大青山区油松人工林降雨分配特征研究

以大青山区30 a生油松人工林为研究对象,系统观测了林分对降雨的再分配作用,根据2006年的观测结果显示,油松人工林林冠穿透雨量、林冠截留、树干茎流所占降雨的比例分别为65.83%、33.04%、1.13%,枯枝落叶层有效拦蓄量为0.62mm,截留率为8.9%,地表径流率为2.6%;林冠穿透雨量、树干茎流量与林外降雨量均呈显著的线性正相关,而林冠截留量与降雨量呈幂函数关系。     

兴安落叶松林降雨再分配特征

以兴安落叶松人工林为研究对象,通过冠层结构稳定时期20场降雨数据,分析了落叶松林冠层对降雨的截留再分配规律。结果表明:(1)观测期内落叶松林穿透雨量、树干径流量和冠层截留量依次为198.9mm,12.6mm,127.6mm,分别占同期林外降雨的58.65%,3.72%,37.63%;(2)根据模型估算,当降雨量超过4.2mm落叶松林开始出现穿透雨,降雨量超过7.2mm才能产生树干径流;(3)穿透雨、树干径流及林冠截留的绝对量均随降雨量的增大而显著增加,但其占林外雨的比例却表现出不同的变化趋势;(4)穿透雨量的空间变异随降雨量的增大显著减小,二者呈显著负相关(p<0.05);(5)本研究林冠层截留率处于兴安落叶松林冠截留(13.04%~39.89%)的较高水平,高于全国主要森林平均林冠截留(14.7%~31.8%)。     

模拟降雨条件下谷子和冬小麦植株对降雨再分配过程的影响

以谷子（ Setaria italica）、冬小麦（ Triticum aestivum Linn 。）为研究对象,利用人工模拟降雨测定了不同降雨强度和生长阶段两种作物植株的穿透雨,采用人工喷雾法测定了不同生长阶段的冠层截留,根据水量平衡法计算了不同观测阶段的茎秆流。结果表明：谷子、冬小麦冠层对降雨的再分配作用显著,谷子冠下穿透雨率平均约为79％,茎秆流率平均约为20％,冠层截留率平均约占1％;冬小麦冠下穿透雨率平均约为79％,茎秆流率平均约为19％,冠层截留率平均约占2％。在其全生育期内,两种作物冠下穿透雨与茎秆流呈彼此消长趋势。穿透雨量和茎秆流量与降雨强度呈显著正相关关系,但是穿透雨率和茎秆流率与降雨强度的关系不显著。茎秆流量和冠层截留量及其二者占总降雨量的比率均与作物叶面积指数呈显著正相关关系,但穿透雨量及穿透雨率随叶面积指数增加呈显著下降趋势。     

古尔班通古特沙漠梭梭和白梭梭树干茎流特征

通过对古尔班通古特沙漠2个主要建群种梭梭(Haloxylon ammodendron)和白梭梭(Haloxylon persicum)树干茎流的野外实验观测,分析植株冠层和降雨特征对树干茎流形成的影响,并明确了树干茎流量在降雨再分配中的比例。结果表明：当降雨量≥2.4 mm时,梭梭和白梭梭开始有树干茎流产生。梭梭、白梭梭的树干茎流量随树冠体积的增大而增加,但是,当梭梭树冠体积大于4 m³,白梭梭树冠体积大于1.5 m³时,树干茎流量随树冠体积的增加不再增大,甚至有下降趋势。梭梭和白梭梭的树干茎流量和降雨量之间存在显著正相关,累计树干茎流量分别占降雨总量的9.1%和6.4%。梭梭和白梭梭的集流率均随降雨量增加而增大,能够有效地将树干茎流汇聚到树干基部, 梭梭表现出更强的汇集树干茎流的潜力。     

基于GPD模型的黑河出山径流极值变化分析

以黑河出山径流为研究对象, 利用黑河上游1944-2010年67 a的实测月均径流资料, 采用广义Pareto分布模型（GPD模型）, 对黑河未来出山月均径流的变化进行了预测。结果表明：运用超阈值的观测资料建模的GPD模型, 能够达到信息量使用的最大化, 对黑河极值变化的预测精度较高; 黑河出山径流重现期为25 a、50 a、100 a和150 a的月均径流量极大值分别为219.8 m³•s^-1、235.3 m³•s^-1、 249.5m³•s^-1和257.4 m³•s^-1; 重现期为25 a、50 a、100 a和150 a的月均径流量极小值分别为9.0 m³•s^-1、8.8 m³•s^-1、8.6 m³•s^-1和8.5 m³•s^-1;在当前“暖湿”的气候背景下, 黑河出山径流变化不大。     

