Estimation of Reservoir Discharges from Lake Nasser and Roseires Reservoir in the Nile Basin Using Satellite Altimetry and Imagery Data
Estimation of Reservoir Discharges from Lake Nasser and Roseires Reservoir in the Nile Basin Using Satellite Altimetry and Imagery Data
复制标题
DOI：
10.3390/rs6087522
复制
发表时间：
2014-08
期刊：
影响因子：
--
通讯作者：
Eric Muala;Y. Mohamed;Z. Duan;P. Zaag
中科院分区：
文献类型：
--
作者：
Eric Muala;Y. Mohamed;Z. Duan;P. Zaag
本文介绍了利用卫星测高和图像有限的现场数据，估算2002 - 2010年期间Roseires水库（苏丹）和1999-2002年和2005-2009年期间阿斯旺高坝/纳赛尔湖（埃及）流量的可行性。排放量是利用水库的水量平衡计算的。降雨量和蒸发量数据来自公共数据来源。还获得了流入和流出的原位测量值（用于验证）。其他水分平衡分量，如水位和表面积，用于推导储存量的变化，来自卫星测量。Roseires水库的水位来自Hydroweb，纳赛尔湖的水位来自Hydroweb和全球水库和湖泊监测器（GRLM）。水面面积是从陆地卫星TM/ETM+图像使用归一化差异水指数（NDWI）。通过对各水库的面积-水位关系进行积分，估算了各水库的水量变化。对于Roseires水库，来自Hydroweb的水位与现场水位一致（RMSE = 0.92 m; R2 = 0.96）。也获得了良好的协议与现场测量的估计水量（RMSE = 23%; R2 = 0.94）和计算流量（RMSE = 18%; R2 = 0.98）。对于典型的水库运行应用，计算出的流量的准确性被认为是可接受的。对于纳赛尔湖，测高水位也与现场水位一致，无论是Hydroweb（RMSE = 0.72米; R2 = 0.81）和GRLM（RMSE = 0.62米; R2 = 0.96）数据。对于估计的水量也观察到类似的协议（RMSE = 10%-15%）。然而，从卫星数据估计的流量与观测到的流量，Hydroweb（RMSE = 70%; R2 = 0.09）和GRLM（RMSE = 139%; R2 = 0.36）一致性较差。该误差可归因于流量对存储量误差的高敏感性，因为与流入/流出系列相比，存储量巨大。这也可能与流入托什卡洼地的不明泄漏、流入水量的高估和开放水域蒸发的错误有关。因此，测高水位和卫星图像数据可用作监测Roseires水库运行的信息来源，不确定性相当低，而纳赛尔湖的误差太大，无法监测其运行。
This paper presents the feasibility of estimating discharges from Roseires Reservoir (Sudan) for the period from 2002 to 2010 and Aswan High Dam/Lake Nasser (Egypt) for the periods 1999–2002 and 2005–2009 using satellite altimetry and imagery with limited in situ data. Discharges were computed using the water balance of the reservoirs. Rainfall and evaporation data were obtained from public domain data sources. In situ measurements of inflow and outflow (for validation) were obtained, as well. The other water balance components, such as the water level and surface area, for derivation of the change of storage volume were derived from satellite measurements. Water levels were obtained from Hydroweb for Roseires Reservoir and Hydroweb and Global Reservoir and Lake Monitor (GRLM) for Lake Nasser. Water surface areas were derived from Landsat TM/ETM+ images using the Normalized Difference Water Index (NDWI). The water volume variations were estimated by integrating the area-level relationship of each reservoir. For Roseires Reservoir, the water levels from Hydroweb agreed well with in situ water levels (RMSE = 0.92 m; R2 = 0.96). Good agreement with in situ measurements were also obtained for estimated water volume (RMSE = 23%; R2 = 0.94) and computed discharge (RMSE = 18%; R2 = 0.98). The accuracy of the computed discharge was considered acceptable for typical reservoir operation applications. For Lake Nasser, the altimetry water levels also agreed well with in situ levels, both for Hydroweb (RMSE = 0.72 m; R2 = 0.81) and GRLM (RMSE = 0.62 m; R2 = 0.96) data. Similar agreements were also observed for the estimated water volumes (RMSE = 10%–15%). However, the estimated discharge from satellite data agreed poorly with observed discharge, Hydroweb (RMSE = 70%; R2 = 0.09) and GRLM (RMSE = 139%; R2 = 0.36). The error could be attributed to the high sensitivity of discharge to errors in storage volume because of the immense reservoir compared to inflow/outflow series. It may also be related to unaccounted spills into the Toshka Depression, overestimation of water inflow and errors in open water evaporation. Therefore, altimetry water levels and satellite imagery data can be used as a source of information for monitoring the operation of Roseires Reservoir with a fairly low uncertainty, while the errors of Lake Nasser are too large to allow for the monitoring of its operation.