基于基流分割集成技术与SWAT模型耦合运用的植被变化基流时空响应模拟

Simulation of spatiotemporal response of baseflow to vegetation variations based on coupled application of ensemble baseflow separation technique and SWAT model

摘要

【目的】基流是径流中相对稳定的组成部分。精确刻画流域基流的时空分布特征，特别是植被变化影响作用下的基流响应，对水资源缺乏的北方山区水资源管理和流域管理具有重要意义。【方法】本文耦合运用SWAT模型与数值模拟基流分割集成技术，以小滦河流域为例，分析研究区基流的时空变化，并探讨植被变化等对流域基流的影响控制。【结果】结果表明：(1)SWAT模型与基流分割集成技术的耦合运用可较好模拟基流较少地区的水文过程，基流模拟效果较好，决定系数高达0.9,该方法技术具有较强的适用性；(2)2006—2020年期间，小滦河流域年尺度和生长季径流、基流整体呈减少趋势，但趋势不显著；而非生长季径流、基流则显著增加(p<0.05);(3)研究期内，流域约35.85%的面积片区基流基本稳定，上中下游各部均有分布；在接坝山地片区，部分子流域基流量甚至呈显著增加(占流域的22.47%);而在坝上高山草甸片区，基流量则呈轻微减少(占流域的18.32%)或显著减少趋势(占总面积的19.82%);(4)植被是研究流域基流过程改善的重要影响因素之一，接坝山地大部片区植被NDVI与基流呈正相关关系，部分子流域甚至呈显著正相关(占总流域10.68%),表明植被恢复一定程度有利于该研究区基流过程的改善。【结论】当前，研究区植被覆被增加对基流过程具有一定正向影响控制作用，但由于存在春季融雪水补给等过程的交互影响，未来气候变化下植被对基流的影响控制需要持续观测探讨。

Abstract

[Objective] Baseflow is a relatively stable component of runoff. Accurately characterizing the spatiotemporal distribution characteristics of baseflow in river basins, especially its response to vegetation variations, is crucial for water resource and river basin management in the water-scarce mountainous areas of northern China. [Methods] The SWAT model was coupled with the numerical simulation-based ensemble baseflow separation technique. Taking the Xiaoluan River Basin as an example, the spatiotemporal variations of baseflow in the study area were analyzed, and the controlling effect of vegetation variations on river basin baseflow were investigated. [Results] The result showed that:(1) the coupled application of the SWAT model and the ensemble baseflow separation technique could effectively simulate the hydrological processes in areas with limited baseflow. The baseflow simulation performed well, with a coefficient of determination as high as 0.9, demonstrating strong applicability of this method.(2) From 2006 to 2020, the annual and growing-season runoff and baseflow in the Xiaoluan River Basin showed an overall decreasing trend, although the trend was not significant. In contrast, the runoff and baseflow during the non-growing season increased significantly(p<0.05).(3) During the study period, baseflow remained generally stable in approximately 35.85% of the river basin area, with distribution across the upper, middle, and lower reaches. In the mountainous area near the dam, baseflow in some sub-basins even showed a significant increase(accounting for 22.47% of the river basin area). In contrast, in the alpine meadow area above the dam, baseflow showed a slight decrease(accounting for 18.32% of the river basin area) or a significant declining trend(accounting for 19.82% of the total area).(4) Vegetation was one of the important influencing factors for the improvement of baseflow processes in the study basin. In most parts of the mountainous area near the dam, NDVI and baseflow showed a positive correlation, and some sub-basins even showed a significant positive correlation(accounting for 10.68% of the total river basin), indicating that vegetation restoration was conducive to the improvement of baseflow processes in the study area to a certain extent. [Conclusion] At present, the increase in vegetation cover in the study area has a certain positive controlling effect on baseflow process. However, due to the interaction of processes such as spring snowmelt recharge, the controlling effect of vegetation on baseflow under future climate change requires continuous observation and investigation.

关键词

SWAT模型 / 基流分割集成技术 / 基流时空变化 / 小滦河流域 / 影响因素

Key words

SWAT model / ensemble baseflow separation technique / spatiotemporal variations of baseflow / Xiaoluan River Basin / influencing factors

基金资助

国家重点研发计划项目(2022YFF1302501-02)