Discussion of “Assessments of Impacts of Climate Change and Human Activities on Runoff with SWAT for the Huifa River Basin, Northeast China” by Aijing Zhang; Chi Zhang; Guobin Fu; Bende Wang; Zhenxin Bao; and Hongxing Zheng

Zhang et al. (Water Resour Manag doi:10.1007/s11269-012-0182-2, 2012) studied the impacts of climate change and human activities on the runoff for the Huifa River basin. They employed a soil and water assessment tool (SWAT), which was calibrated for the baseline period 1956–1964, and then used to reconstruct the natural runoff for the climate change period 1965–2000. Results showed that both climate change and human activities decrease the observed runoff. Climate change impacts on annual runoff were ?37.7, ?59.5, +36.9, and ?45.2 mm/a for 1965–1975, 1976–1985, 1986–1995, and 1996–2005 respectively, compared with the baseline period 1956–1964. Human activities decreased runoff and caused a relatively larger magnitude impact than those of climate change after 1985. Human activities decreased the annual runoff by ?32.9, ?46.8, ?67.8, and ?54.9 mm/a for 1965–1975, 1976–1985, 1986–1995, and 1996–2005 respectively. Human activities further decreased runoff in wet years due to regulation and storage of water projects.     

Trends and attribution of runoff changes in the upper and middle reaches of the Yellow River in China

Natural changes of river regime have been strongly interfered globally by human activities. This gives rise to the demand of quantifying the contribution of natural and human impacts to runoff changes of rivers for river management. In this study, Mann-Kendall test and BFAST algorithm were used to evaluate the trends of runoff change in the upper and middle reaches of the Yellow River from 1965 to 2016, and to identify the breakpoints of runoff changes in the two reaches. Based on the data-driven analysis of runoff generation mechanism, the natural annual runoff was related with a comprehensive climatic factor integrating temperature and precipitation, and the impacts of human activities and climate change on the runoff changes were quantitatively distinguished by comparing the measured runoff with the “natural runoff”. For revealing the periodical changes in correlation between climate factors and runoff, the method of cross wavelet transform was used, and the time-frequency characteristics of precipitation/temperature against runoff were also examined. The results show that the breakpoints were the year 1987 in the upper reaches, 1986 and 2003 in the middle reaches. Compared with the baseline period (1965–1987), the contribution rates of climate change and human activities to runoff change in the upper reaches of the river were 56% and 44% respectively in 1988–2016. For the middle reaches, compared with the reference period (1965–1986), the contribution from climate change in 1987–2003 and 2004–2016 was 38% and 41% respectively, and that from human activities was 62% and 59% respectively. The results of cross wavelet transform analysis support the growth of climatic contribution to runoff reduction in the middle Yellow River from 1987–2003 to 2004–2016. Apparently, the influencing degree of climate change on runoff in the upper reaches was similar to that of human activities, while human activities played a dominant role in runoff change in the middle reaches. Moreover, the construction of reservoirs and human water consumption were the key factors for the decline of runoff in the upstream, and the reduction of runoff in the middle reaches was related to the large-scale implementation of water conservancy and soil and water conservation in the region.     

永定河流域径流变化特征及影响因素分析

根据永定河流域石匣里站、响水堡站和官厅水库站1956年-2003年的年径流资料,应用Mann-kendall检验法、Pettitt检验法、滑动T检验和小波分析法等方法分析了永定河流域年径流量的趋势性、周期性及突变特征,并从气候变化及人类活动两方面分析其影响因素。结果表明永定河流域年径流量一直处于显著下降趋势中,存在27(28)年的第一主周期和20(21)年的第二主周期;1982年-1983年径流量发生突变,突变前后变化较大。径流量变化的主要影响因素是人类活动,如土地利用、闸坝工程建设以及地下水过度开采等;气候变化对径流量也有一定的影响。     

长江源区径流年内分配时程变化影响因子分析

长江源区是长江水文循环的起始地,源区的水量、水质变化和人类不合理活动对水环境的影响将波及广大的下游地区.在气候变化和人类活动的影响下,长江源区河川径流没有发生显著趋势性变化,本文根据长江源区1956-2005年月径流资料和降水、气温、蒸发资料,采用主成分分析法、线性趋势分析法,研究影响径流年内分配的主要气候因子.结果表明:降水和水面蒸发是影响径流年内分配时程变化的主要因子,气温的影响相对小.     

