The Challenges of Water Pollution, Threat to Public Health, Flaws of Water Laws and Policies in Pakistan

In an era of unprecedented urbanization, population and industrial growth pressure is serious threat for the water management in Pakistan in present days. Water pollution from raw sewage, industrial wastes, and agricultural runoff limited natural fresh water resources in the country. Human health is facing serious problems due to deteriorating drinking water quality. Current review paper provides an insight to the water quality problems in Pakistan with an attempt to emphasize the challenges of water laws enforcement. Although Pakistan has developed many water laws the state of implementation is dominant, intermediate pollution crises are still remaining. We could come to the conclusion that strictly enforcement is compulsory for water environment regulations in Pakistan. Moreover, it is necessary to establish a reliable risk assessment system for water quality, human health and ecological safety.

Gas-Water Production of a Continental Tight-Sandstone Gas Reservoir under Different Fracturing Conditions

A numerical model of hydraulic fracture propagation is introduced for a representative reservoir(Yuanba continental tight sandstone gas reservoir in Northeast Sichuan).Different parameters are considered,i.e.,the interlayer stress difference,the fracturing discharge rate and the fracturing fluid viscosity.The results show that these factors affect the gas and water production by influencing the fracture size.The interlayer stress difference can effectively control the fracture height.The greater the stress difference,the smaller the dimensionless reconstruction volume of the reservoir,while the flowback rate and gas production are lower.A large displacement fracturing construction increases the fracture-forming efficiency and expands the fracture size.The larger the displacement of fracturing construction,the larger the dimensionless reconstruction volume of the reservoir,and the higher the fracture-forming efficiency of fracturing fluid,the flowback rate,and the gas production.Low viscosity fracturing fluid is suitable for long fractures,while high viscosity fracturing fluid is suitable for wide fractures.With an increase in the fracturing fluid viscosity,the dimensionless reconstruction volume and flowback rate of the reservoir display a non-monotonic behavior,however,their changes are relatively small.

On the Law Right of the Gas Water of Water Resources

With the development of science and technology, the researches and application of water resources including the gas water have been constantly developed. Through an analysis on the flaws of the water right theory, and by executing reconstruction and renewal of the theory and system of water right in modem society, the water right position of the gas water will be established, leading to the maturity of the whole law effectiveness and substantial results of water right.

Seepage field distribution and water inflow laws of tunnels in water-rich regions

Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.

Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.

Preliminary Study on Water Demand Law of 1-0 Rooted Cuttings of Populus szechuanica

In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and the law of water demand of P.szechuanica was grasped.In this paper,potted seedlings of 1-0 rooted cuttings of P.szechuanica were taken as research objects,and change situation of water consumption under different water control gradients was measured regularly by using weighing method,further analyzing dynamic change of water consumption of P.szechuanica and revealing water demand law of 1-0 rooted cuttings of P.szechuanica.The results showed that total change of water consumption of 1-0 rooted cuttings of P.szechuanica had"slow-fast-slow-fast"double-peak trend in the growth period of the current year,and corresponded with univariate linear relation(R^(2)=0.7137),with significant difference.In whole growth period,water consumption in August was the highest,which was 2.7 times of that in June and July and 1.5 times of that after September.In different water control treatments,the dynamic changes of daily and monthly water consumption were significantly different.In seven water control treatments,monthly water consumption was between(6315.95±1690.70)and(10105.28±3065.30)g/month,and mean was(8211.07±2308.23)g/month.With intensification of water control treatment,water consumption increased,but there was no seedling death due to water shortage.P.szechuanica has great plasticity in water demand,and can survive in both arid and humid environments.Meanwhile,it is revealed that P.szechuanica is the most widely distributed tree species in the region.

Study on Development Law of Complex Fluvial Reservoir under Water

The Bozhong oilfield (Hereinafter referred to as BZ oilfield) is a typical representative of complex fluvial reservoirs in the Bohai Sea, located in the southern Bohai Sea, with an average porosity of 30.3% and an average permeability of 643 × 10-3 μm2, belonging to medium high porosity and permeability reservoir, the reservoir has good connectivity, and the average underground crude oil viscosity is 5 mPa·s. There are many plane fault blocks, and the longitudinal oil well section is long, so the oil-water relationship is very complex. With the further development of the oilfield, the vertical and horizontal oil-water movement law, residual oil distribution and potential are unclear, resulting in rapid bottom water coning, unbalanced injection and production in the oilfield, and increasingly prominent contradictions among layers, planes and layers in the oilfield. Through numerical simulation analysis and comparison of displacement law and recovery degree under different influence conditions, this paper studies the development effect of actual sand body under different influence conditions such as different well types, different development methods and well layout positions, and takes appropriate development methods for the oilfield, which is of great significance to improve the development effect of the oilfield.

