Multi-criteria decision model for assessing groundwater pollution risk in the urban-rural interface of Mar del Plata City (Argentina).

In developing countries, conflict between the objectives of environmental policies and those focused on economic development, a low availability of human resources and infrastructure, and the lack of continuity and incentives, contribute to the inability to successfully implement environmental policies. Moreover, in these countries, population growth in the peri-urban areas has resulted in serious water pressures, poor water management, and severe non-point source pollution. The aim of this paper is to implement a procedure of aquifer pollution risk assessment for identifying priority areas in an urban-rural interface based on multi-criteria decision tools. In this sense, a multi-criteria decision model was designed, in terms of environmental and socio-economic criteria and sub-criteria relevant to water resource management, by using the software Criterium Decision Plus 4.0. This model was applied to the northwestern peri-urban area of Mar del Plata City, Argentina, which is embedded in the second most important fruit-horticultural belt of the country. Here, groundwater is the only source of water supply. The proposed decision model allowed establishing a ranking of priority areas for defining action guidelines in order to minimize the risk of pollution of the aquifer. Aquifer pollution hazard criterion mainly contributes to alternatives classified as very high priority whilst in the case of low and very low priority classes, social vulnerability criterion mostly influences the final results. The first alternatives will require an intervention in a short-term time horizon, and the last ones must be monitored in order to avoid their shift to a worse environmental condition.

Decision support model for assessing aquifer pollution hazard and prioritizing groundwater resources management in the wet Pampa plain, Argentina.

This paper gives an account of the implementation of a decision support system for assessing aquifer pollution hazard and prioritizing subwatersheds for groundwater resources management in the southeastern Pampa plain of Argentina. The use of this system is demonstrated with an example from Dulce Stream Basin (1,000 km(2) encompassing 27 subwatersheds), which has high level of agricultural activities and extensive available data regarding aquifer geology. In the logic model, aquifer pollution hazard is assessed as a function of two primary topics: groundwater and soil conditions. This logic model shows the state of each evaluated landscape with respect to aquifer pollution hazard based mainly on the parameters of the DRASTIC and GOD models. The decision model allows prioritizing subwatersheds for groundwater resources management according to three main criteria including farming activities, agrochemical application, and irrigation use. Stakeholder participation, through interviews, in combination with expert judgment was used to select and weight each criterion. The resulting subwatershed priority map, by combining the logic and decision models, allowed identifying five subwatersheds in the upper and middle basin as the main aquifer protection areas. The results reasonably fit the natural conditions of the basin, identifying those subwatersheds with shallow water depth, loam-loam silt texture soil media and pasture land cover in the middle basin, and others with intensive agricultural activity, coinciding with the natural recharge area to the aquifer system. Major difficulties and some recommendations of applying this methodology in real-world situations are discussed.

Groundwater vulnerability assessment combining the drastic and dyna-clue model in the Argentine pampas.

Vulnerability assessment is considered an effective tool in establishing monitoring networks required for controlling potential pollution. The aim of this work is to propose a new integrated methodology to assess actual and forecasted groundwater vulnerability by including land-use change impact on groundwater quality. Land-use changes were simulated by applying a spatial dynamics model in a scenario of agricultural expansion. Groundwater vulnerability methodology DRASTIC-P, was modifyed by adding a land-use parameter in order to assess groundwater vulnerability within a future scenario. This new groundwater vulnerability methodology shows the areas where agricultural activities increase the potential level of groundwater vulnerability to pollution. The Dulce Creek Basin was the study case proposed for the application of this methodology. The study revealed that the area with Very High vulnerability would increase 20% by the year 2020 in the Dulce Creek Basin. This result can be explained by analyzing the land-use map simulated by the Dyna-CLUE model for the year 2020, which shows that the areas with increments in crop and pasture coincide with the area defined by the Very High aquifer vulnerability category in the year 2020. Through scenario analysis, land-use change models can help to identify medium or long term critical locations in the face of environmental change.

Assessing groundwater pollution hazard changes under different socio-economic and environmental scenarios in an agricultural watershed.

This paper proposes a modeling approach for assessing changes in groundwater pollution hazard under two different socio-economic and environmental scenarios: The first one considers an exponential growth of agriculture land-use (Relegated Sustainability), while the other deals with regional economic growth, taking into account, the restrictions put on natural resources use (Sustainability Reforms). The recent (2011) and forecasted (2030) groundwater pollution hazard is evaluated based on hydrogeological parameters and, the impact of land-use changes in the groundwater system, coupling together a land-use change model (Dyna-CLUE) with a groundwater flow model (MODFLOW), as inputs to a decision system support (EMDS). The Dulce Stream Watershed (Pampa Plain, Argentina) was chosen to test the usefulness and utility of this proposed method. It includes a high level of agricultural activities, significant local extraction of groundwater resources for drinking water and irrigation and extensive available data regarding aquifer features. The Relegated Sustainability Scenario showed a negative change in the aquifer system, increasing (+20%; high-very high classes) the contribution to groundwater pollution hazard throughout the watershed. On the other hand, the Sustainability Reforms Scenario displayed more balanced land-use changes with a trend towards sustainability, therefore proposing a more acceptable change in the aquifer system for 2030 with a possible 2% increase (high-very high classes) in groundwater pollution hazard. Results in the recent scenario (2011) showed that 54% of Dulce Stream Watershed still shows a moderate to a very low contribution to groundwater pollution hazard (mainly in the lower area). Therefore, from the point of view of natural resource management, this is a positive aspect, offering possibilities for intervention in order to prevent deterioration and protect this aquifer system. However, since it is quite possible that this aquifer status (i.e. groundwater quality) changes in the near future, the implementation of planning measures and natural resource management is recommended.