展与蔓延。同时提出了合理开采地下水、大力开展水循环利用、发展节水农业等对策。     

Effects of climate change on coastal fresh groundwater resources

This study evaluates the impacts of climate change on fresh groundwater resources specifically salinity intrusion in water resources stressed coastal aquifers. Our assessment used the Hadley Centre climate model, HadCM3 with high and low emission scenarios (SRES A2 and B2) for years 2000–2099. In both scenarios, the annual fresh groundwater resources losses indicate an increasing long-term trend in all stressed areas, except in the northern Africa/Sahara region. We also found that precipitation and temperature individually did not show good correlations with fresh groundwater loss. However, the relationship between the aridity index and fresh groundwater loss exhibited a strong negative correlation. We also discuss the impacts of loss of fresh groundwater resources on socio-economic activities, mainly population growth and per capita fresh groundwater resources.     

Climate�Csoil�Cvegetation control on groundwater table dynamics and its feedbacks in a climate model

Among the three dynamically linked branches of the water cycle, including atmospheric, surface, and subsurface water, groundwater is the largest reservoir and an active component of the hydrologic system. Because of the inherent slow response time, groundwater may be particularly relevant for long time-scale processes such as multi-years or decadal droughts. This study uses regional climate simulations with and without surface water?Cgroundwater interactions for the conterminous US to assess the influence of climate, soil, and vegetation on groundwater table dynamics, and its potential feedbacks to regional climate. Analyses show that precipitation has a dominant influence on the spatial and temporal variations of groundwater table depth (GWT). The simulated GWT is found to decrease sharply with increasing precipitation. Our simulation also shows some distinct spatial variations that are related to soil porosity and hydraulic conductivity. Vegetation properties such as minimum stomatal resistance, and root depth and fraction are also found to play an important role in controlling the groundwater table. Comparing two simulations with and without groundwater table dynamics, we find that groundwater table dynamics mainly influences the partitioning of soil water between the surface (0?C0.5?m) and subsurface (0.5?C5?m) rather than total soil moisture. In most areas, groundwater table dynamics increases surface soil moisture at the expense of the subsurface, except in regions with very shallow groundwater table. The change in soil water partitioning between the surface and subsurface is found to strongly correlate with the partitioning of surface sensible and latent heat fluxes. The evaporative fraction (EF) is generally higher during summer when groundwater table dynamics is included. This is accompanied by increased cloudiness, reduced diurnal temperature range, cooler surface temperature, and increased cloud top height. Although both convective and non-convective precipitation are enhanced, the higher EF changes the partitioning to favor more non-convective precipitation, but this result could be sensitive to the convective parameterization used. Compared to simulations without groundwater table dynamics, the dry bias in the summer precipitation is slightly reduced over the central and eastern US Groundwater table dynamics can provide important feedbacks to atmospheric processes, and these feedbacks are stronger in regions with deeper groundwater table, because the interactions between surface and subsurface are weak when the groundwater table is deep. This increases the sensitivity of surface soil moisture to precipitation anomalies, and therefore enhances land surface feedbacks to the atmosphere through changes in soil moisture and evaporative fraction. By altering the groundwater table depth, land use change and groundwater withdrawal can alter land surface response and feedback to the climate system.     

渭河谷地地下水位变化与作物需水关系

根据天水农试站１９８３—１９９２年地下水位观测资料，分析得出了当地地下水位的变化规律和地下水对土壤水分变化的影响，并根据当地主要粮食作物的生长特点，对其需水与地下水位变化的关系进行了探讨。     

黄河流域城镇化对地下水的影响分析

黄河流域是我国重要的生态屏障,也是我国粮食作物的主要产区。近年来,随着城镇化的发展,当地水资源分配出现了显著变化。因此,厘清黄河流域城镇化作用下水循环的改变对制定黄河流域城镇化政策具有重要意义。本文利用资源环境科学与数据中心的黄河流域下垫面数据、世界人口数据集的人口密度和Gravity Recovery and Climate Experiment (Grace)的Center for Space Research (CSR)陆地总水储量格点数据,开展了黄河流域城镇化过程中地下水的变化特征分析工作。结果表明：黄河流域城镇化程度具有显著的空间差异,下游存在明显的城镇化加剧现象;全域人口密度整体呈上升趋势,其中下游的人口增长趋势最大;黄河流域的地下水呈下降趋势,以下游的地下水下降最为显著。通过对比黄河流域新增城镇、不变城镇和消失城镇的地下水变化差异,发现地下水下降幅度最小出现在消失城镇,新增城镇的地下水下降幅度小于不变城镇的区域。因此,黄河流域城镇化对地下水的减少具有显著的作用,新增城镇地下水并没有出现显著下降的结果也说明近年来城镇化后的地下水保护政策取得的效果良好。     

