Risk assessment of maize drought disaster in southwest China using the Environmental Policy Integrated Climate model

The East Asian monsoon has a tremendous impact on agricultural production in China. An assessment of the risk of drought disaster in maize-producing regions is therefore important in ensuring a reduction in such disasters and an increase in food security. A risk assessment model, EPIC（Environmental Policy Integrated Climate） model, for maize drought disasters based on the Erosion Productivity Impact Calculator crop model is proposed for areas with the topographic characteristics of the mountainous karst region in southwest China. This region has one of the highest levels of environmental degradation in China. The results showed that the hazard risk level for the maize zone of southwest China is generally high. Most hazard index values were between 0.4 and 0.5,accounting for 47.32% of total study area. However,the risk level for drought loss was low. Most of the loss rate was ＆lt;0.1, accounting for 96.24% of the total study area. The three high-risk areas were mainlydistributed in the parallel ridge–valley areas in the east of Sichuan Province, the West Mountain area of Guizhou Province, and the south of Yunnan Province.These results provide a scientific basis and support for the reduction of agricultural drought disasters and an increase in food security in the southwest China maize zone.

The Assessment of Groundwater Vulnerability Due to Leaching of Chemicals: The Review of Attenuation Factor

To assess the groundwater vulnerability due to leaching of chemicals, the groundwater system in the unsaturated zone is characterized by conceptual models that are further extended and refined with more detailed mathematical models to understand the governing physical processes in detail. However, due to lack of data and uncertainty level, an intermediate transition through index based models is researched. The attenuation factor (AF) approach, which works under the assumption that the chemicals degrade following a first-order kinetics and determines the fraction of the chemicals that goes to groundwater table, is one of the index based models that has been widely used due to its simplicity. Therefore, the objective of this paper is to review the research works done using the AF approach, to outline the future research needs. Furthermore, the mathematical implementation of the AF approach and the associated uncertainty levels is explained through an example and MATLAB source code.

Vulnerability Assessment of Shallow Groundwater in Ordos Cretaceous Basin

[Objective] The aim was to evaluate the vulnerability to pollution of shallow groundwater in Or（los Cretaceous Basin system. [Method] Mathematical modeling, GIS spatial analysis and multivariate statistical analysis technologies were introduced to improve the traditional groundwater vulnerability assessment model of DRASTIC in view of its strong subjective for expert estimation and weight assigning. In the meantime, the intensi- ty and reasons of vulnerability to pollution of groundwater in the area were studied, and measures to protect local groundwater were proposed. [Resultl Using improved DRASTIC method to assess the vulnerability to pollution of groundwater in Ordos Cretaceous Basin system was objective and reliable. The application of fertilizer was the main influential factors to the vulnerability to pollution of groundwater in Ordos Cretaceous Basin sys- tem. It was advised to lessen the usage of fertilizer and not to drink water from lake or deep ground water. Density, rock, and evaporation were fac- tors that led to intensive vulnerability to pollution of groundwater in shallow areas. [ Conclusion] The study provided a new method for the evaluation of vulnerability to pollution of groundwater in Ordos Basin.

Groundwater Quality Analysis and Vulnerability Assessment in Longdong Area

Groundwater is important drinking water source in Longdong area. In recent years,as gradual expanding of industrial and agricultural production scales,seen from change trend of water quality,major impact factors of groundwater in the zone were ammonia nitrogen,COD,sulfate and total dissolved solid. By using specific thought of parameter system method,vulnerability assessment factor system of groundwater and meter point system calculation model in the zone were established. Via calculation and analysis,vulnerability distribution of groundwater in the zone was obtained. According to vulnerability index（ higher,moderate and lower）,zone dividing was conducted,and the areas were respectively 623. 25,4 005. 00 and 6 621. 75 km2,which respectively accounted for 5.54%,35. 60% and 58. 86%. The evaluation provided research basis for prevention,control and protection of groundwater environment in Longdong area.

Groundwater characteristics and climate and ecological evolution in the Badain Jaran Desert in the southwest Mongolian Plateau

