黄河中游皇甫川水沙变化及其对气候和人类活动的响应

黄河水沙变化一直是备受关注的热点。近年来，受气候变化和人类活动的影响，黄河水沙锐减，导致河道萎缩，断流现象频发。定量评价黄河水沙变化特征与驱动因素，对黄河水沙的科学调控、流域综合管理与区域生态环境的可持续发展具有重要意义。黄河河口镇—龙门区间是黄河中游暴雨洪水多发区和泥沙主要来源区，是黄河流域水土保持生态建设重点区。自20世纪80年代以来，河口镇—龙门区间径流量和输沙量大幅减少，水沙关系发生显著变化。本研究系统分析河口镇—龙门区间水沙变化特征，并选择典型支流—皇甫川流域为研究对象，采用Mann-Kendall趋势检验法、Pettitt突变检验法、水文法和弹性系数法研究了皇甫川流域1954—2012年降水、径流、输沙的演变特征，定量评价人类活动和降水变化对流域水沙的贡献率;同时采用SWAT水文模型评价了气候变化、土地利用/覆被和坝库工程对流域水沙的影响程度，并选取流域内的黄家沟淤地坝研究其淤积特征，并结合降水资料，计算了黄家沟小流域的侵蚀产沙强度，用与模型模拟结果对比验证。主要研究结论如下:(1)明确了黄河河口镇—龙门区间径流和输沙量变化特征及对降水和人类活动的响应。河口镇至龙门区间56年(1957—2012年)来径流量和输沙量均呈显著减小趋势，分别以每年1.101亿m3和0.195亿t的速度减少;径流量和输沙量以1979年为临界年份发生突变性减少，但年降水量并未发生显著突变;人类活动是导致降水—径流、降水—输沙关系变化的主要原因，其对区间径流量、输沙量减少的贡献率分别为79.2%和88.1%。(2)皇甫川流域1954—2012年降水、径流和输沙量年内分配极不均匀，降水集中期变化比较稳定，方位角变化范围为195.85°~234.54°，主要集中在7、8月份，多年平均不均匀系数为1.26;受降水影响，流域径流量和输沙量年内分配也主要集中在7、8月份。皇甫川流域在年降水量未发生显著变化的情况下，径流量和输沙量呈显著减少趋势，径流量于1984年发生突变，输沙量于1989年发生突变。人类活动依然是皇甫川流域水沙减少的主要因素，通过弹性系数法计算的径流对降水变化的敏感性为1.3，降水对径流减少的贡献率为16.9%，采用水文法计算的降水变化对径流减少的贡献率为23.7%，与采用弹性系数法计算结果基本一致。(3)基于皇甫川水沙序列突变特征，采用基准期1976—1984年皇甫站的月径流输沙数据对SWAT模型进行率定和验证，模型模拟径流输沙结果的纳什系数NS和决定系数R2均超过了0.6，说明模型模拟结果满足精度要求，能够反映皇甫川流域水沙逐月变化过程，可进一步评价水沙变化对气候、土地利用/覆被和坝库工程变化的响应。(4)研究了皇甫川流域不同时期土地利用/覆被和坝库工程建设动态变化。分析了1978年、1990年和2006年土地利用/覆被时空变化，1978—1990年间，耕地、居民地、林地呈增加趋势，其中耕地增加速度最快，1990—2006年间，耕地、沙地呈减少趋势，草地呈增加趋势;流域淤地坝建设分为三个时期，1972年之前为初步建设试验阶段，该时期淤地坝数量仅45座，1973—2003年为发展阶段，该时期淤地坝增加至303座，平均每年增加9.5座，2004—2009年为大规模建设阶段，流域淤地坝数量增加了200座，平均每年增加28.6座，总库容达5.7亿m3。(5)辨析了土地利用/覆被和坝库工程对皇甫川流域水沙变化的影响。近期(1999—2012年)人类活动对皇甫川流域径流和输沙量减少的贡献率分别为74.6%和89.2%，与水文法计算的贡献率相近;其中坝库工程数量、库容及拦沙量逐年增长是引起流域径流量、输沙量减少的主要因素，分别占人类活动引起径流及输沙减少量的65.7%和69.4%，未考虑坝库的径流量和输沙量多年平均(1978—1984年)模拟值比考虑坝库的模拟值分别偏高0.32亿m3和0.122亿t;不同时期流域土地利用/覆被变化对流域产流产沙影响不同，与1978年土地利用/覆被状况相比，1990年和2006年土地利用/覆被条件引起流域产流量分别减少15.9mm和20.8mm，引起流域产沙模数分别减少0.43万t/km2和0.62万t/km2。(6)结合野外调查、实验，对比验证SWAT模型模拟结果。皇甫川流域下游的黄家沟小流域1974—2015年年均侵蚀产沙模数为1.577万t/(km2·a)，属于剧烈侵蚀区;该小流域淤地坝剖面的泥沙沉积颗粒组成中，砂粒含量最高，粘粒含量最低，剖面中值粒径随深度变化有增大趋势，说明近期淤地坝拦蓄的泥沙较细;2001—2012年皇甫川流域模拟多年平均产沙模数为1.854万t/(km2·a)，而通过野外剖面采样计算的黄家沟小流域的多年平均产沙模数为1.551万t/(km2·a)，模拟值与实测值的偏差为19.5%，模拟结果比实测值偏高。