Climatic responses to anthropogenic groundwater exploitation: a case study of the Haihe River Basin,Northern China

In this study, a groundwater exploitation scheme is incorporated into the regional climate model, RegCM4, and the climatic responses to anthropogenic alteration of groundwater are then investigated over the Haihe River Basin in Northern China where groundwater resources are overexploited. The scheme models anthropogenic groundwater exploitation and water consumption, which are further divided into agricultural irrigation, industrial use and domestic use. Four 30-year on-line exploitation simulations and one control test without exploitation are conducted using the developed model with different water demands estimated from relevant socioeconomic data. The results reveal that the groundwater exploitation and water consumption cause increasing wetting and cooling effects on the local land surface and in the lower troposphere, along with a rapidly declining groundwater table in the basin. The cooling and wetting effects also extended outside the basin, especially in the regions downwind of the prevailing westerly wind, where increased precipitation occurs. The changes in the four exploitation simulations positively relate to their different water demands and are highly non-linear. The largest changes in climatic variables usually appear in spring and summer, the time of crop growth. To gain further insights into the direct changes in land-surface variables due to groundwater exploitation regardless of the atmospheric feedbacks, three off-line simulations using the land surface model Community Land Model version 3.5 are also conducted to distinguish these direct changes on the land surface of the basin. The results indicate that the direct changes of land-surface variables respond linearly to water demand if the climatic feedbacks are not considered, while non-linear climatic feedbacks enhance the differences in the on-line exploitation simulations.     

Climate change implications for irrigation and groundwater in the Republican River Basin,USA

This study investigates the influence of climate change on groundwater availability, and thereby, irrigation across political boundaries within the US High Plains aquifer. A regression model is developed to predict changes in irrigation according to predicted changes in precipitation and temperature from a downscaled dataset of 32 general circulation models (GCMs). Precipitation recharge changes are calculated with precipitation-recharge curves developed for prognostic representations of precipitation across the Nebraska-Colorado-Kansas area and within the Republican River Basin focal landscape. Irrigation-recharge changes are scaled with changes in irrigation. The groundwater responses to climate forcings are then simulated under new pumping and recharge rates using a MODFLOW groundwater flow model. Results show that groundwater pumping and recharge both will increase and that the effects of groundwater pumping will overshadow those from natural fluctuations. Groundwater levels will decline more in areas with irrigation-driven decreasing trends in the baseline. The methodologies and predictions of this study can inform long-term water planning and the design of management strategies that help avoid and resolve water-related conflicts, enabling irrigation sustainability.     

IPCC AR6报告解读：地下水

地下水已成为满足全球农业生产和生活用水需求的重要来源,也是实现联合国2030年可持续发展议程的关键资源。地下水的数量和质量会直接或间接地受到气候变化的影响。IPCC第六次评估报告（AR6）第二工作组报告对全球和区域历史时期及未来地下水变化趋势进行了评估。报告指出：(1)自21世纪初以来,由于地下水灌溉用水量增加,全球许多国家和地区地下水储量呈现下降趋势。(2)在气候变化背景下,地下水开采量将持续增加,包括全球主要含水层中不可再生的地下水。(3)在热带和半干旱地区,气候变化引起强降水发生频率加快,导致地下水补给量呈增加趋势;在高寒地区,受气候变化影响地下水主要补给期从春季向冬季演变,由于融雪周期和融雪量的减少造成高寒地区春季地下水补给量减少。在地下水退化区域开展渐进式生态修复,是应对气候变化和保障水安全的重要措施。     

陆面过程模式中地下水位的参数化及初步应用

田间研究表明地表水和地下水有重要的相互作用,它与土壤含水量密切相关.土壤含水量不仅在陆气相互作用系统水和能量平衡中,而且在干旱、洪水预报、水资源管理、生态系统研究中起十分重要的作用.因此,研究地表水和地下水的相互作用,建立陆面模式中地下水位的动态表示,对于气候与水资源研究具有重要意义.将地下水位的动态表示问题归结为饱和与非饱和流问题,发展了其数值计算方案,建立了地下水位的动态表示,并与陆面过程模型耦合,建立了陆气相互作用中地下水位的动态表示,并进行了数值模拟研究.     

