FLOW ANALYSIS OF LANDSLIDE DAMMED LAKE WATERSHEDS: A CASE STUDY1

Abstract: The Chi-Chi earthquake, which occurred on September 21, 1999, and had a magnitude of 7.3 on the Richter scale, resulted in an extensive landslide that blocked the Ching-Shui Creek in Taiwan, forming a large lake with a storage volume of 40 million m³. This paper describes an analytical procedure used to perform flow analysis of the Tsao-Ling watershed, which includes the new landslide dammed lake. In this study, a digital elevation model was applied to obtain the watershed geomorphic factors and stage-area storage function of the landslide dammed lake. Satellite images were used to identify the landslide area and the land cover change that occurred as a result of the earthquake. Two topography-based runoff models were applied for long term and short term streamflow analyses of the watershed because the watershed upstream of the landslide dam was ungauged. The simulated daily flow and storm runoff were verified using limited available measured data in the watershed, and good agreement was obtained. The proposed analytical procedure for flow analysis is considered promising for application to other landslide dammed lake watersheds.     

LAKE EUTROPHICATION–A NATURAL PROCESS1

Lake eutrophication is an economic, recreational, and aesthetic problem that affects every lake of the world. Eutrophication is the natural process of lake aging, and progresses irrespective of man's activities. Pollution, however, can hasten the natural rate of aging and shorten the life expectancy of a body of water. The eutrophication of a lake consists of the gradual progression from one life stage to another based on the degree of nourishment or productivity. The extinction of a lake is attributed to enrichment by nutritive materials, biological productivity, decay, and sedimentation. Presently used methods for retarding eutrophication are the abatement of cultural enrichment, treatment of eutrophic symptoms, and control of fundamental causes.     

淮阴开发湖泊水产发展“三高”农业

本文依据淮阴目前农业的发展趋势和境内面大量广的湖泊资源优势，论述大力开发湖泊水产资源是淮阴发展“三高”农业的一条重要途径，并提出围绕“三高”确定开发方向，途径和目标，以及实现目标的战略措施。     

WATER QUALITY TRENDS IN LAKE TOHOPEKALIGA,FLORIDA, USA: RESPONSES TO WATERSHED MANAGEMENT1

ABSTRACT: Water quality in eutrophic Lake Tohopekaliga, Florida, improved markedly from 1982 to 1992 as a result of reductions in phosphorus and nitrogen loading to the lake. Annual budgets of water, chloride, phosphorus and nitrogen were constructed for the lake, and indicate it is a sink for phosphorus and a source for nitrogen. Water column concentrations of total phosphorus, soluble reactive phosphorus, total nitrogen, dissolved inorganic nitrogen, and chlorophyll a all declined as external inputs of nutrients decreased. Water column nitrogen: phosphorus ratios have increased, suggesting a probable shift from nitrogen- to phosphorus-limitation. This apparent shift in nutrient limitation status also is supported by comparisons of the mean Trophic State Indices for phosphorus, nitrogen, and chlorophyll a. These improvements in water quality are attributed to the diversion of wastewater treatment plant effluent from the lake, and the increased use of wet retention ponds for stormwater runoff.     

1980-2007年喜马拉雅东段洛扎地区冰湖变化遥感研究

利用1980年地形图、1988/1990年Landsat TM、2000年Landsat ETM+、2007年ALOS AVNIR-2遥感资料和近42 a (1967-2008年)的气温、降水量资料对喜马拉雅东段洛扎地区的冰湖变化特征及其原因进行了研究。 结果表明:①1980年到2007年,53个冰湖(1980年面积大于0.02 km²)的总面积由1980年的9.97 km²增加至2007年的13.05 km²,增加了3.08 km²,增加的比例为30.9%。通过与非冰川补给湖的对比发现,1980年的冰湖面积比非冰川补给湖的面积大,分布的规模等级和海拔梯度更为广泛;1980-2007年冰湖面积扩张是非冰川补给湖面积扩张的102.7倍,远大于后者。可见,冰川补给对于冰湖的分布和变化有重要的影响。②1980-2007年,错那站的年平均气温呈波动上升趋势,与全球变暖的趋势一致;年降水量在波动变化中略有上升。温度升高引起的冰川融水的增加和降水的增加共同决定了研究区内冰湖面积的增长。本区冰川变化和冰湖变化主要是由温度升高引起的,但降水增加也有一定贡献。③对研究区2007年面积大于0.1 km²的32个可辨识冰湖的溃决危险性评价表明,错嘎龙浦、加朗卡、昂格错、白朗错几个冰湖的溃决危险程度最大。     

