CONFLICT AND COOPERATION OVER INTERNATIONAL FRESHWATER RESOURCES: INDICATORS OF BASINS AT RISR1

ABSTRACT: In this paper we seek to identify historical indicators of international freshwater conflict and cooperation and to create a framework to identify and evaluate international river basins at potential risk for future conflict. We derived biophysical, socioeco‐nomic, and geopolitical variables at multiple spatial and temporal scales from GIS datasets of international basins and associated countries, and we tested these variables against a database of historical incidents of international water related cooperation and conflict from 1948 to 1999. International relations over freshwater resources were overwhelmingly cooperative and covered a wide range of issues, including water quantity, water quality, joint management, and hydropower. Conflictive relations tended to center on quantity and infrastructure. No single indicator—including climate, water stress, government type, and dependence on water for agriculture or energy—explained conflict/cooperation over water. Even indicators showing a significant correlation with water conflict, such as high population density, low per capita GDP, and overall unfriendly international relations, explained only a small percentage of data variability. The most promising sets of indicators for water conflict were those associated with rapid or extreme physical or institutional change within a basin (e.g., large dams or internationalization of a basin) and the key role of institutional mechanisms, such as freshwater treaties, in mitigating such conflict.     

浅谈长江中下游地区渔业与水域环境的协调发展

长江中下游地区自然条件优越，淡水资源丰富，过去，现在和将来都是我国重要的渔业基地，但是工业污染和盲目开发渔业已对水环境造成严重危害，降低了水体的多重社会功能，也损害了渔业自身，为了建立可持续发展的健康渔业，必须迅速转变渔业经济增长方式，从粗放型转到集约型和效益型，并按照生态学和经济学原理，运用现代科学技术与管理手段，结合传统渔业的精华，协调发展与环境之间，资源保护与利用之间的关系，形成生态和经济的     

干湿比对砂土地下渗滤系统净化能力的影响

通过搭建以砂土为主的地下渗滤系统,考察不同干湿比条件对地下渗滤系统污染物净化能力的影响。在水力负荷为0.08 m3/(m2·d)时,设5种运行条件,分别为连续运行及4个干湿比条件(1∶2、1∶1、2∶1、3∶1)。研究表明:干湿运行对地下渗滤系统的净化能力影响显著,其中干湿比为1∶1时污染物净化效果最好,COD、氨氮、TN、TP去除率分别达到90%、95%、70%、85%。建议北方以砂质土壤为主的地区采用地下渗滤系统处理污水时,稳定运行最佳干湿比为1∶1。     

河水-地下水侧向交互带地球化学特征:以重庆市马鞍溪为例

河水-地下水交互带是河水与地下水相互交换和混合的区域,在河流、地下水生态和水质的保护方面具有重要作用.为了解河水-地下水侧向交互带地球化学特征,以重庆市马鞍溪为研究对象,对河水及交互带的水温、溶解氧(DO)、pH值、电导率(EC)进行自动监测,结合对水样离子浓度和交互带沉积物中元素含量的分析.结果表明,马鞍溪侧向交互带水化学类型为HCO_3-Ca·Mg型.监测期间交互带受河水入渗影响为主,交互带的缓冲作用使其温度、DO、pH值、EC等指标变异系数较河水低.随距河岸距离的增加,马鞍溪侧向交互带在物理、化学、生物综合作用下形成了迅速进入缺氧状态的氧化还原环境,以及pH值先降低后升高的酸碱环境.在其影响下,K~+、NH_4~+-N、NO_3~-、SO_4~(2-)呈下降趋势,全Mn、EC、Na~+、Ca~(2+)、Mg~(2+)、Sr~(2+)等先上升后下降,全Fe、Al~(3+)等呈上升趋势.受河水、地下水长期交互影响,在距河岸约30 cm处的交互带沉积物中元素含量较高,形成独特的水化学梯度.据此可推断出马鞍溪侧向交互带边界可能在距河岸30~50 cm处,其中浅层交互带的边界可能在距河岸10 cm左右的位置.在河水补给地下水过程中,河水-地下水侧向交互带对净化水质有重要作用.     

Developments in water quality monitoring and management in large river catchments using the Danube River as an example

Effective management of water quality in large rivers requires information on the influence of activities within the catchment (urban and rural) throughout the whole river basin. However, traditional water quality monitoring programmes undertaken by individual agencies normally relate to specific objectives, such as meeting quality criteria for wastewater discharges, and fail to provide information on basin-scale impacts, especially in transboundary river basins. Ideally, monitoring in large international river basins should be harmonised to provide a basin-scale assessment of sources and impacts of human activities, and the effectiveness of management actions. This paper examines current water quality issues in the Danube River Basin and evaluates the approach to water quality monitoring in the context of providing information for a basin-wide management plan. Lessons learned from the monitoring programme in the Danube are used to suggest alternative approaches that could result in more efficient generation of water quality data and provide new insights into causes and impacts of variations in water quality in other large international river basins.     