页岩气开发过程水资源管理及水环境保护对策探讨

水力压裂和水平钻井技术是页岩气高效经济开采的关键,随着页岩气大规模商业性开发,会带来水资源大量消耗、地表水与地下水污染风险等水环境问题,可能造成页岩气开发区域内水环境影响。为此,本文系统对比研究了中国、美国、加拿大的页岩气开发水资源管理、水环境保护、监管制度相关的环保法规与标准规范,在借鉴北美页岩气开发的环保经验基础上,结合我国页岩气开发过程面临的水资源管理问题,以及国内页岩气企业在水管理中的实践经验,分别从取水用水、废水处置、水污染预防和控制三个方向提出水资源管理及水环境保护措施建议,目的在于促进页岩气企业规范水资源保护措施,改进清洁生产工艺、采用先进的技术与设备、不断改善管理水平,源头削减新鲜水消耗,减少处置风险,提高水资源循环利用效率,最大限度缓解页岩气开发中的用水问题。

水下声学超表面异常折射方向调控研究

针对波束调控的问题,本文提出了一种控制波前相位的声学超表面。本文依据广义斯奈尔定律,利用不同声速的均匀介质构建了水中多频声学超表面模型,给出声学超表面产生异常声折射的基本原理,验证了声学超表面在多个频点下可以实现异常声折射现象,揭示了频率以及声波入射角对声学超表面异常折射现象的影响规律,制备了声学超表面实物在水箱中对理论结果进行验证。结果表明:在入射波频率为基频的整数倍时,超表面模型可以实现折射角相同的异常折射现象,并且入射角在一定范围内可以实现负折射现象。实验测量了水中钢板和超表面的折射情况,相较于均匀介质,在不同入射角度下设计的超表面均可以实现异常折射,并且测量值与理论值吻合较好。

黄土地基不均匀沉降对现浇管廊影响的试验研究

湿陷性黄土地基浸水后的不均匀沉降会使现浇管廊结构产生附加内力,造成管廊结构开裂甚至破坏,严重威胁其运营安全.为深入研究黄土地层湿陷变形对现浇管廊的影响,开展了黄土地层局部浸水湿陷的模型试验.在试验中,设定局部浸水范围,以地基浸水深度为变量,对管廊结构底部位移、土体接触压力、表面应变和地表沉降进行了监测,并分析了其发展趋势.试验结果表明:当局部基底浸水深度达到20 cm,管廊结构在浸水区出现明显的弯曲变形,结构在湿陷区内的最大下沉达到0.57 mm;结构与土体接触压力变化较大区域为湿陷区边缘的管廊底板处;在管廊底部局部浸水发生不均匀沉降时,结构受力形式表现为底板受拉,顶板受压,且越远离管廊中部,所产生的应变越小,拉压应变在湿陷区边缘发生转变;地表也会发生沉降现象,最大沉降值为2.24 mm.试验结果可为湿陷黄土地区现浇管廊的设计和相关病害的防治提供参考.

多分水口长距离输水工程停泵水锤防护措施

为了能够有效避免多泵且多分水口输水系统在无防护抽水断电时可能出现较为严重的负水锤带来的危害,建立了全长106.46 km的大型供水工程的数学模型进行系统过渡过程计算,选择空气阀与两阶段液控蝶阀联合防护与单向塔防护2种方案消除其负水锤,在前者远不达理想防护效果后针对后者进行优化.结合工程实际在确定了单向塔的数量、位置以及塔高后,对不同位置单向塔的底面积进行多种方案的对比选取,最终选用塔1#的底面积为28.26 m^(2),塔2#的底面积为176.63 m^(2);为了防止单向塔漏空需要分水口以及供水终端调流阀配合关闭,在确保管道最大压力不超出其承压能力的前提下,创新性地对各分水口调流阀与供水终端调流阀的关闭时间规律进行了效果比较,使输水系统能够更加经济安全地稳定运行,为此类长距离多分水口多泵供水工程的水锤防护提供了优化方向.

