Re-analysis of the nineteenth century hydrology and sediment load data for the ayeyarwady river, myanmar
スポンサーリンク
概要
- 論文の詳細を見る
The Ayeyarwady (Irrawaddy) River of Myanmar (formerly Burma) is generally though to have the 5^＜th＞ largest suspended load of any world river, and the 4^＜th＞ highest total dissolved load. From these flux estimates, the combined systems of the Ayeyarwady and Thanlwin (Salween) rivers are regarded as contributing 20% of the total flux of material from the Himalayan-Tibetan orogen and deliver it over a short length of coastline into the Gulf of Martaban in the eastern Indian Ocean. The estimates for the Ayeyarwady are taken from published quotes of a 19^＜th＞ Century dataset (Gordon 1885) and there are no available published data for the Thanlwin. We present a re-analysis of the Ayeyarwady data from the original 550 page report of Gordon (1879) covering ten years of discharge (1869-1879) and one year of sediment concentration measurements (1877) and demonstrate that the commonly cited values of sediment loads (and therefore chemical fluxes) are in error. Taken at face value, the sediment flux estimates are conservatively assessed as being underestimated by 18%, and possibly as much as 38%, due to omission of the fine particulate load. However, an early 20^＜th＞ Century Ayeyarwady River engineer criticised Gordon's discharge measuring methods, suggesting they lead to over-estimation of both water and sediment fluxes. These two opposing uncertainties require careful review. We describe the approaches employed, evaluate Gordon's measurements, calculations, and subsequent adjustments and present our revised interpretation of daily and annual discharges and sediment fluxes along with an estimate of uncertainty. Our re-evaluation suggests that the annual sediment flux from the Ayeyarwady-Thanlwin system may be significant for ocean geochemistry and estimation of denudation rates. The new values suggest that the Ayeyarwady and Thanlwin rivers contribute half the present day Ganges-Brahmaputra flux to the Indian Ocean. The catchments of the Ayeyarwady and Thanlwin are affected by ongoing land-use change, and our recently collected water and sediment flux data suggest that modern sediment loads are lower than those in the late 19^＜th＞ Century.
- 首都大学東京の論文
首都大学東京 | 論文
- シンガポールの中国政策
- フランスにおける社会保障給付と内外人平等原則(二・完) : 無拠出給付に焦点をあてて
- フランスにおける社会保障給付と内外人平等原則(一) : 無拠出給付に焦点をあてて(渕倫彦教授退職記念論文集)
- 1999年度社会福祉基礎ゼミ(後期)の評価
- 生活時間と介護の社会化