Caracteristici morfometrice ale reliefului bazinului râului Bucovăț

In the sense of digital terrain modeling, there is a set of techniques for obtaining a Digital Elevation Model (DEM). But, as expected, modeling the terrestrial surface, its representation in a virtual space, involves certain problems that are related to the surface specificity itself and our way of measuring it. Numerical altitude models, once performed, find their usefulness as input data for derivation of some topographical attributes of geomorphometric parameters, morphometric variables or general information about the land respectively.

People Participatory Approach: A Study Of Drought Management Programmes Through Mnrega In Mewat Region, Haryana

The paper examines the people participatory approach towards executive process of drought management programmes of Mewat region of Haryana. It is an empirical study, based on 93 respondents, taken from three villages, who have been engaged in varied drought management activities within these villages. The study has thrown an adequate light on various levels of benefits and varied degree of satisfaction, derived from the drought management projects, executed in these villages, characterized with different topographical attributes. On the basis of findings of the study, varied inferences have been drawn from the study. This participatory approach has also been testified with correlation technique which shows the results in accordance with responses, responded by the people; belonged to various strata of rural society in their respective villages of Mewat region.

The use of LIDAR as a data source for digital elevation models – a study of the relationship between the accuracy of digital elevation models and topographical attributes in northern peatlands

It is important to study the factors affecting estimates of wetness since wetness is crucial in climate change studies. The availability of digital elevation models (DEMs) generated with high resolution data is increasing, and their use is expanding. LIDAR earth elevation data have been used to create several DEMs with different resolutions, using various interpolation parameters, in order to compare the models with collected surface data. The aim is to study the accuracy of DEMs in relation to topographical attributes such as slope and drainage area, which are normally used to estimate the wetness in terms of topographic wetness indices. Evaluation points were chosen from the high-resolution LIDAR dataset at a maximum distance of 10 mm from the cell center for each DEM resolution studied, 0.5, 1, 5, 10, 30 and 90 m. The interpolation method used was inverse distance weighting method with four search radii: 1, 2, 5 and 10 m. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. The accuracy of the estimated elevation for different slopes was tested using the DEM with 0.5 m resolution. Drainage areas were investigated at three resolutions, with coinciding evaluation points. The ability of the model to generate the drainage area at each resolution was obtained by pairwise comparison of three data subsets. The results show that the accuracy of the elevations obtained with the DEM model are the same for different resolutions, but vary with search radius. The accuracy of the values (NMAD of errors) varies from 29.7 mm to 88.9 mm, being higher for flatter areas. It was also found that the accuracy of the drainage area is highly dependent on DEM resolution. Coarse resolution yielded larger estimates of the drainage area but lower slope values. This may lead to overestimation of wetness values when using a coarse resolution DEM.

Effects of land use and topographical attributes on soil properties in an agricultural landscape

Knowledge about soil properties associated with land use and topographical attributes is vital for modelling soil–landscape relationships and establishing sustainable on-field management practices. Our study focuses on an arable area in south-western China, where paddy fields and vegetable growing are dominant land uses. These are representative of millions of hectares of farmland in south-western China. Samples from 120 sites were collected according to a gridded sampling scheme and analysed. Land-use map units were delineated at a scale of 1 : 2000 from field survey. Topographical indicators (elevation, aspect, slope) were extracted from a digital elevation model with a resolution of 2 m. One-way and two-way analyses of variance and Pearson correlations were adopted to investigate the effects of land use and topographical variables on the selected soil properties: pH, organic matter (OM), ammonium-nitrogen (N), available phosphorus (P), available potassium (K), exchangeable calcium (Ca), and exchangeable magnesium (Mg). Statistically significant differences were found for OM, P, Ca, Mg, and pH between the land-use types and elevation gradient as well as slope classes. Mean contents of OM and P in paddy fields (lower and flat locations) were lower than in vegetable lands (higher and steep places) (P < 0.05). Mean values of Ca, Mg, and pH in paddy fields were higher than in vegetable lands (P < 0.05). Further analysis combining with management practice demonstrated that the redistribution of pH, OM, N, P, Ca, and Mg was mainly controlled by the interactive effects of topography and land use. Therefore, interactions between topography and land-use types need to be considered in regional soil properties inventory assessments.