Predictors of urban variable source area: a cross‐sectional analysis of urbanized catchments in the United States          下载免费PDF全文

Theodore Chao Lim 《水文研究》2016,30(25):4799-4814

Many studies have empirically confirmed the relationship between urbanization and changes to the hydrologic cycle and degraded aquatic habitats. While much of the literature focuses on extent and configuration of impervious area as a causal determinant of degradation, in this article, I do not attribute causes of decreased watershed storage on impervious area a priori. Rather, adapting the concept of variable source area (VSA) and its relationship to incremental storage to the particular conditions of urbanized catchments, I develop a statistically robust linear regression‐based methodology to detect evidence of VSA‐dominant response. Using the physical and meteorological characteristics of the catchments as explanatory variables, I then use logistic regression to statistically analyze significant predictors of the VSA classification. I find that the strongest predictor of VSA‐type response is the percent of undeveloped area in the catchment. Characteristics of developed areas, including total impervious area, percent‐developed open space and the type of drainage infrastructure, do not add to the explanatory power of undeveloped land in predicting VSA‐type response. Within only developed areas, I find that total impervious area and percent‐developed open space both decrease the odds of a catchment exhibiting evidence of VSA‐type response and the effect of developed open space is more similar to that of total impervious area than undeveloped land in predicting VSA response. Different types of stormwater management infrastructure, including combined sewer systems and infiltration, retention and detention infrastructure are not found to have strong statistically significant effects on probability of VSA‐type response. VSA‐type response is also found to be stronger during the growing season than the dormant season. These findings are consistent across a national cross‐section of urbanized watersheds, a higher resolution dataset of Baltimore Metropolitan Area watersheds and a subsample of watersheds confirmed not to be served by (combined sewer systems). Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Forests and water in South America          下载免费PDF全文

Julia Jones  Auro Almeida  Felipe Cisneros  Andres Iroumé  Esteban Jobbágy  Antonio Lara  Walter de Paula Lima  Christian Little  Carlos Llerena  Luis Silveira  Juan Camilo Villegas 《水文研究》2017,31(5):972-980

South America is experiencing rapid change in forest cover, of both native and planted forest. Forest cover loss is primarily attributable to fire, logging, and conversion of native forest to agriculture, pasture, and forest plantations, and types of change vary within and among the many diverse types of forests in South America. Major changes in forest cover and growing policy concerns underscore an urgent need for research on sustainable forest management and water ecosystem services in South America. Differences in land ownership and management objectives create trade‐offs between wood production and water ecosystem services from forests. Work is needed to quantify how forest change and management affect ecosystem services, such as wood production versus water provision. Current scientific understanding of forest management effects on water ecosystem services in South America has important limitations, including a scarcity of long‐term records and few long‐term integrated watershed studies. Industry, government, universities, and local communities should collaborate on integrated applied studies of forests and water. Data archiving and publically available data are required. The creation of national networks and a multi‐country South America network to identify and implement common water research protocols, share results, and explore their implications would promote common and well‐supported policies. Hydrologists working in South America are well placed to tackle the challenges and opportunities for collaborative research that will maintain the intrinsic values and water ecosystem services provided by South America's forests.  相似文献   

Annual fossil organic carbon delivery due to mechanical and chemical weathering of marly badlands areas     

Yann Graz  Christian Di‐Giovanni  Yoann Copard  Nicolle Mathys  Alexandre Cras  Vincent Marc 《地球表面变化过程与地形》2012,37(12):1263-1271

A key issue in the study of the carbon cycle is constraining the stocks and fluxes in and between C‐reservoirs. Among these, the role and importance of fossil organic carbon (FOC) release by weathering of outcropping sedimentary rocks on continental surfaces is still debated and remains poorly constrained. Our work focuses on FOC fluxes due to chemical and mechanical weathering of marls in two experimental watersheds with typical badlands geomorphology (Draix watersheds, Laval and Moulin, Alpes de Haute Provence, France). Organic matter from bedrock, soil litter and riverine particles are characterized by Rock‐Eval 6 pyrolysis. FOC fluxes due to mechanical weathering are then estimated by monitoring the annual particulate solid exports at the outlets of the watersheds (1985–2005 period). FOC fluxes from chemical weathering were calculated using Ca²⁺ concentrations in dissolved loads (year 2002) to assess the amount of FOC released by the dissolution of the carbonate matrix. Results show that FOC delivery is mainly driven by mechanical weathering, with a yield ranging from 30 to 59 t km^‐2 yr^‐1 in the Moulin (0.08 km²) and Laval (0.86 km²) catchments, respectively, (1985–2005 average). The release of FOC attributed to chemical weathering was 2.2 to 4.2 t km^‐2 for the year 2002. These high FOC fluxes from badlands are similar to those observed in tectonically active mountain catchments. At a regional scale, badland outcropping within the Durance watershed does not exceed 0.25% in area of the Rhône catchment, but could annually deliver 12 000 t yr^‐1 of FOC. This flux could correspond to 27% of the total particulate organic carbon (POC) load exported by the Rhône River to the Mediterranean Sea. At a global scale, our findings suggest that erosion of badlands may contribute significantly to the transfer of FOC from continental surfaces to depositional environments. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Stream turbidity responses to storm events in a pristine rainforest watershed on the Coral Coast of southern Fiji     