新时期长江流域水资源保护规划及管理工作的思考

组织编制并实施水资源保护规划是国家赋予水行政主管部门的法定职责,也是水利部门履行水资源管理和生态环境保护责任的重要工作。长江流域水资源保护规划经历了从起步、探索、实践与发展到形成完善体系的过程,推进了流域水资源保护与管理科学有序发展。随着国家机构改革部门职能调整和《中华人民共和国长江保护法》出台,为更好地推进和落实新时期长江流域水资源保护规划和管理工作,系统梳理长江流域水资源保护规划发展历程与成效,分析当前流域水资源保护面临的形势与挑战,厘清流域水资源保护工作定位和思路,并据此提出新时期流域水资源保护规划及管理的工作建议,对凝聚流域水资源保护规划共识、建立流域水资源保护规划体系、推进水资源保护高质量发展、助力实现治江现代化具有重要的指导意义。

地下膜调控润灌对冬小麦土壤水分及生长的影响

【目的】探索地下膜调控润灌下冬小麦适宜灌溉制度。【方法】针对地下膜调控润灌,设定300 m^(3)/hm^(2)(W1)、450 m^(3)/hm^(2)(W2)和600 m^(3)/hm^(2)(W3)3种灌水定额,采取连续灌溉(S1)、间歇灌溉(S2)和传统畦灌(CK)3种灌水模式,通过灌水定额与灌水模式田间小区组合试验,研究土壤水分分布和冬小麦的生长性状、耗水规律、产量构成和水分利用效率。【结果】①W3S1处理和W3S2处理较CK灌溉水更集中分布于作物根系层,下渗量减少,提高了株高、籽粒产量和水分利用效率(WUE);②地下膜调控润灌下,随着灌水定额的增加,20~60 cm土层土壤含水率增加;S2处理较S1处理可降低灌溉水向80~100 cm土层下渗;③冬小麦各生育阶段株高、叶面积指数(LAI)和全生育期耗水量均和灌水定额呈正相关;灌水模式对株高和LAI的影响不显著,但可显著提高全生育期耗水量;④随着灌水定额增加,S2处理较S1处理分别增产6.52%、13.11%和3.46%,籽粒产量和WUE呈现先增加后减少的趋势。【结论】相较于CK,地下膜调控润灌可实现节约灌溉用水并提高产量,综合考虑灌后土壤水分分布、作物生长性状、耗水规律、产量和WUE,W2S2处理是最优的灌溉制度,可以在获得更高籽粒产量的同时,提高WUE。

滴灌定额对香梨耗水特征的影响

【目的】探究省力化栽培模式梨园土壤含水率分布特征及其耗水规律。【方法】以2021—2023年库尔勒省力化栽培模式香梨为研究对象,设置4种地表滴灌定额(3750(W0)、5250(W1)、6750(W2)、8250 m^(3)/hm^(2)(W3)),并以漫灌为对照(10000 m^(3)/hm^(2)(CK)),研究滴灌定额对香梨耗水规律及水分利用效率的影响。【结果】灌溉定额增加,土壤含水率上升;土壤水分变异系数、香梨产量随灌溉定额呈先升高后降低趋势,W2处理产量(7285.91 kg/hm^(2))较其他处理高1.4%~20.89%;滴灌定额增加,导致香梨水分利用效率和灌溉水利用系数下降。滴灌香梨全生育期耗水量为444.83~695.27 mm,香梨果实迅速膨大前期与果实迅速膨大期耗水量占比最高。果实迅速膨大期耗水强度最高为3.77~6.16 mm/d;2021—2023年W3处理香梨耗水量较W0、W1、W2处理高10.11%~36.02%,2023年W2处理香梨耗水量较2021、2022年高3.74%~7.15%,W2处理果实迅速膨大期耗水强度为4.71~5.48 mm/d。滴灌香梨生育期作物系数为0.48~0.84,萌芽期花期、果实迅速膨大前期作物系数低于FAO的标准参考值,果实迅速膨大期、收获期作物系数分别为0.7~1.07、0.72~1.21。【结论】推荐地表滴灌的库尔勒香梨生育期灌溉定额不低于6750 m^(3)/hm^(2)。

断块油藏高含水井关井后剩余油再动用运移规律微观模拟

基于微观可视化光刻玻璃模型,从微观角度定性、定量研究了断块油藏高含水井关井后剩余油再动用运移规律,并开展了影响因素分析。结果表明:水驱后关井期间剩余油再动用类型主要为滴状、柱状和簇状。关井期间剩余油会沿模型倾斜方向向高部位运移聚集,有利于后续水驱阶段进一步提高驱油效率。地层倾角的增大、原油黏度的减小有利于剩余油再动用;关井时间的增加有利于剩余油向高部位采出端接近聚集;后续水驱阶段注入速度的增大会增加波及面积。

