流域尺度典型节水灌溉方式的生态水文影响模拟研究

The agricultural irrigation can have a profound impact on the watershed hydrological cycle and the ecological processes. With the widespread adoption and promotion of the efficient water-saving irrigation methods (WSIMs), the watershed eco-hydrological processes would inevitably be modified significantly. Currently, however, there are few attentions paid to the comprehensive impacts of the typical WSIMs on the surface water and groundwater system and ecosystem of a watershed, and to the eco-hydrological responses to the WSIMs under the changing environments such as the variations in irrigation extents and water supply conditions. Taken the middle and lower Heihe River Basin (HRB), a typical inland river basin in the arid regions, as the study area, this proposal is to improve and extend the existing Hydrological-Ecological Integrated watershed-scale FLOW (HEIFLOW) model, based on which the reallocations of the watershed water resources under the typical WSIMs (i.e., sprinkler and drip) as well as the eco-hydrological effects of the WSIMs under different scenarios of farmland expansions and water resource allocations will be investigated through the modelling experiments and scenario analyses. In addition, the issue of “efficiency paradox” possibly generated under the WSIMs will be explored and discussed. This proposal mainly aims to advance the understanding of the mechanisms of the responses of the surface water and groundwater system and ecosystem to the WSIMs in the inland river basin of the arid regions; to scientifically assess the water saving potentials of the WSIMs at the watershed scale; and to provide theoretical references and decision supports for water resources managements in the HRB as well as the other inland river basins.

农业灌溉是影响流域水文循环和生态过程的重要因素。随着高效节水灌溉方式的广泛应用和推广，流域生态水文过程必然随之发生显著的变化。尽管如此，典型节水灌溉方式对流域地表-地下水及生态系统的综合影响，以及变化环境（如灌溉规模和供水条件变化）下节水灌溉方式的生态水文响应，目前受到的关注明显不足。本项目将选择干旱区典型内陆河流域—黑河流域中下游为研究区，通过改进和扩展已有的流域生态水文集成模型HEIFLOW，并结合模型实验与情景分析，研究典型节水灌溉方式（喷灌和滴灌）下流域水资源的再分配特征，分析不同扩耕和水资源配置情景下典型节水灌溉方式的生态水文效应，探讨节水灌溉方式下可能产生的“效率悖论”问题。本项目旨在深入认识干旱区内陆河流域地表-地下水及生态系统对节水灌溉方式的响应机制，科学评价节水灌溉方式在流域尺度的节水潜力，为黑河乃至其它内陆河流域水资源管理提供理论依据和决策支持。

典型节水灌溉方式在流域生态水文模型的刻画一直是难点问题，同时节水灌溉在流域或区域尺度是否能真正实现节水，目前也是一个富有争议性的问题。围绕上述两方面关键科学问题，本项目在已有的生态水文模型中提出并实现了基于湿润体的滴灌模拟方法，发展了基于遥感产品和径流观测的模型并行式、分布式标定方法，研究了滴灌对流域生态水文过程的影响及其节水潜力，并在宏观尺度探析了节水灌溉的“效率悖论”问题。本项目将为生态水文模型提供新的滴灌模拟思路和模型标定方法，有助于丰富和完善流域模型的功能和提升模型的可靠性，提升对节水灌溉生态水文响应机制的认识。项目研究成果可发挥重要的决策支持作用，服务于农业水资源优化管理，保障水与生态安全。