Three-Dimensional Tidal Model and Its Application to Numerical Simulation of Water Quality in Coastal Waters

The turbulence mechanism plays an important part in the mixing process and momentum transfer of turbulence. A three-dimensional Prandtl mixing length tidal model has been developed to simulate tidal flows and water quality. The eddy viscosities and diffusivities are computed from the Prandtl mixing length model. In order to model the water quality of an estuary or coastal area many interdependent processes need to be simulated. These may be conveniently separated into three main groups: transport and mixing processes, biochemical interaction of water quality variables and the utilization and re-cycling of nutrients by living matter. The model simulates full oxygen and nutrient balance, primary productivity and the transport, reaction mechanism and fate of pollutants over tidal time-scales. The model is applied to numerical simulation of tidal flows and water quality in Dalian Bay. The model has been calibrated against a limited data set of historical water quality observations and in general demonstrates excellent agreement with all available data.

A Three-Dimensional Water Quality Model and Its Application to Jiaozhou Bay, China

A three-dimensional coupled physical and water quality model was developed and applied to the Jiaozhou Bay to study water quality involving nutrients, biochemical oxygen demand, dissolved oxygen, and phytoplankton that are closely related to eutrophication process. The physical model is a modified ECOM-si version with inclusion of flooding/draining processes over the intertidal zone. The water quality model is based on WASP5 which quantifies processes governing internal nutrients cycling, dissolved oxygen balance and phytoplankton growth. The model was used to simulate the spatial distribution and the temporal variation of water quality in the Jiaozhou Bay for the period of May 2005 to May 2006. In addition, the effect of reduction of riverine nutrients load was simulated and evaluated. The simulated results show that under the influence of nutrients discharged from river, the concentrations of nutrients and phytoplankton were higher in the northwest and northeast of the bay, and decreased from the inner bay to the outer. Affected by strong tidal mixing, the concentrations of all state variables were vertically homogeneous except in the deeper regions where a small gradient was found. Obvious seasonal variation of phytoplankton biomass was found, which exhibited two peaks in March and July, respectively. The variation of riverine waste loads had remarkable impact on nutrients concentration in coastal areas, but slightly altered the distribution in the center of the bay.

Three-dimensional physical simulation and optimization of water injection of a multi-well fractured-vuggy unit

With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.

Three-Dimensional Water-Quality Simulation for River Based on VOF Method

In the present study, considering the transport and transformation processes of variables, a threedimensional water quality model for the river system was established, which coupled the volume of fluid(VOF) method with the k-ε turbulence mathematical model. Then, the water hydrodynamic characteristics and transport processes for BOD_5, NH_(3^-)N and TP were analyzed. The results showed that the water surface of convex bank was a little lower than that of concave bank due to the centrifugal force near the bend, and most concentrations were inferior to the type Ⅴ standard indexes of surface water environmental quality. The model validation indicated that the errors between the simulated and monitored values were comparatively small, satisfying the application demands and providing scientific basis and decision support for the restoration and protection of water quality.

The 3D simulation and optimized management model of groundwater systems based on eco-environmental water demand

Through the study of mutual process between groundwater systems and eco-environmental water demand, the eco-environmental water demand is brought into groundwater systems model as the important water consumption item and unification of groundwater抯 economic, environmental and ecological functions were taken into account. Based on eco-environmental water demand at Da抋n in Jilin province, a three-dimensional simulation and optimized management model of groundwater systems was established. All water balance components of groundwater systems in 1998 and 1999 were simulated with this model and the best optimal exploitation scheme of groundwater systems in 2000 was determined, so that groundwater resource was efficiently utilized and good economic, ecologic and social benefits were obtained.

Water resource utilization characteristics and driving factors in the Hainan Island

