坪底水库枢纽布置及工程设计

坪底水库是石楼县为解决城镇生活用水和工业用水为主的供水工程。针对水库工程区的地形地质条件及来水来沙情况,选择了符合实际的混凝土重力坝、表孔溢流、泄洪排沙洞枢纽总布置,枢纽布置紧凑合理,并采用空库度汛的方式,可有效地提高水库的使用寿命。论述了枢纽布置与工程设计。     

关中地区蓄水池的结构与应用探究

城市雨水的有效利用已成为了社会发展过程中的热点问题。根据关中地区的气候条件和园林行业的用水需求,对现行广泛使用的蓄水池进行结构改良,防渗透和水质净化处理,使其适合在关中地区的城市绿地中推广使用,发挥出极大的生态效益和社会效益。     

山西省1949—1988年气象产量指数分布特征及其与气候条件的关系

以气象产量指数指示气候条件对粮食生产的影响,分析了山西省1949～1988年气象产量指数时空分布特征及其与气候条件的关系,发现山西气象产量指数极差大、变幅大,与降水相关密切,涝或偏涝年均可获正常以上收成,反之旱或偏旱年则多数减产.与气温关系不密切且为反相关.可见,山西气候状况降水较少、平均雨量不敷农业需求,是制约农业生产的根本因素.山西多样的气候使得气象产量变化也呈多样性,一些区域与另一些区域(面积比约为4∶6)为反相关,由于这种互补性使山西难以形成全省性灾害.     

水库修建对黄河水沙问题的负面影响

修建水库是我国乃至世界各国治理水患、满足生产生活用水和用电需求重要途径之一。水利工程固然可以产生可观的经济效益,然而巨大的环境代价不容忽视。尤其近几十年在“水沙异源、水少沙多、时空分布不均匀”的黄河上修堤筑坝、修建水库,改变了黄河的水沙条件,严重影响了水沙运行环境。主要从水库尤其是龙羊峡、刘家峡和三门峡水库的修建与运作对黄河中下游水沙问题与流域造成的环境影响着手,通过近几十年来黄河径流、流域来水来沙情况及河道形态等在时间和空间序列上的数据分析,指出水库建设对黄河水沙状况带来的负面影响,降低了黄河中高流量频次,使得黄河径流出现显著均匀化、可控化的特征;影响黄河天然的来水来沙状况,造成河道淤积增强;加剧黄河断流;从而更加恶化黄河洪水和泥沙问题。从可持续发展的角度提出了黄河水沙问题的相关解决对策。     

1952—2017年出山店水库上游降水时空变化

为了探究出山店水库上游流域近65 a来降水的时空变化特征,基于出山店水库上游流域13个雨量站1952—2017年的逐日降水资料,运用气候倾向率法、Mann-Kendall趋势检验、Morlet小波分析和反距离权重IDW插值法等多种方法,研究了降水的年际变化、周期性与空间分布特征。结果表明:(1)流域1952—2017年多年平均降水量为1 028.3 mm,年降水量的气候倾向率为-20 mm/10 a(p<0.05),呈显著下降趋势,从季节上看,春、夏、冬降水随时间变化呈现减少趋势,秋季的降水呈现增加趋势;(2)年降水量呈现南高北低的空间分布,而年降水量的气候倾向率的变化趋势则与之相反;(3)流域降水量变化呈现20 a左右的第一主周期,同时流域的周期性变化也存在一定的空间分布特征。近65 a来,出山店水库上游年降水量变化趋势为先增加后减少,在整个时间域上有显著的下降趋势,并呈现20 a左右的周期性变化。     

灌区田间灌溉蓄水工程的规模优选

针对灌区缺乏调蓄的实际情况,提出了一个优选田间灌溉蓄水工程规模的模型。模型同时考虑灌区来水与用水的随机性,以旬为分析时段单元,生成泉源来水和灌溉需水的人工长系列,基于蒙特卡罗(Monte Carlo)方法,模拟计算了不同规模的蓄水工程在设计运行期内对灌溉区农业的增产效益,以净效益最大为标准优选田间蓄水池规模,结果表明,对于单位灌溉面积最优的蓄水工程规模为2100 m³,相应的灌溉可靠度提高到95.0%。     