Variations of water and sediment in the Yellow River have long been a research hotspot. In recent years, affected by climate change and human activities, the water and sediment load in the Yellow River has decreased sharply, leading to river channel shrinkage and frequent river cutoff events. Quantitatively evaluating the variation characteristics and driving factors of water and sediment in the Yellow River is of great significance for the scientific regulation of water and sediment, integrated watershed management and the sustainable development of regional ecological environment. The Hekouzhen-Longmen Reach of the Yellow River is a key area in the middle reaches of the Yellow River, characterized by frequent rainstorms and floods, serving as the main source of sediment, and also a priority zone for soil and water conservation and ecological construction in the Yellow River basin. Since the 1980s, the runoff volume and sediment load in this reach have decreased significantly, leading to remarkable changes in the water-sediment relationship. This study systematically analyzes the characteristics of water-sediment variations in the Hekouzhen-Longmen Reach. Taking the typical tributary, the Huangfuchuan Basin, as the research object, we investigated the evolutionary characteristics of precipitation, runoff and sediment load in the basin from 1954 to 2012 using the Mann-Kendall trend test, Pettitt change-point test, hydrological method and elastic coefficient method, and quantitatively evaluated the contribution rates of human activities and precipitation changes to the basin’s water-sediment variations. Meanwhile, the SWAT hydrological model was adopted to assess the impacts of climate change, land use/cover change and dam/reservoir projects on water and sediment in the basin. Additionally, the Huangjiagou silt dam in the basin was selected to study its sedimentation characteristics, and combined with precipitation data, the erosion sediment yield intensity of the Huangjiagou small watershed was calculated and verified by comparing with the model simulation results. The main research conclusions are as follows: (1) Clarified the variation characteristics of runoff and sediment load in the Hekouzhen-Longmen Reach and their responses to precipitation and human activities. Over the 56-year period from 1957 to 2012, both runoff and sediment load in this reach exhibited significant decreasing trends, with annual reduction rates of 110.1 million m³ and 19.5 million t, respectively. Abrupt decreases in runoff and sediment load occurred in 1979, while no significant abrupt change was observed in annual precipitation. Human activities were the primary cause of the changes in the precipitation-runoff and precipitation-sediment load relationships, with their contribution rates to the reduction of runoff and sediment load in the reach being 79.2% and 88.1%, respectively. (2) The intra-annual distributions of precipitation, runoff and sediment load in the Huangfuchuan Basin from 1954 to 2012 are extremely uneven. The precipitation concentration period shows relatively stable changes, with an azimuth range of 195.85° to 234.54°, and precipitation is mainly concentrated in July and August, with a multi-year average unevenness coefficient of 1.26. Affected by precipitation, the intra-annual distributions of runoff and sediment load in the basin are also mainly concentrated in July and August. Despite no significant change in annual precipitation, the runoff and sediment load in the Huangfuchuan Basin exhibit significant decreasing trends, with abrupt changes occurring in runoff in 1984 and in sediment load in 1989, respectively. Human activities remain the main factor contributing to the reduction of water and sediment in the basin. The sensitivity of runoff to precipitation changes calculated by the elastic coefficient method is 1.3, with the contribution rate of precipitation changes to runoff reduction being 16.9%. The contribution rate of precipitation changes to runoff reduction calculated by the hydrological method is 23.7%, which is basically consistent with the result obtained via the elastic coefficient method. (3) Based on