The management of peat swamp forests in Malaysia contends with two major issues: forest fires and the effects of abandoned forest-logging drainage systems or canals. Forest fire occurs during low rainfall season relat...The management of peat swamp forests in Malaysia contends with two major issues: forest fires and the effects of abandoned forest-logging drainage systems or canals. Forest fire occurs during low rainfall season related to the local people activities. The drainage networks change the hydrological function of the intact forest ecosystem. A key function of the hydrological system in the undisturbed forest is to absorb water during rainfall season, thus delaying downstream runoff and preventing flash floods. The objective of the project described here is to restore the hydrological function of peat swamp forest (PSF) at Ayer Hitam North Forest Reserve (AHNFR) in Muar, Johor, Malaysia. The oil palm plantations, especially in the southern part of the area affect the forest reserve. Water flows out of the forest reserve through the drainage system constructed for managing these plantations. In 2016 and 2017, two water block structures or check dams were constructed near the boundaries of the forest reserve to hold the water and raise the groundwater level in the forest reserve. The implementation of the check dams at the two locations has conserved the groundwater level and subsequently, about 1.2 million m<sup>3</sup> of water was saved annually from leaving the forest reserve from each of the check dam. This project is also part of the Coca-Cola Company’s sustainability commitment for water strategy with the global that is to replenish 100% of the equivalent volume of water consumed in their products and production by 2020. Replenishment is the key sustainability commitment for the Company.展开更多
This paper reviews the significant contribution of hydrologic continuity in the development, evolution and fate of the Niger Delta. Formed from the aggregation of sediments from a drainage catchment area of over 2 mil...This paper reviews the significant contribution of hydrologic continuity in the development, evolution and fate of the Niger Delta. Formed from the aggregation of sediments from a drainage catchment area of over 2 million km<sup>2</sup>, the Niger Delta has evolved into a prolific sedimentary basin with a dense network of rivers and creeks. The ecological system is in a fragile state with fresh and saline water ecosystems maintaining a dynamic equilibrium. Rainfall typically varies from 2500 - 4000 mm per year compared to average annual evaporation of about 1500 mm, resulting in net antecedent moisture. Over 70% of the rainfall occurs in 4 months between May and September, creating a potential for flooding. Water level varies from less than 1.5 m in the estuaries to about 8 m at the apex of the delta, with Nun River having a slightly higher elevation compared to Forcados River, implying that canals connecting both rivers at the same reach would experience water movements from Nun to Forcados River. Similarly, water level gradients vary across the stretch of the rivers from 8.6 to 9.5 × 10<sup>-5</sup> (cm/km) between Onitsha and Asamabiri, 7.5 to 7.7 × 10<sup>-5</sup> (cm/km) on the Forcados River downstream of Asamabiri, and from 7.4 to 7.6 × 10<sup>-5</sup> (cm/km) on the Nun River. At peak flood, about 23 × 10<sup>3</sup> m<sup>3</sup>/sec of runoff enters the Niger Delta. At the same time, about 16 × 10<sup>3</sup> m<sup>3</sup>/sec discharges from the estuaries into the ocean in a semi-diurnal tidal flow leaving a surplus that accumulates to cause flooding. The delta thus acts like a sponge, absorbing the shear amount of flow and releasing slowly stored water through at least twenty-one outlet estuaries into the Atlantic Ocean. The shear amount of discharge overwhelms the capacity of the network of distributaries and predisposes the delta to flooding. Assessment of the capacity of the rivers to evacuate pollutants showed that rivers to the west of Brass which are fed by Forcados River exhibited relatively stronger flux efficiencies prior to 1998 but are presently weaker compared to rivers fed by Nun. The rivers to the east between New Calabar and Imo Rivers exhibited very weak ebb tide asymmetry or net upstream flow largely because these rivers receive little or no freshwater influx from upstream sources. Flood and erosion are the major hydrological hazards in the region.展开更多
根据电站运行要求,确定下游库水位波动范围,并利用DHI Mike 21得到相应的龙口下游水位,采用水力学方法计算不同下游水深对应的龙口最大流速,用截流标准表征截流风险,反映下游库水位变化幅度对截流风险提高或降低的程度,引入工程案例验...根据电站运行要求,确定下游库水位波动范围,并利用DHI Mike 21得到相应的龙口下游水位,采用水力学方法计算不同下游水深对应的龙口最大流速,用截流标准表征截流风险,反映下游库水位变化幅度对截流风险提高或降低的程度,引入工程案例验证了计算模型的可靠性和合理性,计算结果证明了工程方法的可行性。展开更多