Long-term joint e ect of nutrients and temperature increase on algal growth in Lake Taihu, China

To study how global warming and eutrophication a ect water ecosystems, a multiplicative growth Monod model, modified by incorporating the Arrhenius equation, was applied to Lake Taihu to quantitatively study the relationships between algal biomass and both nutrients and temperature using long-term data. To qualitatively assess which factor was a limitation of the improved model, temperature variables were calculated using annual mean air temperature (AT), water temperature (WT), and their average temperature (ST), while substrate variables were calculated using annual mean total nitrogen (TN), total phosphorus (TP), and their weighted aggregate (R), respectively. The nine fitted curves showed that TN and AT were two important factors influencing algal growth; AT limited growth as algal photosynthesis is mainly carried out near the water surface; N leakage of phytoplankton and internal phosphorus load from sediment explains why TN was the best predictor of peak biomass using the Monod model. The fitted results suggest that annual mean algal biomass increased by 0.145 times when annual mean AT increased by 1.0°C. Results also showed that the more eutrophic the lake, the greater the e ect AT had on algal growth. Subsequently, the long-term joint e ect of annual temperature increase and eutrophication to water ecosystems can be quantitatively assessed and predicted.     

云南大理洱海溶解氧日变化特征分析

利用大理国家气候观象台依托于JICA项目,在洱海湖中建立的自动观测系统2009年全年的观测资料,分析了溶解氧的日变化特征。结果表明:洱海湖中溶解氧表现为日出后最小、日落后最大的日变化特征。全年变化范围为2.31～7.98 mg/L,最大值出现在12月20:00时,而最小值出现在9月10:00时;较小时段出现在6-10月,各月月平均12月最大,9月最小,年较差为4.83 mg/L;四季中冬季偏大,夏季偏小,冬春季比夏秋季明显偏大。四季中各个典型日的日较差相对于各季的平均偏大,峰值、谷值出现时间大都偏晚。连阴雨出现后,由于受低温阴雨寡照的影响,洱海溶解氧偏高。     

同位素示踪技术在环境领域中的应用研究

稳定碳氮同位素作为一种有效的示踪手段,在研究外源有机质来源和氮循环,特别是污染源的识别方面有着重要意义。在简要总结碳氮同位素的应用现状、分馏效应的基础上,重点论述和分析了稳定氮同位素在富营养化湖泊中的氮源识别,并结合研究现状探讨了研究前景。     

温度对植物浮床净化富营养化水体能力的影响

利用生态浮床系统研究了温度对豆瓣菜和水芹净化富营养化水体能力的影响.结果表明,不同温度(10、22和35℃)处理明显影响植物浮床系统对NH4+-N、TN、TP、Chla、CODMn、BOD5的去除效率;植物浮床系统在22℃时对TN、NH4+-N,Chla的去除率分别达79%、82%、76%以上,在35℃时对TP、COD...     

洱海流域土地利用格局研究

基于GIS和Erdas平台,利用2007年TM影像,对洱海流域不同高程、不同方位的用地方式、布局状态及其景观格局进行了研究。研究表明,洱海流域以有林地、灌木林地、草地、农田、水域用地5类用地方式为主,但用地布局和格局不甚合理;从不同方位布局看,东部和南部片区的景观破碎度相对较高,景观连通性相对较低。建议将高干扰用地景观部分向洱海东部片区转移,并优化和重组洱海流域景观结构。