The Badain Jaran Desert is the third largest desert in China,covering an area of 50000 km2.It lies in Northwest China,where the arid and rainless natural environment has a great impact on the climate,environment,and human living conditions.Based on the results of 1∶250000 regional hydrogeological surveys and previous researches,this study systematically investigates the circulation characteristics and resource properties of the groundwater as well as the evolution of the climate and ecological environment since the Quaternary in the Badain Jaran Desert by means of geophysical exploration,hydrogeological drilling,hydrogeochemistry,and isotopic tracing.The results are as follows.(1)The groundwater in the Badain Jaran Desert is mainly recharged through the infiltration of local precipitation and has poor renewability.The groundwater recharge in the desert was calculated to be 1.8684×10^(8)m^(3)/a using the water balance method.(2)The Badain Jaran Desert has experienced four humid stages since the Quaternary,namely MIS 13-15,MIS 5,MIS 3,and the Early‒Middle Holocene,but the climate in the desert has shown a trend towards aridity overall.The average annual temperature in the Badain Jaran Desert has significantly increased in the past 50 years.In detail,it has increased by about 2.5℃,with a higher rate in the south than in the north.Meanwhile,the precipitation amount has shown high spatial variability and the climate has shown a warming-drying trend in the past 50 years.(3)The lakes in the hinterland of the Badain Jaran Desert continuously shrank during 1973‒2015.However,the vegetation communities maintained a highly natural distribution during 2000‒2016,with the vegetation cover has increased overall.Accordingly,the Badain Jaran Desert did not show any notable expansion in that period.This study deepens the understanding of groundwater circulation and the climate and ecological evolution in the Badain Jaran Desert.It will provide a scientific basis for the rational exploitation of the groundwater resources and the ecological protection and restoration in the Badain Jaran Desert.

China-PEARL和PRZM-GW模型潍坊市场景农药地下水风险评估研究

农药地下水暴露模型China-PEARL已开始在我国农药地下水风险评估中应用。本文利用China-PEARL潍坊市场景数据,为PRZM-GW构建了潍坊市场景。在潍坊市场景下,利用2个模型计算了56种农药在5种作物上共计145种施用方式下的预测环境浓度(PEC)值,利用商值法(RQ)进行风险评估。结果显示有8种农药共13种施用方式在潍坊市场景下存在不可接受的地下水风险。其中,2个模型均显示有不可接受风险的农药是多菌灵和氟磺胺草醚。2个模型PEC值比较结果显示,PRZM-GW的农药风险评估趋势与China-PEARL一致性高,从而验证了China-PEARL的可信性。模型PEC值影响因素分析显示,土壤有机碳分配系数(Koc)对2个模型输出影响最大,可将Koc>400L·kg-1作为判断某种农药预测浓度<0.1μg·L-1经验性指标。2个模型的PEC值和土壤好氧半衰期的对数呈线性关系,当土壤好氧半衰期>10d时,模型的PEC值随土壤好氧半衰期的增大而迅速增高。水解半衰期为PRZM-GW模型输入项,决定了PRZM-GW模型模拟的农药浓度随年变化趋势。水中溶解度是China-PEARL的输入项,但对模型PEC值影响很小。

基于改进DRASTIC模型的莒县地下水脆弱性评价

对传统的DRASTIC模型进行了修改,将包气带介质类型(I)、含水层水力传导系数(C)替换为土地利用类型(L)和地下水水质(Z)两项指标,提出了DRASTLZ模型,以更好地评估地下水系统对污染的敏感程度。首先建立DRASTLZ模型评分体系,赋予7个影响指标不同的权重,采用ArcGIS平台,对搜集到的数据进行处理和统计分析,分别建立地下水位埋深(D)、地下水净补给量(R)、含水层介质(A)、土壤介质(S)、地面坡度(T)、土地利用类型(L)和地下水水质(Z)7个评价指标的评分图,然后对7个图层进行叠加,按照所分配的权重进行计算,得出莒县地下水脆弱性综合指数值,并通过自然间断点分级法划分为低脆弱性、较低脆弱性、中等脆弱性、较高脆弱性、高脆弱性区5个分区,最终完成莒县地下水脆弱性评价。计算结果表明:莒县地下水脆弱性总体水平偏高,地下水较高脆弱区占比最大,约38%,地下水中等脆弱性区和高脆弱性区占比较大,分别为36%和15%,地下水较低脆弱性区和地下水低脆弱性区占比较小,分别为10%和1%。地下水脆弱性评价结果与水质取样点的超标情况呈现正相关性,这表明在莒县地区,构建的DRASTLZ评价模型具有较高的适用性,其评价结果贴近实际情况。DRASTLZ模型的成功应用,为将来类似区域的地下水脆弱性评价研究提供了有益的经验和指导。

Maize drought disaster risk assessment of China based on EPIC model

Digital Agriculture is one of the important applications of Digital Earth.As the global climate changes and food security becomes an increasingly important issue,agriculture drought comes to the focus of attention.China is a typical monsoon climate country as well as an agricultural country with the world’s largest population.The East Asian monsoon has had a tremendous impact upon agricultural production.Therefore,a maize drought disaster risk assessment,in line with the requirements of sustainable development of agriculture,is important for ensuring drought disaster reduction and food security.Meteorology,soil,land use,and agro-meteorological observation information of the research area were collected,and based on the concept framework of‘hazard-inducing factors assessment(hazard)-vulnerability assessment of hazard-affected body(vulner-ability curve)-risk assessment(risk),’importing crop model EPIC(Erosion-Productivity Impact Calculator),using crop model simulation and digital mapping techniques,quantitative assessment of spatio-temporal distribution of maize drought in China was done.The results showed that:in terms of 2,5,10,and 20 year return periods,the overall maize drought risk decreased gradually from northwest to southeast in the maize planting areas.With the 20 year return period,high risk value regions(drought loss rate]0.5)concentrate in the irrigated maize region of Northwest china,ecotone between agriculture and animal husbandry in Northern China,Hetao Irrigation Area,and north-central area of North China Plain,accounting for 6.41%of the total maize area.These results can provide a scientific basis for the government’s decision-making in risk management and drought disaster prevention in China.

