Evaluation of small-scale on-farm ponds in northeast Thailand using hydrologic model and GIS
2005
Suzuki, K.(Japan International Research Center for Agricultural Sciences, Tsukuba, Ibaraki) | Yamamoto, Y. | Ando, M.
We proposed a method for evaluating the hydrology of small-scale on-farm ponds in northeast Thailand. First, we made interviews to farmers in the study site about their usage of on-farm ponds, and confirmed the ponds were used multipurposely. Then, we simulated to estimate changes of water depths in typical ponds in catchment areas with different sizes. By the results, the relation between catchment area and minimum water depth for the past five years was shown. When the catchment area ratio (Rca: catchment area/on-farm pond area) was less than 5, the minimum water depth was 1m or less, which makes fish culture difficult. When Rca was 9 or more, the minimum water depth was more than 1.75m, and approximately 500m(3) of extra water per pond was available in dry season. These ratios were used as thresholds for categorization of ponds into three categories (category A: Rca =9; category B: Rca 5-9, and category C: Rca 5) based on the catchment area which was determined from satellite imagery. We applied the method to 180 ponds in the study area. Half were belonged to category A, 10% to B, and 40% to C. The amount of water that was not being stored due to inappropriate pond location was more than 20% of the total pond capacity.
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