井水位下降采取的灌水技术措施

井灌工程是平原农业区抗御干旱灾害的重要水利设施。近几年来气候连续干旱,普遍分布的地下潜水得不到大气降水的入渗补给,又加上抗御干旱大量开采地下潜水,致使潜水位连年下降,在地势稍高处水位埋深已接近离心式水泵的有效吸程,造成离心泵抽水时出水量不足,灌水时间延长,灌水成本提高。 在非故河道分布段广泛采用的塑管真空井、因井来水量减少而报废;在沿地下水强泄水带的河流两岸因井水位太深离心泵不能利用,只得更换为潜水电泵后,才能正常使用。 造成井水位下降的根本原因是地下水资源失衡问题,在治水战略上必须采取补源措施。解决补源的途径有三条:其一是地域性调水;其二对地表水体实行截、拦、蓄工程措施,增加地表水源灌溉用水量,碱少地下水开采     

焉耆盆地地下水合理开采量研究

针对焉耆盆地大量引用地表水灌溉,造成地下水水位大面积上升,引发严重土壤盐碱化的现实状况,设计了5种增加地下水开采量、减少地表水引水量的方案,并运用数值模拟模型对各方案进行模拟和预测。焉耆盆地合理地下生态水位上限是防止地表土壤盐碱化的地下水水位,埋深为3.2 m;下限是防止地表植被退化的水位,埋深为4.5 m。根据不同开采方案的模型预测结果,结合地下水生态水位,并考虑地表水、地下水的转化关系,确定焉耆盆地不引起地表生态环境退化的地下水可持续开采量为3.8亿m3/a。     

西安市黑河引水灌区续建配套工程运行后灌区地下水位及土壤次生盐渍化分析

通过对引水灌区水文地质条件的调查及地下水水位变化的分析预测,论述了黑河引水灌区在引水灌溉后,灌区地下潜水位的变化及土壤次生盐渍化.     

灌溉变化对华北平原地下水可持续利用的影响

针对华北平原地下水可持续利用问题,利用校准好的分布式水文MIKE SHE模型,考虑灌溉变化对地下水利用的影响,设定3种情景（现状保持型情景MS1、灌溉水量改变情景MS2和灌溉频率改变情景MS3）对华北平原未来20 a地下水利用进行预测。结果表明：(1)3种情景下华北平原未来20 a地下水水位均呈下降趋势,MS1、MS2和MS3下地下水水位年均降幅分别为0.335～1.648、0.298～1.588和0.303～1.607 m/a,东部沿海和京津地区出现了较严重的地下水降落漏斗问题,灌溉变化对地下水降落漏斗缓解效果并不显著。(2)灌溉变化在一定程度上能促进华北平原地下水水位和含水层储量恢复,且减少灌溉频率的作用大于降低灌溉水量的作用;相对于MS1, MS2和MS3可使含水层储量在20 a后分别恢复0.06 m和0.12 m。(3)采用灌溉变化无法彻底解决华北平原地下水水位和含水层持续消耗问题,须与其它措施结合,才能从长远角度保证华北平原地下水可持续利用。研究成果可为水资源规划与管理提供科学的依据和建议。     

变化环境对华北平原地下水可持续利用的影响研究

针对华北平原地下水利用中存在的问题,采用分布式水文MIKE SHE模型,考虑人类活动（农业节水措施和南水北调工程）和气候变化等变化环境的影响,通过设定4大类情景（每类情景中均设定了3类气候变化子情景）模拟了2019-2028年华北平原地下水的利用状况。结果表明：农业节水措施和南水北调工程等人类活动对华北平原地下水水位、水均衡和含水层储量有较大的影响;相对于现状保持型情景(SQM),模拟期末(2028年12月31日)农业节水型情景(AWS)、南水北调工程供水型情景(SNWDP)和综合利用型情景(CU)下华北平原饱和含水层储量分别增加0.168、0.558和1.433 m;气候变化对华北平原地下水的影响量级与人类活动的影响相当,且地下水水位、水均衡和含水层储量变化的方向和大小均与未来气候条件的干湿程度呈正相关关系,到模拟期末,相对于现状保持型情景(SQM),湿润、正常和干旱的气候情景下华北平原饱和含水层储量分别为增加0.972~2.239 m、增加0.119~1.540 m和减少0.372~0.940 m;只有综合考虑各种引水和节水措施,多管齐下,才能保证华北平原地下水的可持续利用。     