利用环境同位素技术研究沈阳浑河与地下水的水力联系

查明地下水与河水之间的水力联系,是研究浑河污染水体对地下水环境影响的前提。采用环境同位素技术研究浑河沿岸地下水演化规律,沿浑河冲洪积扇地下水流动方向取地下水样13个、河水样3个。结果表明:通过对水样进行D(氘)、18O分析,查明了浑河与地下水之间的水力联系,确定了河水对地下水的补给宽度,定量计算了河水对沿岸地下水的贡献比例。从浑河的上游至下游,河水对地下水的贡献比例由大变小,平均约为50%;河水对地下水强补给带位于浑河以南约1 km的范围内,二者的水力联系密切。     

Assessment of groundwater impact on water quality in the built-up areas at the Lower Don

The impact is assessed that the groundwater flow from the built-up areas on the left bank of the Don River in the Rostov oblast produces on the chemical composition and quality of surface water in the lower river reaches. It is demonstrated that the total average annual groundwater flow from the built-up areas on the left river bank is very small and equals 0.002 km3/year on average or 0.01% of the average annual water flow in the estuarine outlet. Despite the rather high degree of contamination of groundwater and the high content of principal ions, this causes the insignificant impact of groundwater runoff on water quality in the Lower Don. The average total mass of substances that annually come from the left-bank urbanized areas in the groundwater flow is about 4.9 x 10³ t or 0.04% of total mass of substances transported by the Don River to the Taganrog Bay.     

城市污水地下回灌的试验研究

研究了应用SBR中试系统处理后的城市污水的深度处理工艺,并以地下回灌为目的,通过2个模拟土壤柱对比,分析了渗滤速度对地下回灌的影响,并讨论了土壤对氨氮的处理效果和在土壤中氮的迁移与转化。     

Annual drought flow and groundwater storage trends in the eastern half of the United States during the past two-third century

Low flow drainage from a river system, in the absence of precipitation or snowmelt, derives directly from the water stored in the upstream aquifers in the basin; therefore, observations of the trends of the annual lowest flows can serve to deduce quantitative estimates of the evolution of the basin-scale groundwater storage over the period of the streamflow record. Application of this method has allowed for the first time to determine the magnitudes of the trends in groundwater storage over the past two-third century in some 41 large prototypical basins in the United States east of the Rocky Mountains. It was found that during the period 1940–2007 groundwater storage has generally been increasing in most areas; these positive trends were especially pronounced in the Ohio and Upper Mississippi Water Resources Regions, but they were weaker in most other regions. Notable exceptions are the northern New England and especially the South Atlantic-Gulf regions, which saw prolonged declines in groundwater levels over this nearly 70-year long period. These observed long-term trends are generally in agreement with previous studies regarding trends of other components of the water cycle, such as precipitation, total runoff, and terrestrial evaporation. Over the most recent 20 years, from 1988 through 2007, except for the Ohio and the Souris-Red-Rainy regions, most regions have experienced declining average groundwater levels to varying degrees, with maximal values of the order of ?0.2 mm a^?1.     

Incorporating groundwater dynamics and surface/subsurface runoff mechanisms in regional climate modeling over river basins in China

To improve the capability of numerical modeling of climate-groundwater interactions, a groundwater component and new surface/subsurface runoff schemes were incorporated into the regional climate model RegCM3, renamed RegCM3_Hydro. 20－year simulations from both models were used to investigate the effects of groundwater dynamics and surface/subsurface runoff parameterizations on regional climate over seven river basins in China. A comparison of results shows that RegCM3_Hydro reduced the positive biases of annual and summer (June, July, August) precipitation over six river basins, while it slightly increased the bias over the Huaihe River Basin in eastern China. RegCM3_Hydro also reduced the cold bias of surface air temperature from RegCM3 across years, especially for the Haihe and the Huaihe river basins, with significant bias reductions of 0.80C and 0.88C, respectively. The spatial distribution and seasonal variations of water table depth were also well captured. With the new surface and subsurface runoff schemes, RegCM3_Hydro increased annual surface runoff by 0.11－0.62 mm d－1 over the seven basins. Though previous studies found that incorporating a groundwater component tends to increase soil moisture due to the consideration of upward groundwater recharge, our present work shows that the modified runoff schemes cause less infiltration, which outweigh the recharge from groundwater and result in drier soil, and consequently cause less latent heat and more sensible heat over most of the basins.     

人为扰动对陆面水分能量的影响——以沩水河流域为例

以沩水河流域为例,基于陆面模式CLM4.5,建立了综合考虑作物种植、地下水开采及灌溉等人类活动的流域陆面水文模型。利用所发展模型,针对1981~2012年,取500 m空间分辨率,探讨人为扰动对陆面过程的影响。研究表明:1）地下水侧向流使得中下游地区地下水位有所提高,平原地下水埋深分布在4 m左右,山区埋深可达到几十米;模拟的叶面积指数较静态MODIS叶面积指数偏大1左右,由此使得种植区月蒸腾量提高约10 mm,土壤蒸发和地表产流有所减少;在灌溉作用下,作物叶面积指数略增长,蒸散发稍有提高,而在假设水稻采用漫灌的情况下,水库灌溉补偿了作物生长产生的水消耗,提高了该区域土壤湿度,增加潜热通量;研究区地下水开采存在但其水文效应并不显著。2）土地覆盖变化自1990年有较大变动,1990~2000年以林地为主,2000年后以耕地为主,其中,1990~2000年土地覆盖类型变化不明显,2001~2012年耕地面积呈先减少再增加又减少的趋势,林地面积则先增加再减少又增加,耕地与林地在2012年所占比例基本持平;同一土地类型内,植被类型变化较为明显,导致陆面水文模拟结果差异较大。     

