Sensitivity of Simulating Hydrologic Processes to Gauge and Radar Rainfall Data in Subtropical Coastal Catchments

This research evaluated the impact of three rainfall datasets on hydrologic process simulations in two coastal catchments located in Alabama. In this study, rain gauge time series recorded by the U.S. National Oceanic and Atmospheric Administration (NOAA) and Geological Survey (USGS) along with radar precipitation data derived from NOAA National Weather Service (NWS) were input into the Hydrological Simulation Program??FORTRAN (HSPF). Automatic parameter calibration was performed using daily streamflow data recorded at USGS Fish and Magnolia River gauge stations from 07/01/2002 to 12/31/2008. HSPF parameters were optimized using the Model-Independent Parameter Estimation (PEST) program. Model parameter ranges were refined by incorporating physical characteristic of the study areas and after analyzing observed streamflow time series. This approach, in turn, helped PEST optimization tool to find the most physically-related set of parameters that can be transferred to any watershed with similar characteristics and minimum parameter calibration. On average, annual USGS and radar rainfall values were around 480?mm and 250?mm, respectively lower than NOAA precipitation records. Overall, it is found that the NOAA precipitation input data resulted in better daily flow simulations than results from radar and USGS rainfall time series. Streamflows derived from USGS rainfall time series showed the worst model performance at both catchment outlets because of missing data, low amounts, and temporal delay of peaks. This study found that annual actual evapotranspiration values were closed among rainfall time series and varied from 900 to 958?mm. Deep percolation values for Magnolia and Fish River, regardless of rainfall source, ranged from 66 to 192?mm/year. Major discrepancies were found at storm runoff values. Gauge rainfall time series yielded the closest streamflow values compared to observed flow time series at both watershed outlets. Rainfall derived from radar yielded consistent and acceptable runoff results in Fish and Magnolia River models. In both case studies, the high spatial variability of rainfall storm events was not adequately captured by any of the rainfall datasets and yielded high uncertainty in model results.     

浅析岛屿和内陆应用稳定同位素分析地下水补给关系的效果

分析参与水循环过程的不同水体中D和18O组成的变化特征,是应用氢氧稳定同位素示踪技术研究水循环机理的必要前提.通过在北京市和广东湛江硇洲岛应用稳定同位素分析地下水补给关系,从而对比分析其在岛屿和内陆的应用效果.结果表明,沿海岛屿和内陆应用氢氧同位素作为示踪剂研究水循环中不同水体的补给来源,以及地表水和地下水之间的相互转化关系均具有良好的效果,这说明采用氢氧同位素进行地下水的研究具有普遍的适用性.     

Effect of Land-Use Change and Artificial Recharge on the Groundwater in an Arid Inland River Basin

The spatial-temporal variability of groundwater in an inland basin is very sensitive to human activity. This study focused on groundwater changes in the Alagan area within the Tarim Basin, China, with the aim of analyzing the effects of land-use change and artificial recharge on the response characteristics of groundwater. The distributed hydrological model MIKE SHE was introduced for modeling the influence of land use and artificial recharge on groundwater. Based on the runoff variation of this area, we selected three periods to simulate and analyze the response of groundwater. The results of land-use change indicated that there were significant changes from 1980 to 2000. The changed region accounted for 11.93 % of the total area, and the low coverage grasslands showed the greatest reduction. The simulation of hydrological processes before artificial recharge showed that the groundwater depths differed greatly with land-use types. Response analysis of groundwater to artificial recharge showed that the regions in which groundwater decreased were mainly distributed in grassland and bare land. Moreover, spatial autocorrelation coefficients indicated positive spatial autocorrelation of groundwater depths, but these began to reverse in 2010. Overall, land use and artificial recharge have a great influence on the time and spatial distribution of groundwater. Artificial recharge has played a positive role in improving groundwater conditions, but did not change the decreasing trend in time and space. The adaptation of environment to the decrease of groundwater presents as degradation. Groundwater conditions could be improved to some extent by the artificial recharge, but its change seems to be an irreversible process. Overall, this response study provides insight into estimations for exploration of water resources in arid areas.     

