Spatio-Temporal Model of a Product–Sum Simulation on Stream Network Based on Hydrologic Distance

The modeling of spatio-temporal processes is crucial in many fields such as environmental science, hydrology, and water storage engineering. A basic concept the model an auto-covariance function. stream network based on Euclidean distance function for investigating river pollution will potentially face a serious accuracy problem, due to material or pollutant movement only occurring within travelled not following path network. use hydrologic may overcome problem because, statistically, distance-based valid if it negative-definite. Therefore, this study develops generalized product–sum with positive-definite property. proposed built and, subsequently, then verified mathematically be positive-definite. Furthermore, relationships between distance, spatial configurations are also investigated. simulation result shows some semivariogram models. follow exponential model.