基于改进灰色聚类模型的本溪地区地下水脆弱性评估分析

文中结合地下水脆弱性评估指标,采用改进的灰色聚类模型对本溪地区地下水脆弱性进行评估。评估结果表明,改进后的模型对于区域地下水脆弱性评估更为合理。经评估,本溪地区从东向西,其地下水脆弱性评估指数逐步加大。研究成果对于区域地下水双控措施的科学规划具有重要参考价值。

基于修正RISKE模型的重庆岩溶地区地下水脆弱性评价

岩溶地下水脆弱性评价是保护、管理和利用岩溶地下水的基础与有效方法。我国西南岩溶区绝大多数地区由于缺少应有的地下水保护带,地下水比较容易受污染。运用修正的RISKE模型,对重庆岩溶地区地下水进行脆弱性评价。结果表明:岩溶在4个地区所占面积从高到低依次为渝东北(43.14%)、渝东南(42.82%)、渝东(9.82%)、渝西地区(4.22%)。重庆岩溶地区地下水脆弱性中度以上,面积比例由高到低依次为渝东南(33.29%)、渝东北(29.21%)、渝东(6.68%)、渝西地区(2.37%)。地下水水质检测由差到好依次为渝东南、渝东北、渝西和渝东地区。地下水脆弱性在空间分布上的特征不仅显示了岩性、土壤、落水洞、岩溶裂隙等自然特征对其脆弱性的影响,同时也反映了人类活动对地下水的影响。因此在自然条件无法改变的情况下,控制人类活动对地下水的污染就显得尤为重要。

基于MapInfo的大沽河地下水库脆弱性评价

在大沽河地区自然地理和水文地质调查的基础上 ,充分利用MapInfo建立缓冲区功能来划分评价区域 ,并以MapInfo强大的地图查询运算能力和目前常用的DRASTIC方法进行了全面的脆弱性评价。研究结果表明 :大沽河地下水库大部分地区约 60 .8%属于脆弱性中等区域 ,2 5 .0 %是属于脆弱性较强区域 ,另外还有 10 .1%属于脆弱性较弱区域。总的来讲 ,大沽河水库库区是相对脆弱的 ,今后应尽量避免兴建污染性强的项目 ,减少化肥和农药的大量使用 ,防止地下水污染的发生和发展。

基于分区变权模型的煤层底板突水脆弱性评价--以开滦蔚州典型矿区为例

在解决煤层底板突水预测预报评价难题时,传统的常权模型存在固定权重不能反映各主控因素指标值在突变情况下及各主控因素之间组合关系的变化,以及因素权重也应随之变化的情况。为此,笔者将分区变权理论引入底板突水脆弱性预测评价中,构建了符合煤层底板突水预测评价问题变化规律的分区状态变权向量及分区变权模型。同时以开滦蔚州典型矿区为例,应用分区变权模型对目标煤层底板突水脆弱性进行了预测评价,并和传统常权模型下的预测评价结果进行对比分析,结果证明变权模型的预测评价效果更好。

九江市地下水易污性评价——基于DPASTIC指标的模糊综合评价模型

从污染物入渗土壤-包气带-含水层的过程出发,以地质、地貌、水文地质条件为主控因素,选取地下水埋深(D)、降雨入渗补给量(P)、含水层岩性(A)、土壤类型(S)、地形坡度(T)、非饱和带介质(I)及含水层渗透系数(C)7个指标,建立了九江市地下水易污性评价DPASTIC指标体系。结合模糊数学理论和方法,建立了基于DPASTIC指标的模糊综合评价模型。该模型克服了指标参数级别划分定额差异和指标值不连续性变化的缺陷,寻求出最优的级别定额划分状态和指标值的连续性变化情况;在指标级别定额划分上,引用了指标标准特征值的概念,根据实测参数数据资料,建立了10个级别的指标标准特征值矩阵,确定指标参数的最优相对隶属度。结合MAPGIS软件得出最后的地下水易污性分区,评价结果与规划区的实测及预测的水环境质量相吻合。

