Assessment of groundwater storage depletion by overexploitation using simple indicators in an irrigated closed aquifer basin in Iran

In arid and semi-arid regions irrigation is usually needed to provide enough water for crop growth in cultivated areas. As surface waters are scarce, especially in summertime when the water is needed, groundwater is heavily used to supply the water demand. Overexploitation of the aquifer in dry years causes depletion of the groundwater storage and systematical lowering of the piezometric levels. This is a particular problem in aquifers developed in closed basins where lateral inflow is nearly absent and replenishment is constrained by rainfall recharge. In this paper, simple indicators derived from meteorological data, abstraction rates and piezometric time series are compared with the groundwater storage depletion as obtained from a calibrated groundwater flow model. Application of the method to the overexploited Shahrekord basin in Iran shows that for the simulated period 1989-2003 an accumulative index of the difference of aquifer recharge, as calculated by a soil moisture balance method, and groundwater abstraction has a correlation coefficient of nearly one with model calculated storage. Indicators based on the filling index derived from piezometric time series or on the ratio of aquifer discharge to recharge have slightly lower correlations. The accumulated index indicator can be used to follow aquifer storage in the future without the need to run the full groundwater flow model. This simple approximation is restricted to aquifer systems with a limited lateral inflow and outflow.     

地下水控制性关键水位探讨——以双发乡为例

【目的】有效管理肇州县地下水开采。【方法】以双发乡为例,将地下水位划分为上蓝线水位、下蓝线水位、上红线水位和下红线水位,采用地下水位动态模拟分析法、含水层厚度比例等方法确定了双发乡各关键水位。【结果】双发乡下红线水位值为11.09 m,上红线水位值2 m;上蓝线水位为2.8 m,下蓝线水位值为10.66 m。【结论】针对不同的水埋深,基于水位和开采量的地下水"双控"管理模式。     

GIS tools applied to the sustainable management of water resources: Application to the aquifer system 08-29

The sustainable exploitation of water resources requires planning and control methods that allow the incorporation of a great number of spatial and temporal variables. Because of its features, a Geographic Information System (GIS) seems the most suitable tool to aid in the management of available hydric resources. In this study, we have developed a specific GIS within the GESMO Project in order to better manage the 08-29 aquifer system (Mancha Oriental). This tool is intended for use by the JCRMO: Junta Central de Regantes de la Mancha Oriental (General Board of Irrigation Users of Eastern La Mancha), the organism responsible for aquifer management.This system is designed to integrate information from different sources, such as remote sensing, fieldwork data or administrative files with the cadastral subplot as a common reference. One of its functions is to expedite the control and monitoring, in real time, of the exploitation plans, which constitute the legal instrument to regulate water extractions. It will allow us to estimate the spatial and temporal distribution of water extractions needed for crops and their irrigation systems. These estimates will be highly valuable for aquifer modelling. The system also permits display of information on maps for easy handling. This visualisation allow users to more readily participate in decision-making processes.     

辐射井在银北灌区开发浅层地下水中的应用

辐射井是开发浅层地下水的理想井型。针对银北灌区的水文地质条件。阐述了在银北灌区利用辐射井技术开发浅层地下水的设计方法，如竖井结构、井深设计、水平辐射管设计及涌水量计算等。并对成井技术、试验井的水量和水质等进行了探讨。     

Flexible delivery schedules to improve farm irrigation and reduce pressure on groundwater: a case study in southern Italy

