Comparison of Flow Patterns of Rivers

par of F broken in Patterns of RiversIntroductionComparing the menstruum patterns of rivers in different regions washbowl be most revealing to the contemporary geographer. As Veissman and Lewis have emphasised, every waterways are influenced by the six components of the hydrological cycle.1 These are foolhardiness levels, infiltration, evaporation, transpiration, surface run-off and give water hightail it. such(prenominal) factors, along with topography, often vary considerably inside relatively sm every last(predicate) geographical boundaries.For the purposes of this investigation the persist era curves (FDCs) of the rivers Owen more(prenominal), Funshion, rye whisky piddle and Fane, which are located in the Republic of Ireland, sh any be subjected to reassessment and comparison.The F subaltern Duration CurveAs Singh has none the flow duration curve (FDC) is one of the simplest but most informative tools in hydrology and shows the office of time during which specified flows were equalled or exceeded during the period of record.2In essence, the FDC is a impersonate which can be apply by hydroelectric companies and other agencies in order to determine the energy potentiality of a river, normally on an annual basis. The vertical, or Y, axis represents the flow localize (Q) measured in cubic metres per second (m/s) and the horizontal, or X, axis represents the percentage of time oer a specific period in which flow exceeds the value on the Y axis. Thus, the area below the curve shows the potential energy potentiality of the river.The shape of the FDC is influenced by the six components of the hydrological cycle and alike the topography and shape of the rivers catchment area. As Ward and Robinson have highlighted, a steeply sloping FDC is ordinary of highly variable flows with a stupendous quick flow component.3 Such a cut back is associated with waterways in the Mediterranean region due to extremes in precipitation levels, high surface run-o ff and a low storage capacity of the injury. On the contrary, a gently sloping curve indicates a large delayed flow component.4 This is typical of many rivers in tempe straddle climates which pass to receive through-flow during periods of low precipitation from water stored in the surrounding soil and bedrock. The lower end of the FDC is indicative of perennial storage in the basin.5 Thus, if the FDC flattens out, the catchment area has a considerable degree of water stored which will flow into the river during prohibitionist periods.A Comparison of RiversThe Flow Duration Curves of both the rivers Owenmore and Funshion are mistakable in shape and exhibit a much steeper trend in comparison to the FDCs of rivers rye weewee and Fane. However, the curve of the Funshion flattens out more than that of the Owenmore. Flow account neer decreases below 1.8m/s on the Funshion whereas on the Owenmore it can be as low as 0.8m/s. This shows that the Funshion benefits from a great level of through flow and storage capacity within its drain basin. Indeed, this is understandable when one considers that the total area of the Funshions catchment exceeds that of the Owenmore by 64 Km . Specific run-off is in addition 0.9 m/s higher in the area of the Owenmore which accounts for the river having a higher maximum flow rate of 20.90 m/s. In whole 5% of the time, 17.3% of the total annual flow rate passes through its water channel. Mean flow rate of the River Funshion is 8.14 m/s, the highest of all the rivers. Flow rate exceeded for 95% of the year (Q95) is 0.495 and emphasises that the Funshion has the greatest minimum river flow of all the waterways.The rivers Rye Water and Fane have a flow carry which is less than that of the Owenmore and Funshion. Maximum flow rate is 11.8 m/s on the Rye Water and 8.0 m/s on the Fane. This is due in part to the lower drainage area of both basins. The Fanes is tho 234 km and the Rye Waters is the smallest of the four at 215 km . Th e flow rate exceeded for 95% of the year (Q95) of the Fane is 0.085 m/s to the Rye Waters 0.046 m/s. The Fanes catchment exhibits a greater degree of storage capacity than that of the Rye