西南红层浅层地下水特征及其开发利用模式

西南红层地区人畜饮用水季节性短缺问题一直未能解决。通过地质调查与研究工作,本文总结了四川省、重庆市红层浅层地下水分布广、埋藏浅、补给充沛、更新速度快的自然规律,结合红层区农户居住分散、人畜饮用需水量小的用水特点,提出了红层浅层地下水资源化的认识和相应的"小口径浅井"开采技术、"一户一井"分散式供水模式。

改进的DRASTIC地下水脆弱性评价模型及应用

针对DRASTIC模型存在的不足,综合考虑研究区水文地质特征和人类活动的影响,提出改进的地下水脆弱性指标体系,分别采用层次分析法(AHP)、熵权法及AHP-熵权法对各指标赋权,建立改进的DRASTIC地下水模型。应用基于上述3种方法改进的模型对南京市江宁区中部地区地下水脆弱性进行评价,3种模型得到的脆弱性指数整体均呈现由中部向东北、西南方向逐渐降低的趋势,但不同模型中同一脆弱性区的面积有所差异;通过线性相关分析验证模型评价结果。结果表明,基于AHP-熵权法改进的DRASTIC模型评价结果较其他两种模型更客观真实地反映了研究区的实际情况。

西南地区典型岩溶地下水系统污染模式

岩溶地下水资源是西南地区社会和经济发展的重要保障,随着城市化进程的不断加快,西南地区岩溶地下水污染问题也日益凸显,直接威胁当地群众的健康安全,已成为社会热点。以西南地区典型岩溶地下水系统污染实例为研究对象,通过分析每个岩溶地下水系统污染实例的水文地质条件、污染源特征、污染物迁移规律及污染危害等方面,归纳总结西南地区典型岩溶地下水系统污染模式,分为四种:间歇型入渗污染、持续型入渗污染、灌入型污染和越流型入渗污染。该项研究便于识别污染物的运移特征及规律、掌握污染范围和污染程度,为西南岩溶地区地下水污染物的防治工作提供重要的借鉴意义。

基于DEM的山区旱灾风险评价模型——以西南地区为例

旱灾研究中,地形导致的水热再分配容易造成地域间旱灾灾情的明显差异,因此地形因子对于旱灾风险的准确评价及灾情的客观评估至关重要。采用气象站点观测数据和DEM数据,通过模拟复杂地形影响下的下垫面真实水分情况,加入地形因子的影响,建立了以干旱致灾因子(水分条件)、孕灾环境(地形)、承灾体(农作物脆弱性曲线)综合的旱灾风险评价三度模型;并以地形复杂、旱灾多发的西南地区为例,编制了旱灾风险等级图,以期为客观评估旱灾灾情,有效开展区域旱灾风险防范提供科学依据。

基于GIS应用DATUW模型评价地下水环境脆弱性

地下水环境脆弱性是当前地下水研究领域中的一个热点,其评价结果对于城市规划、垃圾堆放场址建设、地下水源选取与保护等具有非常重要的作用。本文是在MapGIS平台上,基于DRASTIC评价技术,选取地下水位埋深、含水层介质、地形坡度、含水层上覆地层、单井涌水量五个因子,利用DATUW模型,评价哈尔滨市区的地下水环境脆弱性。根据评价结果,将研究区的地下水环境划分为高、中、低三个脆弱性区,并就分区结果,提出了防护建议。

基于改进的DRASTIC模型对香溪河典型岩溶流域地下水脆弱性评价

南方岩溶流域的地表水与地下水转换频繁,地下水环境对人类活动响应敏感,地下水环境脆弱。为探索岩溶流域地下水脆弱性评价的方法,以岩溶流域为评价对象,选取植被覆盖率、地形坡度、土壤类型、地下水水位埋深、地下水补给模数、土地利用类型6个指标,通过改进DRASTIC模型的评价指标体系,建立了基于VTSDRL模型的岩溶流域地下水脆弱性评价指标体系。以香溪河岩溶流域地下水为例,利用层次分析法计算了评价指标权重,基于地理信息系统的叠加分析功能对香溪河岩溶流域地下水脆弱性进行了定量评价。结果表明:香溪河岩溶流域地下水脆弱性以中等脆弱区为主,占比达到86.6%;地下水补给模数和土地利用类型对地下水脆弱性的影响作用最强,地下水脆弱性高的区域主要分布于溶丘洼地区,其面临农业活动污染的风险最大。该研究可为我国南方岩溶流域地下水脆弱性评价和岩溶水资源保护提供参考。

地下水脆弱性评价和污染风险管理

地下水脆弱性评价和风险评估是地下水污染防治的有用工具和工作步骤,是地下水资源管理和地下水污染修复的重要依据。文章对地下水脆弱性评价和污染风险评价的研究背景和进展进行了简要综述,提出了目前地下水脆弱性评价研究中存在的问题,并对今后基于风险管理的地下污染环境修复及其总体思路进行了展望。