This study was conducted on an irrigated area of southern Italy to analyze the current operation of a large-scale irrigation delivery system and the effects of the operation procedures on crop irrigation management and aquifer salinity increase. The area is characterized by relatively high levels of groundwater salinity in the summer that are probably due to intensive groundwater pumping by farmers during periods of peak irrigation demand, with the resulting seawater intrusion. Two alternative delivery schedules, namely the rotation delivery schedule and the flexible delivery schedule, referred to as RDS and FDS, respectively, were simulated using a soil-water balance model under different combinations of crop, soil and climatic conditions. The first set of simulations concerned the farm irrigation management constrained by the rotational delivery used by the local water management organization. The second scenario simulated the farm irrigation schedule most commonly used by growers in the area for maximizing crop yields. Based on crop irrigation management under RDS and FDS, two alternative operational scenarios were also developed at the scheme level and then compared for evaluation. Winter and summer salinity maps of the aquifer were developed by interpolating salinity measurements of the groundwater samples collected during the 2006 irrigation season. From these maps, a close relationship can be inferred among delivery schedule, aquifer exploitation and salinity increase, which justifies the need for implementing FDS that might reduce the groundwater demand for irrigation.     

Cost-effectiveness of groundwater conservation measures: A multi-level analysis with policy implications

Groundwater in Spain, as in other arid and semiarid countries worldwide, has been widely used in the expansion of irrigated agriculture. In the Spanish Mancha Occidental aquifer, the excessive, and sometimes illegal, water abstraction for irrigation has promoted outstanding socioeconomic development in the area, but it has also resulted in exploitation of the aquifer and degradation of valuable wetlands. Water policies implemented in the region have not yet managed to restore the aquifer and face strong social opposition. This paper uses a multi-scale modeling approach to explore the environmental and socio-economic impacts of alternative water conservation measures at the farm and basin levels. It also analyzes their comparative cost-effectiveness to help policy makers identify the least costly policy option for achieving the goal of the Mancha Occidental aquifer's sustainability. To conduct this analysis, a Mathematical Programming Model has been developed to simulate: the closing-up and taxed-legalization of unlicensed wells, uniform volumetric and block-rate water prices, water quotas, and water markets. Aggregate results show that net social costs are not substantially different across policy option, so none of the considered policy options will be clearly more cost-effective than the others. However, there are significant differences between private and public costs (at the farm and sub-basin levels), which will be critical for determining the application in practice of these policies. Results show that controlling illegal water mining (through the legalization of unlicensed wells) is necessary, but is not sufficient to recover the aquifer. Rather, effective water management in this area will require the implementation of other water management policies as well. Among them, uniform volumetric and block-rate water pricing policies will entail the lowest net social cost, but will produce important income losses in the smallest and most water-intensive farms, which might put at risk the viability of these farms and the social acceptance of the policies. Further investigations on social costs, policy enforcement capacity and public participation in water management are highly recommended.     

Modeling approach for the assessment of recharge contribution to groundwater from surface irrigation conveyance system

Rice–Wheat rotation system utilizes surface, ground and rain water resources conjunctively. Recent studies have shown increasing contribution of groundwater for crop irrigation. As the system utilizes water pumped from the underlying aquifer and partly seeps back, a cycle of recharge and discharge continues. Sustainability of groundwater system for the on-going drought in the country depends mainly on the recharge of the aquifer. The reported study was, therefore, carried out to measure and assess the recharge contribution of a distributary of canal in Punjab, Pakistan. Assessment of recharge through distributary was carried out using a groundwater flow “MODFLOW” model, which utilized the observed watertable, climatic, crop and soil for a period of about 1 year in addition to hydraulic conductivity, evapotranspiration and aquifer characteristics data. The requisite primary data for “MODFLOW” were collected from field and secondary data from public sector organizations dealing with water. Model calibration involved changing input parameters within reasonable limits until acceptable matches were obtained between the observed and simulated water levels for all observed hydrographs. The external inputs such as, recharge through irrigation, precipitation, stresses due to evaporation, lateral flow and stream were simulated to calculate the monthly water budget of aquifer. As concluded, recharge contribution was 16.5% of the inflow rate of the distributary. Using predicted results of the model a relationship between recharge (R) and discharge (Q) was also developed. Although, the presented results of recharge contribution were limited to one distributary of canal irrigation system, yet the developed methodology can be extended to the other canal systems of the Indus Basin.     

