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Taschenbuch. Condizione: Neu. nach der Bestellung gedruckt Neuware - Printed after ordering - Sampling, which is supposed to provide adequate and unbiased representation of a study interest, is often faced with challenges such as choice of the minimum cost-effective sampling size, accurate location of sampling sites and statistical justification of both location of the sites and accuracy of the sampling process. Although there are many statistical sampling protocols in the literature, they largely emphasize on accuracy tests for unbiased sampling size. There is still a lack of statistical routines for unbiased sample locations. This has led to a lot of errors in spatial modeling of many environmental processes LHS is a robust and efficient statistical framework that has been widely used to guide the determination of sample sizes given a set of constraints. When combined with GIS software such as ArcView, LHS can improve sample size selection and subsequent unbiased strategic location of the samples in the landscape. ArcView scripts were written in avenue language for various applications in environmental engineering. The scripts were then integrated into one unit to produce the LHS extension in ArcView GIS.…

Taschenbuch. Condizione: Neu. nach der Bestellung gedruckt Neuware - Printed after ordering - An SDUH model was developed using digital DEM elevation data and land use data collected during a field survey. The SDUH model was applied to a 5km2 agricultural watershed in the Upper Athi river region of the entire Athi river basin. The USGS DEM (30-m) resolution was used to estimate the slope, aspect, flow distance and upstream area for each cell. The watershed was divided into overland and channel flow cells based on the area upstream above each cell. If the area was larger than the threshold of 1.2km2 (1300cells), the cell was assumed to be dominated by channel flow. The flow velocity for the overland cells was estimated using a kinematic wave approximation. Channel velocities were predicted by estimating the channel dimensions and combining the equilibrium flow rate with Manning's equation. The cumulative travel time to the watershed outlet was estimated by routing runoff over the elevation surface and summing the travel time through each cell along the runoff flow path. The objectives of this research were to develop a SDUH model that directly reflects spatial variation in the watershed in generating runoff hydrograph.…