ANALYSIS OF POND SEEPAGE FOR APPLICATION IN FISHERIES AND AQUACULTURE1

ABSTRACT: The purpose of this research was to examine through modeling and experimentation if seepage out of a pond through stratified soil can be predicted, and effectively collected and managed to augment streamflow during a low precipitation period extending three months or more. The 55 m² experimental pond with sandy/loamy banks was excavated to hardpan, and its bottom was approximately 0.7 above the water table. Output from a mathematical model containing both bottom and bank seepage elements agreed with experimental data, and showed that as compared to bottom seepage, the bank seepage contributed approximately 25 percent of the total seepage. Seepage collection (as measured from a circumscribing ditch) linearly varied with stage (r² < 0.99). There was an 8 to 22 percent over‐collection at the lower pond stages, and a 9 to 45 percent under‐collection at the highest stage. As an example of its utility, the model was applied to estimate the pond size and shape needed to supply a hypothetical stream and maintain fish stocks during a three‐month low‐precipitation period. Future work will focus on nutrient transport and removal.     

RIVER-QUALITY ASSESSMENTS1

ABSTRACT: In 1972, the U.S. Geological Survey began a pilot program of river-quality assessments. The objectives of the program are (1) to define the character, interrelationships, and apparent causes of existing river-quality problems, and (2) to devise and demonstrate the analytical approaches and the tools and methodologies needed for developing water-quality information that will provide a sound technical basis for planners and managers to use in assessing river-quality problems and evaluating management alternatives. The most noteworthy finding of a pilot assessment of the Willamette River basin, Oregon, was that across-the-board advanced waste treatment was not the answer to the problem of meeting stringent water-quality standards established for the river. The assessment also found that existing water-quality data generally are inadequate for defining the critical cause-effect relationships that control river-quality problems and that intensive, synoptic surveys keyed to local problems and conditions would be required in most river basins to develop an adequate information base for managing important river-quality problems. The study illustrated that rigid nationwide standards and regulations are likely to result in unneeded expenditures in some river basins and in undesirable quality in others.     

Impact of Residential Soil Disturbance on Infiltration Rate and Stormwater Runoff1

Woltemade, Christopher J., 2010. Impact of Residential Soil Disturbance on Infiltration Rate and Stormwater Runoff. Journal of the American Water Resources Association (JAWRA) 46(4): 700-711. DOI: 10.1111/j.1752-1688.2010.00442.x Abstract: Soil disturbances such as excavation and compaction in residential developments affect lawn infiltration rates and stormwater runoff. These effects were investigated via measuring saturated infiltration rates at 108 residential sites and 18 agricultural sites near Shippensburg, south-central Pennsylvania, using a double-ring infiltrometer. Residential sites included four neighborhoods distributed across three soil series classified as hydrologic soil group (HSG) B. Additional parcel data included date of house construction, percentage impervious area, lawn condition, and woody vegetation condition. Measured infiltration rates ranged from 0 to >40 cm/hour. Analysis of variance indicated significantly different mean infiltration rates (p < 0.001) for lots constructed pre-2000 (9.0 cm/hour) and those constructed post-2000 (2.8 cm/hour). Test results were used to determine a “field-tested” HSG for each site, representing disturbed soil conditions. Stormwater runoff was estimated from residential lots for a range of 24-hour design storms using the TR-55 model and several alternative methods of determining curve numbers, including five different representations of soil conditions. Curve numbers and stormwater runoff were substantially higher when based on field-tested HSGs for lots constructed post-2000 compared with lots built pre-2000 and when based on the HSG for undisturbed soils, documenting the magnitude of possible error in stormwater runoff models that neglect soil disturbance.     

Examining Modeling Approaches for the Rainfall‐Runoff Process in Wildfire‐Affected Watersheds: Using San Dimas Experimental Forest

Wildfire can significantly change watershed hydrological processes resulting in increased risks for flooding, erosion, and debris flow. The goal of this study was to evaluate the predictive capability of hydrological models in estimating post‐fire runoff using data from the San Dimas Experimental Forest (SDEF), San Dimas, California. Four methods were chosen representing different types of post‐fire runoff prediction methods, including a Rule of Thumb, Modified Rational Method (MODRAT), HEC‐HMS Curve Number, and KINematic Runoff and EROSion Model 2 (KINEROS2). Results showed that simple, empirical peak flow models performed acceptably if calibrated correctly. However, these models do not reflect hydrological mechanisms and may not be applicable for predictions outside the area where they were calibrated. For pre‐fire conditions, the Curve Number approach implemented in HEC‐HMS provided more accurate results than KINEROS2, whereas for post‐fire conditions, the opposite was observed. Such a trend may imply fundamental changes from pre‐ to post‐fire hydrology. Analysis suggests that the runoff generation mechanism in the watershed may have temporarily changed due to fire effects from saturation‐excess runoff or subsurface storm dominated complex mechanisms to an infiltration‐excess dominated mechanism. Infiltration modeling using the Hydrus‐1D model supports this inference. Results of this study indicate that physically‐based approaches may better reflect this trend and have the potential to provide consistent and satisfactory prediction.     

大江大河流域水资源管理问题讨论

世界范围内水危机的日益严重,越来越显现出流域水资源管理的重要性。从分析国内外大江大河水资源研究的热点入手,介绍了国内江河流域水资源管理思路的转变和实践;系统分析了大流域水资源存在问题的根本原因,认为是由于对人水关系和流域生态演化规律,河流、湿地的生态功能、流域的整体性管理重视不够造成的。从河流的生态整体性出发,以生态学为理论基础,提出了考虑社会—经济—环境复合生态系统,以生态和谐行为、协调发展、因地制宜、流域整体性调控体制和生态文化建设等维持大流域水资源可持续利用和保护的生态可持续性的保障措施。