This presentation aims to show datasets of water contamination patterns on earth surface systems that potentially extend as a subject to apply data assimilation. Two main topics will be presented from ongoing research works. One is the results of groundwater flow simulation coupled with nitrogen transportation and transformation in Kumamoto area in Japan. The other topic is about law of river water nitrate contamination patterns as well as other relevant major ions patterns over Japan, which can potentially be deduced from multiple informatics including land use and geological distributions other than direct measurement by the chemical analysis. Data assimilation techniques may shed a new light on the robust visualization of material flux on earth surface systems without performing chemical laboratory works, an important aspect for more effective sustainable water resource management and environmental assessments.