祁连山青海云杉林苔藓层降雨再分配特征及其影响因素

研究苔藓层的降雨再分配对于认识其实际截持降雨过程及水文循环机理具有重要意义。本文以祁连山排露沟小流域青海云杉林苔藓层为研究对象,利用室内实验和野外观测相结合的办法,对祁连山苔藓层蓄积量、持水量(率)、林外(内)降雨量和苔藓穿透雨量进行测定,分析青海云杉林苔藓层持水特征、降雨再分配特征及其与影响因素的关系。结果表明:(1)苔藓层的厚度为2.8~12.6 cm,蓄积量为18.6~65.7 t·hm~(-2),最大持水率为218.6%~536.1%,最大持水深为8.6~19.2 mm,且苔藓层的最大持水量约为自身干重的3.5倍。(2)青海云杉林苔藓层的穿透雨总量和截留总量分别为156.5 mm和100.0 mm,分别占林内降雨总量的61.0%和39.0%,并在不同降雨量等级之间存在明显的差异。(3)苔藓层降雨再分配各组成要素(穿透雨和截留)与林内降雨量、林外降雨量、降雨历时和空气相对湿度呈极显著的相关性。林内降雨量、林外降雨量和降雨历时与苔藓穿透雨量均呈线性正相关关系(P0.01),而与穿透雨率、截留水量和截留率均呈对数函数关系(P0.05)。因此,苔藓层的持水性能及再分配特征,除与苔藓层的厚度、蓄积量和初始含水量相关外,也与林外各气象因子相关。     

基于SWMM的海绵城市LID设施规划与布局 ——以萍乡市为例

[目的]萍乡市是我国第一批海绵城市的试点城市,大尺度范围的雨水设施格局规划或布控研究需要进一步研究,旨在为萍乡市和其他南方多雨型城市的海绵城市建设提供技术参考与案例借鉴.[方法]以萍乡市主城区的年径流总量控制率为海绵城市建设目标,借助GIS技术,利用排水管网、降雨量、用地现状等基础资料,建立研究区域的SWMM模型,再利用AHP法和容积法计算得出LID设施布设方案,并通过不同降雨事件模拟其径流控制效果.[结果]在该目标下绿色屋顶率、渗透铺装率和生物滞留设施率分别需要达到44.51％,22.80％和14.10％;该方案对重现期p=1a、p=2a、p=5a、p=10a、p=20a的降雨径流削减比例分别为47.25％,44.23％,42.51％,40.67％和37.76％.[结论]海绵城市LID设施布设后能够满足要求并有效缓解城市内涝现象,但面对大雨、暴雨仍需要结合传统排水系统共同发挥作用.     

黄河流域内蒙古区间降雨径流模拟及水量平衡分析

以黄河内蒙古流域为研究区,利用GIS/RS技术获取流域水循环空间分布信息,选取黄河上游石嘴山、中游万家寨水文站为研究区的入、出站,利用近30年的降水等气象资料和近10年的水文资料,构建了基于SWAT(Soil and Water Assessment Tool)分布式水文模型的黄河流域内蒙古区间的降雨径流模型。通过对模型的校准、验证,初步分析了该区间降水与径流量的关系及水量平衡。结果表明:黄河流域内蒙古区间农用灌溉、池塘蓄水等人为因素对径流量的影响要大于气候变化对其的影响;且在干旱的气候条件下,降水少,蒸散发量较大,从年尺度上看,通过降雨形成的径流量是非常有限的。构建的模型基本能够反映黄河流域内蒙古的月径流水文过程,水量平衡分析也揭示了当地干旱气候下径流的特征。     

1961-2010年白龙江上游水文气象要素变化规律分析

以1961-2010年白龙江流域月均温、月降水和上游武都水文站月径流资料为基础,采用Mann-Kendall法、R/S分析法和Morlet小波分析法,研究了白龙江上游水文气象要素的变化特征,并采用多元线性回归分析法探讨了气候变化和人类活动对径流变化的影响.结果表明:近50年来白龙江上游气温显著上升,降水微弱减少,径流显著减少.在未来一段时段内气温仍将持续上升,降水微弱增加,径流持续减少.气温、降水、径流具有多时间尺度特性,年均温、年降水和年径流有6-7年、12-13年、20年准周期.1961-1990年径流变化主要受气候变化影响,人类活动影响较小.1991-2010年径流变化受气候变化和人类活动的综合影响,两者作用相当.     