Assessment of groundwater risk using intrinsic vulnerability and hazard mapping: Application to Souassi aquifer, Tunisian Sahel

Special attention has been paid to risk assessment in water resource management in arid and semi-arid regions like the Souassi aquifer, Tunisia. Risk assessment, using vulnerability and hazard mapping, is considered as a fundamental aspect of sustainable groundwater management. To determine the degree of risk affecting the study area, an attempt has been made to combine hydro-geologic parameters using the DRASTIC method and the hazard assessment by taking the product of the weighted hazard value (H_I), the ranking factor (Q_N) and the reduction factor (R_f).All parameters used in this risk assessment were prepared, classified, weighted and integrated in a GIS environment. Data treatment shows that large areas in the Souassi aquifer can be classified as high or very high risk areas corresponding to pollution sources located in high vulnerability zones. The areas with low and very low risk are situated in the south, which could, consequently, be interesting for future development and long term planning of protective measures. Sensitivity analyses indicated that the removal of groundwater depth, net recharge and aquifer media parameters from the DRASTIC index, causes large variation in vulnerability assessment. Moreover, hydraulic conductivity and topography were found to be more effective in assessing aquifer vulnerability. Therefore, they should have higher weights than those assumed by the DRASTIC standard method, and contrary to the impact of the vadose zone parameter. The validity of the DRASTIC and the risk methods, verified by comparing the distribution of nitrates in the groundwater and the different vulnerability classes, shows a high similarity.     

沉降中心减采对北京平原地下水利用的影响分析

【目的】研究沉降中心减采对北京平原地下水利用的影响。【方法】采用非稳定流地下水模型和情景分析的方法,通过设计4个情景(现状保持(情景BAU)、沉降中心完全停采(情景PR100)、沉降中心减采50%(情景PR50)及沉降中心不同地区减采不同比例(情景PR520))模拟了地下水减采的影响。【结果】预测期内平均来说,情景BAU消耗1.16亿m3/a的含水层储存量,而情景PR100、PR50和PR520的储存量恢复分别为3.52亿、1.18亿和2.83亿m3/a。设计满足控沉目标的情景R:八仙庄、天竺和王四营用于工业和生活的地下水分别减采0.51亿、0.12亿和1.76亿m3,总开采量19.28亿m3,R是满足地面沉降控制要求条件下北京平原应采取的开采情景。【结论】沉降中心减采能有效恢复北京平原地下水水位和含水层储存量,是解决北京市地下水严重超采及其带来的地面沉降等生态环境问题最直接有效的方法,但要合理确定减采的比例,保证社会经济和地下水的协调发展。     

基于蚁群算法的含水层参数识别方法

含水层参数的确定,是进行地下水资源科学管理的基础和关键。针对传统一些求参方法的缺点,提出了基于蚁群算法的含水层参数识别方法,并给出了实施该方法的具体步骤。以无界承压含水层井流模型为例,讨论了蚁群算法在含水层参数反演中的应用。实例分析结果表明,蚁群算法在确定含水层参数的优化问题中不仅可行,而且具有求解精度高和鲁棒性强等特点,显示了蚁群算法在水科学优化问题中的应用前景。     

Identification of nitrate leaching hot spots in a large area with contrasting soil texture and management