《国际泥沙研究》2016,(4):279-290

On the Coral Coast of Viti Levu Island in Fiji, inadequate knowledge of suspended sediment delivery patterns in small pristine coastal watersheds hinders any future assessment of accelerated erosion in disturbed areas nearby. This study adopts a rainfall–stream turbidity monitoring approach in the Votua Creek, which drains a small, steep but minimally-disturbed coastal rainforest catchment. Storm rainfall characteristics, stream depth and water turbidity were continuously monitored over one complete Fiji wet season from October 2009 to April 2010. The aim was to evaluate whether these parameters provide sufficient information to illustrate basic features of storm–sediment transport responses, in the case of limited stream gauging and very simple sediment rating curves. This is important because Pacific Island nations like Fiji do not have the resources to initiate long-term gauging and sediment sampling pro-grammes across numerous small catchments.
A significant power function demonstrates that turbidity (T) is a suitable proxy for total suspended solids (TSS) for turbidity measurements above 5 NTU, with TSS?0.930T1.111 (r?0.98, Po0.001). Over the study period, 10 individual storms 11.2–120.1 mm in size produced a‘significant turbidity response’ (STR) in the Votua Creek. Rainfall parameters (totals and intensities) showed positive linear relationships (r ? 0.72–0.94) with stream turbidity parameters (mean, maximum, duration), whilst relationships of similar strength (r ? 0.76–0.98) were also derived between stream flow depth and turbidity. This implies that for small rainforest watersheds in Fiji, rainfall parameters offer no substantial disadvantage over flow as predictors of stream sediment responses to major storms. Event-based analysis revealed that negative (anticlockwise) hysteresis is a typical flow–turbidity pattern for STR events. Negative hysteresis is produced when secondary episodes of renewed (heavy) rainfall occur after maximum intensity, in the later phase of storm events. Tropical Cyclone Mick in December 2009 generated the largest flood and the greatest turbidity response (Tmax ? 1021 NTU, Tmean ? 207 NTU). This concurs with earlier work confirming that tropical cyclones are the most important events for sediment transport in Fiji stream networks.  相似文献   

利用简单生物圈模式SiB2模拟锡林浩特草原地表湍流通量   总被引：1，自引：0，他引：1  

何志强  沈新勇  王英舜  高志球 《气候与环境研究》2011,16(3):353-368

利用简单生物圈模式SiB2模拟了2007年7月1日至9月30日期间锡林浩特草原的地表能量分配、CO2通量、地表有效辐射温度和土壤湿度.采用锡林浩特国家气候观象台野外试验基地实地测量资料确定SiB2所需要的参数和初始值后,由该资料中30 min一次的太阳短波辐射、大气长波辐射、水汽压、气温、水平风速和降水驱动SiB2,最...  相似文献   

Conceptual model for transferring information between small watersheds     

Emery?T.?CleavesEmail author 《Environmental Geology》2003,45(2):190-197

Stream and watershed management and restoration can be greatly facilitated through use of physiographic landform classification to organize and communicate natural resource, hazard, and environmental information at a broad scale (1:250,000) as illustrated by the Piedmont and Coastal Plain Provinces in Maryland, or at a small scale (1:24,000) as illustrated using divisions and zones combined with a conceptual model. The conceptual model brings together geology, surficial processes, landforms and land use change information at the small watershed scale and facilitates transfer of information from one small watershed to another with similar geology and landforms. Stream flow, sediment erosion, and water quality illustrate the use of the model.  相似文献   

COMPARISON　OF　SEDIMENT　DISCHARGE　PREDICTIONS　FOR　SMALL　WATERSREDS　IN　THE　SOUTRWESTERN　UNITED　STATES     

Yakov WIGDOR  Vicente L.LOPES  Peter F.FFOLLIOTT 《国际泥沙研究》1996,(1)

