A NEW FLASHINESS INDEX: CHARACTERISTICS AND APPLICATIONS TO MIDWESTERN RIVERS AND STREAMS1

ABSTRACT: The term flashiness reflects the frequency and rapidity of short term changes in streamflow, especially during runoff events. Flashiness is an important component of a stream's hydrologic regime. A variety of land use and land management changes may lead to increased or decreased flashiness, often to the detriment of aquatic life. This paper presents a newly developed flashiness index, which is based on mean daily flows. The index is calculated by dividing the pathlength of flow oscillations for a time interval (i.e., the sum of the absolute values of day‐to‐day changes in mean daily flow) by total discharge during that time interval. This index has low interannual variability, relative to most flow regime indicators, and thus greater power to detect trends. Index values were calculated for 515 Midwestern streams for the 27‐year period from 1975 through 2001. Statistically significant increases were present in 22 percent of the streams, primarily in the eastern portion of the study area, while decreases were present in 9 percent, primarily in the western portion. Index values tend to decrease with increasing watershed area and with increasing unit area ground water inputs. Area compensated index values often shift at ecoregion boundaries. Potential index applications include evaluation of programs to restore more natural flow regimes.     

我国黄土高原地区农业生产的气候脆弱性变化预测

在生态脆弱的黄土高原地区,农业生产受到气候变化的影响波动很大。本文在介绍脆弱性的有关定义和农业生产的气候脆弱性评估方案的基础上,对1997年的脆弱性状况做了初步评估,并利用有关GCM预测结果,估算了有关灾害指标的可能变化,对未来黄土高原地区农业生产的气候脆弱性可能变化进行了预测,其评估方法和预测结果可为有关部门决策提供一定的科学依据。     

河西走廊的农业资源与集约化生产结构

通过对甘肃省河西走廊农业自然资源优势的分析,本文讨论了光热资源和水资源潜力的开发利用,提出用高新技术手段建立集约化的半闭路式生态农业生产体系,促进河西走廊农业再上新台阶．     

汕头经济特区二次创业与农业产业化

本文介绍了农业产业化的基本理论,分析了汕头经济特区的经济现状与问题,并提出了汕头经济特区发展农业产业化的建议。     

福建省农业自然资源持续利用探讨

本文分析了福建省农业自然资源利用中存在的突出问题及其形成原因,并根据持续发展新模式提出了持续利用的对策。     

黄河三角洲农业开发与可持续发展研究

本文分析了黄河三角洲农业开发的有利条件、开发现状和存在的主要问题,探讨了农业生产的合理布局,提出了农业可持续发展的对策．     

LARGE AREA HYDROLOGIC MODELING AND ASSESSMENT PART I: MODEL DEVELOPMENT1

ABSTRACT: A conceptual, continuous time model called SWAT (Soil and Water Assessment Tool) was developed to assist water resource managers in assessing the impact of management on water supplies and nonpoint source pollution in watersheds and large river basins. The model is currently being utilized in several large area projects by EPA, NOAA, NRCS and others to estimate the off-site impacts of climate and management on water use, non-point source loadings, and pesticide contamination. Model development, operation, limitations, and assumptions are discussed and components of the model are described. In Part II, a GIS input/output interface is presented along with model validation on three basins within the Upper Trinity basin in Texas.     

陕南秦巴山地农业资源立体专业化开发利用

本文对秦巴山地农业环境特点、资源构成和分异规律进行了系统分析,提出了农业地域专业化开发利用的原则和模式.     

农业生产潜力指数评价方法的研究

本文提出了农业生产潜力指数评价的基本理论和方法，并利用这一评价方法对内江市主要家业作物的生产潜力的进行了评价分析。     

加强水土保持 防止生态恶化

本文论述了水土水流失对生态环境的影响和对农业生产的危害，阐明增强环境意识，加强水土保持时防止生态恶化，是我国振兴农业的重要性与紧迫性的任务。