1956-2016年拉萨河径流量变化及影响因素分析

通过分析拉萨河径流量的演变规律和突变情况,开展降水和人类活动对径流量变化的成因分析,为拉萨河流域水资源管理与利用提供科学依据。基于1956-2016年的径流和降水数据,利用Mann-Kendall趋势分析、累积距平-滑动t检验法和降水－径流双累积曲线法,统计分析拉萨河径流序列的趋势性和突变性,计算降水与人类活动对拉萨河汛期6-9月径流量变化的贡献率。结果表明： 1956-2016年拉萨河径流量年际变化波动较大,其中1995和2005年为径流量突变年份。以1956-1994年为基准期,通过双累积曲线法定量分析表明1995-2004年人类活动对汛期径流量变化的贡献率小于50%,而2005-2016年人类活动的贡献率增大至70%以上,即人类活动成为汛期径流量改变的主要影响因素,且下游河道人类活动的影响程度更大,主要原因是新建的直孔和旁多水库调控了下游河段的流量过程。     

Impacts of Climate Change and Human Activities on the Surface Runoff in the Tarim River Basin over the Last Fifty Years

The impacts of climate change and human activities on the surface runoff were analyzed by the Mann–Kendall and trend analysis methods based on the hydrological, meteorological and socioeconomic data over the last 50 years in the Tarim River basin. Results show that the runoff in the headstreams increased but that in the mainstreams decreased significantly during the past 50 years. The former is a response to climate change, and the later is due to human activities. The surface runoff in the mainstreams decreased by 41.59, 63.77 and 75.15% in the 1970s, 1980s and 1990s, respectively, as compared to that without being disturbed by human activities in the same period. The main human activities are the irrigated agriculture combined with population increase in the region. As a consequence, the ecosystem in the lower reaches of Tarim River has degenerated, largely owing to inappropriate allocation of water resources.     

黑河径流的沿程分布格局变化研究

基于内陆河流域河川径流在河流坐标上的演变规律,采用径流的溯源性与零水资源尺度两个概念,分析黑河径流的沿程分布变化。结果表明：从1956-1970年、1971-1985年和1986-2000年3个时段河川径流均值看,地表水资源存在着出山口以后的各断面河川径流的溯源变化;存在着水资源整体集中度从下游向上游缩进的趋势;莺落峡与正义峡区间的径流延时分布概率在40 m^3/s以上显著不同。     

气候变化和人类活动对白河流域径流变化影响的定量研究

分析气候变化和人类活动对白河流域径流变化的贡献率,可为流域水资源规划与管理提供依据。以白河流域作为研究对象,首先采用线性趋势法、滑动平均法分析水文气象要素的年际变化趋势,其次采用Mann-Kendall检验、有序聚类检验和滑动t检验探究年径流量的突变年份,最后采用基于Budyko假设的水量平衡法评估气候变化和人类活动对径流变化的影响。结果表明:白河流域年径流量呈下降趋势,2008-2017年平均径流量仅为1960-1969年平均径流量的36.5%;年径流量在1979年发生突变,在1986年以后呈显著下降趋势;与基准期相比,变化期流域的干旱指数在增加,2001-2017年流域的干旱更为明显;人类活动是白河流域径流变化的主要原因,1980-2000年、2001-2017年人类活动对径流变化的平均贡献率分别为85.6%、73.6%,说明2000年以后气候变化对径流变化的影响呈上升趋势。     

气候变化和人类活动对汉江上游径流变化影响的定量研究

以汉江上游为例,基于弹性系数法和水文模拟法定量估算气候变化和人类活动对流域径流的影响,探讨了变化环境下流域径流对气候变化和人类活动的响应特征。研究结果表明:1961年-2013年汉江上游流域径流呈明显下降趋势,并在1985年前后发生了突变;降水及潜在蒸散发在同时期内也逐渐降低,但变化趋势不显著。气候变化对径流变化的贡献率为42.8%~43.5%,人类活动对径流变化的贡献率为56.5%~57.2%,相比人类活动对汉江上游径流的影响稍大,且其对径流变化的影响呈现增长的趋势。     

变化环境对潮河下游径流一致性的影响

水文分析要求径流资料的时间序列一致性,但变化的环境破坏了径流序列的稳定一致性变化规律。在气候变化和频繁的人类活动的影响下(水利工程建设、植被覆盖改变和城市化建设等),流域的下垫面条件和产流物理机制发生了明显变化,导致径流序列出现变异情况,不能满足频率计算分析水文时间序列一致性的要求和同分布的假定。应用Mann-Kendall非参数秩次检验法、Pettitt检验法、方差分析法对潮河流域下游下会站1976年-2012年的年、月径流和降水时间序列的趋势成分、突变成分、周期成分和随机成分分别进行了检验和识别,并通过对比分析降雨和径流时间序列的成分,推断出气候变化和人类活动对潮河流域下游降水和径流演变过程的影响。