衡水湖水位变化特征及其影响因素分析

利用衡水湖1994—2017年间的水位资料,采用滑动平均法和Mann-Kendall法分析衡水湖水位年际变化特征;计算以月为单位的平均水位,分析衡水湖水位年内变化特征;采用Pearson相关分析法和累积距平法分析各因素与水位变化之间的相关关系;绘制月水位与降水量(蒸发量)、引水量(工业用水量)的折线图,分析各因素对年内水位的影响。结果表明,衡水湖年际水位变化表现为波浪式上升趋势,上升速率为0.077 m/a;月平均水位从年初至年末表现为明显的下降趋势,2—7月下降速率为0.139 m/月;年水位变化受蒸发量影响显著,受降水量的影响较弱,与引水量的相关性最弱。     

人类活动对乌伦古湖环境演化的影响

基于水量平衡方程,通过水位还原计算,反演了乌伦古湖天然情形下的水位变化,大致区分出人类活动对湖水位变化的贡献约为70.01%;结合湖泊盐量平衡方程,反演了乌伦古湖1960年以来的矿化度变化,初步推断出湖区流域范围内农业灌溉引水量增加是造成入湖淡水补给量减少、湖水咸化加速的主要原因.     

基于SDSM模型的博斯腾湖流域水资源变化模拟

全球气候变暖对陆地水循环会产生重大影响,统计降尺度方法是解决大尺度气候信息和小尺度水文响应的空间尺度不匹配问题的有效方法之一。文章采用SPEI指数与SDSM(Statistical Down-Scaling Model)方法,进行流域气候变化特征量的降尺度研究。结果表明:近50 a来,塔里木河流域SPEI指数呈显著上升趋势并在1986年发生突变;博斯腾湖水位变化与流域SPEI指数变化具有一致性,湖水位在1955—1986年以下降为主,1987—2002年以上升为主;SDSM模型的气温模拟能力较好,对日降水的模拟值偏小,未来日均、日最高气温在A2、B2两种情景下均呈上升趋势,日最低气温在B2情景下呈下降趋势;2种情景下的年降水量在2020年和2030年均呈下降趋势;在A2情景下,开都河出山口日径流量呈下降趋势;在B2情景下,日径流量在2010年时段呈增加趋势,在2020年和2030年呈持续下降趋势。     

未来气候变化影响下的流域面源污染负荷特征响应评估

针对流域面源污染负荷在未来气候变化影响下的变化特征,以我国新安江上游率水流域为例,使用通用流域污染负荷模型(GWLF),对其2000-2013年的水量及总氮、总磷面源污染负荷通量进行了模拟,并解析了其负荷来源分配。在此基础上,基于政府间气候变化专业委员会(IPCC)的气候变化评估报告结果,利用GWLF模型分析了到21世纪20年代、50年代、80年代在A1FI(最高排放)和B1(最低排放)情景下,率水流域的水文及总氮、总磷面源污染负荷特征变化。结果表明:未来气候变化对流域水文及面源污染负荷特征均有一定影响。年水资源量先减少后增加,地表径流量和蒸发量逐渐上升而地下水量逐渐下降。到2080s,A1FI情景比B1情景有更多的水资源量。年总氮通量先增加后减少,在2050s最高,而年总磷通量则逐渐增加,且两种污染物均在A1FI排放情景下有更高的污染负荷量,表明人类温室气体的排放会潜在地增加流域水体面源污染负荷。     

乌龙坝截潜灌溉工程设计

本文介绍的是以地下工程截取矿井洗煤排水形成的河道地表径流,过滤后进行引水灌溉的工程实例。通过在河道下设置的截潜工程和埋设在地下的网笼及输水管路,成功地将地表径流引入河畔的蓄水方塘内,进行引水灌溉,本文为此类工程的结构型式提供了一种新的思路。     