Comment on “short‐wave radiation balance in an urban aerosol layer”: Correspondence

Abstract

Long‐term observations of the water balance elements were carried out in the Izhora plateau located in northwest Russia. As a result of these investigations, the average recharge of the Leningrad artesian basin located south of the plateau was calculated. The infiltration to the karstic groundwater table was determined on the basis of groundwater fluctuations in the observations wells.     

黑河下游额济纳旗生态环境对调水的响应

利用额济纳旗水文监测资料、额济纳旗气象局1961—2007年地面气象观测资料、额济纳旗水务局2000—2009年地下水位和下泄水量和额济纳旗2002—2009年生态监测资料,结合实地调查,分析了黑河调水动态变化对下游地下水埋深、绿洲植被变化及东居延海水域面积的影响。结果表明:黑河调水后,下游下泄水量逐年增加,额济纳绿洲地下水位埋深逐年回升,东、西居延海恢复一定的水域面积,并且东居延海连续5年不干涸,绿洲面积有所增加,生态环境恶化及时得到遏制,缓解了下游水资源紧缺的状况,使得下游地区生态环境得到了初步改善,总体调水效果明显。     

Nitrate in groundwater of China: Sources and driving forces

Identifying the sources of reactive nitrogen (N) and quantifying their contributions to groundwater nitrate concentrations are critical to understanding the dynamics of groundwater nitrate contamination. Here we assessed groundwater nitrate contamination in China using literature analysis and N balance calculation in coupled human and natural systems. The source appointment via N balance was well validated by field data via literature analysis. Nitrate was detected in 96% of groundwater samples based on a common detection threshold of 0.2 mg N L^?1, and 28% of groundwater samples exceeded WHO's maximum contaminant level (10 mg N L^?1). Groundwater nitrate concentrations were the highest beneath industrial land (median: 34.6 mg N L^?1), followed by urban land (10.2 mg N L^?1), cropland (4.8 mg N L^?1), and rural human settlement (4.0 mg N L^?1), with the lowest found beneath natural land (0.8 mg N L^?1). During the period 1980–2008, total reactive N leakage to groundwater increased about 1.5 times, from 2.0 to 5.0 Tg N year^?1, in China. Despite that the contribution of cropland to the total amount of reactive N leakage to groundwater was reduced from 50 to 40% during the past three decades, cropland still was the single largest source, while the contribution from landfill rapidly increased from 10 to 34%. High reactive N leakage mainly occurred in relatively developed agricultural or urbanized regions with a large population. The amount of reactive N leakage to groundwater was mainly driven by anthropogenic factors (population, gross domestic product, urbanization rate and land use type). We constructed a high resolution map of reactive N source appointment and this could be the basis for future modeling of groundwater nitrate dynamics and for policy development on mitigation of groundwater contamination.     

Satellite evidence on the trade-offs of the food-water–air quality nexus over the breadbasket of India

Access to food, water, and good air quality is indispensable for human life, as reflected in various United Nations Sustainable Development Goals (SDGs); however, pursuing food security may pose threats to water security and/or air quality. An important case is northwest India including the Punjab and Haryana states, which is the ‘breadbasket’ of India with a significantly increasing paddy rice area. The rapid expansion of rice farming has stressed groundwater resources and impacted air quality. Satellite observations have the potential to provide data for better decisions on food security, water storage, and air pollution, which would be vital for regional sustainable development. Based on observations from multiple satellites from 2001 to 2018, we found that paddy rice expansion (+22%) increased groundwater depletion (−1.50 cm/yr), residue burning (+500%), and air pollution (+29%, PM_2.5) in the breadbasket of India. Moreover, satellite observations showed changes in these interactions after the enactment of a groundwater protection policy in 2009, which decelerated groundwater depletion (−1.20 cm/yr) due to delayed rice planting and harvest dates (∼15d); the latter elevated air pollution in November (+29%, PM_2.5). Our finding stresses the need to reconcile the trade-offs and consider the interactions among SDGs 2 (food), 3 (good health), 6 (clean water), and 11 (air quality in cities), in policy-making for sustainable development. An efficient crop residue ultilization and management system, bottom-up groundwater use regulations, and cropping system shift towards less water-consuming crops are critically required to resolve the trade-offs of the food-water–air quality nexus in the northern India. Our study also showcases remote sensing approaches and methods to support and aid the achievement of the SDGs and track their progreses to support regional sustainable development.