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In the mathematical modeling of urban watershed, the parameters that are necessary to know are the factors of the basin that can modify the surface runoff. The green roofs can modify (from its capacity of retention and delay the water flow originated by the rainfalls), the superficial run-off. But the magnitude that they can do it, will depend on the response of the above mentioned green roofs to the rainfalls and this response will be different according to the type of green roof (basically substrate thickness and type of vegetation). Because of it, in the mathematical simulation models, the modeling will be more precise depending on the precision of the information sources used. The aim of this work has been to determine the capacity of retention that present green roof, extensive and intensive, planted with Carpobrotus acinaciformis. The results would allow affirming, for the studied conditions, that the Carpobrutus acinaciformis, can realize a contribution to the decrease of the urban runoffs for cities located in the Buenos Aires coast as that of this work. [ABSTRACT FROM AUTHOR]

Urbanization is defined as the physical growth of urban areas. About half of the world's population now lives in cities, and expected that this amount will increase to 61% by 2030, this growth will be more pronounced in developing countries. Cities are the habitat for excellence of human, and present environmental characteristics (urban climate) common in many parts of the world, as for example the presence of the island of urban heat (ICU). The urban heat island reveals the impact of habitat built on the physical environment and the increase in temperature that produces. The majority of greenhouse gas emissions that contribute to global climate change come from urban areas. Climate change is affecting climate globally and in cities not only modifies the conditions of the hydrological cycle, but also affects the ICU. The increase of the temperature according to the models established by the Intergovernmental Panel on climate change could emphasize over the next decades. For Buenos Aires the models predict, specifically in the 2020-2029 period, an increase of average maximum temperatures in 0.6°C to 2°C (for the minimum temperature average). Law number 3.871, called: adaptation and mitigation to climate change in the Autonomous city of Buenos Aires, proposed minimum solutions of adaptation. One of these proposed solutions are the green roofs, which (mentions the law), mainly can help as buffer against temperature extremes and the urban heat island. The objective of the present study was to determine, for the climatic conditions of the Autonomous city of Buenos Aires (CABA), if the green roofs (built with substrates and vegetation available at the study site), can make a contribution to the regulation of the temperature. The study make it possible to say, for the analyzed case and in the climatic conditions of the CABA in the period and types of green roofs studied, that the same may be a contribution to the thermal regulation of buildings. [ABSTRACT FROM AUTHOR]

Climatic change effects and the processes of urban growth caused environmental deterioration in the city of Buenos Aires. This situation alters the natural hydrological cycle and the hydrograph of floodwaters in urbanizing watersheds will modify, presenting flows higher peak and shorter rise times as it progresses. On the other hand, the global warming has caused an increase in mean annual precipitation and extreme values generated by storms of connective type, in the central region and North of Argentina. One of the possibilities to mitigate these effects is the implementation of extensive green roofs systems in terraces of buildings and houses built that help to reduce runoff factor. The objective of this paper was: to determine the reduction of surface runoff and water quality delivered for different types of green roofs with different types of vegetation implanted in normal rainfall in the city of Buenos Aires. The results of the study that was carried out along one year, showed that the retention capacity of the tested lots varied, depending upon precipitation, type of vegetation and coverage. For the range of 21 and 41 mm the retention ratesreached between 63% and 68%, with rainfall between 42 and 60 mm are observed percentages of retention from 31% to 39%. For the range of 61 to 80 mm the retention percentage was similarly to the range previously analyzed, 25% to 38%, and finally analyzing rainfall greater than 90 mm, the percentage of retention varies between 16% and 22%. The Aptenia cordifolia presented minors values of retention in all ranges except the first. The results of the test showed that green roofs system represent a good alternative in the integrated management of water runoff in urban watersheds. [ABSTRACT FROM AUTHOR]

Flash floods in urban areas caused by overload of drainage networks are a recurrent problem of raising importance. Greenroofs retain part of the stormwater, lowering surface flow and generating runoff hydrographs with lower and delayed peak flows. Therefore, this technology can contribute to mitigate the overload of drainage networks. The results of the study that was carried out in City of Buenos Aires along almost two years, showed that the retention capacity of the tested lots tasted varied, depending upon precipitation, coverage and depth of the substrate. With precipitation less than or equal to 20 mm, the retention fraction was high (73% to 100%), and when precipitation reached 35 to 40 mm, the maximum percentage of retention was around 60%. However, when the rainfall was approximately 100 mm, the retention fraction was reduced substantially, reaching values nearing 30%. The results of the test showed that green roofs system represent a good alternative in the integrated management of water runoff in urban watersheds. [ABSTRACT FROM AUTHOR]

Basic information about watershed relief, drawn from analytical-descriptive methodologies, allows for the physical parameters necessary to the study of natural resources, such as watershed integrated management, environmental impact, soil degradation, deforestation, water resource conservation, among others. All these processes linked to a strong spatial component allow the use of geographic information systems. Digital elevation models (DEMs) and their derivatives are an important component of these data sources. In this work we evaluated DEMs generated from indirect source data (digitized points from existing contour maps) to determine whether elevation accuracy varies with DEM spatial resolution (grid size). We also assessed the possible existence of some interaction between grid size and the software used that could influence the altimetric quality of the DEM. It was concluded that spatial resolution affects DEM quality. We also found that it is possible to find an ideal grid size in terms of the altimetric accuracy and computer weight size of the generated DEM. Regarding the existence of an interaction between grid size and the software used, which could affect the quality of models obtained based on the methodology of source data acquisition, we found that this possibility does exist when the database is generated from digitized points. [ABSTRACT FROM AUTHOR]