The scarcity of water resources caused by the unique topography and uneven rainfall distribution in Hainan Island has become a major factor restricting local development. In order to provide effective and scientific reference basis for the overall water resource utilization status and solving this problem, this study calculated the water resource utilization situation of Hainan Island from 2017 to 2021 in detail using methods including water resource ecological footprint analysis. Furthermore, a spatial correlation analysis was conducted to examine the island's water resource utilization characteristics, and the driving factors behind the changes in water resource utilization over the past five years were analyzed using the LMDI model. The results show that:(1) During the study period, the water resource ecological footprint in Hainan Island exhibited a slow growth trend, while the ecological carrying capacity showed a downward tendency.The per capita ecological deficit of water resources remains relatively high, and the water consumption per 10 000 yuan GDP in the whole land continues to decrease, indicating that the overall pressure on water resource demand remains high with significant regional differences accompanied by the efficiency of water resource utilization steadily improving at the same time;(2) Agricultural water use accounts for the highest proportion in the entire water use structure, while ecological water use represents the smallest share, with a year-on-year increase, indicating that Hainan Island highlights the agricultural development and is increasingly conscious of the ecological environment;(3) Significant spatial differentiation in water resource utilization characteristics exists in Hainan Island, with the western region being a hot spot aggregation area for per capita water resource ecological footprint, per capita ecological carrying capacity of water resources, water consumption per 10 000 yuan GDP, while it is a cold spot cluster area for per capita ecological deficit of water resources. The opposite holds true for the eastern region of Hainan Island;(4) Economic and technological factors have a major impact on the changes in water resource ecological footprint within the designated area. Among them, economic factors drive the growth of the water resource ecological footprint in Hainan Island, and exacerbate local water resource consumption, while technological factors negatively contribute to the amount of water resource utilization in Hainan Island, indicating that advanced technology has improved water resource utilization efficiency and significantly reduced water resource consumption.

基于BP-DEMATEL的山西省冬小麦水足迹影响因素识别

针对山西省冬小麦水足迹历史演变及关键影响因素识别问题,分析了1993—2021年山西省冬小麦水足迹历史演变规律,利用BP神经网络-决策实验室(BP-DEMATEL)模型对冬小麦水足迹演变的关键影响因素进行识别,将其分为驱动型因素及特征型因素,并揭示了影响因素之间的作用机制。结果表明:1993—2021年山西省冬小麦水足迹及单位水足迹均呈下降趋势;2021年山西省冬小麦总水足迹为27亿m^(3)(蓝水占比57%),单位水足迹为1 122 m^(3)/t,与前期高点相比分别下降38%(较1994年)和21%(较1993年);气温、相对湿度和灌溉面积为冬小麦水足迹演变的关键驱动型因素,化肥施用量和农业机械总动力为关键特征型因素。

基于LMDI模型的湖北省农业水足迹时空分布与驱动力研究

结合水足迹理论和传统农业用水核算方法,分析2005—2020年湖北省各市州农业水足迹时空演变特征,并利用LMDI模型对农业水足迹变化量进行驱动力因素分解。结果表明:1)湖北省农业水足迹呈现先上升再下降的波动趋势;湖北省各市州农业水足迹存在明显的时空分布差异,这是自然因素和经济因素共同作用的结果。2)各驱动力对湖北省农业水足迹变化的影响程度为经济效应>技术效应>人口效应,经济效应对农业水足迹变化量的贡献值,达53.72%,技术效应和人口效应的贡献值分别为32.86%和13.42%;其中,经济效应对农业水足迹起正向驱动作用,技术效应和人口效应对农业水足迹起到反向驱动的作用。研究结论拓展了长江流域农业水足迹及驱动力分析,同时对于提高农业可持续发展、增加农业用水效率有指导意义。

长江流域水资源利用效率及影响因素研究--基于Shephard水资源距离函数

分析长江流域水资源利用效率、时空分布特征及影响因素,对于解决长江流域水资源问题和促进长江经济带发展至关重要。为科学评价长江流域水资源利用效率及空间分布差异,以2012—2020年长江流域11个省(市、自治区)为研究对象,构建Shephard水资源距离函数的随机前沿模型,对长江流域水资源利用效率及影响因素进行实证分析并探究长江流域水资源利用效率时空分异特征。研究表明:1)通过计算水足迹发现,长江流域各省水足迹消费总量趋于稳定,上游省份用水量较少,中下游省份水资源消费量较大,省际水足迹总量差异显著,农业生产是水足迹主要的来源,其次是工业用水;2)运用Shephard水资源距离函数的随机前沿模型计算长江流域水资源利用效率发现,省与省之间差异显著,空间上呈现“中游低,上下游高”的特征,并有逐年降低的趋势;2012—2020年上游省份水资源利用效率自西向东递减,中下游省份水资源利用效率在低水平上保持稳定并有降低趋势;3)选取的影响因素指标系数均通过了显著性检验,水资源禀赋的系数显著为负,表明人均水资源拥有量提高对长江流域水资源利用效率有正向促进作用;经济发展水平的系数显著为负,表明经济发展对水资源效率提升有推动作用;城镇化率的系数显著为负,表明城镇化水平越高,水资源的利用效率高,但影响程度较低;而第三产业占GDP的比重的系数显著为正,表明产业结构调整对水资源利用效率起抑制性作用。最后针对研究结果,提出以下对策建议:建立跨部门协调机制,加强水资源管理和监测;推动区域合作,加强信息共享;优化产业结构,促进可持续发展。

