A comparative analysis of methods for mapping groundwater pollution hazard: application to the Gallocanta Hydrogeologic Unit (Spain)

Anthropogenic activities are the main sources of groundwater pollution. In order to prevent groundwater degradation and to apply suitable mitigation measures, hazard maps are a useful instrument for decision makers. The ultimate goal of the research is to analyse the effectiveness of several groundwater hazard indexes at the Gallocanta Lagoon Basin. To do so, the Hazard Index, the Danger of Contamination Index and the Pollutant Origin and its Surcharge Hydraulically method were applied and compare, and the potentialities and weaknesses of the resulting maps have been analysed. Accurate hazard maps were obtained and, based on their methodological approach, significant differences were found in relation to the rating process, the inventory of the sources, and the treatment of quantity and likelihood. In the light of the results, the indexes tended to undervalue the hazard level of agricultural activities, which were the main sources of pollution of the study area. Therefore, due to the characteristic land uses of the study area, typical of the Mediterranean context, some proposals to improve the indexes have been suggested.

Multi-hazard Groundwater Risks to Water Supply from Shallow Depths: Challenges to Achieving the Sustainable Development Goals in Bangladesh

Groundwater currently provides 98% of all drinking-water supply in Bangladesh. Groundwater is found throughout Bangladesh but its quality (i.e., arsenic and salinity contamination) and quantity (i.e., water-storage depletion) vary across hydrological environments, posing unique challenges to certain geographical areas and population groups. Yet, no national-scale, multi-parameter groundwater hazard maps currently exist enabling water resources managers and policy makers to identify vulnerable areas to public health. We develop, for the first time, groundwater multi-hazard maps at the national scale of Bangladesh combining information on arsenic, salinity, and water storage. We apply geospatial techniques in ‘R’ programming language and ArcGIS environment, linking hydrological indicators for water quality and quantity to construct risk maps. A range of socioeconomic variables including access to drinking and irrigation water supplies and social vulnerability (i.e., poverty) are overlaid on these risk maps to estimate exposures. Our multi-parameter groundwater hazard maps show that a considerable proportion of land area (5–24% under extremely high to high risks) in Bangladesh is currently under combined risk of arsenic and salinity contamination, and groundwater-storage depletion. As small as 6.5 million (2.2 million poor) to 24.4 million (8.6 million poor) people are exposed to a combined risk of high arsenic, salinity, and groundwater-storage depletion. Our groundwater hazard maps reveal areas and exposure of population groups to water risks posed by arsenic and salinity contamination and depletion of water storage. These geospatial hazard maps can potentially guide policy makers in prioritizing mitigation and adaptation measures in order to achieve the United Nation’s Sustainable Development Goals across the water, agriculture, and public health sectors in Bangladesh.

Changes in the groundwater quality of the main useful aquifer as a result of the hazard of nitrates from agricultural sources

The article presents the results of research, conducted in central Poland, where agriculture is the dominant type of land use. This activity is considered as a common potential hazard to groundwater quality because of the use of nitrate fertilizers, especially for small groundwater intakes used for the purpose of rural water supply. For this kind of intake seven scenarios of groundwater quality hazard were elaborated based on the results of the hydrodynamic modelling research in this area including the following: calculation of volume and time of leakage through the aquitard formations to the main useful aquifer, verification of the indirect protection zone and definition of the size of the well capture zone. The scenarios considered the current groundwater quality hazard as well as changes in agricultural land use or changes in fertilizer doses needed to decrease groundwater hazard by nitrates in the intake.

Prediction and mapping of landslide hazard

The paper describes a mechanics-based methodology for prediction of landslide hazard on hillside slopes. The principal components are estimation of infiltration and groundwater response, and estimation of safety factor and failure probability. Predictions with the models are made by using the best estimates of the input parameters and the associated uncertainties. The uncertainties about the inputs and the sensitivities of the model outputs to uncertainties about the inputs are evaluated and translated into failure probability. Our objective was to provide a method that can be used to estimate landslide hazard over a large area prior to making detailed site investigations. The method was applied to slopes along the South Fork of Tilton River, in the Cascade Mountains of Washington State. Predicted hazards were compared with results of a landslide inventory. The data used in the examples were derived from published sources. However, the procedures developed are not limited to this condition and can readily incorporate additional information derived from more detailed investigations.Key words: failure probability, groundwater, hazard, landslides, mapping, slope stability.

Site-Specific Pesticide Recommendations: The Final Step in Environmental Impact Prevention

A screening procedure to minimize adverse water quality impacts of pesticide application is presented that matches pesticide parameters to site-specific soil ratings. The pesticide parameters include a Relative Leaching Potential Index (RLPI), a Relative Runoff Potential Index (RRPI), the U.S. Environ. Prot. Agency (USEPA) lifetime health advisory level (HAL), and aquatic toxicity (LC50). Criteria used in developing soil ratings are described. Pesticide selection is accomplished by matching pesticide parameters values for the array of pesticides that control the pest of interest to soil ratings at the application site using selection criteria. A worksheet is presented to facilitate organization of information for the selection procedure and to serve as a record of the pesticide applicator's decision. The linking of an environmental fate model to a geographic information system (GIS) to create thematic maps of pesticide leaching potentials in terms of probability of exceeding the HAL in groundwater is described. A cost vs. groundwater hazard index frontier is described that suggests a method to assess the economic consequences of alternative pesticide selections.