五台山两种林分不同层次对氮的截留效应初探

在氮(N)沉降不断增加和气候变化的背景下,为研究五台山典型亚高山林分各层次对N的截留效应,在五台山选择两种林分:华北落叶松林(HL)和云杉×华北落叶松混交林(YH),于2016年5月至9月,采集大气降雨、林内雨、枯落物渗滤液、地表径流,检验水体pH和TN、NH_4~+、NO_3~-浓度。结果表明:五台山降雨呈弱酸性(pH 6.89),HL林冠层及土壤层对水体pH缓冲效果优于YH。HL林冠层截留了降雨中TN、NH_4~+,YH林冠层则释放了TN、NH_4~+、NO_3~-。HL枯落物层截留了NO_3~-,YH枯落物层则拦截了NH_4~+。HL和YH土壤层都拦截TN、NH_4~+、NO_3~-,但HL林内雨、枯落物渗滤液和地表径流中TN、NH_4~+、NO_3~-浓度全部低于YH。因此,HL对水体中N的截留能力优于YH,且土壤层是改善水质的主要层次。     

Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1-R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m²) was 11.1% higher than that from NH plot (457.9 g/m²) in R1-R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.     

Glacier mass balance and its impacts on streamflow in a typical inland river basin in the Tianshan Mountains,northwestern China

Glaciers are known as natural 'solid reservoirs', and they play a dual role between the composition of water resources and the river runoff regulation in arid and semi-arid areas of China. In this study, we used in situ observation data from Urumqi Glacier No. 1, Xinjiang Uygur Autonomous Region, in combination with meteorological data from stations and a digital elevation model, to develop a distributed degree-day model for glaciers in the Urumqi River Basin to simulate glacier mass balance processes and quantify their effect on streamflow during 1980-2020. The results indicate that the mass loss and the equilibrium line altitude (ELA) of glaciers in the last 41 years had an increasing trend, with the average mass balance and ELA being -0.85 (±0.32) m w.e./a (meter water-equivalent per year) and 4188 m a.s.l., respectively. The glacier mass loss has increased significantly during 1999-2020, mostly due to the increase in temperature and the extension of ablation season. During 1980-2011, the average annual glacier meltwater runoff in the Urumqi River Basin was 0.48×10⁸ m³, accounting for 18.56% of the total streamflow. We found that the annual streamflow in different catchments in the Urumqi River Basin had a strong response to the changes in glacier mass balance, especially from July to August, and the glacier meltwater runoff increased significantly. In summary, it is quite possible that the results of this research can provide a reference for the study of glacier water resources in glacier-recharged basins in arid and semi-arid areas.     

Mulching mode and planting density affect canopy interception loss of rainfall and water use efficiency of dryland maize on the Loess Plateau of China

High and efficient use of limited rainwater resources is of crucial importance for the crop production in arid and semi-arid areas. To investigate the effects of different soil and crop management practices(i.e., mulching mode treatments: flat cultivation with non-mulching, flat cultivation with straw mulching, plastic-covered ridge with bare furrow and plastic-covered ridge with straw-covered furrow; and planting density treatments: low planting density of 45,000 plants/hm~2, medium planting density of 67,500 plants/hm~2 and high planting density of 90,000 plants/hm~2) on rainfall partitioning by dryland maize canopy, especially the resulted net rainfall input beneath the maize canopy, we measured the gross rainfall, throughfall and stemflow at different growth stages of dryland maize in 2015 and 2016 on the Loess Plateau of China. The canopy interception loss was estimated by the water balance method. Soil water storage, leaf area index, grain yield(as well as it components) and water use efficiency of dryland maize were measured or calculated. Results showed that the cumulative throughfall, cumulative stemflow and cumulative canopy interception loss during the whole growing season accounted for 42.3%–77.5%, 15.1%–36.3% and 7.4%–21.4% of the total gross rainfall under different treatments, respectively. Soil mulching could promote the growth and development of dryland maize and enhance the capability of stemflow production and canopy interception loss, thereby increasing the relative stemflow and relative canopy interception loss and reducing the relative throughfall. The relative stemflow and relative canopy interception loss generally increased with increasing planting density, while the relative throughfall decreased with increasing planting density. During the two experimental years, mulching mode had no significant influence on net rainfall due to the compensation between throughfall and stemflow, whereas planting density significantly affected net rainfall. The highest grain yield and water use efficiency of dryland maize were obtained under the combination of medium planting density of 67,500 plants/hm~2 and mulching mode of plastic-covered ridge with straw-covered furrow. Soil mulching can reduce soil evaporation and retain more soil water for dryland maize without reducing the net rainfall input beneath the maize canopy, which may alleviate the contradiction between high soil water consumption and insufficient rainfall input of the soil. In conclusion, the application of medium planting density(67,500 plants/hm~2) under plastic-covered ridge with bare furrow is recommended for increasing dryland maize production on the Loess Plateau of China.     