降水补给地下水过程中包气带变化对入渗的影响

采用野外试验和室内试验方法，通过对不同降水量的入渗过程中岩土含水率和水势变化规律分析，发现入渗水流在包气带内下渗过程的岩土吸水、过水(即水分通量不变、且不等于零)和脱水的不同阶段，当岩土水势的梯度分别大于、等于和小于1cmH2O/cm(厘米水柱/厘米)时，岩土含水率分别表现为增加、稳定和减少。对包气带不同埋深的岩土含水率和水势变化特征分析表明，随着地下水位不断下降，包气带增厚对降水入渗补给地下水的影响程度和方式都发生改变。当包气带厚度小于潜水蒸发极限深度时，包气带的增厚使得岩土水分亏缺累积量增大，导致入渗速率和地下水获取的总入渗补给量减小；当包气带厚度大于潜水蒸发极限深度时，随着包气带厚度增大，入渗速率趋于稳定，无限时间内地下水获取的总入渗补给量不因包气带增厚而变化，但是有限时间内地下水获取的入渗补给量趋小。这是因为入渗途径的延长导致入渗所需时间增加，以至在有限时间内包气带内过剩的入渗水分尚未充分排出补给地下水。     

基于降雨空间变异的潜水运动随机模拟方法Ⅰ——非条件模拟

将降雨视为随机场，考虑降雨入渗补给量与地下水埋深的关系，采用二维稳定-非稳定潜水运动的KLPC模型，分析了降雨的空间变异性对水头均值、方差和协方差的影响，利用变异系数描述了水头、流速和水动力弥散系数的变异程度。结果表明，KLPC算法的随机模型具有优越的计算效率；水头方差随降雨场方差和相关长度的增大而增大；在降雨空间变异的条件下，水头随机场呈现出明显的非平稳特性且具有各向异性结构；在非稳定流中，水头协方差表现出“扩散”和“平移”的特性；水头的变异程度较小，在随机模拟中可以不考虑降雨空间变异对地下水流动的影响；但水头的变异导致了流速和水动力弥散系数强烈的变异性，在溶质运移的随机分析中需要予以充分重视。     

Trends in the Lake Superior Water Budget Since 1948: A Weakening Seasonal Cycle

An analysis of Lake Superior water levels from 1948–1999 reveals that the seasonal cycle has decreased in amplitude by 20% (from 40 cm to 32 cm). This change is manifested as a downward trend in summer and autumn lake levels (when levels are typically highest) accompanied by roughly no change in winter and spring lake levels (and an overall 4-cm drop in annual mean levels). The decreased rates of seasonal rise and fall in lake level over the 51-year interval reflect a large decrease in the net monthly influx of water during the late spring (up to –1,360 m³/s) coupled with a nearly compensating increase in net influx during late autumn (up to +1,100 m³/s). Analysis of the Lake Superior water budget indicates that these changes are primarily the result of trends in runoff and over-lake precipitation. A systematic decrease in outflow through the St. Marys River is also evident during July-December (in association with the lower lake levels), as well as a moderate shift in the seasonal pattern of lake evaporation (but not the annual mean). The observed water budget trends are primarily related to variations in climate, rather than lake regulation. Land surface effects are also important, as suggested by a 20% increase in annual mean evapotranspiration during the 51-year interval and large changes in monthly storage (e.g., snowmelt, groundwater, etc.). Significant uncertainties are present in the calculated water budget, and it is suggested that a likely source of error is in measured precipitation and (especially) runoff.     

北三河流域水资源供需平衡对降水变化的敏感性

分析不同区域水资源供需平衡对降水变化的敏感性,并结合考虑云水资源和降水效率的空间分布,有助于常态化人工增雨作业地点的确定,对实现空陆水资源的统筹利用具有重要意义。以北三河流域为研究区域,基于新安江模型和彭曼-蒙特斯公式分析了研究区需水量对降水变化的响应,并探讨了不同计算单元水资源供需平衡对降水变化的敏感性。结果表明:当降水量增加时,流域平水年产水量增加的比例大于枯水年与特枯年,农田灌溉需水量随降水量的增加大致呈线性减小趋势;在不考虑外调水和地下水超采的情况下,自然降水情景的流域资源性缺水量分别为35.46亿m3（降水频率p=50%）、43.17亿m3（p=75%）和46.30亿m3（p=95%）,缺水峰值分别出现在5月、7月和8月;各单元缺水量对降水变化的敏感性主要由产水变化主导,空间上呈由北向南逐渐递减的趋势,当平水年降水量增加20%时,北部地区缺水量相对减少率达到150%以上,中部介于30%~50%,南部则小于15%。     

