Collaborative Research: Hydrogeochemical Investigation of Seasonal Transition and Land Use Change Effects on Tropical Hydrology

过去六年，巴拿马热带季节的水文和地球化学研究揭示了在温带气候中未曾见过的径流行为。这一综合国际研究计划结合了季节性热带的水文、地球化学和地球物理测量，包括现场数据收集和分析，并通过使用天然和引进的示踪剂和建模得到加强。这一合作研究项目的总体目标是了解季节性热带地区重要的径流生成过程，以及季节转换和土地利用变化对径流机制阈值的作用。在一系列尺度上收集的水文、地球化学和同位素数据将比较几乎原始的414平方公里老里约热内卢查格斯河流域和邻近330平方公里森林大量砍伐的里约帕科拉流域，以检查土地利用变化的影响。不同的基岩类型覆盖着这些盆地，因此将使用地球化学和同位素来帮助确定流动路径和停留时间，并用于模型和假设检验。潮湿的热带地区覆盖了地球陆地表面的22%，居住着36%的人类。选定的研究区域代表了潮湿的热带地区，这促进了所获得的知识可转移到地理上较大的区域。这项研究将帮助回答三个非常重要的问题。砍伐森林或重新造林对季节性热带分水岭的水量有何影响？为什么雨季初期的径流产生行为与一年中的其他时间不同？我们如何通过改进的水文模型更好地预测这些影响？巴拿马运河分水岭对世界贸易极其重要，因为分水岭的径流驱动着巴拿马运河，而巴拿马运河对美国至关重要。这些研究成果将传达给巴拿马运河管理局、巴拿马大学，并通过同行评议文章广泛传播。该项目每年将举办热带水文学国际实地课程，向合格的美国和巴拿马研究生和本科生开放。该项目是对史密森热带研究所(STRI)巴拿马运河分水岭实验的赞扬，STRI是合作者，巴拿马运河管理局和巴拿马理工大学也是合作者。

Hydrological and geochemical studies in the seasonal tropics of Panama over the past six years have revealed runoff behaviors not seen in temperate climates. This integrated international research program combines hydrological, geochemical, and geophysical measurements in the seasonal tropics including in situ data collection and analysis, enhanced by the use of natural and introduced tracers and modeling. The overall objective of this collaborative research program is to understand important runoff generating processes in the seasonal tropics and the roles of seasonal transitions and land-use changes on runoff mechanism thresholds. Hydrologic, geochemical and isotopic data collected over a range of scales will compare the virtually pristine 414 km2 old-growth Upper Rio Chagres and adjacent 330 km2 largely deforested Rio Pacora watersheds to examine land-use change effects. Different bedrock types underlay these basins, so geochemistry and isotopes will be used to assist in identifying flow paths and residence times and in model and hypothesis testing. The humid tropics cover 22% of the Earth's land surface and are home to 36% of humanity. The selected study area is representative of the humid tropics promoting transferability of the knowledge gained to a geographically large region. There are three very important questions that this research will help answer. What is the effect of deforestation or reforestation on the water yields from watersheds in the seasonal tropics? Why does runoff generation behave differently early in the rainy season than at other times of the year? How can we better predict these effects by improved hydrologic models? The Panama Canal watershed is extremely important for world commerce because the runoff from the watershed drives the Panama Canal, which is vitally important to the United States. These research results will be communicated to the Panama Canal Authority, Panamanian Universities, and broadly disseminated through peer-review articles. An international field course on tropical hydrology will be held each year of the project and will be open to qualified U.S. and Panamanian graduate and undergraduate students. The project compliments the Smithsonian Tropical Research Institute (STRI) Panama Canal Watershed Experiment, and STRI is a collaborator, as are the Panama Canal Authority and the Technological University of Panama.