The objective of this study was to develop a hydro-chemical model using the Soil and Water Assessment Tool (SWAT) and to evaluate the climate change impacts on discharge and nitrate-nitrogen loads from Ise Bay watersheds (the Kiso, Nagara, Ibi, and Shonai rivers). Using a regional climate model, through the dynamic downscaling approach, present and future climate data were generated at a 2 km spatial resolution. The pseudo-global warming downscaling approach under the A1B scenario was adopted for future climate prediction. Then, the optimized SWAT model, driven by the present and future climate data, was executed. The following results were obtained: (1) the significant increase of precipitation in May and June and decrease in August in the future climate scenario, and consequent discharge from the target watersheds also increased in May and June and decreased in August and September; (2) Due to the change in discharge, nitrate-nitrogen loads of the Kiso, Nagara, and Ibi rivers also increased in May and June and decreased in August and September; and (3) While nitrate-nitrogen load from deciduous forest tends to decrease, the one from evergreen forest tends to increase. The response of the model indicated the possibility of an increase in nitrogen uptake by deciduous forests.

中文翻译：

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建立伊势湾流域的水化学模型，并评估气候变化对排放量和硝酸盐氮负荷的影响

这项研究的目的是使用土壤和水评估工具（SWAT）建立水化学模型，并评估气候变化对伊势湾流域（Kiso，Nagara，Ibi和Iso）的排放和硝酸盐氮负荷的影响。庄内河）。使用区域气候模型，通过动态降尺度方法，以2 km的空间分辨率生成了当前和将来的气候数据。在未来气候预测中采用了A1B情景下的拟全球变暖降尺度方法。然后，执行了由当前和未来气候数据驱动的优化SWAT模型。得到了以下结果：（1）在未来的气候情景中，5月和6月的降水显着增加，而8月则减少，因此，目标流域的排放量在5月和6月也有所增加，而在8月和9月有所减少；（2）由于流量的变化，木曾河，长良河和伊比河的硝酸盐氮负荷在5月和6月也有所增加，而在8月和9月则有所减少；（3）虽然落叶林的硝酸盐氮负荷有降低的趋势，但常绿林地的硝酸盐氮负荷有升高的趋势。该模型的响应表明，落叶林可能吸收更多的氮。