Evaluating the Applicability of a Two‐dimensional Flow Model of a Highly Heterogeneous Domain to Flow and Environmental Management

Two‐dimensional simulation of highly heterogeneous domains, especially those with disparate length scales, roughness conditions, and geometries, often leads to challenges such as long computation times and numerical instability. Simulation of challenging domains is often needed to guide flood management and environmental regulation agencies in operation and potential domain modifications. This work evaluates the ability of a two‐dimensional unsteady hydrodynamic model to represent long‐duration transient flows over a domain with highly heterogeneous roughness, geometric characteristics, and length scales through bed roughness representation. The domain includes 13 km of Cache Creek and the 14.5 km² Cache Creek Settling Basin, which traps both sediment and mercury. Calibration under different bed roughness methods, validation, and modeling results of bathymetric modification scenarios are presented. The modeling approach's performance supports its application as a tool for management of similar domains, such as settling basins, leveed floodplains, and reservoirs. Accurate representation of flow dynamics can also inform environmental management that involves transport of sediments, nutrients, and heavy metals. This study found that a two‐dimensional unsteady flow model can accurately represent long‐duration transient flow in a large settling basin with highly heterogeneous characteristics without parsing of the domain or flow events simulated.     

海河流域河流空间分布特征及演变趋势

海河流域涵盖我国"京津冀"经济圈,河流对流域内人类生存和经济发展具有重要支撑作用,研究河流空间分布及演变趋势对于合理利用河流水资源、保护河流生态和实现经济可持续发展具有重要意义.本文运用遥感资料的GIS分析方法,对海河流域的河流地貌、水系结构、河流曲率和河网密度、闸坝等指标进行分析,发现:1海河流域河流地貌划分为上游山区段、中部平原段和下游滨海段,3个区段水系形状依次为树枝状(受人为干扰小),编织状(中度人为干扰),稀疏编织状(人为干扰强烈);2流域水库和水闸修建阻断河流纵向连续性,五大水系(滦河、北三河、永定河、大清河、子牙河)连续性指标值低于5;320世纪60年代—80年代—2000年,流域河流平均曲率不断减小,河网密度呈现不定向波动,反映出人为控制对河道形态改变程度大.今后应减少人类活动对河流自然属性的改变,河流治理和修复过程中应充分考虑保护和改造河流地貌、水系结构、河流曲率和河网密度.     

四川省农村面源污染状况与治理对策研究

四川省农村面源主要分为农田面源、畜禽养殖粪便污染面源和农村生活污染面源,研究根据排放因子法计算了两种主要考核污染物化学需氧量和氨氮的排放量.根据四川省农村面源污染状况特征提出了面源治理对策措施,其中农田面源治理措施包括:推广测土配方施肥、农田面源生态拦截技术等;畜禽养殖污染治理措施包括:加强小型畜禽养殖污染治理,推广农牧结合、干清粪、发酵床处理工艺等;农村生活污染治理措施包括:推进农村生活污水收集及小型污水处理设施等.     

四川水利水电工程建设对生态环境的影响研究

四川水利工程建设几十年,为四川人民带来巨大利益,为广大人民的经济效应带来巨大的提高.同时,四川水利工程建设也对生态环境产生了一定的不利影响.随着人们对环境保护意识的不断提高,四川生态环境可持续发展日益得到重视.结合四川水利工程生态环境影响的特点,分析了四川水利工程的建设对局部地区的气候、水文地质、泥沙淤积、土壤环境、水生生物、陆生生物等方面造成的生态环境的影响,同时提出了水生、陆生生态环境的保护及恢复措施,为四川的生态环境做出贡献.     

四川省气候变化适应行动现状、问题和建议研究

作为遭受气候变化不利影响较为严重的省份之一,四川省面临着可持续发展能力提升和应对新增气候变化风险的挑战.文章在简要介绍气候变化对四川省的影响、系统梳理其在适应气候变化中取得成效的基础上,进一步剖析了存在的问题,最后结合四川省省情和气候变化适应行动现状,提出了从健全法律法规到完善适应气候变化的体制机制,从加强适应基础建设到强化适应能力建设等方面的建议.     

四川省煤层气开发利用的必要性与可行性分析

四川省拥有丰富的煤层气资源，预测资源量3481亿m^3。煤层气的开发利用有利于弥补常规能源的不足，有利于改善煤矿安全生产条件和减轻大气污染。目前国内外煤层气地面开采技术、井下瓦斯抽放技术均已成熟，四川煤层气开发利用是可行的。     

流域可持续发展系统的建模

流域可持续发展是以流域作为特殊区域的一种可持续发展模式。文章将流域可持续发展视为一个整体，称为“流域可持续发展”。它是一类开放的复杂巨系统，对于因素众多、规模庞大、结构复杂、功能综合、关系较为模糊、开放复杂的这一类巨系统的建模，近年来引起许多学者的关注，文章对流域可持续发展系统分析的有关建模问题进行了讨论。在对流域可持续发展系统进行分析研究的基础上，给出了流域可持续发展系统建模的原则、方法和步骤。     

REASONABLY FULL HYDROLOGIC DEVELOPMENT OF RESERVOIR SITES1

The size of multipurpose reservoir development is usually determined by an economic analysis of reservoir capabilities and the present and projected water resources needs which can be satisfied. This analysis is referred to as project formulation, wherein optimum conditions are sought. In responding to multiple objectives, i.e., national economic development, regional development and environmental quality, which are being considered in river basin planning in recent years, reservoirs should provide for reasonably full hydrologic development. Additional storage will be needed to provide opportunities for economic development, as well as meet unexpected development. Also, it provides more flow regulation capability for quality of environment considerations. An analysis has been made on twelve reservoir sites in the New York State portion of the Susquehanna River Basin to determine the so-called “reasonably full hydrologic development of reservoir sites.” Hydrologic, economic, environmental and physical characteristics of the sites are taken into consideration. For normal conditions, it can be concluded that a yield equivalent to about 80 percent of the average discharge (runoff) can be considered as reasonably full hydrologic development for reservoir sites in the Susquehanna River Basin in New York. The same technique can be applied elsewhere to determine reasonably full hydrologic development of reservoir sites.     

牡丹江流域生态环境现状及保护对策

"十一五"期间,牡丹江市土地没有退化,森里和草原资源丰富。牡丹江干流水生态环境良好,水生生物优势种明显。牡丹江市辖区河段果树场-牛场村,生物多样性高,水土保持较好。牛场村-温春镇兴隆河段,水生生物多样性已呈减少趋势,陆生生物多样性一般,土壤侵蚀中等。牡丹江市区河段,水生生物多样性差,陆生生物很少,水土流失现象严重。结合牡丹江流域生态环境特点,提出适宜的生态保护对策。     

基于信息扩散和模糊评价方法的四川盆地气候干旱综合评价

利用1961~2005年历史气象资料,以受旱天数、湿润度指数、标准化降水指数、温度距平、日照距平百分率等5个要素作为干旱评价指标,应用信息扩散方法建立了各单个评价指标的春、夏、伏旱旱情等级划分标准,采用模糊综合评价方法对1961~2006年四川盆地气候干旱进行评价,并给出了各市干旱出现的频率。结果表明:2006年四川盆地发生了严重的春旱、夏旱和特别严重的伏旱,盆区17个市均有伏旱发生,其中有13个市伏旱特别严重;伏旱期少雨天气平均为30年一遇,高温天气平均为60年一遇,约29%的台站的少雨和90%的台站的高温为50年以上一遇;春、夏旱主要出现在盆地西北部和盆地南部,约2.5年出现一次,伏旱则主要出现在盆地东部,约2年出现一次。