软弱富水地层超大直径盾构下穿长江堤防变形分析

软弱富水地层上长江堤防变形受浅埋超大直径盾构隧道施工扰动影响大。以盾构开挖直径为15.07 m的某双线隧道工程为背景,基于现场监测资料,研究盾构过堤时无为长江堤防沉降的时空演化规律,并对掘进参数与堤防加固措施的合理性进行分析。研究结果表明,压密注浆加固处理可有效减小堤防地表沉降幅度。右线隧道过堤时,中轴线上方堤防沉降变形总体随着盾尾离开天数的增加而增大,最大沉降位于堤前段,为20.37 mm,远离中轴线部位普遍产生轻微隆起。左线隧道下穿堤防后,堤防竖直变形整体呈“左线堤前段与堤后段隆起、堤坝段沉降,右线整体沉降,幅度从堤前段往堤后段沉减小”的分布规律。盾构下穿长江堤防时,切口压力、推力、扭矩等掘进参数的调整受堤坝超载效应影响。

金矿尾渣固结体重金属浸出规律和水质评价

以贵州某金矿尾渣固结体为研究对象,通过静态浸泡实验,分析尾砂直接浸泡以及固结养护不同时期(7、14、28 d)后浸出的重金属浓度变化情况。研究结果表明:(1)尾渣固结后浸出的重金属Ni、Cd、Sb的浓度比固结前更小,并且养护龄期越长,其浸出量越小;(2)尾渣直接浸泡所测的重金属浸出浓度值与浸泡时间进行函数拟合发现,离子的浸出最大浓度在达到平衡后分别为Ni 2.45μg/L、Cd 0.14μg/L、Sb 360.46μg/L,而Cu离子在此静态浸泡的过程中易饱和沉淀及再浸出,难以达到一个平衡量;(3)固结后尾渣浸出重金属Ni、Cd、Cu、Sb的浓度会最终达到一个平衡量,且随着固结养护龄期越长,各重金属离子浸出的最大浓度越小;(4)尾渣固结前后浸出的重金属浓度均使得水质为Ⅴ类水,但是尾砂固结后,水质整体得到了很大的改善,且养护龄期越长,对地下水水质改善的效果越明显。

事故停泵工况下蝶阀关闭规律对并联大型离心泵组的水锤影响研究

泵后蝶阀是泵站水锤防护的重要装置,采取合适的关阀规律是降低事故停泵时水泵最大反转转速和管线最大压力,保证水泵安全运行的关键,本文以犬木塘输水工程为研究对象,利用一维特征线法对事故停机水锤进行数值模拟计算,分析了液控蝶阀线性关闭规律与两阶段关闭规律对并联大型离心泵组的影响。采取控制变量法,分别以快关时间、慢关时间、快关阀门关闭量作为变量着重分析了两阶段关闭规律下供水系统最大压力和水泵最大反转转速的变化,通过比较2泵同停和1泵运行1泵停止工况下停泵水锤,得到了最佳的关阀规律。结果表明:相比于线性关闭规律,合适的两阶段关闭规律能显著降低管线最大压力,减少水泵最大反转转速,影响水泵最大反转转速的主要因素为快关阀门关闭量,次要因素为阀门快关时间和阀门慢关时间;在合适的阈值内快关阀门关闭量越大、阀门快关时间越短、阀门慢关时间越短为最佳的两阶段阀门关闭规律。

鄂尔多斯盆地双河地区延长组长6油层组地层水化学特征分布规律

致密油藏油水关系复杂,地层水化学组分及其分布规律对指导致密油勘探具有重要意义。基于此,对双河地区长6油层组地层水化学组成、矿化度、水化学特征参数与沉积微相、有效厚度及产能之间的关系进行了深入研究。研究表明,双河地区地层水类型主要为CaCl_(2)型,地层水的矿化度主要分布在2201.2~153670.9 mg/L,平均为53947.2 mg/L。矿化度在50000 mg/L之前,含油饱和度随着矿化度的增加而降低的,而在50000 mg/L之后,含油饱和度随着地层水矿化度的增加而增加。这是由于,较高的矿化度代表好的保存条件,利于油气长期大规模聚集,因而含油饱和度较高;而当目的层矿化度处于10000~20000 mg/L相对低的范围时,主要对应3~5 m薄层单砂体组成的复合砂体,因而含油饱和度也相对较高。分析认为,目的层矿化度、钠氯系数、镁钙系数特征均表明目的层处于相对封闭的沉积环境,有利于油气的保存,这些水化学参数均与致密油藏聚集及产能有较为显著的相关性。