An assessment of groundwater quality for drinking and agricultural purposes in Ca Mau peninsula, Vietnamese Mekong Delta

Groundwater serves as the major source for drinking water and the only fresh water source in the dry season in Ca Mau province, the Vietnamese Mekong Delta. The study is performed to assess groundwater quality in the area. Groundwater Quality Index (GWQI), magnesium hazard (MH), sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI) combined with geostatistical tools were conducted by using groundwater quality data from 400 samples collected from private wells. GWQI values suggest that 7%, 63%, 28%, 2%, 1% of total samples are classified into excellent, good, poor, very poor and unsuitable for drinking water. High Cl and TDS are the main cause of high GWQI values suggesting that saltwater intrusion deteriorates groundwater quality. For irrigation purposes, 4%, 17%, 36%, 43% of total samples classify into Good, Permissible, Doubtful, Unsuitable respectively by Na% indicator; 55.0%, 30.9%, 11.9%, 2.2% of total samples is Excellent, Good, Doubtful and Unsuitable according to SAR, 54% samples are unsuitable by MH index, and all samples are good by PI. This study provides useful information on groundwater quality for various purposes in Ca Mau province, that could help water management and water users to identify the necessary approach for groundwater protection and water-treatment methods before utilising the groundwater source for specific purposes in the study area.

Assessment of Groundwater Vulnerability using COP Method to Support the Groundwater Protection in Karst Area

The karst landform holds considerable water resource potential and is known for its underground rivers. On the other hand, the high porosity carbonate rocks on this landform cause the decrease of the natural protection function against groundwater pollution. Hence, the analysis of groundwater vulnerability in the karst area is prominent before making the spatial planning regulation. This recent study aimed to analyze the groundwater vulnerability in the karst area located in a part of Umbulrejo Village, Yogyakarta, Indonesia, and proposed action in groundwater protection. The method used in this research was based on the COP method. The data acquisition was conducted by survey method both for primary and secondary data. The COP (Concentration of flow, overlaying layers, and precipitation) analysis was supported by ArcGis software. The analysis of groundwater vulnerability showed that there were two vulnerability classes, i.e., very high (48.6%) and high (51.4%). These results were influenced mainly by the close distance of the recharge area to swallow holes and the lithology type (karst), which contributed to a very high value in reducing protection against groundwater. A proposed action to support groundwater protection is regulating the land utilization in the area of the settlements.

Effectiveness of Voluntary Measures to Reduce Agricultural Impact on Groundwater as a Source for Drinking Water: Lessons Learned from Cases in the Dutch Provinces Overijssel and Noord-Brabant

Agricultural practices cause diffuse water pollution issues, which is a policy concern across the globe. This paper addresses the reduction in agricultural impact on groundwater as source for drinking water with a governance approach based on a mutual gains approach (MGA) using voluntary measures only. We performed case studies in Overijssel and in Noord-Brabant, both located in the Netherlands, to study the effectiveness of the governance approach on nutrients and pesticides, respectively. The effectiveness was studied by analyzing the engagement process qualitatively and by analyzing the impact of measures at farm scale as quantitative indicators. For nutrients, the effectiveness is expressed in the N-surplus at farm scale and the realization of groundwater quality objectives in groundwater protection areas (GWPA). For pesticides, the effectiveness is expressed in environmental impact points (EIP) at farm scale and the level of groundwater protection areas (GWPA). The results indicate that the engagement process based on voluntariness creates a platform for meaningful engagement, adds to the economics of the farm and reduces the agricultural impact on groundwater quality. However, the nitrate objectives of the Water Framework Directive (WFD) are not met at the level of GWPAs in Overijssel. Due to the voluntariness of the approach, the participation rate relies on the farmers’ expectation of the costs and benefits of the process, and diminishing economic returns prevent the further improvement of efficient nutrient use. Although an enforceable objective and strict deadline for pesticides is missing, the objective has been met at the level of GWPAs using voluntary measures only in Noord-Brabant. An important driver for this effectiveness is the fact that these results can be obtained without incurring economic losses, which may tie into the high participation rate of farmers.

Karst hydrogeology of the Chalk and implications for groundwater protection

The Chalk is an unusual karst aquifer with limited cave development, but extensive networks of smaller solutional conduits and fissures enabling rapid groundwater flow. Small-scale karst features (stream sinks, dolines, dissolution pipes, and springs) are common, with hundreds of stream sinks recorded. Tracer velocities from 27 connections between stream sinks and springs have median and mean velocities of 4700 and 4600 m.d.−1. Tests to abstraction boreholes also demonstrate very rapid velocities of 1000s m.d.−1. Natural gradient tests from observation boreholes have rapid velocities of 100s m.d.−1. There is strong geological control on karst with dissolution focused on stratigraphical inception horizons. Surface karst features are concentrated near the Palaeogene boundary, or where thin superficial cover occurs, but rapid groundwater flow is also common in other areas. The Chalk has higher storage and contaminant attenuation than classical karst, but recharge, storage and flow are influenced by karst. Point recharge through stream sinks, dolines, losing rivers, vertical solutional fissures, and soakaways enables rapid unsaturated zone flow. Saturated zone networks of solutional fissures and conduits create vulnerability to subsurface activities, and enable long distance transport of point source and diffuse pollutants, which may be derived from outside modelled catchment areas and source protection zones.

Foreign legislation in the field of drinking groundwater protection (literature review)

The need to protect underground sources of drinking and household water supply. Many reasons, including climatic changes, an increase in anthropogenic pressure, and an increase in the need for drinking water, dictate the need to protect underground sources of drinking and domestic water supply. The USSR was the pioneer in the field of drinking water protection in the world. Already in 1956, USSR put an instruction on the establishment of sanitary protection zones (SPZ) into effect. The United States took the first steps in resolving this issue only seven years later. Along with Soviet developments, the USA and German guidelines are still fundamental and contain fundamental recommendations for groundwater protection. The requirements related to the protection of water intakes in the legislative acts of various states have been implemented at the international level (Directive 2000/60 / EU, Directive 2006/118 / EU), nationally (Australian National Strategy, USA Safe Drinking Water Law, PRC Law on Drinking Water Pollution Prevention and Control) and Local Levels (New Jersey safeguard zone (SGZ) Guidelines). Among the standard features is the allocation of belts in the S with different permitted use regimes: belt I (strict regime) - 10-50 m, belt II -50 days -10 years, belt III - the entire catchment area. Conclusions. Despite the fact that each country uses different approaches to protecting groundwater, in general, there is a similarity in the establishment and organization of SGZ for groundwater intakes, in which certain activities are prohibited or restricted. In the Russian Federation, it seems important to formalize the results of scientific research and existing experience in the protection of underground sources of drinking water supply in the form of Guidelines to allow ensuring optimal management of drinking water resources and preserve the quality of drinking water, to guarantee their availability in the future.