A GIS‐BASED MODELING APPROACH FOR EVALUATING GROUNDWATER VULNERABILITY TO PESTICIDES¹

Abstract

The Attenuation Factor (AF), a screening model, was used to evaluate the relative degree of vulnerability of groundwater to pesticide contamination in Louisa County, Virginia. For evaluating the contamination potential of pesticides, three scenarios of pesticide leaching represented by high, moderate, and low cases of degradation and sorption in the soil were considered. Data layers were overlaid within a Geographic Information System (GIS) for spatial computation of AF for the actual and 2m groundwater depths. This spatial database was divided into five contamination potential categories namely high, medium, low, very low, and unlikely, based on the numerical values of the AF for each cell (119 ha). The results for the three most mobile pesticides are presented in this paper. The performance of the AF model was evaluated by comparing its predicted results with the field data from an experimental watershed. The AF model was able to identify most of the frequently detected pesticides in the watershed. A sensitivity analysis was also performed. The results of this study provide information about the potential groundwater threat by pesticides to the citizens ahd decision‐makers in the County and can be used for formulating an appropriate land use management plan to protect the groundwater quality.

Herbicide leaching as affected by macropore flow and within‐storm rainfall intensity variation: a RZWQM simulation

“…Water quality models are tools policy‐makers can use to help make decisions and scientists can use to investigate water quality issues 1, 2. To describe or predict adequately the water quality impacts of chemical transport in soils, two effects are clearly important, inadequately investigated and likely to be interacting: the contribution of macropores to leaching, and the effect of rainfall intensity variation during events.…”

Groundwater management and development by integrated remote sensing and geographic information systems: prospects and constraints

“…Finally, a regional GIS-driven integrated assessment approach is proposed, which is based on costbenefit analysis, and incorporates both physical and economic factors that can be used in a regulatory decision process. Shukla et al (1998) developed a GIS-based attenuation factor (AF) model to evaluate the relative degree of groundwater vulnerability to pesticide contamination in Louisa County, Virginia. Spatial (land use, soils, and groundwater recharge) and tabular databases (soils and pesticides) were used within a GIS environment to create contamination livelihood maps based on the AF values.…”

Methoden zur Abschätzung der Verschmutzungsempfindlichkeit des Grundwassers

“…B. das Vorhandensein einer gering durchlässigen Deckschicht oberhalb des Grundwasserleiters (DVGW 1995). Eine direkte Quantifizierung der Verschmutzungsempfindlichkeit des Grundwassers (in SI-Einheiten) ist nicht möglich (NRC 1993 & COLLIN 1987, FOSTER 1987, NRC 1993, U. S. EPA 1993, SCHLEYER 1993 LOAGUE et al 1996, SHUKLA et al 1998, TIM et al 1996 TEUTSCH 1995, GÖRRES & GOLD 1996, WU et al 1996, LASSERRE et al 1999 …”