受电站下泄非恒定流影响,溪洛渡下游30 km区域通航水流条件复杂,威胁船舶通航安全。通过原型观测,对非恒定流传播规律及其主要影响因素进行研究。结果表明,各码头的水位变化与泄流变化趋势一致,传播过程中沿程坦化现象明显,传播速度快,...受电站下泄非恒定流影响,溪洛渡下游30 km区域通航水流条件复杂,威胁船舶通航安全。通过原型观测,对非恒定流传播规律及其主要影响因素进行研究。结果表明,各码头的水位变化与泄流变化趋势一致,传播过程中沿程坦化现象明显,传播速度快,大河湾—顺河段的平均波速为11.2 m s,汛期大河湾码头水位变幅及变率高达4.38 m、1.21 m h。溪洛渡坝下河道非恒定流特性与下泄流量变幅、变化时长及向家坝库水位有关,其中对流量变幅的响应最大。泄流增加(减少)时,电站下泄流量变幅越大,变化时长越短,向家坝库水位越高(低),非恒定流传播速度就越快,码头水位变幅及水位变化率就越大。展开更多
文摘The management of peat swamp forests in Malaysia contends with two major issues: forest fires and the effects of abandoned forest-logging drainage systems or canals. Forest fire occurs during low rainfall season related to the local people activities. The drainage networks change the hydrological function of the intact forest ecosystem. A key function of the hydrological system in the undisturbed forest is to absorb water during rainfall season, thus delaying downstream runoff and preventing flash floods. The objective of the project described here is to restore the hydrological function of peat swamp forest (PSF) at Ayer Hitam North Forest Reserve (AHNFR) in Muar, Johor, Malaysia. The oil palm plantations, especially in the southern part of the area affect the forest reserve. Water flows out of the forest reserve through the drainage system constructed for managing these plantations. In 2016 and 2017, two water block structures or check dams were constructed near the boundaries of the forest reserve to hold the water and raise the groundwater level in the forest reserve. The implementation of the check dams at the two locations has conserved the groundwater level and subsequently, about 1.2 million m<sup>3</sup> of water was saved annually from leaving the forest reserve from each of the check dam. This project is also part of the Coca-Cola Company’s sustainability commitment for water strategy with the global that is to replenish 100% of the equivalent volume of water consumed in their products and production by 2020. Replenishment is the key sustainability commitment for the Company.
文摘This paper reviews the significant contribution of hydrologic continuity in the development, evolution and fate of the Niger Delta. Formed from the aggregation of sediments from a drainage catchment area of over 2 million km<sup>2</sup>, the Niger Delta has evolved into a prolific sedimentary basin with a dense network of rivers and creeks. The ecological system is in a fragile state with fresh and saline water ecosystems maintaining a dynamic equilibrium. Rainfall typically varies from 2500 - 4000 mm per year compared to average annual evaporation of about 1500 mm, resulting in net antecedent moisture. Over 70% of the rainfall occurs in 4 months between May and September, creating a potential for flooding. Water level varies from less than 1.5 m in the estuaries to about 8 m at the apex of the delta, with Nun River having a slightly higher elevation compared to Forcados River, implying that canals connecting both rivers at the same reach would experience water movements from Nun to Forcados River. Similarly, water level gradients vary across the stretch of the rivers from 8.6 to 9.5 × 10<sup>-5</sup> (cm/km) between Onitsha and Asamabiri, 7.5 to 7.7 × 10<sup>-5</sup> (cm/km) on the Forcados River downstream of Asamabiri, and from 7.4 to 7.6 × 10<sup>-5</sup> (cm/km) on the Nun River. At peak flood, about 23 × 10<sup>3</sup> m<sup>3</sup>/sec of runoff enters the Niger Delta. At the same time, about 16 × 10<sup>3</sup> m<sup>3</sup>/sec discharges from the estuaries into the ocean in a semi-diurnal tidal flow leaving a surplus that accumulates to cause flooding. The delta thus acts like a sponge, absorbing the shear amount of flow and releasing slowly stored water through at least twenty-one outlet estuaries into the Atlantic Ocean. The shear amount of discharge overwhelms the capacity of the network of distributaries and predisposes the delta to flooding. Assessment of the capacity of the rivers to evacuate pollutants showed that rivers to the west of Brass which are fed by Forcados River exhibited relatively stronger flux efficiencies prior to 1998 but are presently weaker compared to rivers fed by Nun. The rivers to the east between New Calabar and Imo Rivers exhibited very weak ebb tide asymmetry or net upstream flow largely because these rivers receive little or no freshwater influx from upstream sources. Flood and erosion are the major hydrological hazards in the region.
文摘受电站下泄非恒定流影响,溪洛渡下游30 km区域通航水流条件复杂,威胁船舶通航安全。通过原型观测,对非恒定流传播规律及其主要影响因素进行研究。结果表明,各码头的水位变化与泄流变化趋势一致,传播过程中沿程坦化现象明显,传播速度快,大河湾—顺河段的平均波速为11.2 m s,汛期大河湾码头水位变幅及变率高达4.38 m、1.21 m h。溪洛渡坝下河道非恒定流特性与下泄流量变幅、变化时长及向家坝库水位有关,其中对流量变幅的响应最大。泄流增加(减少)时,电站下泄流量变幅越大,变化时长越短,向家坝库水位越高(低),非恒定流传播速度就越快,码头水位变幅及水位变化率就越大。
