基于MIKE SHE模型的华北平原水资源利用情景分析

气候变化和人类活动是影响流域水文循环和水资源可持续利用的两大驱动因素,在校准的MIKE SHE模型基础上考虑气候变化和人类活动的影响,设定8个情景对华北平原2009-2028年的水文循环及水资源利用进行预测。结果表明:考虑南水北调工程的情景在预测期末的地下水水位有较大程度(0. 06~1. 26 m)的恢复,预测期内华北平原水量总流入小于总流出会导致含水层储量的消耗和地下水的不可持续利用,但在适当情景下可以较大程度缓解这种不可持续性。气候变化对华北平原含水层储量有较大的影响:降水量减少5%,地下水储量将减少0. 27 m;降水量增加5%,地下水储量将增加0. 3 m。南水北调工程和农业节水措施的实施对华北平原地下水水位的恢复、缺水程度的缓解作用显著。     

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。     

基于水资源配置情景的地下水演变模拟研究——以海河流域平原区为例

在分析研究国内外地表水-地下水联合应用模型研究现状基础上,提出水资源配置模型与地下水模型联合运用实现用水变化情景下的海河平原区地下水演变模拟。通过数据展布构建两个模型不同时空尺度的数据转换输入。通过动态插值推求从水资源配置水平年年数据结果到连续时间过程的地下水模拟模型动态时间序列数据输入,进而模拟以现状为初始状态的地下水演变趋势。通过不同条件的配置情景模拟得出未来海河平原地下水演变规律以及南水北调工程和地下水限采措施的影响。结果表明,在没有南水北调情景下,海河平原区在2005年-2020年期间地下水负均衡量将接近50亿m3,南水北调工程通水后负均衡量减少到不足14亿m3,典型漏斗区的水位将少下降5~25 m,地下水恶化的趋势将得到有力的缓解。     

分布式水文模型在华北平原水资源管理中的应用

自20世纪80年代以来,地下水过度开采导致了华北平原水位快速下降。在过去几十年里,研究华北平原的大多数水文模型或者只与地下水有关,或者只在局部范围内进行。针对目前为止的研究状况,利用MIKE SHE软件建立了华北平原地表水-地下水耦合的分布式水文模型,模拟主要水文循环过程。利用地下水水头观测数据对模型进行校准(2000～2005年)和验证(2006～2008年)。均方根误差(大多数值4 m)和相关系数(0.36～0.97)的分析结果均表明了模型校准和验证的有效性。水均衡分析结果表明:大约70%的水通过蒸散发的形式离开系统,29%的水通过地下水开采的形式离开系统。根据分析结果,对华北平原水资源可持续管理进行了深入分析,提出了包括减少蒸散发、南水北调工程调水、节水灌溉技术推广和水质保护相关措施。     

北京市平原区地下水动态要素的时间变化及其启示

地下水补径排过程中的水量交换满足质量守恒定律,具体为地下水量的输入输出最终要满足水均衡方程。对反映地下水量交换规律的地下水动态要素及其时空变化规律的掌握,是进行地下水资源评价和未来供水能力预测的基础。采用水均衡理论和水位动态均衡法,对北京市平原区地下水动态与均衡要素(水位、补给量、排泄量)的时间变化规律及相互关系进行了分析,并得到以下主要结论:(1)地下水总输出量连续多年大于总输入量,使含水层长年"入不敷出",储量亏损越积越多;(2)平均水位每下降(上升)1m,含水层可释放(储存)约4.76亿m3的水量;(3)近些年地下水的开采量有相当一部分来自袭夺的天然排泄量,且两者呈良好的负线性相关关系;(4)地下水位变动带内(埋深在7.50~22.92m之间)含水层的给水度总体上随埋深的增加而减小,等效给水度为0.077。     

华北地区沧县出现的地下水环境问题与对策

以沧县为例,探讨了沧县地区含水层疏干、水位下降、地面沉降、水质变咸为特征的地下水环境问题。同时提出地下水环境控制措施:通过水价、水权与水市场建设,达到效益节水和强制节水,实现用水总量指标控制和定额指标管理;通过"引黄"、"南水北调"工程解决缺水问题。     