水旱轮作对土壤微生物群落构建过程的影响机制

为探究稻田生态系统微生物学机制,采集水旱轮作稻田土壤,并以相同土壤母质下长期淹水的藕田土壤以及旱作的果树土壤为对照,研究了稻田生态系统细菌群落结构以及基于零模型的群落构建机制。结果表明:旱作和水旱轮作两个生态系统,由于频繁耕作以及施肥管理等农业措施形成特定的生态位格局,确定性过程主导群落构建。旱作生态系统下确定性过程占78.6%,随机性过程占10.7%;相对于旱作,由于水旱轮作的淹水条件,土壤肥力积累,水体连通性较好等特性导致内部环境变化缓和,其随机性过程(39.3%)影响增加,确定性过程(50.0%)下降;同理,长期淹水的水生生态系统中随机性群落构建(50.0%)成为主导过程。群落构建影响细菌群落结构和功能,因此随机性生态过程的增强进一步增加了细菌多样性以及物种生态网络的交互度和稳定性,增强了微生物抵抗外部环境扰动的能力,该过程有助于维持农田生态系统功能的稳定性和可持续性。     

冉渡滩水库取用水合理性分析

冉渡滩水库工程主要以供水和灌溉为主,属中型水库。取用水合理性分析结果表明:设计总取水量9 400万m3/a,在保障城镇供水、工业园区用水、农村人畜饮水、农灌用水及水力发电用水情况下,水量利用系数为78.4%。水库取用水量适当,取水可靠性高,水源水量水质均有保障。     

灌区用水决策支持系统的现状及展望

文章系统分析和回顾了井灌区、渠灌区灌溉决策支持系统和综合利用水库优化决策支持系统的国内外研究现状及发展历程.指出了各类型灌区用水决策支持系统存在的不足与缺陷,并提出了一些改进措施与方法.在此基础上,结合现阶段灌区用水的实际及管理中出现的问题,提出了以后灌区用水决策支持系统的发展趋势.     

生态住宅的水环境规划：I.水循环

生态住宅已成为住宅建设的发展趋势和潮流,水环境是生态住宅小区的重要组成部分。文章以中信保利达美景度假区为实例,根据度假区建筑总体规划方案,结合当地自然条件和水环境现状,探讨生态住宅小区的水环境规划,全面统一规划住宅小区内各种水系统,提出小区水环境总体规划方案,充分发挥各系统的功能,使其相互衔接、协调与补充。重点对项目所在区域开发前后的水量平衡,水库的水位变化及其安全性,极端气候条件下的库区水量变化及其因应对策,高尔夫球道的用水方案以及项目开发后的水循环模型做了深入探讨,旨在为生态住宅的水环境建设提供范例。     

基于STELLA和气候变化情景的灌区农业供需水量模拟

为了评估气候变化对灌区农业供需水量的影响,基于系统动力学软件STELLA(structure thinking experimental learning laboratory with animation)建立了宝鸡峡灌区供需水量计算模型,结合灌区气象水文数据,利用非一致性水文频率计算原理,预估了未来可供水量和气候变化情景,模拟了气候变化情景下不同规划水平年灌区农业供需水状况。结果表明:灌区主要水源渭河径流在1989年发生跳跃变化,跃幅为-14.25亿m3,各典型年预估径流量(1989-2030年)比原序列(1954-2010年)对应值减少40%~55%,导致农业可供水量锐减;在α=0.05的显著水平上,1981-2010年灌区降水下降不显著,平均气温、最高气温显著上升而相对湿度和风速显著下降,其他因子无明显趋势;灌区未来各典型年农业需水量2030年比2010年增加1.08~2.19亿m3,水资源供需平衡指数上升9.06%~14.46%,说明灌区农业供需水平衡状况受气候变化影响显著,必须在规划、设计和管理中予以考虑并采取积极的应对措施。研究结果为气候变化条件下灌区农业水资源合理配置提供了参考。     

基于Copula函数的区域需水量随机模拟

受社会经济发展、气候等因素的影响,区域需水量不可避免存在一定的随机性。鉴于Copula函数可以用来描述事件序列的自相关结构,该文建立了基于Copula函数的区域需水量随机模拟模型。该模型能够考虑各月需水量间的相关性,克服了分离处理各月需水量而导致模拟精度不高的缺点。将模型应用于汉江中下游地区的需水模拟,并与现有的基于Cholesky因子分解模拟模型进行比较,研究了该模型的适用性。结果表明,该模型所模拟需水序列的均值、均方差等统计参数的相对均方误差均较小,同时能够保持各月需水量之间的相关关系,为区域的需水模拟提供了新思路。     

