Groundwater level monitoring-importance global groundwater monitoring network

The paper illustrates the concept, methodology, essential components and importance of groundwater level monitoring in terms of various aquifers such as multiple aquifer, karst aquifer and other aquifers. The groundwater resources in Mekong countries including Cambodia, Laos PDR, Myanmar, Thailand and Vietnam have also been reviewed. Finally, the author briefly presents Global Groundwater Monitoring Network.

Upgrading a regional groundwater level monitoring network for Beijing Plain,China

Monitoring of regional groundwater levels provides important information for quantifying groundwater depletion and assessing impacts on the environment. Historically, groundwater level monitoring wells in Beijing Plain, China, were installed for assessing groundwater resources and for monitoring the cone of depression. Monitoring wells are clustered around well fields and urban areas. There is urgent need to upgrade the existing monitoring wells to a regional groundwater level monitoring network to acquire information for integrated water resources management. A new method was proposed for designing a regional groundwater level monitoring network. The method is based on groundwater regime zone mapping. Groundwater regime zone map delineates distinct areas of possible different groundwater level variations and is useful for locating groundwater monitoring wells. This method was applied to Beijing Plain to upgrade a regional groundwater level monitoring network.

Entropy-Based Approach to Remove Redundant Monitoring Wells from Regional-Scale Groundwater Network

An entropy-based approach is applied to identify redundant wells in thenetwork. In the process of this research, groundwater-monitoring network is considered as acommunication system with a capability to transfer information, and monitoring wells are taken asinformation receivers. The concepts of entropy and mutual information are then applied to measurethe information content of individual monitoring well and information relationship betweenmonitoring well pairs. The efficiency of information transfer among monitoring wells is the basis tojudge the redundancy in the network. And the capacity of the monitoring wells to provideinformation on groundwater is the point of evaluation to identify redundant monitoring wells. Thisapproach is demonstrated using the data from a regional-scale ground-water network in Hebei plain,China The result shows that the entropy-based method is recommendable in optimizing groundwaternetworks, especially for those within media of higher heterogeneities and ani-sotropies.

Study on Establishing a Monitoring System for Groundwater in the Condition of Climate Change and Sea Level Rise： Case Study of Ma River Basin in Vietnam

The results presented in this paper are a part of the research results of the thesis ＂research on scientific basis and practice of develop a system of monitoring the impacts of climate change on surface water and groundwater＂. Case study： Ma river basin in Vietnam. The results were implemented： （i） data collection, fieldwork survey, synthesis and analysis of information and data; （ii） partitioning the influence degree of climate change and sea level rise to groundwater; （iii） determining criteria to select monitoring routes, location of monitoring groundwater in the condition of climate change and sea level rise and （iv） developing the monitoring system. The research＇s results have practical implications for the water resources management in the context of climate change and sea level rise in Ma river basin.

Quantitative Estimation of Groundwater Leakage from Namco Lake by SAR Monitoring

Objective This study focused on the Namco, the largest lake on the Tibet plateau as well as the highest large lake in the world. A large imbalance between water input and output of this lake has attracted great attention in the field of hydrogeology during recent years. As there is no surface outflow from Namco, the large water imbalance can only be explained by water seepage. Synthetic aperture radar （SAR） image data were used for the first time in combination with hydrological data actually measured in the field and meteorological station data, to quantitatively acquire the information of surface fluctuation, water storage variation, and to estimate groundwater leakage from Namco Lake. The results provide theoretical support and data for further understanding the processes and extent of water resource response to global climate change, and also provide a scientific basis for rational development and utilization of water resource in the Tibetan Plateau.

Health Risks Assessment Due to Exposure to Vinyl Chloride in Groundwater from a Closed Landfill： A Case Study as a Contaminant of Concern and Effect of Subsurface Characteristics

The purpose of this study was to analyze the migration pathways of contaminants from closed landfills and to estimate health risks based on soil characteristics. The health risks were estimated using Framework for Risk Analysis Multimedia Environmental Systems （FRAMES） software. The sensitivity of human health risks and hazard indices due to vinyl chloride contamination in groundwater were performed in relation to soil characteristics such as Darcy velocity, thickness of soil layer, mass of contaminant present in the aquifer. Based on the analysis, Darcy velocity showed no effect on estimated risks. Since soil layer thickness had a significant effect on the estimated health risks, effects of different soil types on estimated risks were analyzed. The results showed that soils from the least appropriate to the most appropriate for risk management due to groundwater contamination were sand, sandy clay, sandy loam, loam and clay loam. FRAMES model was suitable for assessing the health risks due to vinyl chloride contamination in groundwater originating from a municipal solid waste landfill. The model showed the changes in both carcinogenic and non carcinogenic risks over time. The estimated health risks were directly correlated with the levels of vinyl chloride detected in groundwater.

DESIGN OF GROUNDWATER LEVEL MONITORING NETWORK WITH ORDINARY KRIGING

The primary network of groundwater level observation wells aims at realizing a regional groundwater management policy. It may give a regional picture of groundwater level with emphasis on the natural situation. Observation data from the primary network can be used to estimate the actual state of groundwater system. Since the cost of the installation and maintenance of a groundwater monitoring network is extremely high, the assessment of effectiveness of the network becomes very necessary. Groundwater level monitoring networks are the examples of discontinuous sampling on variables presenting spatial continuity and highly skewed frequency distributions. Anywhere in the aquifer, ordinary kriging provides estimates of the variable sampled and a standard error of the estimate. In this article, the average Kriging standard deviation was used as a criterion for the determination of network density,and the GIS-based approach was analysized. A case study of groundwater level network simulation in the Chaiwopu Basin, Xinjiang Uygur Autonomous Region, China, was presented. In the case study, the initial phreatic water observation wells were 18, a comparison of the three variogram parameters of the three defferent variogram models shows that the Gaussian model is the best. Finally, a network with 55 wells was constructed.

Main progress and prospect for China’s hydrogeological survey

This paper reviewed the main achievements of hydrogeological survey in China,summarized the significant progress of hydrogeological survey over the past decade,and forecasted the key responsibilities for hydrogeological survey in the“14th Five-year Plan”.The significant progress includes:China established the 1:50000 standard hydrogeological survey system with Chinese characteristics and produced the new generation of highquality hydrogeological maps;the national groundwater monitoring project was completed and accepted,which marks China taking the leading position in groundwater monitoring internationally;fruitful results were achieved in the national groundwater quality survey,and groundwater quality background values were basically identified and checked;hydrogeological and environmental geological survey was continuously promoted in karst areas and the ecological restoration of rocky desertification achieved remarkable results;China strengthened layer exploration techniques for groundwater,integrating the key and practical techniques of layer exploration and monitoring;the exploration of groundwater in the poverty-stricken regions and old revolutionary base areas were effectively promoted to strongly guarantee the poverty alleviation and drinking water safety;the mystery of desert groundwater was uncovered,making up for the shortage of 1:250000 hydrogeological survey in the Badain Jaran Desert;and more efforts were made to conduct survey on the water resources in the basin,and to finish the unified measurement of national-scale groundwater level.