气候变化对灌区农业需水量的影响研究

气候变暖不仅影响水资源量及其时空分布的变化,而且也会使农作物蒸发蒸腾量增加,从而加剧农业水资源供需矛盾。因此,研究气候变化对农业需水量的影响对保障农业用水安全具有重要的意义。本文利用陕西省宝鸡峡灌区11个气象站28 a的气象资料,分析了灌区气候变化特征;计算了主要作物需水量和农田灌溉需水量;利用单因素敏感性分析法研究了气候变化对农业需水量的影响。研究结果表明:灌区年平均气温显著上升,降水量持续下降,蒸发量明显增大,大部分地区相对湿度和风速显著下降,而日照时数有所增加;冬小麦、玉米、棉花和油菜生育期需水量明显增加;各气候因素对农田灌溉需水量影响顺序为:降水量>相对湿度>最高气温>日照时数>平均气温>风速,气温的上升、相对湿度的下降、降水量的减少以及日照时数的增大使作物需水量明显增大,而灌溉面积减小使农业需水量有减少的趋势。     

Impacts of Receding of the Lakes Located in the Arid and Semi-arid Areas on the Coastal Groundwater: Integrated Modeling and Experimental Study

The dropping of the water level of the lakes located in the arid lands leads to salt concentration increase. In this study, a combined experimental-computational method is developed to explore the effect of seawater concentration on the elevation of groundwater table and the rate of saltwater intrusion, while the lake water level is dropping. At the laboratory tank scale, we have collected experimental data by varying the saltwater concentration by 2.0 and 2.5 times its initial value while measuring the height of the groundwater table. Our simulation has shown an unexpected increase in height of groundwater by 5.0 and 13.0% relative to the head difference at the boundaries of the domain. Also, the intrusion rate of saltwater wedge increased by 2.0 and 3.0 times, respectively. We have used the verified model for a field state and found that if density variations are neglected in simulation, the calculated groundwater level is affected more than 2 times in response to fluctuation of lake water level (relative to simulations by including the effect of fluid density changes). Based on the results density variations can counteract; even reverse, the effect of water table changes. Remarkably, our simulations have shown that despite a severe decrease in the water level of a saline lake over time, the saltwater wedge has indeed intruded further because of the substantial increase in the density of the lake water due to the rising salinity. Based on the findings, to reach a reasonable result in the study of interaction between saline water of shrinking lakes with coastal groundwater, saltwater concentration as well as saline water density in the modeling must be considered.

     

Impacts of Climate Change on Water Resources Availability and Agricultural Water Demand in the West Bank

Global climate change is predicted as a result of increased concentrations of greenhouse gasses in the atmosphere. It is predicted that climate change will result in increasing temperature by 2 to 6°C and a possible reduction of precipitation of up to 16% in the Mediterranean basin. In this study, the West Bank is taken as a case study from the Mediterranean basin to evaluate the effects of such climate change on water resources availability and agricultural water demands. Due to the uncertainty in climate change impacts on temperature and precipitation, a number of scenarios for these impacts were assumed within the range of predicted changes. For temperature, three scenarios of 2, 4 and 6°C increase were assumed. For precipitation, two scenarios of no change and 16% precipitation reduction were assumed. Based on these scenarios, monthly evapotranspiration and monthly precipitation excess depths were estimated at seven weather stations distributed over the different climatic and geographical areas of the West Bank. GIS spatial analyses showed that the increase in temperature predicted by climate change could potentially increase agricultural water demands by up to 17% and could also result in reducing annual groundwater recharge by up to 21% of existing values. However, the effects of reduced precipitation resulting from climate change are more enormous as a 16% reduction in precipitation could result in reducing annual groundwater recharge in the West Bank by about 30% of existing value. When this effect is combined with a 6°C increase in temperature, the reduction in groundwater recharge could reach 50%.     