the abrupt change characteristics of the water-sediment series in the Huangfuchuan Basin, the SWAT model was calibrated and validated using the monthly runoff and sediment load data from the Huangfu Hydrological Station during the baseline period (1976–1984). Both the Nash-Sutcliffe Efficiency coefficient (NSE) and coefficient of determination (R²) of the model’s simulated runoff and sediment load results exceed 0.6, indicating that the model simulation results meet the accuracy requirements and can reflect the monthly variation process of water and sediment in the Huangfuchuan Basin, enabling further evaluation of the responses of water-sediment variations to climate change, land use/cover change and dam/reservoir project changes. (4) Investigated the dynamic changes of land use/cover and silt dam construction in the Huangfuchuan Basin across different periods. The spatiotemporal changes of land use/cover in 1978, 1990 and 2006 were analyzed. During 1978–1990, the areas of cropland, residential land and forestland showed increasing trends, with cropland having the fastest growth rate. During 1990–2006, cropland and sandy land showed decreasing trends, while grassland exhibited an increasing trend. The construction of silt dams in the basin can be divided into three stages: the preliminary construction and test stage before 1972, with only 45 silt dams; the development stage from 1973 to 2003, during which the number of silt dams increased to 303, with an average annual increase of 9.5; and the large-scale construction stage from 2004 to 2009, during which the number of silt dams increased by 200, with an average annual increase of 28.6, and the total storage capacity reached 570 million m³. (5) Discriminated the impacts of land use/cover change and silt dam projects on water-sediment variations in the Huangfuchuan Basin. In the recent period (1999–2012), the contribution rates of human activities to the reduction of runoff and sediment load in the basin were 74.6% and 89.2%, respectively, which are close to the contribution rates calculated by the hydrological method. Among them, the annual growth of the number, storage capacity and sediment retention capacity of silt dams are the main factors causing the reduction of runoff and sediment load in the basin, accounting for 65.7% and 69.4% of the runoff and sediment load reductions caused by human activities, respectively. The multi-year average (1978–1984) simulated values of runoff and sediment load without considering silt dams were 32 million m³ and 12.2 million t higher than those with silt dams considered. The impacts of land use/cover change in different periods on runoff and sediment yield in the basin vary. Compared with the land use/cover status in 1978, the land use/cover conditions in 1990 and 2006 reduced the basin’s runoff yield by 15.9 mm and 20.8 mm, respectively, and reduced the basin’s sediment yield modulus by 0.43 ten thousand t/km² and 0.62 ten thousand t/km², respectively. (6) Combined with field investigations and experiments, the SWAT model simulation results were compared and verified. The average annual erosion sediment yield modulus of the Huangjiagou small watershed in the lower reaches of the Huangfuchuan Basin from 1974 to 2015 was 1.577 ten thousand t/(km²·a), which belongs to the severe erosion zone. In the sediment deposition profile of the silt dam in this small watershed, sand content is the highest and clay content is the lowest, and the median particle size of the profile increases with depth, indicating that the sediment trapped by the silt dams in recent years is relatively fine. The multi-year average simulated sediment yield modulus of the Huangfuchuan Basin from 2001 to 2012 was 1.854 ten thousand t/(km²·a), while the multi-year average sediment yield modulus of the Huangjiagou small watershed calculated via field profile sampling was 1.551 ten thousand t/(km²·a). The deviation between the simulated value and the measured value is 19.5%, and the simulated result is higher than the measured value.

搜集汇总

背景与挑战

背景概述

该数据集聚焦于黄河中游皇甫川流域1954年至2012年的水沙变化特征及其驱动因素分析。研究采用多种方法定量评估了人类活动和降水变化对径流与输沙的影响，其中人类活动是导致水沙减少的主要因素，特别是坝库工程和土地利用变化发挥了关键作用。