农户节水灌溉技术认知及其影响因素分析

研究农户节水灌溉技术认知及其影响因素,旨在为科学分析农户灌溉技术选择的行为和转变农户粗放型灌溉方式提供基础。以陕西省温室作物生产地区的10个县(区)17个乡镇的296份入户调查资料为样本,采用结构方程模型研究农户对节水灌溉技术的认知及其影响因素。结果表明:认知程度直接影响节水灌溉技术的扩散;对节水灌溉技术的已有认知、对现有灌溉方法的满意度、政策补贴的方式和力度、灌水成本、受教育程度、是否为干部、技术培训经历和种植经验等因素均不同程度地影响农户对节水灌溉技术的认知水平;促进农户对传统灌溉方式的理性认知、拓展农户对节水灌溉技术认知的广度和深度、加强政府的宏观调控与扶持力度、建立完善的节水农业技术推广体系,有助于提升农户对节水灌溉技术的认知水平、规范农户灌溉行为选择,提高农户采用节水灌溉技术的积极性。     

基于区间多阶段随机规划模型的灌区多水源优化配置

灌区多水源灌溉系统中存在许多不确定性因素,随着系统环境的变化及不确定性因素的影响,导致其配水过程具有动态特征。针对灌区多水源灌溉系统的配水特点,该文建立基于区间多阶段随机规划的灌区多水源优化配置模型。同时,考虑灌溉水对作物产量的影响,引入水分敏感指数权重系数,并以黑龙江省和平灌区水稻不同生育阶段灌溉水资源优化配置进行实例研究。结果表明,在不同来水情境下,管理者可根据各个生育阶段水分敏感指数权重系数,判断作物不同生育阶段的需水敏感程度,当来水情境的来水量多时,会产生余水量,可调配给下一生育阶段;当来水情境的来水量少时,管理者可在减少灌溉水量与增加外调水之间进行权衡,并根据需水关键期与需水非关键期做出决策,使水资源在作物生育阶段间及作物生育阶段内进行分配,实现灌区多水源灌溉系统的动态配水。该模型的应用在确保作物产量的同时,使灌溉水资源在作物各个生育阶段进行合理配置,有效地避免了水资源浪费,对提高灌溉水利用效率、保证水资源的可持续利用具有重要意义。     

Stochasticity dominates assembly processes of soil nematode metacommunities on three Asian mountains

Nematodes play an important role in ecosystems; however, very little is known about their assembly processes and the factors influencing them. We studied nematode communities in bulk soils from three Asian mountain ecosystems to determine the assembly processes of free-living nematode metacommunities and their driving factors. On each mountain, elevations span a range of climatic conditions with the potential to reveal assembly processes that predominate across multiple biomes. A phylogenetic nu...     

An Air Quality Management Model Based on an Interval Dual Stochastic-Mixed Integer Programming

The issue of air pollution has become the focus of the world because of its significant influence to the economic development and public health. This paper proposes an interval dual stochastic-mixed integer programming (IDSIP) approach for regional air quality management. The IDSIP approach can be effectively communicated into the optimization processes and resulting solutions, which is formulated through integrating interval-parameter integer programming (IIP) within a two-stage stochastic programming (TSP) joint chance-constrained programming (CCP) and could deal with uncertainties expressed as not only probability distributions but also interval values. Moreover, the left-hand-side (LHS) constraints with stochastic variables could be handled at different risk levels with varied reliability scenarios. In the modeling formulation, penalties are imposed when expected policies are violated. The results indicate that reasonable solutions for air quality management system have been generated, which can help decision makers draw up productive strategies taking into account the trade-off between system economy and air quality under uncertainty.     

Environmental similarity is more important than distance in the community structuring processes of ammonia-oxidizing archaea in agricultural soils

Ammonia-oxidizing archaea(AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic processes has poorly been understood. We compared AOA communities across the North China Plain, targeting the amoA gene. A phylogenetic null modelling approach was used to calculate the beta nearest taxon index to quantify the influence of stochastic and deterministic processes. We f...     