基于SD模型的张掖盆地水资源生态足迹核算与预测

根据水资源生态足迹模型,通过构建张掖盆地水资源利用SD模型,设计5类不同情景来核算和预测现状(2000—2020年)和未来(2021—2050年)张掖盆地水资源生态足迹和生态承载力。结果表明:对于现状,人均水资源生态足迹、生态承载力和生态盈亏均值分别为3.517、0.272和-3.245 hm^(2)/人,水资源生态压力指数和生态足迹强度均值分别为12.969和2.822 hm^(2)/104元;农业用水在张掖盆地水资源生态足迹核算中占绝对优势但占比在下降,农业领域是节水的重点且潜能较大;水资源生态足迹强度明显下降(降幅90.21%),证明了张掖盆地用水效率的上升;张掖盆地的水资源利用压力较大。平均而言,预测期内张掖盆地不同情景中人均水资源生态足迹均大于人均水资源生态承载力,由此导致人均水资源生态亏损的出现;各情景下水资源生态压力指数和生态足迹强度均值分别为12.932、13.483、10.055、12.698和9.846及0.281、0.206、0.201、0.281和0.196 hm^(2)/104元,未来时间里张掖盆地的水资源利用仍然处于不安全的状态。2021—2050年张掖盆地无法有效缓解水资源利用紧张的状况,需采用经济发展与水资源保护兼顾的发展方案,推荐政府部门采用情景ZS 5。因此,张掖盆地未来水资源利用需要全社会、各部门的通力合作,不断提高水资源利用效率,大力推进节约用水措施和技术的普及与应用,才能确保水资源的可持续利用。

基于灰水足迹的长江经济带耕地利用生态效率时空分异特征

长江经济带面临水生态环境污染制约下的农业发展困境,水环境约束下耕地利用生态效率的提升成为平衡耕地利用中经济效益与生态效益的关键手段,对于探索生态可持续的耕地利用模式、实现农业绿色发展具有重要意义。该研究以灰水足迹为视角,基于SBM-Undesirable模型、空间自相关分析及马尔可夫链模型探明2000—2020年长江经济带耕地利用生态效率时空格局及演变趋势。研究表明:1)长江经济带2000—2020年平均灰水足迹值呈现先增后减趋势,2015年后下降态势更为明显。在空间上呈现为“东西高,中部低”的空间分布特征,灰水足迹高值区域主要集中在粮食主产区省份。2)2000—2020年长江经济带耕地利用生态效率持续下降,效率均值处于0.5~0.8之间,存在较大提升空间。在空间上呈现高值区域多沿水系分布的特点。3)长江经济带市域耕地利用生态效率存在显著空间正相关性,以研究时段演变趋势来看,耕地利用生态效率的演进存在路径依赖,难以实现“跨越式”提升。因受到邻域背景影响,在空间上易显现出“俱乐部收敛”现象,“高-高集聚”与“低-低集聚”分布更为常见。可在农业生产重点区域采用差异化精准农业模式,需重视区域间动态协同发展,完善联防联治的面源污染防控机制,积极引导耕地利用生态效率高值区域逐步形成集中连片,同时对于耕地利用生态效率低效区提供财政与政策支持。研究结果可为各地区探索耕地利用可持续发展模式与农业生产活动中水生态环境保护提供参考依据。

珠三角区域水资源生态足迹动态分析与预测

水资源的短缺和过度开发制约着大多数地区的可持续发展,为分析水资源可持续利用水平,基于水资源生态足迹法,通过指标计算法(水资源生态经济协调度、水资源可持续利用水平、人均万元GDP水资源生态足迹)动态分析了2010—2022年珠三角区域各地市水资源可持续利用情况,同时构建GM(1,1)灰色预测模型模拟未来10 a该区域人均水资源生态足迹的演变情况,结果表明:从整体趋势来看,2010—2022年各地市人均水资源生态足迹都有所下降,其中下降趋势最明显的为中山市,下降幅度达到了47.01%;从时间变化上看,珠三角区域各地市的水资源承载力出现较大的差异而呈波动变化;肇庆市的水资源经济协调度较差;佛山市的水资源压力较大,处于不可持续水平;各地市的人均万元水资源生态足迹值都随年份呈下降趋势,未来10 a该区域人均水资源生态足迹呈稳定下降趋势。研究成果可为未来该地区水资源可持续利用和缓解生态环境压力提供决策依据。

