重庆地下热水径流特征研究

重庆地下热水资源丰富,但对其径流特征缺乏研究,盲目开采致使许多温泉泉流量减小、水温降低,甚至断流、枯竭。为指导地下热水的科学开采,文章对重庆地下热水的常规化学组分及同位素组分特征进行了研究,分析了地下热水补给、径流条件,指出大气降水为其补给源,补给区在重庆以北大巴山及华莹山背斜华莹山和铜锣峡背斜北端的岩溶露头区,嘉陵江组(T1j)为其储水层,地下热水主要沿背斜T1j地层由北往南流,同一背斜地下热水由北到南为一个统一的热水系统。     

不同粒径尾矿中重金属水平迁移转化规律

针对桂北铅锌尾矿中重金属在水平方向上的释放、迁移和转化问题,利用尾矿为研究对象,通过降雨模拟装置进行径流冲刷试验,分析冲刷过程中尾矿重金属浓度和形态的变化。结果表明,在径流冲刷过程中,尾矿中重金属浓度整体呈下降趋势,深度对尾矿中重金属浓度变化的影响不明显,同一深度的尾矿,粒径与其重金属释放量呈负相关关系,粒径小于75μm时重金属Zn减少率高达24%。径流作用下,尾矿的粒径大小与迁移能力成反比。径流冲刷前后,尾矿中重金属含量下降,Cd,Zn和Pb的含量在弱酸提取态下分别减少2.4%,1.6%和0.3%。随降雨时间延长,液相可溶态重金属浓度未发生显著变化,固相颗粒态重金属浓度持续降低,液相颗粒态重金属含量减少最明显。     

Altitudinal Distribution of Meltwater and Its Effects on Glacio‐Hydrology in Glacierized Catchments,Central Asia

In glacierized catchments, elevation is correlated with meltwater through its association with temperature, precipitation, and glacier hypsometry. The revelation of the altitudinal distribution of meltwater, unattended and not fully understood in previous work, might provide a better understanding of climate change impacts on glacio‐hydrology. Here, critical zone approach was defined and applied in 12 glacierized catchments of the Tien Shan–Pamir–Karakorum Mountains, Central Asia using manually calibrated glacier‐enhanced Soil and Water Assessment Tool model over 1966–2005. The critical zone, a sequence of elevation bands with above‐average snow and glacier melt, contributes maximum meltwater to total runoff. The critical zone shared 37%–95% (average = 80%) of meltwater contributions to total runoff, although its size was only 13%–30% of the total elevational relief. The critical zone controlled 76% and 82% variability in relative changes of glacier area and total runoff at the catchment scale, respectively. The increase in temperature was identified as the dominant driver for variations in total runoff in all catchments except Vakhsh and Yurungkash, where precipitation change remained dominant. Overall, glacier hypsometry limited the first‐order control of meltwater distributions on glacio‐hydrology. It is concluded that critical zone approach can interpret the proxy role of elevation to affect water availability under climate and glacier area change in glacierized catchments.     

Impact of Changing Climate and Land Cover on Flood Magnitudes in the Delaware River Basin,USA

Changing climate and land cover are expected to impact flood hydrology in the Delaware River Basin over the 21st Century. HEC‐HMS models (U.S. Army Corps of Engineers Hydrologic Engineering Center‐Hydrologic Modeling System) were developed for five case study watersheds selected to represent a range of scale, soil types, climate, and land cover. Model results indicate that climate change alone could affect peak flood discharges by ?6% to +58% a wide range that reflects regional variation in projected rainfall and snowmelt and local watershed conditions. Land cover changes could increase peak flood discharges up to 10% in four of the five watersheds. In those watersheds, the combination of climate and land cover change increase modeled peak flood discharges by up to 66% and runoff volumes by up to 44%. Precipitation projections are a key source of uncertainty, but there is a high likelihood of greater precipitation falling on a more urbanized landscape that produces larger floods. The influence of climate and land cover changes on flood hydrology for the modeled watersheds varies according to future time period, climate scenario, watershed land cover and soil conditions, and flood frequency. The impacts of climate change alone are typically greater than land cover change but there is substantial geographic variation, with urbanization the greater influence on some small, developing watersheds.     

基于雷达估算降雨的湖北漳河流域径流模拟研究

本文以湖北省漳河流域为研究对象,从2008-2017年中选取了16次洪水过程(10次过程用于率定参数,6次过程用于检验),分别采用了4种方法进行雷达降雨估算,并将估算结果输入到TOPMODEL和新安江模型进行了径流模拟计算。结果表明:4种雷达降雨估算方法中动态Z-I的平均相对误差最小为8.16%,其次是分组Z-I为20.1%,最优Z-I和经典Z-I分别为29.7%和29.02%;从径流模拟结果来看,动态Z-I效果最佳,分组Z-I次之,最优Z-I和经典Z-I模拟效果相对较差,且TOPMODEL模型的洪峰相对误差和峰现时差比新安江模型的模拟结果要小,新安江模型模拟结果的确定性系数与TOPMODEL模型接近。     

Ammonia and phosphorus removal from agricultural runoff using cash crop waste-derived biochars

