【作者】 陈广泉；

【导师】 陈沈良；

【作者基本信息】 华东师范大学 ， 河口海岸学， 2013， 博士

【摘要】 受气候变化和人类活动的双重影响,莱州湾地区已成为我国海水入侵灾害最为严重和典型的区域,入侵面积已超过4000km2。海水入侵已严重制约该地区经济社会发展。日益加剧的海水入侵严重污染该地区地下淡水资源,使土壤次生盐渍化面积不断扩大,对海岸区域的工农业生产和生态环境造成严重影响。本文基于1976至2012年莱州湾地区地下水位和水质监测数据以及环境背景等长时间序列资料,系统总结了近40年来该地区海水入侵的演变过程和发展阶段,定量辨识海水入侵与气候变化和人类活动之间的响应机制,建立现状评价、危险性评价和预警的综合预警评价系统。研究成果对于揭示海水入侵受气候变化和人类活动的影响过程和机制、深入认识和评估未来气候变化的影响,以及海水入侵灾害的有效防治,具有重要的理论意义和应用价值。近40年来莱州湾沿岸地区的海水入侵灾害经历了初始、发展、恶化、缓解及分化等五个发展阶段。据2010年调查结果,莱州湾地区海水入侵面积已达到4300km2。结合海水入侵特征与水文地质环境背景,可将莱州湾地区海水入侵分为四个类型区：原生海水入侵区、混合海水入侵区、人类活动干扰区和入侵后退区。其中,原生海水入侵区面积为1000km2,混合海水入侵区面积为2500km2,人类活动干扰区面积为800km2,入侵后退区面积为70km2,分别占整个研究区的12%、30%、10%和不足1%。研究区海水入侵受气候变化和人类活动的双重影响。其中,气候变化的影响主要体现在年内和年际尺度上,表现为海水入侵的季节性变化(地下水的季节性变咸)和海水入侵的多年变化(枯、丰水年海水入侵的进退)。人类活动的影响表现为海水入侵呈线性增长的趋势。随着经济的不断发展,工农业用水量呈线性增长趋势,水资源量供需失衡,从而导致地下水超采,这是该区域海水入侵恶化的主导因素。综合地下水Cl-浓度、地下水位、入侵面积和负值区面积等海水入侵评判因子与气候变化和人类活动因素,构建海水入侵对气候变化和人类活动响应模式：F(s)=F(w,t)=F(r,e,p,t),其中,F(s)表示海水入侵的变化函数；w为地下水位,反映海水入侵变化特征；r为降雨量,e为蒸发量,二者反映气候变化对海水入侵的影响程度；p为地下水开采量变化,由地下水开采强度和开采系数表示,反映人类活动对海水入侵的影响；t为时间。为定量化辨识莱州湾地区海水入侵对气候变化和人类活动的响应机制,对近30年来的地下水位、降雨量、蒸发量和人类活动强度的长时间序列月均数据进行多元回归分析,量化海水入侵对气候变化和人类活动响应模式。综合分析结果表明,人类活动对海水入侵灾害的影响比重占59%,气候变化因素(降雨量与蒸发量)占41%。建立海水入侵自动监测网络,定量分析地下水电导率与C1-浓度相关关系：Cl-(mg/L)=-157.26+261.20Ec(ms/cm),以电导率1.56ms/cm作为判断莱州湾地区海水入侵的标准。基于监测网络以及地统计分析方法,对莱州湾南岸潍坊滨海地区进行海水入侵现状评价。评价结果显示,研究区内海水入侵成条带状分布,由北向南依次为严重入侵区、入侵区和无入侵区。其中严重入侵区主要分布在大家洼、央子和下营地区,入侵面积2073km2,占总面积43.7%；入侵区位于台头、昌邑一带,入侵面积547km2,占总面积11.5%,最大入侵距离可达30km；无入侵区主要分布在寿光、潍坊市区以及昌邑市区以南,占总面积44.8%。建立5个因子27个变量的海水入侵危险性评价指标体系,根据信息量模型对潍坊滨海地区的海水入侵进行危险性评价,危险性评价结果将潍坊北部滨海地区划分为4个等级：高危险区、较高危险区、低危险区和无危险区。通过计算,高危险区面积为2138km2,占评价总面积45.4%；较高危险区面积为521km2,占评价总面积11.0%；低危险区面积为479km2,占评价总面积10.0%；无危险区面积为1583km2,占评价总面积33.6%。可见,整个潍坊滨海地区约有三分之二的区域处于海水入侵灾害危险区。采用序贯指示模拟方法开展莱州湾地区海水入侵预警评价,根据灾害发生概率与危险性评价等级,将海水入侵预警评价等级分为4级,开展莱州湾地区2013海水入侵预警评价。预警结果表明,整个研究区海水入侵预警区域呈带状分布,预警等级由北向南逐渐降低。根据预警评价结果以及海水入侵的成因特征,针对性地从工程技术、生态修复和行政管理三个方面综合提出海水入侵防治对策。更多还原