湛江市地下水回灌方案分析

针对湛江市的地下水超采状况,提出地下水回灌的必要性,并对地下水回灌方案进行分析,建议采用含水层存储与恢复技术(ASR)进行湛江市地下水人工回灌。分析表明,通过ASR将湛江市的汛期降水、地表弃水通过人工补给储存在含水层中,并在水资源紧张的季节抽取使用,既可以增加枯水季节的水资源保证程度,也可以防止湛江市的地下水降落漏斗的不断扩大,以及地面沉降问题的不断恶化,并且抬高地下水位达到有效阻止海水入侵的效果。     

潜水入渗补给研究进展

目前,对土壤水运移机理研究已从定性走向定量、从均质走向非均质。优先流是地下水入渗的普遍现象,在田间土壤水主要以捷径流方式入渗补给地下水。对优先流研究是潜水入渗补给研究的重点与难点之一,其主要方法为染色示踪与X射线成像和地质雷达技术。潜水入渗补给评价方法众多,且每种方法都有其适用条件。因此,综合采用示踪法、地下水位波动法、地中渗透仪法、零通量法和数值模拟法,相互对比验证,提高评价可靠性,是研究地下水入渗补给最有效的方法。     

乌兰布和沙漠地下水补给研究

利用放射性同位素(~(14)C)测年和氯质量平衡理论,研究乌兰布和沙漠地下水年龄以及地下水补给速率。结果表明:通过~(14)C测年并修正后得出的研究区饱和带地下水年龄为22 000 a～现代,利用氯质量平衡理论推算出非饱和带5.5 m深处地下水年龄为2 645 a;研究区非饱和带地下水的补给速率为0.19～2.55 mm/a,均值为1.12 mm/a,故包气带直接补给潜水和承压水的水量微乎其微。     

Recharge Wells Site Selection for Artificial Groundwater Recharge in an Urban Area Using Fuzzy Logic Technique

In arid and semi-arid area, groundwater is the most important water resources. Surface runoff harvesting is the most important process in the artificial recharge of groundwater that should increase groundwater quality and quantity. Urban impervious area provides an appropriate surface to produce adequate amounts of runoff. Groundwater recharge via recharge wells is one of the successful direct sub-surface methods. As many cities around the world face issues of water scarcity due to a fast and unsustainable urbanization, identify the best locations of groundwater recharge wells is an interesting relevant topic, especially in the arid and semi-arid area. Selection of a suitable area for groundwater recharge could increase efficiency of the recharge wells. In this study, the best location of recharge wells was investigated in Urmia city located in the North-west of Iran using fuzzy logic technique. In this study, locations of the drainage channel junctions with adequate potential of surface runoff were determined using SWMM. Appropriate locations for recharge wells were determined based on different layers including distance to runoff harvesting points, distance to the production water wells and depth of groundwater table. Hydraulic condition (hydraulic conductivity and specific recharge) was also used separately. The input layers were prepared using geostatistical interpolation techniques in ArcGIS 9.3 software. Mamdani fuzzy inference system was applied to incorporate the fuzzified input layers. Finally, in each area, pixels with the highest value were proposed as suitable locations for recharge wells. Based on the results, the number of pixels with “High” priorities increased when the hydraulic conductivity was used to site selection. Comparing hydraulic conductivity layer and selected location of the recharge wells shows that the area with low hydraulic conductivity and the area closed to the production water wells has not suitable priority for recharge wells.     

Cumulative Effects of Small Reservoirs on Streamflow in Northern Coastal California Catchments

With small reservoirs increasingly employed to meet human water needs, tools that consider cumulative effects of multiple small reservoirs through space and time are essential for understanding impacts of these spatially distributed stresses on catchment hydrology and related ecological processes. We used a GIS-based hydrologic model to predict streamflow impairment caused by 438 small reservoirs in a 743 km² study area in Sonoma County, California, USA. The GIS model was designed to consider the varying effects that these reservoirs have through the project area drainage network, as well as the varying effects they have over time (as reservoirs fill and no longer impair flow downstream). Results indicate that, at the onset of the water year (when reservoirs are assumed to be empty), more than 25 % of the drainage network below reservoirs is impaired by over 50 %. Nine weeks into a normal-type water year, approximately 25 % of the drainage network below reservoirs is impaired by at least 25 %; and at 15 weeks, five percent of the drainage below reservoirs is impaired at least 25 %. Impairment is more persistent in a dry-type year. Nine weeks into a dry year, almost 40 % of the drainage network below reservoirs is impaired by at least 25 %; and at 15 weeks, 25 % of the drainage is impaired by at least 25 %. Results illustrate that impairment caused by reservoirs varies appreciably over space, but as reservoirs fill over time, impairment is lower through most of the drainage network.     

Estimating Regional Groundwater Recharge Using a Hydrological Budget Method

Estimating groundwater recharge is a key component in determining the sustainable yield of groundwater resources in arid and semi-arid areas such as southern California. Estimating groundwater recharge on a regional scale requires developing a water budget that incorporates data on boundary conditions, aquifer properties, groundwater levels, and groundwater production. The hydrological budget method proposed herein is simple, cost-effective, and easy to apply. It utilizes matched pairs of groundwater level measurements, groundwater extraction data, and distributed specific yield information for estimating groundwater recharge. In this method, ARCGIS 9.0 Geostatistical and Spatial Analyst applications are used for interpolating/extrapolating and creating grids for specific yield, bedrock elevation, and raw groundwater data. The annual average groundwater recharge for the Hemet subbasin in western Riverside County, California, from 1997 to 2005 is estimated at 12.5 MCM, with wet and dry periods ranging between 14.9 MCM and 11.7 MCM, respectively. The proposed method utilizes information commonly available to most groundwater management entities, such as groundwater production data, groundwater level measurements, and lithologic information.     

