灌区多尺度水热碳循环过程模拟及对节水调控的响应机制

Understanding the hydrological and ecological responses to both climate change and human activities, in irrigated agricultural area, is of great importance to agricultural water resources management and ecological environment conservations. An integrated approach over such basin is expected, including the studies on multi-process and multi-scale water and energy transitions, the impacts of climate evolution and water-saving measures, and the water-carbon actions under the changing climate. Based on long-term observations in the agricultural experiment station for a typical irrigated agricultural region in Northwest China, this research will (1) study the responses of evapotranspiration and carbon cycle, for the typical crop types (i.e., Maize and Wheat), to the elevated carbon dioxide and the irrigation-induced temperature changes, by examing the photosynthesis and respiration processes; (2) improve the performance of terrestiral hydrolgoical model in agrcultural lands, and model the water and energy evolutions under different Representative Concentration Pathways (RCPs) and irrigation patterns; (3) study the water and energy changes under deficit irrigations, and the chain-reacting on groundwater level and downstream ecological flow. This proposal is aimed at multi-scale water-carbon cycle modelling under the changing climate, where the agricultural lands play an important role in the changing cycles due to climate change and irrigation interference. The scientific goal is to better understand how to incorporate the transformation mechanisms of water-carbon cycle in agricultural lands into regional hydrological model, develop the systematical modele characterized by agricultural aspects, and how to simulate these processes in a changing environments. The methodological goal is to provide scientific basis for the sustainable development of regional agriculture and ecosystem in the context of the basin-scale water-carbon cycles.

面向农业灌区水资源的高效利用和区域生态环境保护，需要从流域整体出发，研究灌区水碳循环多环节和多尺度的水量能量转化过程，结合气候变化的预测和节水措施的效用，明晰变化环境下的水碳交互演化。本项目以西北旱区农业实验站多年观测数据为基础，研究在变化环境（如大气二氧化碳浓度增加、灌溉引起的地表温度变化）下， 西北灌区典型农作物（玉米、小麦）光合和呼吸作用对蒸发蒸腾量和碳循环变化的作用机理和模拟方法；提升陆面水文模型在灌区的应用精度，开展不同RCP情景和农业格局变化下灌区的水量能量过程演化模拟；研究非充分灌溉等节水调控下水量能量循环的响应机制，以及流域范围内与水相关生态指标（如地下水位和生态流量）的连锁效应。项目以北方典型农田水碳循环过程研究为突破口，在现有陆面水文模型中融入农业灌区水碳热通量传输机制，开展蕴含农业特色的生态水文系统模拟，从而为以流域整体为背景的农业与生态可持续发展提供科学依据。

项目以我国西北典型农田水碳循环过程研究为突破口，开展蕴含农业特色的生态水文系统模拟，从而为以流域整体为背景的农业与生态可持续发展提供科学依据。研究了在变化环境（如大气二氧化碳浓度增加、灌溉引起的地表温度变化）下， 西北灌区典型农作物（玉米、小麦）蒸发蒸腾量和碳循环的响应机理和模拟方法；提升了陆面水文模型在灌区的应用精度；开展不同RCP情景变化下灌区的水量能量过程演化模拟和非充分灌溉等节水调控下水量能量循环的响应机制，以及相关生态指标（如地下水位）的连锁效应。项目取得了如下重要结果：（1）基于西北旱区人工气候室实验观测数据和灌区长系列水热碳观测资料，构建刻画流域农业生态和水文关键过程的水量能量循环板块，将变化环境（气候变化和灌溉行为）的影响反映到模拟模型中；（2）应用考虑灌溉机制的改进的VIC模型研究黑河流域中上游灌溉对地表水量能量平衡影响，模拟不同灌溉情景（充分灌溉、90%和75%灌溉）的水量能量平衡变化，获得潜热、显热和地表温度对不同灌溉情景的响应，合理估计长期灌溉对农区带来的水热平衡影响；（3）开展了西北灌区玉米、小麦、油菜、大麦产量和作物水生产力对气候要素的多尺度响应研究，预计了未来河西走廊地区谷物的气候减产风险；（4）量化了在未来气候条件下，灌区玉米和小麦的蒸散发的响应变化特征，明晰了大气CO2变化对蒸散发的影响程度，合理估计了未来降水气温变化下的农区蒸散发的改变量；（5）项目共发表学术论文13篇，其中SCI检索11篇， 1篇On-line；结合本项目，正在培养博士研究生3名、硕士研究生2名，已培养硕士研究生4名。项目围绕灌区多尺度水热碳循环过程模拟和对节水调控的响应机制，在变化环境下西北典型农作物耗水和作物水生产力响应等方面获得了一系列研究成果，同时量化了涵盖农区的流域生态演化对区域水循环和不同区域作物产量对干旱的脆弱性等，为农区水热碳循环的模拟提供了有效的量化途径，服务西北地区的绿色农业发展和生态环境保护。