ＣＯＭＰＡＲＩＳＯＮ　ＯＦ　ＳＥＤＩＭＥＮＴ　ＤＩＳＣＨＡＲＧＥ　ＰＲＥＤＩＣＴＩＯＮＳ　ＦＯＲ　ＳＭＡＬＬ　ＷＡＴＥＲＳＲＥＤＳ　ＩＮ　ＴＨＥ　ＳＯＵＴＲＷＥＳＴＥＲＮ　ＵＮＩＴＥＤ　ＳＴＡＴＥＳＹａｋｏｖＷＩＧＤＯＲ；ＶｉｃｅｎｔｅＬ．ＬＯＰＥＳ...  相似文献   

Watershed simulation in a sandy terrain of the Thar desert using GIS   总被引：2，自引：0，他引：2  

P.C. Moharana  A. Kar   《Journal of Arid Environments》2002,51(4):489

The sandy landscape in a desert contains very few stream channels. This poses a problem for delineating watersheds for analysis. Since large-scale topographical sheets of sandy terrain also contain very little information on height, delineation of watersheds from topographical sheets often becomes difficult. In order to find a simple solution to the problem in the Thar desert of Rajasthan, India, the authors used the well-known ARC/INFO software for simulation of height and drainage network using the scarce topographical information for a sandy terrain near Jodhpur. Superimposition of data layers generated from remote sensing and secondary sources validated the simulation results, and suggested suitability of the method for application in similarly handicapped areas.  相似文献   

Climatic effects on the runoff conditions in Hungary     

Bla Novaky 《地球表面变化过程与地形》1991,16(7):593-599

Using runoff and climatic observations from 37 small watersheds in Hungary a regional climate-runoff relationship has been established. This non-linear relationship is a modification of Budiko's similar equation and can be used to estimate the effect of climate changes on long-term average runoff. The degree of change in runoff depends not only on changes in precipitation and temperature, but also on the present climate characteristics. The regional relationship is verified only within a relatively narrow range of precipitation and temperature and this fact limits its use in climate impact assessment. Model calculations show that a relatively slight shift in climate, an increase in annual temperature by 0.5°C, and a decrease of annual rainfall by 0.08 mm d^?1 may lead to a decrease of runoff by 25-30 per cent in small watersheds of Hungary.  相似文献   

Investigating the impact of the temporal resolution of MODIS data on measured phenology in the prairie grasslands     

Tengfei Cui  Lawrence Martz  Liang Zhao  Xulin Guo 《地理信息系统科学与遥感》2020,57(3):395-410

ABSTRACT

The temporal resolution of vegetation indices (VIs) determines the details of seasonal variation in vegetation dynamics observed by remote sensing, but little has been known about how the temporal resolution of VIs affects the retrieval of land surface phenology (LSP) of grasslands. This study evaluated the impact of temporal resolution of MODIS NDVI, EVI, and per-pixel green chromatic coordinate (GCCpp) on the quality and accuracy of the estimated LSP metrics of prairie grasslands. The near-surface PheonoCam phenology data for grasslands centered over Lethbridge PhenoCam grassland site were used as the validation datasets due to the lack of in situ observations for grasslands in the Prairie Ecozone. MODIS Nadir Bidirectional Reflectance Distribution Function (BRDF)-Adjusted Reflectance (NBAR) data from 2001 to 2017 were used to compute the time series of daily reference and to simulate 2–32 day MODIS VIs. The daily reference and simulated multi-day time series were fitted with the double logistic model, and the LSP metrics were then retrieved from the modeled daily time series separately. Comparison within satellite-based estimates showed no significant difference in the phenological metrics derived from daily reference and multi-day VIs resampled at a time step less than 18 days. Moreover, a significant decline in the ability of multi-day VIs to predict detailed temporal dynamics of daily reference VIs was revealed as the temporal resolution increased. Besides, there were a variety of trends for the onset of phenological transitions as the temporal resolution of VIs changed from 1 to 32 days. Comparison with PhenoCam phenology data presented small and insignificant differences in the mean bias error (MBE) and the mean absolute error (MAE) of grassland phenological metrics derived from daily, 8-, 10-, 14-, and 16-day MODIS VIs. Overall, this study suggested that the MODIS VIs resampled at a time step less than 18 days are favorable for the detection of grassland phenological transitions and detailed seasonal dynamics in the Prairie Ecozone.  相似文献