This study presents a remote sensing and geographic information systems-based approach for using US EPA’s Storm Water Management Model (SWMM) in urban environment. Cartosat-1 PAN + IRS-P6 LISS-IV merged product was used to map land cover in part of Surat city at 1:10,000 scale. Cartosat-1 stereo pair was used for deriving digital elevation model of the study area. Geo-informatics-based methods were developed for delineation of sub-catchment areas, assignment of sub-catchment outlets and estimation of characteristic width. It was observed that 59% of the developed area in the study region was directly or indirectly connected to the storm water drainage network. Furthermore, dynamic rainfall-runoff simulation on three-day rainfall indicated that the average runoff coefficient on the urbanized sub-catchment areas which were directly connected to the drainage network was 0.92 as against 0.88 on those urbanized sub-catchments without having direct access to storm water drainage. 相似文献
Urban environments lie at the confluence of social,cultural,and economic activities and have unique biophysical characteristics due to continued infrastructure development that generally replaces natural landscapes with built-up structures.The vast majority of studies on urban perturbation of local weather and climate have been centered on the urban heat island(UHI)effect,referring to the higher temperature in cities compared to their natural surroundings.Besides the UHI effect and heat waves,urbanization also impacts atmospheric moisture,wind,boundary layer structure,cloud formation,dispersion of air pollutants,precipitation,and storms.In this review article,we first introduce the datasets and methods used in studying urban areas and their impacts through both observation and modeling and then summarize the scientific insights on the impact of urbanization on various aspects of regional climate and extreme weather based on more than 500 studies.We also highlight the major research gaps and challenges in our understanding of the impacts of urbanization and provide our perspective and recommendations for future research priorities and directions. 相似文献
The biogeochemistry of riparian alder wetlands was studied from 1995 to 1997. Nutrient and DOC chemistry was related to water level changes. The spatial and temporal patterns of nutrients (P and N) and dissolved organic carbon (DOC) were measured in the surface water flowing through a riparian alder fen and in the adjacent creek. Nutrient and DOC concentrations were extremely variable temporally but not spatially within the wetland. In the wetland and the adjacent creek concentrations of NO3-N, PO4-P and DOC were homogenous during high-flow periods and frozen conditions. After low-flow conditions water bodies were isolated from the creek. The concentration of NH4-N, PO4-P and DOC in these isolated water bodies was significantly higher than in the adjacent creeks due to low oxygen levels.
Enclosures of different sizes were installed in the wetland to study possible release rates. A large enclosure experiment in the flooded alder fen showed the same concentrations as after high-flood conditions except for DOC. The DOC concentrations were enriched in the large enclosure after decomposition from leaf litter during fall season. Small enclosures with low oxygen levels confirmed data obtained from low-flow conditions. The release rates were calculated for low-flow conditions from small enclosure experiments for 2 months a year when the alder fen is not flooded. The rates for July and August were 11.6 kg/ha NH4-N, 8.6 kg/ha PO4-P and 57.6 kg/ha DOC. The DOC concentrations for fall estimated from the large enclosure-experiments were 168.2 kg/ha for the months September and October.
This means possible output rates of N, P and DOC during the summer and DOC during fall in the adjacent river system. This can cause eutrophication and organic pollution depending on the length of the low-flow conditions and the size of the alder fen. Water level changes must be regarded as important for the management of riparian wetlands such as alder fens. The riparian alder system may vary from a nutrient sink to a nutrient source at different times of a year depending on high or low water levels. 相似文献