Active Water Quality Management in Rural Small Watersheds

Diverse land and water uses are found in rural areas of Monsoon regions. Based on field studies in Japan and Bangladesh, water quality management problems are considered at small watershed levels. A study site in Japan is chosen in a hilly area. Upland tea plantations in the site are the major source of nitrate pollution to the downstream water bodies because of heavy fertilizer application. Utilizing paddy fields and irrigation tanks as buffer of the polluted water is feasible, but it risks vulnerable aquatic ecosystems. Another study site is in the floodplains of Bangladesh. Countless ponds are used in the rural communities for domestic, animal watering and fishery purposes. Introduction of comparatively warm groundwater into the ponds during winter seasons may accelerate the growth of fish. However, groundwater depletion is the major concern. The concept of Markov decision processes is applied to find the optimal actions for the two different water quality management problems.