Identification of nitrate (NO₃) leaching hot spots is important in mitigating environmental effect of NO₃. Once identified, the hot spots can be further analyzed in detail for evaluating appropriate alternative management techniques to reduce impact of nitrate on groundwater. This study was conducted to identify NO₃ leaching hot spots in an approximately 36,000 ha area in Serik plain, which is used intensively for agriculture in the Antalya region of Southern Turkey. Geo-referenced water samples were taken from 161 wells and from the representative soils around the wells during the period from late May to early June of 2009. The data were analyzed by classical statistics and geostatistics. Both soil and groundwater NO₃-N concentrations demonstrated a considerably high variation, with a mean of 10.2 mg kg⁻¹ and 2.1 mg L⁻¹ NO₃-N for soil and groundwater, respectively. The NO₃-N concentrations ranged from 0.01 to 102.5 mg L⁻¹ in well waters and from 1.89 to 106.4 mg kg⁻¹ in soils. Nitrate leaching was spatially dependent in the study area. Six hot spots were identified in the plain, and in general, the hot spots coincided with high water table, high sand content, and irrigated wheat and cotton. The adverse effects of NO₃ can be mitigated by switching the surface and furrow irrigation methods to sprinkler irrigation, which results in a more efficient N and water use. Computer models such as NLEAP can be used to analyze alternative management practices together with soil, aquifer, and climate characteristics to determine a set of management alternatives to mitigate NO₃ effect in these hot spot areas.     

Modelling seawater intrusion in the Burdekin Delta Irrigation Area,North Queensland,Australia

The Burdekin Delta is a major irrigation area situated in the dry tropics of North Queensland. It is unique in that (i) it overlies shallow groundwater systems that serve as a major water supply for the irrigation of sugarcane, and (ii) it is adjacent to the world heritage listed Great Barrier Reef. Water management practices include large recharge pits and surface spreading of water to assist with replenishment of the groundwater. This has been useful in maintaining groundwater levels to help control seawater intrusion. This technique, however, can be costly and ineffective in unconfined aquifer systems, which are subjected to large amounts of groundwater pumping for irrigation. There are more than 1800 production bores currently used for irrigation in the Burdekin Delta and the large volumes of water extracted have at times lowered the regional water tables and made it difficult to control seawater intrusion.     

河套灌区永济灌域地下水数值模拟

以内蒙古河套灌区永济灌域为研究对象,采用Visual Modflow软件建立了地下水三维非稳定流模型,运用手动调参和Pest模块调参相结合进行参数率定,选取的14口观测井的观测值和模拟值趋于一致,表明本文率定的参数合理,具有较高的精度。利用该模型模拟了不同开采方案下的地下水埋深变化,同一开采条件下,灌区南部地下水位埋深下降相对北部和中部较小,可适当加大南部的地下水开采量来减少引黄灌溉,该模拟结果存在一定的实用价值。     

安徽淮北平原井灌几个问题的探讨

安徽淮北平原宜井灌溉面积占总耕地面积近80%。从该区井灌水量平衡分析入手，指出在一般干旱年份（P=75%）淮北平原井灌区的灌溉率（可灌面积/耕地面积）仅为54%左右，即使考虑短期超采，缺水率仍达23%；由于存在两类不均匀系数，井灌的实际可开采程度只有可开采地下水资源量的70%左右，考虑这一因素的影响，对井灌区的地下水资源量进行了校核，结果表明对于一次灌溉而言井灌区的地下水实际可开采量大于灌溉需水量，完全能满足灌溉开采的需求；同时，推荐了该区合理的机井数量、布井方式及井点密度，并就井灌工程建设和地下水的开发利用提出了几点建议。     

Mutual monitoring in a tradable water rights system: A case study of Zhangye City in Northwest China

Tradable water right systems are becoming important ways to achieve distributive efficiency in water resources. In 2002, China's Ministry of Water Resources initiated a pilot project in Zhangye City in Northwest China. The project was designed to establish a new water use rights system with tradable water quotas with the hope of reallocating water resources more efficiently through market-based instruments. However, the tradable water right system is not well enforced. Based on both primary and secondary data, we find that mutual monitoring can improve the effectiveness of a water allocation and trading program. For both surface water and groundwater irrigation systems, the conditions needed to stimulate mutual monitoring include: (1) a hierarchical management system; (2) well defined water rights or quotas; (3) control of total water quotas and water sources by the upper hierarchy; and (4) an approximate balance between the water supply or pumping capacity and the water quota. We describe also the institutional requirements for stimulating mutual monitoring.     

