喜马拉雅山珠峰绒布冰川流域径流模拟

基于2009年5-10月喜马拉雅山北坡珠峰绒布冰川流域实测水文气象数据、 50 m分辨率DEM和中国第一次冰川编目资料, 在HYCYMODEL水文模型中加入冰川消融子模块, 模拟了绒布冰川流域径流过程.冰川消融子模块以海拔5 180 m基站的实测日气温、 日降水作为模型输入, 把气温、 降水插值到该流域40个高程带中, 分别计算各高程带的冰川消融和裸地蒸发, 并考虑液态降水对冰面的加热作用.野外气象观测表明: 2009年5-10月流域海拔5 180~5 750 m内, 月气温递减率在0.63~0.73 ℃·(100m)^-1之间, 均值为0.70 ℃·(100m)^-1; 同期降水观测显示, 海拔5 180 m以下降水梯度为-7.3 mm·(100m)^-1, 该高度之上降水梯度为22 mm·(100m)^-1. HYCYMODEL水文模型的敏感性检验表明, 该流域径流变化主要受气温影响, 降水变化引起的径流变化较小, 气温和降水变化对流域径流的影响是非线性的.

Runoff Simulation of the Rongbuk Glacier Watershed around the Mt.Qomolangma,Central Himalaya,Using HYCYMODEL

Using a hydrological model named HYCYMODEL with a module for glacier ablation, the runoff of a debris-covered glacier watershed on the northern slopes of the Himalayas, China, was simulated successfully. The daily mean temperature and daily mean precipitation at the altitude of 5 180 m a. s. l., obtained during the field work period from May to October, 2009, were the input variables. Besides the above, DEM with a resolution of 50 m and the glacier data from the Glacier Inventory of China were also used. The whole watershed was divided into 40 belts every 50 meters using GIS technique, of which temperature and precipitation were extrapolated. Glacier ablation and evaporation at each belt were calculated based on temperature and precipitation. Monthly temperature lapse rate was calculated ranging from 0.63 ℃·(100m)^-1 to 0.73 ℃·(100m)^-1 with a mean value of 0.70 ℃·(100m)^-1. Precipitation observation from May to October in 2009 revealed that below the altitude of 5 180 m precipitation decreased with altitude with a gradient of -7.3 mm·(100m)^-1, and above the altitude of 5 180 m precipitation increased with altitude with a gradient of 22 mm·(100m)^-1. Sensitivity analysis revealed that variation of runoff as a whole was primarily influenced by air temperature and the effect of precipitation on the runoff variation was limited. Since the evaporation and heating effect of liquid precipitation on the glacier melting were taken account of, the runoff for the whole watershed responding to the changes of temperature and precipitation was nonlinearly.