• Orange tree residuals biochar had a better ability to adsorb ammonia. • Modified tea tree residuals biochar had a stronger ability to remove phosphorus. • Partially-modified biochar could remove ammonia and phosphorus at the same time. • The real runoff experiment showed an ammonia nitrogen removal rate of about 80%. • The removal rate of total phosphorus in real runoff experiment was about 95%. Adsorption of biochars (BC) produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff. In this study, BC made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride (Al-modified) and ferric sulfate solutions (Fe-modified) under various pyrolysis temperatures (200°C–600°C) and residence times (2–5 h). All produced and modified BC were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10–40 mg/L and 4–12 mg/L, respectively. Fe-modified Tea Tree BC 2h/400°C showed the highest phosphorus adsorption capacity of 0.56 mg/g. Al-modified Orange Tree BC 3h/500°C showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g. FTIR characterization showed that P = O bonds were formed after the adsorption of phosphorus by modified BC, N-H bonds were formed after ammonia adsorption. XPS analysis revealed that the key process of ammonia adsorption was the ion exchange between K⁺ and NH₄⁺. Phosphorus adsorption was related to oxidation and interaction between PO₄^3– and Fe³⁺. According to XRD results, ammonia was found in the form of potassium amide, while phosphorus was found in the form of iron hydrogen phosphates. The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption, while the Langmuir equation fits better for ammonia adsorption. The simulated runoff infiltration experiment showed that 97.3% of ammonia was removed by Al-modified Orange tree BC 3h/500°C, and 92.9% of phosphorus was removed by Fe-modified Tea tree BC 2h/400°C.     

成都市雨水分布特征及其利用潜力分析

雨水是一种可供人类使用的宝贵淡水资源。为缓解成都水资源供需矛盾,有效利用雨水资源,本文针对成都市的降雨情况,分析了降雨年内分布特征、雨水水质特点和雨水利用潜力,给出了雨水收集、利用的相应措施,可为城市雨水利用工程规划与建设提供科学参考。     

基于SWAT模型的汉江流域水资源对气候变化的响应

汉江流域未来的气候变化趋势和对水资源的影响,将直接关系到南水北调工程和引江济汉工程的使用和效益。因此,分析研究汉江流域水资源对气候变化的响应特点,可为地面调水、空中水资源开发、应对气候变化的不利影响和更好地保护南水北调中线水源区的水资源提供科学依据。以1971～2000年为基准期,应用SWAT模型对汉江流域基准期内的逐月径流进行了模拟;在30 a基准期径流模拟的基础上,以全球变化背景下可能出现的25种不同气候变化模式为假设条件,模拟出各假设气候变化模式下汉江流域水资源状况,获得了各气候变化模式下汉江流域水资源相对于基准期的变化率,研究了汉江流域水资源对气候变化的响应程度。结果表明：模型模拟精度高于评价标准（〖WTBX〗Ens>05,r2>06〖WTBZ〗）,SWAT模型适用于汉江流域的径流模拟;不同气候变化情景下,汉江流域径流变化较实际蒸散发的变化明显;降水对地表径流、基流的影响要大于气温;气温对实际蒸散发的影响大于降水;降水增加或气温降低都会导致径流增加,而降水增加或气温增加都会导致实际蒸散发的增加.     

Daily Updating of Operational Statistical Seasonal Water Supply Forecasts for the western U.S.1

Abstract: Official seasonal water supply outlooks for the western United States are typically produced once per month from January through June. The Natural Resources Conservation Service has developed a new outlook product that allows the automated production and delivery of this type of forecast year‐round and with a daily update frequency. Daily snow water equivalent and water year‐to‐date precipitation data from multiple SNOTEL stations are combined using a statistical forecasting technique (“Z‐Score Regression”) to predict seasonal streamflow volume. The skill of these forecasts vs. lead‐time is comparable to the official published outlooks. The new product matches the intra‐monthly trends in the official forecasts until the target period is partly in the past, when the official forecasts begin to use information about observed streamflows to date. Geographically, the patterns of skill also match the official outlooks, with highest skill in Idaho and southern Colorado and lowest skill in the Colorado Front Range, eastern New Mexico, and eastern Montana. The direct and frequent delivery of objective guidance to users is a significant new development in the operational hydrologic seasonal forecasting community.     

Mobility of dimethoate residues from spring broccoli field

Dimethoate [O, O-dimethyl-S-(N-methylcarbamoyl-methyl) phosphorodithioate] is a broad-spectrum systemic insecticide currently used worldwide and on many vegetables in Kentucky. Dimethoate is a hydrophilic compound (log K_OW = 0.7) and has the potential of offsite movement from the application site into runoff and infiltration water. The dissipation patterns of dimethoate residues were studied on spring broccoli leaves and heads under field conditions. Following foliar application of Dimethoate 4E on broccoli foliage at the rate of 0.47 L acre^?1, dimethoate residues were monitored in soil, runoff water collected down the land slope, and in infiltration water collected from the vadose zone. The study was conducted on a Lowell silty loam soil (pH 6.9) planted with broccoli under three soil management practices: (i) soil mixed with municipal sewage sludge, (ii) soil mixed with yard waste compost, and (iii) no-mulch rototilled bare soil. The main objective of this investigation was to study the effect of mixing native soil with municipal sewage sludge or yard waste compost, having considerable amounts of organic matter, on off-site movement of dimethoate residues into runoff and infiltration water following spring rainfall. The initial deposits of dimethoate were 6.2 and 21.4 μ g g^?1 on broccoli heads and leaves, respectively. These residues dissipated rapidly and fell below the maximum residue limit of 2 μ g g^?1 on the heads and leaves after 10 and 14 d, respectively, with half-lives of 5.7 d on broccoli heads and 3.9 d on the leaves. Dimethoate residues detected in top 15 cm of soil (due to droplet drift and wash off residues from broccoli foliage) one day (d) following spraying, were 30.5 ng g^?1 dry soil in the sewage sludge treatment, and 46.1 and 134.5 ng g^?1 dry soil in the yard waste and no mulch treatments, respectively. Water infiltration was greater from yard waste compost treatment than from no mulch treatment, however concentrations of dimethoate in the vadose zone of the three soil treatments did not differ.