Flash floods in urban areas caused by overload of drainage networks are a recurrent problem with negative impacts of raising importance. "Green roofs" retain part of the storm water, lowering surface low and generating runoff hydrographs with lower and delayed peak flows. Therefore, this technology can contribute to mitigate the overload of drainage networks. This communication presents the first results (partial) of the determination of the efficiency of water retention (indirectly from the drained water), in trial plots simulating green roofs, with two substrate depths and with two coverage situations (with and without vegetation). They show a positive trend of the "green roof"; in contributing to the reduction of runoff, with a greater retention in the vegetated plots and thicker substrate. [ABSTRACT FROM AUTHOR]

Analytical and descriptive methodologies yield basic information on the relief of a watershed, and thereby make it possible to determine the physical parameters needed to analyze projects involving natural resources, such as the comprehensive management of watersheds, environmental impact studies, and studies of soil degradation, deforestation, and the conservation of water resources, among others. All of these have an important spatial component which makes the use of Geographic Information Systems (GIS) extremely helpful. Digital Elevation Models (DEM) and their derivatives constitute a relevant part of this source of data. The products derived from these models, like slope, direction or curvature, will be as precise as the DEM used to derive them. Other way, is fundamental to maximize the ability of the model to represent land variations; for it, is necessary a correct grid size selection, according to the available data for its generation. In this work the topographical quality of six DEMs generated from two different capture systems of source data and different grid size. To determinate the accuracy of DEMs, habitually is used a group of control points considered like "field truth" which are compared with the generated by the model in the same geographic position. The selected area to apply the study, is located at Arrecifes locality, in Buenos Aires province (Argentina), and have a surface of approximately 297 acres. The obtained results for both algorithms and three size grid analyzed, have presented these results: the algorithm DEM from contourn, a RMSE of ± 0.11 m (grid size of 1 m), ± 0.11 m (grid size of 5 m) and ± 0.15 m (grid size of 10 m). The algorithm DEM from vector/points, a RMSE of ± 0.09 m (grid size of 1 m), ± 0.11 m (grid size of 5 m) and of ± 0.11 m (grid size of 10 m). The results allow to conclude that only the DEM generated from field heights points like source data with the small grid size satisfies the standards mentioned in the national and international bibliography. So, it appear as apt for natural resources projects, concerning to the ecotopo (predial scale). The rest of the generated DEMs, display a RMSE that allows to assure their aptitude for the evaluation of natural resources projects, concerning landscape unit (group of ecotopos). [ABSTRACT FROM AUTHOR]

The sustainable use of natural resources related to hydric and soils projects (among others), requires in many cases, the existing relief modification. So it's necessary the adjustment of superior homogeneous soil layer, that is usually denominated like "land leveling". This practice facilitates a more uniform distribution of rains and irrigation water. This modification of the surface relief is made in base to a project whose inclination responds to natural slopes or the established by the designer. This project tries to obtain the smaller soil movement. In projected design execution, in surfaces greater than 5,0 acres, the land leveling, is made with heavy machinery equipment, that don't assure a high efficiency in project execution, because of the material lost in the transport, and also by the no uniform compaction, associated to the complex soil textures. The present work determined the execution efficiency of land leveling project using an internationally accepted statistical index, "Root Mean Squared Error (RMSE)", contrasting the projected topographical altitude and the really obtained after the project execution, in three parcels which used different sequence of agricultural workings and machinery, but with similar complex soil textures, near to "Pilar and La Plata" cities (Argentina). The statistical index (RMSE) allow to assure that, in the studied conditions of complex soils textures, cannot assure in land leveling values lower than four centimeters of difference between the projected and the constructed. [ABSTRACT FROM AUTHOR]

The land leveling is a form of disturbance of the soil that alters its physical properties. In Argentine the leveling of lands is also extended to a different objective: the sport field construction. The movement of soil from one place to another one produces a rupture of the structure with increase of the volume occupied by air. The soil particles are reordered in a different form from the original one. The soil movements often produce a mixture of edafics horizons. This packing effect diminishes the volume occupied by the pores and increases bulk density and soil tension. One of the main problems that are generated by the land leveling is the compaction. When soil is compacted, non-accommodating faces form smaller aggregates pores. During the whole work, different problems appears, such as: leveling precision; project mark errors in the land, the machinery passes calculation to carry out the work; soil moisture content at the land leveling and the rain value during the earth movement. The present study was carried out in fields located 100 km away from Buenos Aires (34°31'47" S 59°02'15" W). The main objectives of the work were i) to contribute with evidence to the now-a-day knowledge platform, related to the soil physical-mechanical behavior in soils subjected to soil movement with sport aims; ii) to feature the mechanical behavior of a typical argiudol soil in a land leveled polo field. The more important results were: a) swelling factor values > 25%, b) the impact of the soil movement on the organic mater content is smaller than the one happened on the physical parameters, c) both, the traffic intensity as well as the machinery weight have influence on the swelling factor index/compaction d) the machinery passes produces subsoil compaction. Top soil compaction is given, in a further degree, in a field in use, due to the uses of maintenance machineries and the horse transit for the game. [ABSTRACT FROM AUTHOR]

The objective was to achieve Indexes of Cut adjusted to the soils of the regions in study and to relate the same ones with simple determinations of laboratory like sedimentation volume. It was observed in the region a great disparity of methods to use for the calculation of the plane project to obtain and the application of values of relationship cut/fill without local validation. The work was carried out in Mendoza's county, 22 parcels were raised in the areas irrigated by the rivers Mendoza and Tunuyán. The averages values obtained of expansion relationship, according to the each soil, were: sandy 1.04; loam 1.4; clay 1.71; sandy loam 1.29; silt clay loam 1.71; clay loam 1.64 and silt loam 1.34. [ABSTRACT FROM AUTHOR]