Evaluation of the groundwater function for conservation of coastal ecosystems
Seagrass and seaweed meadows are regarded as an important coastal ecosystems for their functions of “ecosystem service”, such as carbon stock and habitats. Though conservation of these meadows is a global issue for the healthy cycles of food and materials, their biomass has been decreasing worldwide. Diversity in the coastal environment (e.g. variation in salinity, water temperature, nutrients, bottom materials etc.), produced by both sea-factors and terrestrial-factors, is important for seagrass and seaweed meadows to coexist with the other primary producers. We evaluate the function of “submarine groundwater discharge (SGD)” for diversity production in the coastal environment by field observations, satellite data, and hydrological models.
Human and climate impacts on water environment and water resources
Human activities in urban and rural areas alter the natural hydrologic and material cycles in watersheds. For example, overdrawing groundwater for drinking, irrigation, and industrial use increase the risks of water deficiency, land subsidence, contamination and salinization. Increase of nutrients (e.g. nitrogen, phosphorus) entering the environment by human activities(e.g. agriculture, industries) cause eutrophication of surface water environments and contamination of groundwater resources. We evaluate the current status and future outlook of water resources and environments based on field observations, chemical and isotopic analysis, and hydrological models for several countries in different climate zones, urbanization status, and cultures. We will also suggest the solutions for sustainable water-nutrient cycles for the future.