Estimating groundwater recharge using the chloride mass-balance method in the West Bank,Palestine

Abstract

The quantification of natural recharge rate is a prerequisite for efficient and sustainable groundwater resources management. Since groundwater is the only source of water supply in the West Bank, it is of utmost importance to estimate the rate of replenishment of the aquifers. The chloride mass-balance method was used to estimate recharge rates at different sites representing the three groundwater basins of the Mountain Aquifer in the West Bank. The recharge rate for the Eastern Basin was calculated as between 130.8 and 269.7 mm/year, with a total average replenishment volume of 290.3 × 10⁶ m³/year. For the Northeastern Basin, the calculated recharge rate ranged between 95.2 and 269.7 mm/year, with a total average recharge volume of 138.5 × 10⁶ m³/year. Finally, the recharge rate for the Western Basin was between 122.6 and 323.6 mm/year, with a total average recharge volume of 324.9 × 10⁶ m³/year. The data reveal a replenishment potential within the estimated replenishment volumes of previous studies for the same area. Also, the range was between 15 and 50% of total rainfall, which is still within the range of previous studies. The geological structure and the climate conditions of the western slope were clearly play an important role in the increment of total volume. In some cases, such as the geological formations in the Northeastern Basin, the interaction between Eocene and Senonian chalk formations result in minimum recharge rates.

Citation Marei, A., Khayat, S., Weise, S., Ghannam, S., Sbaih, M. & Geyer, S. (2010) Estimating groundwater recharge using the chloride mass-balance method in the West Bank, Palestine. Hydrol. Sci. J. 55(5), 780–791.     

中国季节积雪资源的初步评价

本文根据2300余个地面气象台站从1951年(或建站)到1980年逐日积雪与降雪观测资料,计算出我国年平均降雪补给量为3451.8 X 10~8m~3,冬季平均积雪贮量为535.6 X 10~8m~3,阐明了季节雪资源的地理分布规律,季节分配特征和长期变化趋势.指出了CO_2增温可能导致我国季节雪资源分布的区域分异倾向进一步加骤,引起北方土壤干旱化.三十年来,雪资源的波动是全球海气异常的结果.多雪冬天与厄尔尼诺南方涛动相同步.雪资源的两个正、负距平时期与我国农田受旱面积的两个明显的低高值时期基本吻合.长期变化趋势准确地反映出了全球气温变化过程,并与气温变化成正相关.     

Estimating water balance components in irrigated agriculture using a combined approach of soil moisture and energy balance monitoring,and numerical modelling

Information on water balance components such as evapotranspiration and groundwater recharge are crucial for water management. Due to differences in physical conditions, but also due to limited budgets, there is not one universal best practice, but a wide range of different methods with specific advantages and disadvantages. In this study, we propose an approach to quantify actual evapotranspiration, groundwater recharge and water inflow, i.e. precipitation and irrigation, that considers the specific conditions of irrigated agriculture in warm, arid environments. This approach does not require direct measurements of precipitation or irrigation quantities and is therefore suitable for sites with an uncertain data basis. For this purpose, we combine soil moisture and energy balance monitoring, remote sensing data analysis and numerical modelling using Hydrus. Energy balance data and routine weather data serve to estimate ET₀. Surface reflectance data from satellite images (Sentinel-2) are used to derive leaf area indices, which help to partition ET₀ into energy limited evaporation and transpiration. Subsequently, first approximations of water inflow are derived based on observed soil moisture changes. These inflow estimates are used in a series of forward simulations that produce initial estimates of drainage and ET_act, which in turn help improve the estimate of water inflow. Finally, the improved inflow estimates are incorporated into the model and then a parameter optimization is performed using the observed soil moisture as the reference figure. Forward simulations with calibrated soil parameters result in final estimates for ET_act and groundwater recharge. The presented method is applied to an agricultural test site with a crop rotation of cotton and wheat in Punjab, Pakistan. The final model results, with an RMSE of 2.2% in volumetric water content, suggest a cumulative ET_act and groundwater recharge of 769 and 297 mm over a period of 281 days, respectively. The total estimated water inflow accounts for 946 mm, of which 77% originates from irrigation.     

塔里木河南岸14团灌区地下水资源评价与分析

本文运用水均衡法和开采系数法,依据水均衡原理建立14团灌区内地下水水均衡模式,对灌区的地下水资源进行评价和分析,目的是科学合理开发利用地下水,保持水土平衡,促进灌区经济可持续发展.     

Application of environmental tracers to study groundwater recharge in a semi-arid area of Central Tunisia

Abstract

Groundwater of the Tertiary-Quaternary Formations in the Jeloula basin (Central Tunisia), together with rain and surface waters, were analysed to investigate the mineralization processes, the origin of the water and its recharge sources. The water samples present a large spatial variability of chemical facies which is related to their interaction with the geological formations. The main sources of the water mineralization are the dissolution of evaporitic and carbonate minerals and cation exchange reactions. Stable isotopes indicate that most groundwater samples originate from infiltration of modern precipitation. Surface water samples from small dam reservoirs show a ¹⁸O/²H enrichment, which is typical of water exposed to open-surface evaporation in a semi-arid region. Considerable data of ³H and ¹⁴C allow the qualitative identification of the present-day recharge that is probably supplied by infiltration of recent flood waters in the Wadi El Hamra valley, and by direct infiltration of meteoric water through the local carbonate outcrops.