Simulation of water temperature distribution in Fenhe Reservoir

In order to evaluate the need of controlling the temperature of water discharged from the Fenhe Reservoir, the reservoir water temperature distribution was examined. A three-dimensional mathematical model was used to simulate the in-plane and vertical distribution of water temperature. The parameters of the model were calibrated with field data of the temperature distribution in the Fenhe Reservoir. The simulated temperature of discharged water is consistent with the measured data. The difference in temperature between the discharged water and the natural river channel is less than 3 ℃ under the current operating conditions. This will not significantly impact the environment of downstream areas.

基于水足迹的多目标农业产业结构优化模型研究

为优化农业产业结构,促进产业发展,以江苏省为例,对1990~2021年江苏省农业水量足迹和灰水足迹进行核算,构建了基于水足迹的多目标农业产业结构优化模型,采用SCEUA全局优化算法寻优。结果表明:①1990~2021年江苏省农业水量足迹呈逐年增长态势,灰水足迹则呈先增后降趋势。主要原因是受需求和净利润影响,畜牧渔养殖数量和蔬菜种植面积明显提升,而粮食作物种植面积缓慢下降。②节水型、均衡型和发展型3种情景下的水量足迹较2021年基准值分别削减了25.39%,0.20%和0.86%;灰水足迹较2021年的基准值分别削减了19.69%,0.06%和0.21%;净利润较2021年的基准值分别增长了0.10%,26.28%和21.50%。③江苏省目前的农业产业结构还有一定调整空间,未来产业结构调整的方向主要为稳定粮食生产,稳定农作物播种面积,适度提升蔬菜种植面积,稳定生猪产量并适度降低淡水鱼养殖面积。

水足迹视角下黄河流域经济作物水土资源匹配格局

水土资源的合理匹配有利于将资源优势转变为经济优势,促进区域农业持续发展。基于水足迹视角,运用水土匹配度、重心迁移模型,结合ArcGIS10.2软件,分析了黄河流域8个省(区)(不包括四川省)不同类型经济作物播种面积及其水足迹,探讨了其水土资源时空匹配格局及重心演化情况。结果表明:谷物等5类经济作物播种面积逐渐上升,豆类等6类经济作物播种面积不断下降,油料播种面积保持相对稳定,且上、中、下游地区存在差异,播种面积呈现东高西低的分布格局;谷物等6类经济作物水足迹波动上升,豆类等6类经济作物水足迹波动下降,且上、中、下游存在差异,水足迹总体呈现增大趋势,呈现东部和中部高、西部低的分布格局;经济作物水土匹配度呈增大趋势,呈现中南部高、北部和西部低的匹配格局;水土匹配度重心轨迹呈现由东北向西南移动的趋势。黄河流域8个省(区)应适当调整经济作物种植结构,减少高耗水经济作物种植;推广节水灌溉技术,改善农业生产条件;发展高效节水农业,实施水系连通工程等,以实现水土资源优化配置和高效利用。

黄河流域水资源利用与经济增长脱钩及影响因素分解

水资源是黄河流域生态保护和高质量发展的最大刚性约束,识别流域水资源利用变化驱动因素具有重要意义。首先从结构视角测度黄河流域水足迹变化,进而基于Tapio脱钩模型与Kaya-LMDI分解模型,解析水足迹与经济增长脱钩状态,并从技术效应、结构效应、规模效应、禀赋效应、城市化效应和人口效应识别水资源利用变化驱动因素。研究发现:①黄河流域水足迹总体呈现上升趋势,农业水足迹占比高达85%,用水结构与产业结构倒挂问题突出。②黄河流域上下游水资源量与水足迹空间分布不匹配,中下游面临更严重水资源约束。③水足迹与经济增长关系主要表现为弱脱钩,但2015—2019年各省区开始向强脱钩转变。④规模效应、城市化效应和人口效应对水足迹变化起拉动作用,技术效应、结构效应和禀赋效应对水足迹变化起抑制作用,但仍有提升潜力,各省区影响因素存在一定差异。为此,需要强化水资源利用技术研发与推广,推动农业集约式发展,提升农业用水效率,进一步优化产业结构和新型城镇化建设,缓解水资源约束困境,推动黄河流域经济高质量发展。