华北典型灌区气候变化条件下地下水响应研究

基于MODFLOW模型,以华北平原人民胜利渠灌区为例,结合研究区水文地质条件,建立地下水运动数值模拟模型,通过参数校准和模型验证,表明建立的地下水运动模型能够合理地反映研究区2012-2013年的地下水运动状况,模拟结果表明该灌区地下水处于负均衡状态。基于模拟结果,进一步预测了气候情景(选取RCP4.5情景NorESM1-M模式)下灌区2030年地下水水位情况。结果表明与1997-2013年相比,2030年灌区地下水位持续下降,漏斗面积逐渐扩大。以此为基础,开展地下水开采量情景分析,将开采量分别增加和减少20%,预测2030年在不同开采量情景下地下水水位变化情况。最后根据预测结果初步提出地下水开采量减少20%的调控方案,以保证地下水水位有所上升,漏斗面积减少。     

石羊河流域地下水水位下降原因及对策研究

石羊河流域位于甘肃省河西走廊东部,由于气候变化和流域内工农业生产的发展,流域内径流减少,地下水大力开采,导致流域内各地的地下水水位下降,近20 a来,流域内民勤县最大地下水水位平均下降速率达0.57 m/a。分析了流域内地下水水位下降的分布情况和原因。要防止地下水水位继续下降,保证流域社会经济可持续发展,需采取关闭部分机井、发展节水高效农业、工程调水补充地下水等措施。     

基于Modflow 的潜水位对气候变化和人类活动改变的响应

采用GMS-Modflow 软件构建了华北平原吴桥县的潜水运动模型,利用验证后的模型模拟了基准、气候变化和人类自主改变3 种情景下未来40年该区潜水位对气候变化和人类活动的响应。结果表明：现状情景下,未来40年潜水位将以平均19.3cm/a 的速度持续下降,从而导致2050年初潜水位较2011年初下降7.74m ;综合考虑气候变化的直接和间接影响时,虽然A1B 、A2 和B1 排放情景下利用GCM预估的未来40年平均年降雨量分别增加为4.1% 、5.37% 和3.86% ,但潜水位仍然以16.9cm/a 、18.5cm/a 和19.3cm/a 的速度下降,说明未来降雨的小幅增加对减缓潜水位降幅的效果微弱,人类必须采取自主措施才能应对潜水位持续下降;采取节水措施减少灌溉量对缓解潜水位下降效果最显著,其次为用非常规水源替代地下水抽水以及增加地表引水能力,而加大深层抽水量、增加非灌溉用水和地表引水量的减少都会导致潜水位下降态势进一步加剧。     

南水北调供水前后京杭运河梁济段沿岸地下水埋深变化预测研究

运用地下水模型软件Visual Modflow建立了地下水数值模拟模型,并利用模型对梁济运河沿岸南水北调受水区进行了地下水数值模拟和趋势的预测。预测结果表明,在预测过程中降水及蒸发量未做改变,河流水位相应提高。在数值模型模拟期末,地下水埋深在京杭运河济宁段的西岸附近在7 m~8m左右,而在预测末期,地下水埋深变为1 m~2 m左右,变化幅度超过5 m,地下水埋深等值线相对密集,说明河流水位的抬升,对地下水位的影响不容忽视。     

Effect of management strategies on reducing negative impacts of climate change on water resources of the Isfahan–Borkhar aquifer using MODFLOW