近50年来喀什噶尔河流域气温、降水及径流的变化趋势

应用喀什噶尔河流域内7个气象站、3个水文站的观测资料,分析了全流域、平原区和帕米尔高原的气温、降水以及出山口控制站年径流量的变化特征.结果显示:①从20世纪90年代开始,喀什噶尔河全流域以及平原区和帕米尔高原的年以及冬、秋季明显增暖,近5年春季迅速增温.从90年代起,全流域与高原区的年降水量明显增加,近5年平原区也明显增加;自90年代起全流域的春季、夏季降水明显增加,而近5年秋、冬季增湿迅速;近5年平原区的秋、春季以及冬季降水增加明显,高原区却以夏、秋季增湿最明显.②喀什噶尔河全流域以及平原区和帕米尔高原的年气温与降水量都呈显著的线性增加趋势.平原区的秋、冬季气温显著上升,冬季最明显,夏季呈不显著的下降趋势;平原区的四季降水呈不显著的上升趋势.帕米尔高原的夏、秋、冬季气温呈显著的上升趋势,秋季最明显;帕米尔高原的四季降水呈上升趋势,只有夏季的增湿趋势较显著.③喀什噶尔河年径流量(3站合计)近47年来呈显著的线性上升趋势,以3.0%·(10 a)-1的速率增加.流域内3条河流情况有所不同,克孜河径流量的线性增加趋势最明显,而盖孜河呈不显著的下降趋势.     

Spatiotemporal variation in vegetation net primary productivity and its relationship with meteorological factors in the Tarim River Basin of China from 2001 to 2020 based on the Google Earth Engine

Vegetation growth status is an important indicator of ecological security. The Tarim River Basin is located in the inland arid region of Northwest China and has a highly fragile ecological environment. Assessing the vegetation net primary productivity (NPP) of the Tarim River Basin can provide insights into the vegetation growth variations in the region. Therefore, based on the Google Earth Engine (GEE) cloud platform, we studied the spatiotemporal variation of vegetation NPP in the Tarim River Basin (except for the eastern Gobi and Kumutag deserts) from 2001 to 2020 and analyzed the correlations between vegetation NPP and meteorological factors (air temperature and precipitation) using the Sen slope estimation method, coefficient of variation, and rescaled range analysis method. In terms of temporal characteristics, vegetation NPP in the Tarim River Basin showed an overall fluctuating upward trend from 2001 to 2020, with the smallest value of 118.99 g C/(m²?a) in 2001 and the largest value of 155.07 g C/(m²?a) in 2017. Regarding the spatial characteristics, vegetation NPP in the Tarim River Basin showed a downward trend from northwest to southeast along the outer edge of the study area. The annual average value of vegetation NPP was 133.35 g C/(m²?a), and the area with annual average vegetation NPP values greater than 100.00 g C/(m²?a) was 82,638.75 km², accounting for 57.76% of the basin. The future trend of vegetation NPP was dominated by anti-continuity characteristic; the percentage of the area with anti-continuity characteristic was 63.57%. The area with a significant positive correlation between vegetation NPP and air temperature accounted for 53.74% of the regions that passed the significance test, while the area with a significant positive correlation between vegetation NPP and precipitation occupied 98.68% of the regions that passed the significance test. Hence, the effect of precipitation on vegetation NPP was greater than that of air temperature. The results of this study improve the understanding on the spatiotemporal variation of vegetation NPP in the Tarim River Basin and the impact of meteorological factors on vegetation NPP.     

