[Assessment of groundwater vulnerability to nitrate in He'nan Province of China based on principal component regression].

According to the hydrological and morphological characteristics, He'nan Province was divided into mountainous region and plain region. The level of rich water, infiltration modulus of precipitation, fertilization level per unit area, proportions of vegetable planting area, and soil texture were selected as the common indices, and the slope and groundwater depth were selected as specific indices to assess the groundwater vulnerability to nitrate. Principal component regression analysis was adopted to determine the index weights, and the spatial distribution of groundwater vulnerability to nitrate in He'nan Province was assessed with ArcGIS 9.