基于水—能—粮关联关系的山西省农业种植结构优化调整

优化水、能源资源,调整农作物种植结构,以实现经济效益和生态效益最大化。以山西省为研究区,采用水足迹和能源消耗核算模型分析主要农作物的耗水及耗能特点,以水资源、能源、粮食等作为约束条件构建多目标规划模型,对主要农作物的种植结构进行优化。结果表明,各类农作物多年平均单产水足迹和能耗存在较大差异,大豆为极高耗水高耗能蓝水消耗型,谷子为高耗水极高耗能灰水消耗型,油料为高耗水高耗能灰水—蓝水消耗型,小麦为中等耗水中等耗能蓝水消耗型,玉米为低耗水低耗能蓝水—灰水消耗型,蔬菜为极低耗水极低耗能灰水—蓝水消耗型作物。优化后的种植结构方案中,玉米、谷子和油料种植面积比例下降,小麦和大豆种植面积比例提高,蔬菜种植比例变化不大。基于水热条件的差异,山西省作物种植结构具有一定的空间差异,玉米、谷子、大豆和油料在全域内均有种植,小麦主要种植于晋南区和晋东南区的平川和丘陵区,蔬菜主要分布于地域条件及水热条件相对优越的盆地。在水—能—粮关联关系的基础上,优化后的种植结构符合山西省“十四五”农业现代化规划,整体方案具有趋于低耗能、低耗水、低污染等特点,有利于促进农业的可持续发展。

我国中部地区水资源利用效率评价及归因分析

为促进水资源的可持续发展,缓解水资源问题,本研究结合水足迹和绿色发展指数建立考虑非期望产出的SBM模型,评估中部地区水资源利用效率,并利用Tobit模型分析其影响因素.结果表明,我国中部地区本地水资源利用程度较高,但由于缺少沿海地区区位优势,虚拟水进出口贸易欠发达;水污染压力呈波动下降,河南省水污染压力最大,该省的污水处理厂数目和处理能力增加能够缓解其水环境污染压力;中部六省的水资源开发程度较高,开发潜力较小,可考虑跨区调水等措施进行缓解;2007-2018年间,中部地区水资源利用方式逐渐高效,边际效益逐渐增加,中部地区水资源利用效率呈“U”型发展趋势,其中安徽省数据离散程度最大,山西省水资源利用效率最高;中部地区的用水成本科技进步、环境污染、水资源禀赋显著影响其水资源利用效率,Tobit回归结果表明,中部地区还需加强水资源利用,可通过加强技术培训、升级改造灌溉设施、水资源再生技术等措施进一步促进水资源可持续发展.

基于水足迹的区域水资源利用与经济发展脱钩关系研究

为了全面探究区域水资源利用与经济发展脱钩关系,从水足迹视角出发,结合脱钩理论和对数平均迪氏指数法,构建了TAPIO-LMDI模型,并以洛阳市为例进行分析。结果表明:洛阳市总水足迹整体有增大趋势,农业水足迹相对较大,水资源利用基本源于内部供应,水资源安全面临较大风险和压力;水资源利用与经济发展整体处于脱钩状态,脱钩率达86.67%,经济发展对水资源的依赖性越来越低,但农业发展对水资源的依赖性依旧明显;用水效率是主要的脱钩驱动因素,而经济收入则是主要的脱钩抑制因素,用水效率产生的效应值绝对值越大、经济收入产生的效应值绝对值越小,区域水资源利用与经济发展越容易脱钩。

基于水足迹理论的沿淮河省份水资源利用的时空变化评价与研究

在碳中和、碳达峰的国际大背景下,亟需对淮河流域自然资源开发利用状况与破坏情况做出全面的调查,文章将从内外水足迹和灰水足迹两大角度出发,结合LMDI模型,分析了沿淮河流域5个省份不同因子影响水足迹的变化趋势,最后对水资源可持续使用评估指标体系进行了建立。结果表明在2017-2021年沿淮河省份总体水足迹呈现波动增长的态势,以农业水足迹增长尤为突出;并且技术要素对水足迹的变动作用较为显著,而人口等数量要素的作用相对较弱。因此在未来淮河流域水资源管理政策的制定与调整中,应促进农业用水高效开发利用,使区域水资源得到可持续利用。