Recently, many studies have investigated the effect of climate change on groundwater resources in semiarid and arid areas and have shown adverse effects on groundwater recharge and water level. However, only a few studies have shown suitable strategies for reducing these adverse effects. In this study, climate conditions were predicted for the future period of 2020–2044, under the emission scenarios of RCP2.6, RCP4.5, and RCP8.5, for Isfahan–Borkhar aquifer, Isfahan, Iran, using MODFLOW‐2000 (MODFLOW is United States Geological Survey product). Results showed that the average groundwater level of the aquifer would decrease to 13, 15, and 16 m in 2012 to 2044 approximately under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively. Then, three groundwater sustainability management scenarios were defined that included 10%, 30%, and 50% reduction in groundwater extraction. These strategies simulated the reduced negative effects of climate change on the aquifer. The results showed that decreases in water withdrawal rates of 10%, 30%, and 50% under RCP8.5 scenario (critical scenario) could decrease the mean groundwater level by 14, 11, and 7 m, respectively. The main result of the study showed that 50% reduction in groundwater withdrawal may increase the groundwater levels significantly in order to restore the aquifer sustainability in the study area. In this study, with assuming that the current harvest of wells in the future period is constant, so the results of studies showed that for the aquifer's sustainability management, the water abstraction from the aquifer should reduce up to 50% of the existing wells. Changing the irrigation method from surface to subdroplet irrigation plays an important role in reducing the withdrawal from the aquifer. The results of a study in Iran have shown that the change in the irrigation method from surface to subdroplet irrigation causes a 40% reduction in water use for agriculture.     

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.     

市场经济条件下农业水资源高效利用模型研究

本文提出了市场经济条件下农业水资源高效利用模型。这个模型可根据不同的水资源利用模式和区域经济发展模式,基于区域水资源开发利用状况和水土资源组合条件,合理组织农业生产的诸要素,通过市场经济中的价值杠杆,对灌区的各种土地利用规模、种植结构和灌溉制度等进行合理配置,使得该研究区内的农业水资源利用在3个方面得到了较好的改进:(1)在实现农业水资源高效利用过程中,充分考虑了农民收入水平的提高;(2)研究了水价变化对农业生产、农民收人和对井渠双灌的促进作用;(3)探讨了水价与各种节水措施之间的关系,以及不同水价条件下各种节水措施规模、节水量和投资效益的定量描述。     

Impact of Changes in Groundwater Extractions and Climate Change on Groundwater-Dependent Ecosystems in a Complex Hydrogeological Setting

Climate change and other future developments can influence the availability of groundwater resources for drinking water. The uncertainty of the projected impact is a challenge given the urgency to decide on adaptation measures to secure the drinking water supply. Improved understanding on how climate change affects the groundwater system is necessary to develop adaptation strategies. AZURE is used, a detailed, well-calibrated hydrological model to study the projected impact of climate change scenarios on the large Veluwe aquifer in the Netherlands. The Veluwe area is an important source of drinking water. However, some existing groundwater extractions in the area affect nearby groundwater-dependent ecosystems. Redistribution of the licensed extraction volumes of these sites is considered to reduce the impact on these ecosystems. The projected impact of climate change and redistribution to groundwater levels is studied. The research shows that in a slowly responding large aquifer the projected climate change may cause rising groundwater levels despite the projected increase in summer dryness. The results indicate that this impact may exceed the impact of redistribution of extraction volumes. In addition, it is shown that the combined effect strongly depends on local conditions, thus highlighting the need for high-resolution modelling.     

Design of Managed Aquifer Recharge for Agricultural and Ecological Water Supply Assessed Through Numerical Modeling

The Walla Walla Basin, in Eastern Oregon and Washington, USA, faces challenges in sustaining an agricultural water supply while maintaining sufficient flow in the Walla Walla River for endangered fish populations. Minimum summer river flow of 0.71 m³/s is required, forcing irrigators to substitute groundwater from a declining aquifer for lost surface water diversion. Managed Aquifer Recharge (MAR) was initiated in 2004 attempting to restore groundwater levels and improve agricultural viability. The Integrated Water Flow Model (IWFM) was used to compute surface and shallow groundwater conditions in the basin under water management scenarios with varying water use, MAR, and allowable minimum river flow. A mean increase of 1.5 m of groundwater elevation, or 1.5 % of total aquifer storage, was predicted over the model area when comparing maximum MAR and no MAR scenarios where minimum river flow was increased from current level. When comparing these scenarios a 53 % greater summer flow in springs was predicted with the use of MAR. Results indicate MAR can supplement irrigation supply while stabilizing groundwater levels and increasing summer streamflow. Potential increase in long-term groundwater storage is limited by the high transmissivity of the aquifer material. Increased MAR caused increased groundwater discharge through springs and stream beds, benefiting aquatic habitat rather than building long-term aquifer storage. Judicious siting of recharge basins may be a means of increasing the effectiveness of MAR in the basin.     