The impact of climate change on geomorphology and desertification along a mediterranean-arid transect

From the perspective of geomorphology, three important aspects of climate should be considered if conditions become more arid: (a) any decrease that might occur in the annual rainfall amount; (b) the duration of rainfall events; and (c) any increase in the intervals between rainfall events. These, together with increasing temperature, lead to less available water, less biomass and soil organic matter content and hence to a decrease in aggregate size and stability. As a consequence, the soil permeability decreases, soils develop surface crusts and infiltration rates decrease dramatically. Such changes in vegetation cover and soil structure lead to an increase in overland flow and in the erosion of the fertile topsoil layer. Positive feedback mechanisms may reinforce these effects and lead to desertification. This paper considers the results of field investigations into the spatial variability of a number of ‘quick response’ variables at two scales: the regional and the plot scales. Concerning the regional scale spatial variability, results of experimental field work conducted along a climatic transect, from the Mediterranean climate to the arid zone in Israel, show that: (1) organic matter content, and aggregate size and stability decrease with aridity, while the sodium adsorption ratio and the runoff coefficient increase; and (2) the rate of change of these variables along the climatic transect is non-linear. A steplike threshold exists at the semiarid area, which sharply separates the Mediterranean climate and arid ecogeomorphic systems. This means that only a relatively small climatic change would be needed to shift the borders between these two systems. As many regions of Mediterranean climate lie adjacent to semiarid areas, they are threatened by desertification in the event of climate change. Concerning spatial variability at the plot scale, different patterns of overland flow generation and continuity characterize hillslopes under different climatic conditions. While in the Mediterranean climate area infiltration is the dominant process all over the hillslope, in the arid area overland flow predominates. In contrast to the uniform distribution of processes in these two zones, a mosaic-like pattern, consisting of locally ‘arid’ water contributing and ‘moist’ water accepting patches is typical of the transitional semiarid area. Such pattern is strengthened by fires or grazing which are characteristic of this area. The development of such mosaic pattern enables most rainfall to be retained on hillslopes. Changes in the spatial pattern of contributing versus accepting water areas can be used as an indicator of desertification and applied to developing rehabilitation strategies. © 1998 John Wiley & Sons, Ltd.     

SIFNP: Simulation-Based Interval-Fuzzy Nonlinear Programming for Seasonal Planning of Stream Water Quality Management

A simulation-based interval-fuzzy nonlinear programming (SIFNP) approach was developed for seasonal planning of stream water quality management. The techniques of inexact modeling, nonlinear programming, and interval-fuzzy optimization were incorporated within a general framework. Based on a multi-segment stream water quality simulation model, dynamic waste assimilative capacity of a river system within a multi-season context was considered in the optimization process. The method could not only address complexities of various system uncertainties but also tackle nonlinear environmental?Ceconomic interrelationships in water quality management problems. In addition, interval-fuzzy numbers were introduced to reflect the dual uncertainties, i.e., imprecision associated with fixing the lower and upper bounds of membership functions. The proposed method was applied to a case of water quality management in the Guoyang section of the Guo River in China. Interval solutions reflecting the inherent uncertainties were generated, and a spectrum of cost-effective schemes for seasonal water quality management could thus be obtained by adjusting different combinations of the decision variables within their solution intervals. The results indicated that SIFNP could effectively communicate dual uncertainties into the optimization process and help decision makers to identify desired options under various complexities of system components.     

Distinct and combined impacts of climate and land use scenarios on water availability and sediment loads for a water supply reservoir in northern Morocco

The objective of this study was to examine the impacts of climate and land use changes on water availability and sediment loads for a water supply reservoir in northern Morocco using data-intensive simulation models in a data-scarce region. Impacts were assessed by comparing the simulated water and sediment entering the reservoir between the future period 2031–2050 and the 1983–2010 reference period. Three scenarios of land use change and two scenarios of climate change were developed in the Tleta watershed. Simulations under current and future conditions were performed using the Soil and Water Assessment Tool (SWAT) model. The simulations showed that climate change will lead to a significant decrease in the annual water supply to the reservoir (−16.9% and −27.5%) and in the annual volume of sediment entering the reservoir (−7.4% and −12.6%), depending on the climate change scenarios tested. The three scenarios of land use change will lead to a moderate change in annual water inflow into the reservoir (between −6.7% and +6.2%), while causing a significant decrease in sediment entering the reservoir (−37% to −24%). The combined impacts of climate and land use changes will cause a reduction in annual water availability (−9.9% to −33.3%) and sediment supplies (−28.7% to −45.8%). As a result, the lifetime of the reservoir will be extended, but at the same time, the risk of water shortages will increase, especially from July to March. Therefore, alternative water resources must be considered.