Combined Assessment of Climate Change and Socio-Economic Development as Drivers of Freshwater Availability in the South of Portugal

A combined assessment of the potential impacts from climate change (CC) and socio-economic development (SED) on water resources is presented for the most important aquifer in the south of Portugal. The goal is to understand how CC and SED affect the currently large pressures from water consuming and contaminating activities, predominantly agriculture. Short-term (2020–2050) and long-term (2070–2100) CC scenarios were developed and used to build aquifer recharge and crop water demand scenarios, using different methods to account for uncertainty. SED scenarios were developed using bottom-up and top-down methods, and discussed at workshops with farmers and institutional stakeholders in the water sector. Groundwater use was quantified for each scenario. Together with the recharge scenarios, these were run through a calibrated groundwater flow model, to study their individual and joint impacts on groundwater levels and discharge rates into a coastal estuary. Recharge scenarios show clear negative long-term trends and short-term increase in temporal variability of recharge, though short-term model uncertainties are higher. SED scenario 1 (SED1), predicting intensification and decline of small farms, considered the most likely by all workshop participants, shows a large drop in agricultural area and water demand. SED2, a most desired scenario by farmers, foresees growth and modernization of agriculture, but proves unsustainable in combination with predicted CC without efficient adaptation measures. The results thus reveal that CC in the region will dynamically interact with economic factors, and going one step beyond, CC could be directly integrated as a constraint in the development of SED scenarios. Exercises involving the integration of CC and SED regionally based scenarios, constructed in both bottom-up and top- down fashion and discussed in participatory contexts are still rarely used for adaptation, and specifically adaptation of agriculture to water scarcity. The joint analysis of CC and SED revealed challenging, as it involved the use of different methods across the border between natural and social sciences. In our view this method contributes in an encouraging manner to a more holistic and transdisciplinary water management, by allowing a more plausible identification of what (and if) adaptation measures are needed.     

A Holistic System Approach to Understanding Underground Water Dynamics in the Loess Tableland: A Case Study of the Dongzhi Loess Tableland in Northwest China

The Loess Plateau in northwest China is one of the most water-scarce areas on Earth. In the loess tableland (LT), the underground water system is the most critical component of terrestrial ecology and the local economy. In this study, a new approach was developed to holistically simulate monthly and yearly underground hydrology in the LT, including the soil water reservoir (SWR) and the groundwater reservoir (GWR). The approach was applied to the Dongzhi Loess Tableland (DLT) to simulate SWR and GWR from 1981 to 2010 to capture the underground water dynamics. The results suggest a strong monthly variability of the SWR, with most time of a year having higher evapotranspiration than the precipitation infiltration, leading to a soil water deficit. The rainy season is the primary period for deep zone recharge, and the water balance of the GWR is generally positive from July to October and negative from November to the following June. In the DLT, The decrease in vertical recharge and increase in human extraction have led to a total groundwater level drawdown of 15.7 m and considerable spring attenuation with an annual ratio of 1.19 % over the past 30 years. If ground water withdraw rate remains the same as since 1981, the GWR will be depleted within approximately 100 years.     

唐山丰南区地下水丰枯季埋深空间变异性分析

探究丰南区丰枯季地下水埋深空间变异规律,为地下水资源管理和调度提供指导。本文基于2001年和2014年丰枯季地下水埋深实测数据,运用地统计学方法,结合GS+和GIS软件,分析了淡水区潜水和咸水区承压水丰枯季地下水埋深的空间变异规律。结果表明：淡水区和咸水区丰枯季地下水埋深空间变化范围较大,丰枯季最大埋深差距明显,最小埋深差异不大,14年间埋深呈增加趋势,其中淡水区和咸水区枯季的最大埋深分别增加23.82 m和36.82 m。不同时期地下水埋深具有中等空间变异强度,空间变异结构可用球状模型进行描述,空间相关距离随年份呈减小趋势;空间分布趋势呈现出南深北浅,带状分布规律;随着人类活动增加,地下水开采量增大引起的采补失衡愈发明显,造成地下水埋深不断增大,补给修复效应减弱,人类可利用地下水的埋深段持续下移。通过研究探明丰南区地下水埋深丰枯季变化规律,可在压采稳产目标下,为地下水开采利用上的优化调控和作物种植结构的优化调整提供理论依据。