【Abstract】 Seawater intrusion is the phenomenon in which seawater or other saltwater travels into the continent along the aquifer. It can be affected by climate change and human activity, both of which alter the hydrodynamic conditions of aquifers in coastal areas. This breaks the equilibrium between seawater and freshwater, causing the salt-fresh interface to move landward. Laizhou Bay suffers the most serious seawater intrusion in China, with an intrusion area of over4000km2. This is has been concretely attributed to climate change and human activity. Seawater intrusion decreases the quality of drinking water by raising salinity to levels exceeding acceptable drinking water standards. This causes environmental contamination and soil secondary salinization. Local economies and social development can be considerably constrained by this increase in seawater intrusion, which affects industry and agriculture. Using data describing groundwater levels, groundwater quality, and the geological environment from1976-2010, this paper discusses the development and variation of the seawater intrusion in the Laizhou Bay over the past40years, quantifies the mechanisms that influence and underlie of seawater intrusion, discusses the involvement of climate change and human activity, and establishes a comprehensive early warning assessment system, which includes a status appraisal model, a risk-assessment model, and a early warning model. The results of the present work may be used to develop an ideal response process and describe the ways in which human activity and climate change affect the mechanism by which seawater intrudes into the Laizhou Bay area.The intrusion of seawater into the Laizhou Bay area has shown five stages of development over the past40years:i) initiation, ii) development, iii) deterioration, iv) release, v) differentiation. According to the investigation in2010, the intrusion area in the Laizhou Bay has exceeded4300km2. Based on the characteristics and hydrogeological environment of the seawater intrusion, the seawater intrusion region can be divided into types:1) original seawater intrusion area,2) mixed area,3) human-disrupted area, and4) intrusion-retreated area. The area (areal fraction) of the five sections are approximately1000km2(12%),2500km2(30%),800km2(10%), and70km2(less than1%), respectively.Seawater intrusion may occur due to human activity or because of natural events. Over-abstraction is considered the main cause of seawater intrusion. Climate change can speed up seawater intrusion. The effect of climate change is mainly reflected in annual scale and inter-annual scale, which involves seasonal changes in seawater intrusion (seasonal salty groundwater) and changes in seawater intrusion over the course of the year (movement of the interface seaward or landward in a wet and dry seasons). The impact of human activity is shown as seawater intrusion in the linear growth trend. Rapid economic development has increased in abstraction from aquifers, causing a serious imbalance between the seawater and freshwater, and the risk of seawater intrusion has increased. A model incorporating climate change, human activity, and factors that can be used to evaluate seawater intrusion, such as the intensity of Cl-, groundwater height, area of sea water intrusion, and negative equivalent area, was established to assess the correlations among climate, human activity, and the variability in seawater intrusion variability. The model is as follows: F(s)=F(w, t)=F(r, e, p, t). In the present formula, F(s) stands for seawater intrusion, w stands for groundwater level, which is one of the characteristics of seawater intrusion; r stands for rainfall; and e stands for evaporation, both of which can reflect the impact of climate change on seawater intrusion; p stands for groundwater exploitation variations represented by intensity and coefficient of groundwater exploitation, which refers to the effects of human activity on the seawater intrusion; and t is time.To determine the mechanism by which human activity and variations in climate influence seawater intrusion, a multi-parameter regression analysis was conducted based on a monthly long time series data of groundwater level,rainfall,evaporation and human activity under the various time scales for nearly30years and on the response of seawater intrusion to these two outside influences. The results show that human activity can account for59%of seawater intrusion, and variations in climate variation can account for41%.An automatic monitoring network of seawater intrusion was established to facilitate assessment of seawater intrusion. The relationship between the conductivity of groundwater and Cl" concentration can be quantitatively analyzed:Cl-(mg/L)=157.26+261.20Ec (ms/cm), and take1.56ms/cm as the standard amount of seawater intrusion into the Laizhou Bay area. The current situation with respect to evaluation of seawater intrusion in Laizhou Bay area involves monitoring networks and geostatistical analysis. Seawater intrusion presents a banded distribution in the study area, and the seriousness of the intrusion increases from north to south. The areas with the most serious invasion are mainly distributed in Dajiawa, Yangzi, and Xiaying, covering a total of2073km2. These areas account for43.7%of the total. Invasion areas in Taitou and Changyi cover547km2, accounting for11.5%. The longest single invasion was30km in Shouguang. Areas with no intrusion were mainly distributed around the city of Shouguang in Weifang and the southern parts of Changyi, accounting for44.8%of the total.The risk evaluation index system for seawater intrusion is established. This system incorporates5factors and27variables. The risk evaluation of seawater intrusion in the Weifang coastal area is performed according to the information model, and the results divide the area in northern Weifang area into four levels:a high danger zone, a moderate danger zone, a low danger zone, and danger-free zone. The high danger zone was calculated to cover an area of2138km2, accounting for45.4%of the total evaluation area; the moderate danger zone covered an area of521km2,11.0%of the total; the low danger zone covered479km2,10.0%of the total; and the danger-free zone covered1583km2,33.6%of the total. Two-thirds of the Weifang coastal area are in a potential disaster zone with respect to seawater intrusion.According to the probability of disaster and level of risk assessment, the Laizhou Bay area early warning level can be divided into4using a sequential indicator simulation that was performed in2013. The early warning result shows that the early warning area of seawater intrusion in Laizhou Bay has a zonal distribution and the danger level gradually decreases from north to south. Based on the early warning result and the characteristic of seawater intrusion, three prevention and controlling measure of seawater intrusion from engineering technology, ecological restoration and administrative management are put forward.更多还原