Editor D. Koutsoyiannis; Associate editor S. Faye     

Time-input,an innovative groundwater-vulnerability assessment scheme: application to an alpine test site

The time-input method provides a new approach to evaluating groundwater vulnerability especially in mountainous areas. Its main factors are: (1) the travel time from the surface to groundwater (about 60%) enhanced by (2) the amount of input as groundwater recharge (about 40%). In contrast to other assessment schemes comparable to this method, the vulnerability is expressed in real time and not classified by dimensionless numbers with the advantage that the credibility of results is easier to check and the evaluation process is more transparent. The Index-Method was applied in a well-studied forested dolomitic karst area in the front range of the Austrian Northern Calcareous Alps. The aspect and the dip of the bedding planes towards or away from the groundwater have been included in this method. These are additional to the traditionally chosen investigation layers such as vegetation, slope inclination, thickness of soil, unconsolidated sediment and unsaturated rock, and fault zones.     

华北平原水资源合理开发利用的思路与举措

经过几十年的大量开采利用,华北平原地下水资源不仅表现为区域超采和局部严重超采,也暴露出地下水补给源严重萎缩的问题。其主要表现在中西部粗质平原的地下水易补给区,因汇流山地水库强力拦蓄,河道主体补给功能丧失,而在中东部细质平原的径流主产区,因水位埋藏浅和水质咸化,降水径流不能形成对地下水的有效补给,蒸发流失严重。以往实践强调山区水利工程建设而轻视了东部低平原区径流拦蓄利用,重视对高海拔咸水体的改造利用而忽视了对低海拔咸水体的改造利用,强化地表水库建设的重要性而忽略了地下水库的重要性。面对华北平原供水紧张的严峻形势,调整水资源开发战略势在必行,其具体思路是:以千方百计提高降水利用水平为中心,调整和改善水资源开发利用整体布局;以地下水补给调蓄为重点,大力集蓄雨洪水和改造利用浅层水,充分发挥地表水和地下水两大功能作用。其具体举措有:实施山前梯级水坝的地下水库"回灌"工程;实施中东部及滨海淡水蓄水利用工程;实施东部浅层地下水规模化改造开发利用工程。若上述措施得以实施,可使降水利用率从现状的20.65%提高到26%以上,则华北平原供水问题有望获得解决。     

Identifying the origin of groundwater for water resources sustainable management in an arid oasis,China

ABSTRACT

Many oases are experiencing severe groundwater depletion due to increased population, expanding agriculture and economic development. For sustainable development, quantifying groundwater recharge resources are fundamentally important. In this study, stable isotope techniques were employed to identify recharge sources of groundwater and quantitatively evaluate their contribution ratios in the Dunhuang Oasis, northwest China. Our findings indicate that heavy isotopes in shallow groundwater are more negative than those in deep groundwater, which is attributed to shallow groundwater that was modern and deep groundwater that was old. Irrigated return water and lateral groundwater flow from the Qilian Mountains are considered as the two main sources of shallow groundwater, accounting for 35% and 65% of the total recharge, respectively. Thus, as the main groundwater source of the Dunhuang Oasis, the Qilian Mountain Front should be protected against over-exploitation. Our results provide not only fundamental knowledge for groundwater management of aquifers of the Oasis, but also valuable water management information for other similar arid oases worldwide.     

北京市平原区地下水资源开采现状及评价

本文分析了北京市平原区地下水资源的开采现状,探讨了水资源开发利用过程中存在的问题.在分析平原区水文地质条件的基础上,采用FEFLOW软件建立了相应的地下水数值模拟模型,基于识别后的模型进行了水资源评价.研究表明:2000～2003年研究区地下水系统均衡分别为-7.73×10 8、-6.02×10 8、-5.95×10 8和-4.38×10 8m 3,地下水系统的补给源主要是大气降水入渗补给和山前迳流补给,主要的排泄是人工开采.多年平均地下水补给资源量为22.98×108m 3.平谷和昌平地区地下水还有开采潜力,密云-怀柔-顺义(密怀顺)平原和城近郊区地下水已过量开采.山前郊县地下水水质优良,城近郊区、大兴、房山和通州部分地区地下水水质较差.文章最后分析了引起地下水污染的主要原因.     

黑河流域走廊平原地下水补给源组成及其变化

通过环境同位素、水文分割法和相关分析研究表明,祁连山区降水、冰川雪融水和基岩裂隙水通过出山口地表径流补给构成黑河流域走廊平原地下水主要补给源,具有年际和年内丰枯动态变化规律,与祁连山区降水量和气温的关联度分别为0.97和0.79,与平原张掖站降水量和气温的关联度分别为0.43和0.60。在自然径流条件下,祁连山区降水量变化是改变走廊平原地下水补给的主导因素,约占91%权重;气温变化是重要影响因素,约占9%权重。20世纪80年代以来祁连山区各补给源处于偏丰期。因此,近年来走廊平原地下水补给量相对50年代减少27.1%,人类活动是重要影响因素,急需加强科学调控。