Effects of climate change and land use/cover change on the volume of the Qinghai Lake in China

Qinghai Lake is the largest saline lake in China.The change in the lake volume is an indicator of the variation in water resources and their response to climate change on the Qinghai-Tibetan Plateau(QTP)in China.The present study quantitatively evaluated the effects of climate change and land use/cover change(LUCC)on the lake volume of the Qinghai Lake in China from 1958 to 2018,which is crucial for water resources management in the Qinghai Lake Basin.To explore the effects of climate change and LUCC on the Qinghai Lake volume,we analyzed the lake level observation data and multi-period land use/land cover(LULC)data by using an improved lake volume estimation method and Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model.Our results showed that the lake level decreased at the rate of 0.08 m/a from 1958 to 2004 and increased at the rate of 0.16 m/a from 2004 to 2018.The lake volume decreased by 105.40×10⁸ m³ from 1958 to 2004,with the rate of 2.24×10⁸ m³/a,whereas it increased by 74.02×10⁸ m³ from 2004 to 2018,with the rate of 4.66×10⁸ m³/a.Further,the climate of the Qinghai Lake Basin changed from warm-dry to warm-humid.From 1958 to 2018,the increase in precipitation and the decrease in evaporation controlled the change of the lake volume,which were the main climatic factors affecting the lake volume change.From 1977 to 2018,the measured water yield showed an"increase-decrease-increase"fluctuation in the Qinghai Lake Basin.The effects of climate change and LUCC on the measured water yield were obviously different.From 1977 to 2018,the contribution rate of LUCC was -0.76% and that of climate change was 100.76%;the corresponding rates were 8.57% and 91.43% from 1977 to 2004,respectively,and -4.25% and 104.25% from 2004 to 2018,respectively.Quantitative analysis of the effects and contribution rates of climate change and LUCC on the Qinghai Lake volume revealed the scientific significance of climate change and LUCC,as well as their individual and combined effects in the Qinghai Lake Basin and on the QTP.This study can contribute to the water resources management and regional sustainable development of the Qinghai Lake Basin.     

新疆塔城地区中小河流径流成因分析及预测

以塔城地区乌拉斯台河为例,根据其年径流量(1966-1995年)序列的长期变化特征,提出了时间序列分解预测模型,即将年径流系列分解为趋势项、周期项、随机项,通过对其各项进行识别、提取,再将各项线性叠加,从而建立年径流量预测模型.从模型的识别过程可得,乌拉斯台河年径流具有不显著的递增趋势和明显的周期变化,同时具有一定的随机性.从模型的检验来看,所建模型具有较好的适应性和预报精度,并且拟合效果较好,说明这种预测方法有一定的实用性.     

开都河源区径流变化的气候响应

气候变化下的山区径流时空变异特征是干旱区水文水资源研究的热点之一。本研究选择天山南坡开都河流域源区为典型研究区,基于1958-2017年大山口水文站和巴音布鲁克水文站径流数据,及巴音布鲁克气象观测数据,采用TFPW-MK趋势检验、小波分析与小波相干等方法分析径流序列的趋势、突变和周期特征及其对气候变化的响应。结果表明:近60 a来,开都河源区径流、降水、气温呈显著增加趋势,并且径流量、降水量与最高气温的增率在加快,而平均气温与最低气温的增率减缓;径流量、降水与平均气温的突变年份集中在20世纪90年代,并且均存在28 a的周期;夏季径流量增加主要受夏季升温的影响,而早春径流量增加主要与冬季降水增加、早春升温有关;在年尺度上,降水是影响开都河径流变化的主要因素,气温主要以积温形式影响着径流的变化;在月尺度上,积温与降水均与径流呈显著正相关关系,且源区上游径流较下游径流对气温变化更为敏感。     

干旱区绿洲城市水资源开发利用的潜力——以乌鲁木齐市为例

西北干旱地区的水资源短缺,严重制约了绿洲城市的健康发展。基于乌鲁木齐市1995-2010年水资源开发利用现状,构建了水资源开发利用潜力的综合评价模型。结果表明：① 地表水是乌鲁木齐市的主要水源,全市多年平均水资源量为11.20×10⁸ m³,人均水资源量远低于新疆平均水平。水资源开发率持续快速增长,用水总量甚至已超过区域当年来水总量。② 用水总量呈波动增长,2010年达10.89×10⁸ m³,农业生产是主要的用水部门,但近年来农业用水比例有所下降,工业与生活用水逐步增加。③ 水资源本底条件和开发利用程度显著恶化,利用效率和管理能力则迅速改善。总体来看,乌鲁木齐市水资源开发利用潜力在波动中逐渐下降,其中人口快速增长、经济高速发展、水资源污染加重是主要因素。