黑龙潭泉域地下水化学特征及补给源识别

以黑龙潭泉域为研究对象,在泉域采取水样测试分析其水化学特征和氢氧同位素特征,通过Piper三线图、Gibbs图、线性回归分析、因子主成分分析及高程反演方法,探讨了黑龙潭泉域水化学组成特征和影响因素,以及各泉群的补给来源,结果表明:研究区地下水化学组分以Ca~(2+)、HCO■、SO■为主,水化学类型为HCO_3-Ca型,水化学组分主要受碳酸盐岩溶滤作用和岩石风化作用影响;水样点基本落在降水线右下方,研究区以大气降水补给为主,水样的补给高程为3 715～4 154 m;水样均接受九子海地区降水补给,但清溪泉群还接受玉龙雪山地区冰雪融水的补给,清溪泉群地下水子系统属于"多源同汇",其他泉群属于"单源单汇"。     

黎河河水与地下水补排关系分析

按照河道对地下水的补给机理，根据引滦输水以来的水文资料，初步分析了黎河河水与地下水的补排关系，揭示了引滦输水损失的原因及变化规律，为引滦输水计量和管理提供参考。     

Optimal Locations of Groundwater Extractions in Coastal Aquifers

A regional water supply management model for coastal aquifers was developed. One of its outcomes is the definition of the optimized locations for groundwater withdrawal. Such a tool permits the analysis of alternative plans for groundwater extraction and the sustainable use of water resources in a coastal aquifer subject to saltwater intrusion. The principal components are the evolutionary optimization and the analytical/numerical simulation models. The optimization technique looks for the best well locations taking into consideration the economic results and the satisfaction of the societal water demand. However these two concerns are conditioned by trying to control the saltwater intrusion, i.e., preserving the environmental equilibrium. The simulation model uses the governing mathematical equations for groundwater movement to find the interface between freshwater and saltwater. Because of the non-linearity in the system and the possibility of a jumping interface, a security distance was defined. This is a controlling variable which can be set by the decision makers. The model was applied to a typical case with interesting results. For example, diagrams showing the relationship between the location of the wells and the security distance(s) are of importance to the managers. It was also crucial to have an understanding of the tradeoffs between groundwater withdrawals, positions of the wells from the coast line, and the security distance. The model was also applied to a real case in order to relate the extractions, distances and artificial recharge (not presented in this paper).     

基于地下水安全的采补均衡曲线研究

通过对吕梁市平川区地下水补给规律及开采规律的分析,概化出地下水补给曲线、开采曲线,提出了补给量的变动、补给的变动、开采量的变动、开采的变动的概念。应用地下水补给量和开采量随降水量增减变化呈互逆变化的特征,提出了地下水采补均衡曲线,为划定地下水开采量的安全性提供了计算依据,对提高区域地下水资源供给安全保障具有现实意义。     

莱西市大沽河沿岸地下水回灌补源措施

针对莱西市大沽河沿岸地下水量不足的问题,采取工程措施进行回灌补源。其中回灌补源工程的水源:一是利用汛期径流进行补源;二是利用水库拦蓄水进行补源。采取的工程措施是:外引、内拦相结合实行面补。利用拦水闸拦蓄由降水形成的地表径流,待各沟、渠水下渗后,再利用大沽河汛期水或产芝水库、高格庄水库拦蓄水,通过渠道向沟、渠引水,浇灌粮田和补充地下水;拦蓄、渗井、渗沟相结合实行点补。利用所建闸将区内地表径流、外引水拦蓄回灌。通过回灌补源地下水位回升,产生了一定的经济效益。     

西北内陆盆地地下水资源可持续利用战略分析

西北内陆盆地气候干旱,水资源缺乏,而地下水分布较广泛,开采方便,在经济建设和环境保护中具有不可替代的作用.结合水资源开发引起的生态环境问题,对地下水可持续利用战略进行了分析,强调西北内陆区地下水开发要与生态建设相协调,保证生态用水,实施科学用水.     

