Traditional agricultural practices, including paddy farming on terraced uplands, have garnered renewed interest in recent years in response to increasing concerns on environmental sustainability and the expected effects of climate change on global food security. However, little systematic research on the potential vulnerabilities of these traditional agroecosystems to future climatic change has been conducted as most are located in remote areas with limited data availability. This paper is a case study on the Ifugao Rice Terraces of the Philippines, a centuries-old farming system whose success is dependent on the year-round allocation of water resources following an intricate agricultural cycle. We developed a site-specific hydrological model coupling the similar hydrologic element response (SHER) model for surface and vadose zone processes and the modular three-dimensional groundwater flow (MODFLOW) model for saturated groundwater movement to evaluate baseline conditions in a selected first-order catchment within the Kiangan terrace cluster. Output from the SHER–MODFLOW model showed good agreement with in situ observations of stream discharge and hydraulic head measured in 2014–2016. To elucidate the impacts of climate change, we downscaled future projections from three global climate models, MRI-CGCM3, GFDL-CM3, and UKMO-HadGEM3, under greenhouse gas concentration pathways RCP-4.5 and RCP-8.5. We used these future climate projections with the calibrated SHER–MODFLOW model to evaluate the combined surface water and groundwater resources in 2041–2050 and 2091–2100. Results indicated trends of increasing temperature for all months, decreasing rainfall and increased risks of water deficits for future dry seasons, and increasing rainfall and increased risks of excess runoff for future wet seasons. These trends will be more pronounced at the end of the century. These results are important in evaluating the sustainability of this traditional agricultural system under climate change, and in designing appropriate local adaptation measures.

中文翻译：

---

气候变化与传统的旱稻种植：菲律宾案例研究

近年来，随着对环境可持续性和气候变化对全球粮食安全的预期影响的关注日益增加，包括梯田高地上的稻田耕作在内的传统农业做法引起了人们的新兴趣。然而，由于大多数传统农业生态系统位于数据可用性有限的偏远地区，因此尚未进行有关这些传统农业生态系统对未来气候变化的潜在脆弱性的系统研究。本文是对菲律宾Ifugao水稻梯田的一个案例研究，菲律宾是一个拥有数百年历史的耕作制度，其成功取决于复杂的农业循环后全年的水资源分配。我们开发了针对特定地点的水文模型，该模型结合了用于地表和渗流带过程的类似水文要素响应（SHER）模型和用于饱和地下水运动的模块化三维地下水流（MODFLOW）模型，以评估选定的一阶基线条件建安梯田集群内的集水区。SHER-MODFLOW模型的输出与2014-2016年实测的河流流量和水头的实测结果吻合良好。为了阐明气候变化的影响，我们根据温室气体浓度路径RCP-4.5和RCP-8.5缩小了三种全球气候模型MRI-CGCM3，GFDL-CM3和UKMO-HadGEM3的未来预测。我们将这些未来气候预测与经过校准的SHER-MODFLOW模型一起使用，以评估2041-2050年和2091-2100年的地表水资源和地下水资源总量。结果表明，所有月份的温度都有升高的趋势，未来干旱季节降雨减少和缺水风险增加，未来雨季降雨增加和径流过多的风险增加。在本世纪末，这些趋势将更加明显。这些结果对于评估这种传统农业系统在气候变化下的可持续性以及设计适当的当地适应措施非常重要。降雨增加，未来雨季径流过多的风险增加。在本世纪末，这些趋势将更加明显。这些结果对于评估这种传统农业系统在气候变化下的可持续性以及设计适当的当地适应措施非常重要。降雨增加，未来雨季径流过多的风险增加。在本世纪末，这些趋势将更加明显。这些结果对于评估这种传统农业系统在气候变化下的可持续性以及设计适当的当地适应措施非常重要。