Water as flow rate never drops below 0.20 m/s. However, the Rye Waters flow rate drops considerably and levels off at only 0.10 m /s for 15% of the year, contributing to the lowest mean flow rate of all the waterways at just 2.16 m/s. The specific run-off rate of the Rye Water is 0.4 m/s higher than that of the Fane.Of all the rivers, the Funshion exhibits the highest meanspirited flow rate whilst the Rye Waters is the lowest. The Owenmore has the widest range of flow rate from 20.90 m /s to only 0.80 m/s. The Fane has the gentlest FDC and ranges from 8.00 m/s at high flow to 0.20 m/s at low flow.Geographical Locations and Factors of InfluenceThe River Owenmore is located in the northwest of the Republic of Ireland and flows from north central Mayo to Sligo Bay. Precipitation levels are high in t his nautical coastal area and average 1163 mm per year. As Mitchell and Ryan have noted, this partition is also omitd by poorly drained peat and gley soils.6 Thus, during periods of heavy rainfall, a large amount of surface run-off flows directly to the river channel. High upland plateaus, which dominate the region to heights of up to 2113 feet, contribute to this phenomena. This explains why the flow rate of the River Owenmore can reach 20.90 m/s during periods of high rainfall. The course of the river traverses terrain utilised for grazing and dairying purposes. Such an expanse of grassland further exacerbates surface run-off during the overwinter months.The River Funshion is a affluent to the Blackwater River in south west Ireland. This region is also overlooked by uplands which can rise to heights of 2000 feet at the semen of the Blackwater. The steepness of the surrounding topography is a potent factor in generating a top flow rate of 20.20 m/s. Heavily forested slopes al so ensure that a higher degree of subsurface water is maintained within the basin than in the sparsely wooded catchment area of the River Owenmore in the north. The Funshion thus receives a higher level of through-flow at times of low precipitation due to this vegetation factor and flow rate never drops below 1.80 m/s. Rainfall averages 1190mm per year in this catchment area, which is the most of all the four drainage basins.The rivers Rye Water and Fane experience lower levels of precipitation due to their location further east. The Fane is situated in the drumlin belt neighboring to the town of Monaghan in South Armagh and the Rye Water is a tributary of the Liffey River which traverses the city of Dublin. The terrain influencing both drainage basins is not as dynamic as that of the west and altitudes rarely reach 655 feet. The highest flow rate of the Rye Water is just 11.80m/s which is testimony to the lower eastern topography. However, urbanisation close to the river channel has contributed to increased surface run-off the river passes through the settlements of Kilcock and Leixlip before entering the Liffey. Orme has noted that the drumlin soils of catchments such as the River Fane are often poorly drained and prostrate to water logging.7 This factor explains why the lower end of the rivers FDC does not drop as abruptly as that of the Rye Water. Clearly the Fane has a higher degree of surface storage in its catchment area.BibliographyHAUGHTON, J. P. GILMOUR, D. A. Geography of Ireland, The department of Foreign Affairs, 1979MITCHELL, F. RYAN, M. Reading the Irish Landscape, Town House Dublin, 1997ORME, A. R. Ireland, Longman, 1970SINGH, V. P. Environmental Hydrology, Kluwer faculty member Publishers, 1995VEISSMAN, W. LEWIS, G. L. Introduction to Hydrology, Pearson Education Inc, Fifth Edition, 2003WARD, R. C. ROBINSON, M. Principles of Hydrology, McGraw-Hill, 2000WHITTOW, J. B. Geology and Scenery in Ireland, Penguin Books, 1974Footnotes1 W Viessman , G L Lewis, Introduction to Hydrology, Pearson, 2003) 22 V P Singh, Environmental Hydrology, Kluwer academician Publishers, 1995) 1133 R C Ward, M Robinson, Principles of Hydrology, McGraw-Hill Publishing Company, 2000) 2584 R C Ward, M Robinson) 2585 R C Ward, M Robinson) 2586 F Mitchell, F Ryan, Reading the Irish Landscape, Town house Dublin, 1997) 3087 A R Orme, Ireland, Longman, 1970) 61