Estimating Pumping Rates and Identifying Potential Recharge Zones for Groundwater Management in Multi-Aquifers System

Agricultural, aquaculture, industrial and domestic activities have placed enormous demands for water, which sometimes results in the over-pumping and associated continually declining groundwater levels. This in turn has led to land subsidence and soil salination. Therefore, it’s important to understand the local pumping activities or the pumping rates in order to implement appropriate water management. The distribution of pumping rates varies spatially and temporally due to the availability of surface water and seasonality. In addition, to have correct estimate of the pumping rates, both the hydrology and geology should be consider. SWAT and MODFLOW are employed and run separately to acquire certain hydrologic components such as the recharge, boundary flow and change of aquifer storage in multi-aquifers. The water balance method (WBM) is then adopted to estimate pumping rates with these components. To validate the proposed model the results of WBM and the official records are compared. Besides, in view of the serious land subsidence occurred, artificial recharge is regarded as an effective tool to alleviate and mitigate the subsidence. Nevertheless, the location of conducting artificial recharge needs to be identified first. The potential recharge zones are assessed based on the simulated recharge rates from SWAT and the spatial distribution of hydrological characteristics of the unconfined aquifer. Ultimately, an optimal recharge zone will be suggested. The proposed methodology is proved capable of estimating the pumping rates and locating the potential recharge zone.     

Modeling of Groundwater Artificial Recharge by Reactivating an Old Stream Bed

This paper refers to the development and verification of a groundwater artificial recharge model in Xanthi plain, Thrace, Greece. The relative geological and hydrogeological research of the study area is described, as well as the artificial recharge application by reactivating an old stream bed of Kosynthos River, since 1994. The simulation of the aquifer system of the study area was achieved by the use of MODFLOW and involves both the model calibration and prediction of the aquifer system response. The verification of the 9-year-period model prediction for the first 7 years (1995–2001) proved successful, while the respective procedure for the last 2 years, 2002 and 2003, could not result in acceptable estimations.     

Optimal Operation of Artificial Groundwater Recharge Systems Considering Water Quality Transformations

In water limited areas as water demand increases alternative sustainable water sources must be identified. One supply augmentation practice, that is already being applied in the arid southwest U.S., is artificial groundwater recharge usingwastewater effluent. The objective of a recharge facility is to supplement the available groundwater resources by storing water for the future. The resulting reclaimed water is used primarily for non-potable purposes but under increasing stressesshifting to potable use is likely to happen. Water quality thenbecomes a more pressing concern. Water quality improvements during infiltration and groundwater transport are significant and are collectively described as soil-aquifer treatment (SAT). To meet user needs, the recharge operation must be efficiently managed considering monetary, water quality and environmental concerns. In this paper, a SAT management model is developed that considers all of these concerns. Within the SAT management model, the shuffled complex evolution algorithm (SCE) is used as the optimization tool. SCEis a relatively new meta-heuristic search technique for continuousproblems that has been used extensively for hydrologic model calibration. In this application, SCE is integrated with the simulation models (MODFLOW, MT3D, and MODPATH) to represent movement and quality transformations. Two steady state case studies on a general hypothetical aquifer (modeled after a field site) were examined using the management model.     

巴丹吉林沙漠南缘地下水补给机制研究

为研究巴丹吉林沙漠南缘水源地的地下水补给机制,分析了采自浅井、深井及湖泊的35个水样的Cl-浓度、TDS含量和氢氧同位素特征。根据巴丹吉林水源地及周边水化学水平分布特征,结合研究区气象和水文条件、水文地质结构、地下水流场发现,戈壁区地下水对沙漠区地下水无明显补给作用,但是沙漠区、戈壁区及山区地下水稳定同位素关系表明,沙漠区地下水来源于南部山区及戈壁区的地下水或降水。通过野外调查发现,沙漠边缘分布大量洪积黏土,认为沙漠外围山区、山前戈壁带降水在季节性河道形成的脉冲式洪流是沙漠区地下水的重要补给来源之一,这一认识不仅解释了采用水化学和同位素技术进行分析而获得不同结论的原因,而且有利于地下水资源评价。     

Estimating Land Use Impacts on Regional Scale Urban Water Balance and Groundwater Recharge

Anthropogenic activities have exerted increasingly large-scale influences on terrestrial ecological systems from the past century, primarily through agriculture; however, the impact of such changes on the hydrologic cycle is poorly understood. As one of the important land use (LU) in the coastal Dogo Plain of the Seto Inland Sea, Japan, paddy fields have been decreasing with the increase in urbanization in recent decades. As the main source of water in the Dogo Plain, groundwater plays an important role in providing people with fresh water and contributing to stream base flow. The purpose of this study is to analyze the water resource and evaluate the effect of LU change on groundwater table fluctuation in this coastal plain. Firstly, the observations of groundwater table and the investigation of water balance were carried out in this alluvial plain. Then, a distributed four-block three-layer water balance model was employed to analyze the groundwater table fluctuation with response to the change of paddy field area. Moreover, the role of paddy field in recharging groundwater in the basin has been clarified. Results show that groundwater table depends not only on rainfall and discharge from rivers, but also on irrigation water and topology of the study area. The net groundwater recharge was positive in irrigation periods whereas that in non-irrigation periods was nearly equal to zero or negative. The results of this study would be helpful to the urban development policy and land use planning decision.