Water quality category evaluation method based on regional underground water flow field direction

The invention provides a water quality category evaluation method based on a regional underground water flow field direction. The method comprises the following steps: determining a research region needing water quality category evaluation; carrying out gridding; processing a data set M (n2) to meet normal distribution; calculating a water quality monitoring parameter estimation value of each unknown sampling point; and performing single-index water quality category evaluation and multi-index water quality category comprehensive evaluation on the research region. When the water quality monitoring parameters of unknown sampling points are subjected to interpolation calculation, distance influence factors of known sampling points on unknown sampling points are considered; meanwhile, the influence of the underground water flow field direction on underground water solute transport is also considered; a semi-variation function model added with an anisotropy angle theta parameter is used forreflecting the spatial c