Braided River System in South-Eastern Spain Essay

Braided River System in South-Eastern Spain - Essay Example Landcover is mostly low bush and grasses with or without trees (Prakash, 2005). Land usage includes agriculture (barley and others under irrigated conditions), grazing, mining (gypsum, gravel and sand) and tourism (movie-making and others) (Prakash, 2005). The gypsum karst of the Tabernas-Sorbas basin of SE Spain is a Neogene intramontane one in the Betic mountain range and is composed of significant deposits of evaporates from the Messinian period (Calaforra and Pulido-Bosch, 2003). The semi-arid environment in the region has assisted in conserving the large numbers of surface and underground gypsum karstic forms and the speleogenetic processes characteristic of such a region (Calaforra and Pulido-Bosch, 2003). In essence, this implies that, at least for this field study at the Western edge of this karstic formation, a semi-confined status existed upon the gypsum strata (Calaforra and Pulido-Bosch, 2003) through which the old braided river section flowed and it is possible that only those speleogenetic processes characteristic of a karst region such as this have been influential in the accretion process of sediment evident today. In study of fluvial systems such as rivers the term 'braided' implies a low proportion of flood-plain mudstones and a high one of sedimentary sand elements like sandstone (Adams and Bhattacharya, 2005). There is characteristic distinction which states that 'meandering' channels have high mudstone-to-sandstone ratios and tend to have high sinuosity combined with single channel flows (Adams and Bhattacharya, 2005). In contrast, 'braided' channels have a high sandstone-to-mudstone ratio and tend to have multiple channel flows (Adams and Bhattacharya, 2005). This distinction is blurred at times by continuity of variables (Adams and Bhattacharya, 2005) but, for the purpose of this field study, it is accepted that the study area comprised of a 'braided' channel portion. Of eminent interest to this study are the depositional and erosional patterns of the river at the meandering stage and the braided one. It has single-layered laterally accreting patterns with similar eroding ones in the me andering stage while accretional patterns in the braided stage are multi-layered and vertical (Adams and Bhattacharya, 2005). Field Work Rationale: To test whether 'braided' stream sections have lateral and/or vertical sorting/fining tendencies. Methodology: Six different randomly selected channels of the known old braided river system in the Urra Field Centre were chosen. From each channel, three samples from the left and right banks and the centre of the stream were taken. Sample bags were used to collect the pebbles from the sample-taking areas. A tape measure was also used to measure the channel sections. A pebble template and a grain size chart were used to size up the collected pebbles. Additionally, a camera was used to collect photos of the sample-taking areas to provide rough assessment of the pebble characteristics at each site. The pebble sizes were measured and the data tabulated as per each site characteristic. In this part of the study the data shall be analysed through multiple statistical descriptive tests such as mean