Predictive Simulation of Flow and Solute Transport for Managing the Salalah Coastal Aquifer, Oman

A three-dimensional numerical model for flow and solute transport was used for the management of the Salalah aquifer. The model calibration procedures consisted of calibrating the aquifer system hydraulic parameters by history matching under steady and transient conditions. The history of input and output of the aquifer were reconstructed in a transient calibration from 1993 to 2005. Predictive simulation of the aquifer was carried out under transient conditions to predict the future demand of groundwater supply for the next 15 years. A baseline scenario was worked out to obtain the piezometric surface and salinity distribution for the “business as usual” conditions of the aquifer. The “business as usual” scenario was predicted and simulated for the period 2006 until 2020. The effectiveness of seven management options was proposed and assessed for comparison with the “business as usual” conditions. The established simulation model was used to predict the distribution of the piezometric surface, salinity distribution, and mass balance under the proposed scenarios for the prediction period 2006–2020. The scenarios were: (1) relocate Garziz and MAF farms far from the freshwater zone, (2) suspend the abstraction of grass production for 4 months a year, (3) changes in agricultural and irrigation system patterns, (4) establish a desalination plant, (5) combined scenario (1 + 4), (6) combined scenario (1 + 3), and (7) combining all scenarios (1 + 2 + 3 + 4). The result of the simulation shows that the best effective option in terms of aquifer groundwater levels is the fifth proposed scenario and the sixth proposed scenario is the best effective option in terms of aquifer groundwater salinity situation during the next 15 years. This project suggested the application of scenario 6 as it is environmentally sound in terms of sustainable management. A prediction has been made which shows that further actions have to be taken within the next two decades to ensure continuity of the municipal water supply. The management scenarios are examined in the case of the Salalah coastal aquifer using groundwater simulation, which can also be applied to other regions with similar conditions. The established model is considered a reasonable representation of the physical conditions of the Salalah plain aquifer, and can be used as a tool by the water and environmental authorities in the management of the groundwater in the region.     

GIS-Based Groundwater Management Model for Western Nile Delta

The limited availability of renewable fresh water is a major constraint on future agriculture and urban development in Egypt. The main water resource that Egypt has been depending on is the River Nile. Nowadays, the role of groundwater is steadily increasing and will cover 20% of the total water supply in the coming decades especially in the reclaimed areas along the desert fringes of the Nile Delta and Valley. Abstraction from groundwater in Egypt is dynamic in nature as it grows rapidly with the expansion of irrigation activities, industrialization, and urbanization. One of these areas is the Western Nile Delta in which the groundwater is exploited in many localities. To avoid the deterioration of the aquifer system in this area, an efficient integrated and sustainable management plan for groundwater resources is needed. Efficient integrated and sustainable management of water resources relies on a comprehensive database that represents the characteristics of the aquifer system and modeling tools to achieve the impacts of decision alternatives. In this paper, a GIS-based model has been developed for the aquifer system of the Western Nile Delta. The GIS provides the utilization of analytical tools and visualization capabilities for pre-and post-processing information involved in groundwater modeling for the study area. The developed model was calibrated for steady state and transient conditions against the historical groundwater heads observed during the last 20 yr. The calibrated model was used to evaluate groundwater potentiality and to test two alternative management scenarios for conserving the aquifer system in Western Nile Delta. In the first scenario, reducing the surface water inflow while increasing the annual abstraction from groundwater by about 450 million m³ and improving the irrigation system could increase the net aquifer recharge by about 5.7% and reduce the aquifer potentiality by about 91%. Constructing a new canal as a second management scenario could increase the annual aquifer potentiality by about 23%. The GIS-based model has been proven to be an efficient tool for formulating integrated and sustainable management plan.     