农业园区开发项目管理成熟度模型及其应用要点

对于我国目前大多数实行企业化经营的农业园区开发项目来说，为了增强自身的市场竞争力，有必要在其开发中实施项目管理、建立并应用成熟度模型来进行“自我评价、持续改进”。参考现有项目管理成熟度模型而提出并设计的农业园区开发项目管理成熟度模型，包括5个等级、相应的关键过程域和相关的评价程序，是持续提高农业园区开发项目整体管理能力的重要工具。     

内蒙古河套灌区地下水开发利用模式的实例研究

内蒙古河套灌区节水改造后,引黄水量大幅度减少。在河套灌区内选择一块有代表性的区域作为研究对象,探讨河套灌区全面实施节水改造方案后,地下水开发利用的可行性以及井渠结合的合理模式。以MODFLOW软件为计算工具,对不同水井布局方案在某一确定的地下水开采强度下计算区地下水动态变化过程进行预测。计算结果表明,井渠结合区每年开采1200 m3/hm2条件下,连续多年运用能够保持采补平衡。不同的水井布局方案的计算表明,1200 m3/hm2开采水平下,以局部集中布井的布局形式较好。     

参数不确定性对地下水数值模拟结果可靠性的影响

以标准矩形为研究区,按介质渗透系数差异将研究区划分为4个单元,应用HydroGeoSphere模拟系统建立数值模型,以含水层渗透系数为目标参数,分析不同参数分区的灵敏度系数;选择高灵敏度的分区建立渗透系数随机场,进行参数不确定随机模拟,分析模拟结果相对确定性模型的可靠度.结果表明:位于模型最顶层的单元1内渗透系数灵敏度最大,这与该单元的分布位置直接相关;随机模拟得到的压力水头按一定频率分布,确定性模型所得到的压力水头变化值290.52 cm出现的频率仅为7%;当认为确定性模型结果的可靠度为100%时,随机模拟结果相对于确定性模型结果的可靠性明显降低,这表明考虑到参数的不确定性时,模拟结果与确定性模型结果存在显著差异.随机模拟结果的概率性分布特征可以更加真实地表达实际情况,有利于水资源决策性管理的风险规避.     

群井开采条件下承压含水层渗流动态模拟

根据有限差分方法 ,编制了承压含水层渗流模拟软件。对某水源地在群井开采情况下地下水渗流动态进行数值模拟。模拟结果显示 ,位于高渗区的井 ,压降漏斗较其它井大 ,压力下降快。当地层中存在裂隙时 ,平行裂隙方向压力下降比垂直裂隙方向要快得多。抽水初期 ,地层压力下降很快 ,以后 ,压力下降逐渐变缓 ,位于低渗透区的井逐渐不能满足流量要求。因此做好地下水资源规划十分重要     

An econometric irrigated crop allocation model for analyzing the impact of water restriction policies

The objective of the Spanish government-funded GESMO project is to research on new water policy evaluation and monitoring tools, applied to aquifer 8/23 in the Eastern Mancha, which covers one of the most important areas under the charge of the Júcar Catchment Confederation. The project is to output two types of end products: Decision Support Systems for defining water use policies, including economic impact and environmental simulators within a single multi-criteria decision-making environment and Measure Monitoring and Control Systems employing tele-detection and simulation of crop water needs. The Decision Support Systems will include three, highly complex, theoretical models in a single information technology product: a three-dimensional aquifer 8/23 behavior simulation model, an econometric model to predict crop allocation depending on the economic environment, water availabilities, etc., and an automatic alternative generation and evaluation system based on a multi-criteria methodology. The objective of the system is to advise on possible water policies and how they would materialize into spatially and temporally distributed water quotas (m³/ha) with the objective of both safeguarding the aquifer in the medium and long term and increasing the economic profitability of regional agriculture. In this paper, a regional econometric model is presented for studying the impact of water use quotas on the main irrigated crops allocation in the region.