Interpolation of contaminant data can present a significant challenge due to sample clustering and sharp gradients in concentration. The research presented in this paper represents a study of commonly used interpolation schemes applied to three-dimensional plume characterization. Kriging, natural neighbor, and inverse distance weighted interpolation were tested on four actual data sets. The accuracy of each scheme was gauged using the cross-validation approach. Each scheme was compared to the other schemes and the effect of various interpolation parameters was studied. The kriging approach resulted in the lowest error at three of the four sites. The simpler and quicker inverse distance weighted approach resulted in a lower interpolation error on the other site and performed well overall. The natural neighbor method had the highest average error at all four sites in spite of the fact that it has been shown to perform well with clustered data. Another unexpected result was that the computationally expensive high order nodal functions resulted in reduced accuracy for the inverse distance weighted and natural neighbor approaches.

This paper examines the effects of irrigation practices and related activities on the environment and human health in the West Bank. Irrigated agriculture in the West Bank covers an area of * 9,473 ha and utilizes 93 million cubic meters of irrigation water annually. The current annual use of fertilizers in the irrigated areas is 18,980 tons of chemical fertilizers and 198,900 to 265,200 tons of organic fertilizers. The total annual use of pesticides (excluding methyl bromide) in irrigated agriculture is 153 tons, of which 27 tons are internationally banned products. Methyl bromide is a dominant soil fumigant in the West Bank with a total estimated annual use of 400 tons, 44% of which is used on vegetables planted in plastic houses and high plastic tunnels. The soil solarization method to control soil-borne diseases is used by only 0.5% of the surveyed farmers.This study indicates that some farmers have suffered health problems due to exposure to pesticides, from the lack of protective clothing. Of the surveyed farmers, 19% suffer from poisoning symptoms and 1% are affected by methyl bromide fumigants. The total quantity of plastic sheets was estimated at 4,750 tons, at least 50% of which becomes waste. Eighty-eight percent of the surveyed farmers collect and burn the plastic wastes on the field, which could harm both the environment and human health through toxic fumes. Some water-related diseases occurred in the study area. Seventy-nine people were affected by leishmaniasis and 14 others by dysentery. Despite the heavy use of fertilizers, water quality analysis did not show high concentrations of nitrate.