THE RELATIONSHIP BETWEEN SUMMER-SEASON RAINFALL EVENTS AND LAKE-SURFACE AREA1

ABSTRACT: Research is presented that statistically analyzes the relationship between lake area and precipitation. These hydrologic variables are assessed in part using LANDSAT MSS satellite data and digital-image processing techniques. Results show dramatic regional hydrologic differences in lake area fluctuations and in lake area response to short term climatic variation.     

THE POTENTIAL FOR REMOTE SENSING OF LOESS SOILS SUSPENDED IN SURFACE WATERS1

ABSTRACT: The potential for detecting the concentration and type of soils suspended in surface water through remote sensing techniques was investigated by studying the spectral reflectance of two types of soils in suspension. In a large tank filled with 7510 liters of water, 20 levels of suspended sediment (soil) concentration (SSC), ranging from 50 to 1000 mg/l were prepared. A high resolution spectroradiometer was used to measure the reflectance at each SSC level. The reflectance spectra of two contrasting soils were distinct in the visible and near infrared (NIR) portions of the electromagnetic spectrum. The wavelength range between 580–690 nm (visible) was found to be optimal for indicating the type of soil, whereas, the wavelength range between 714–880 (NIR) was found to be appropriate for estimating the concentration of sediment suspended in surface waters.     

沿哥伦比亚--厄瓜多尔边界毁林速度和格局变化的卫星检测分析

本研究使用Landsat卫星数据来论证哥伦比亚-厄瓜多尔部分边界23年间(1973～1996)土地覆被变化的速度和格局.人类定居给这两个国家带来了大量毁林.变化的卫星检测分析表明,边界哥伦比亚一侧年毁林速度相对高得多.另外,哥伦比亚一侧森林覆被在研究期间几乎损失了43%,而在厄瓜多尔一侧只损失了22%.研究发现,在边界的任何一侧,都不存在单一的毁林驱动因素;但得出结论哥伦比亚一侧的毁林速度高可能是由于定居压力高、非法古柯种植加剧.卫星图像证明,在厄瓜多尔一侧,毁林格局反映出与石油勘探和开发有关的道路网络.     

Satellite change detection analysis of deforestation rates and patterns along the Colombia-Ecuador border

This study uses Landsat satellite data to document the rates and patterns of land-cover change along a portion of the Colombia-Ecuador border during a 23-yr period (1973-1996). Human colonization has resulted in extensive deforestation in both countries. Satellite change detection analysis showed that the annual rates of deforestation were considerably higher for the Colombian side of the border. In addition, loss of forest cover on the Colombian side for the study period was almost 43%, while only 22% on the Ecuadorian side. The study found that there is no single factor driving deforestation on either side of the border, but concluded that the higher rates on the Colombian side may be due to higher colonization pressures and intensification of illegal coca cultivation. On the Ecuador side of the border the satellite images documented patterns of deforestation that reflected road networks associated with oil exploration and development.     

AIRBORNE THERMAL MAPPING OF A “FLOW-THROUGH” LAKE IN THE NEBRASKA SANDHILLS1

The Sandhills region represents a tremendous water resource for the State of Nebraska. Small shallow lakes, marshes, and subirrigated meadows are abundant due to interactions between ground water and surface water. One theory relating ground water to lake-flow systems in the Sandhills has been termed the “flow-through” concept. Thermal-infrared remotely acquired images document the flow-through model for a test site in Western Nebraska.     

REMOTE MONITORING OF SELECTED GROUND‐WATER DOMINATED LAKES IN THE NEBRASKA SAND HILLS1

ABSTRACT: The Landsat‐Muitispectral Scanner (MSS) data were used to measure lake area fluctuations (1972–1989) for 130 ground‐water dominated lakes in the Western Lakes Region of the Nebraska Sand Hills. In general, the pattern shown in lake area hydrographs was similar to that for in‐situ lake elevations. In‐situ lake‐elevation data verify that remote monitoring of surface‐area fluctuations, even at relatively coarse spatial resolution, is not only practical and useful, but also it elucidates the hydrologic characteristics of groundwater‐dominated lakes of the Sand Hills. The apparent differences in behavior between lakes in the northern and southern portions of the study area may be related to both their location in the regional ground water system and the substantial local hydrologic complexity.