Combined Management of Groundwater Resources and Water Supply Systems at Basin Scale Under Climate Change

Water stress conditions associated with population growth, climate change, and groundwater contamination, represent a significant challenge for all stakeholders in the water sector. Increasing the resilience of Water Supply Systems (WSSs) becomes of fundamental importance: along with an adequate level of service, sustainability targets must be ensured. A long-term management strategy is strictly connected to a holistic approach, based on analyses at different scales. To this end, both groundwater modeling tools and water management models, with different spatial and temporal scales, are routinely and independently employed. Here, we propose a coupled approach combining: i) groundwater models (MODFLOW) to investigate different stress scenarios, involving climate change and anthropic activities; ii) water management models (Aquator), to assess the water resources availability and the best long-term management strategy for large-scale WSS. The management models are implemented starting from input and output flows derived by groundwater models: this leads to establish a comprehensive framework usually not defined in management models and including a quantitative characterization of the aquifer. The proposed methodology, general and applicable to any study area, is here implemented to the WSS of Reggio Emilia Province, and its main groundwater resource, the Enza aquifer, considering three different stress scenarios for groundwater models (BAU, ST1, and ST2), and for management strategies (BAU, BAU_RV2, ST2). Among the key results, we observe that coupling the two model types: i) allows evaluating water resources availability in connection with management rules; ii) leads to examining more realistic operation choices; iii) permits planning of infrastructures at basin scale.

     

Optimal Management of an Overexploited Aquifer under Climate Change: The Lake Karla Case

This paper presents a study for finding the optimal management plan of an overexploited aquifer under global climate change. The study area is the aquifer of the basin of Lake Karla, located in the eastern part of Thessaly in Greece. An optimization method has been used to evaluate the optimum volume of water that can be extracted from the aquifer and the optimum position of the wells with the objective of water table rise to a desirable sustainable level, taking into consideration the climate change forcing. The modelling system consists of a series of interlinked models: a hydrological, a lake-aquifer, a reservoir operation, a groundwater, and an optimization model. The climate change forcing on precipitation and temperature has been evaluated using the outputs of Canadian Centre for Climate Model Analysis General Circulation Model (CGCMa2) and a hybrid downscaling method which combines a multiple regression (MLR) model and a timeseries model for two socioeconomic emissions scenarios. The results of this study show that climate change plays an important role, as it affects the optimum volume of the extracted groundwater and the position of the irrigation wells.     

Assessing Impacts of Conservation Measures on Watershed Hydrology Using MIKE SHE Model in the Face of Climate Change

Climate change triggers changes in temperature, precipitation, evapotranspiration, etc. and has a significant impact on water resources in many regions. Considering the increasing scarcity of water as a result of climate change, conservation of water and groundwater recharge have become crucial factors for water resources planning and management. In this paper, an attempt is made to study the detailed hydrological behaviour of a treated watershed using physically based distributed hydrological modelling system MIKE SHE to assess the impact of conservation measures on watershed hydrology considering future climate change. Three hypothetical management scenarios are simulated for the period 2010–2040. RegCM4 regional climate model is used in the study for RCP 4.5 and RCP 8.5 scenarios. Detailed hydrological water balance is extracted for individual years from 1979 to 2009 to compare relevant components. The evaluation for base period shows 10.06% reduction in surface runoff and 11.33% enhancement in groundwater recharge. Further simulation with RCP 4.5 and RCP 8.5 scenarios show notable reduction in surface runoff and increase in groundwater recharge. The structures in the micro-watershed influence the surface runoff and increase infiltration into the soil, resulting in higher groundwater recharge. MIKE SHE simulations for various structures management scenarios establish the role of conservation measures in reducing surface runoff and enhancing groundwater recharge under substantial effect of climate change. The results will assist in decision-making on watershed development plans in quantitative terms, including planning for water conservation measures in the face of climate change.