关键词: 祁连山, 水源涵养, InVEST模型, 生态系统

Abstract:

In recent years， more and more attention has been paid to the ecosystem service function， and it has gradually become a hot issue for scholars. As one of the important service functions of surface ecosystem， water conservation plays a key role in regulating regional hydrological cycle， improving surface water status and maintaining the normal operation of regional ecosystem. As an important ecological security barrier， the Qilian Mountains is also one of the important water conservation functional areas in Northwest China. Based on the InVEST water wield model and the principle of water balance equation， the water production of each unit is calculated by subtracting the actual evapotranspiration from the precipitation of each unit， at last， the water conservation capacity of the study area is obtained. The model needs input of precipitation， potential evapotranspiration， soil texture， land use type， and vegetation available water grid layer. The meteorological data are from China Meteorological Data Service Center， the soil texture data are from Harmonized World Soil Database， and the soil type data are from Resource and Environment Science and Data Center， Institute of Geographic Sciences and Natural Resources Research， Chinese Academy of Sciences. The spatial and temporal variation characteristics of water yield amount and water conservation amount in the Qilian Mountains were calculated and analyzed， and the influencing factors of water conservation amount were discussed by using Pearson correlation analysis method. It is of great significance to promote the rational allocation of water resources， water management and ecosystem protection in the Qilian Mountains. The results showed that the annual average total amount of water wield and total amount of water conservation were about 93.03×10⁸ m³ and 57.83×10⁸ m³， respectively. The water conservation amount showed a slight upward trend and the change rate was 0.196 mm·a^-1. The total amount of water conservation under different land use types was： grassland （31.87×10⁸ m³） > woodland （16.71×10⁸ m³） > cultivated land （4.92×10⁸ m³） > other land （2.29×10⁸ m³） > building land （0.63×10⁸ m³）. In the aspect of meteorological elements， there is a significantly positive correlation between precipitation and water conservation amount in each period， there is a negative correlation between evapotranspiration and water conservation amount， and there is a positive correlation between average air temperature and water conservation amount， but the correlation is not significant. At the same time， the change of land use types in different periods also has an important influence on water conservation amount， and change of grassland area has a great influence on water conservation amount. While paying attention to regional climate change， land resources should be rationally developed and utilized， and attention should be paid to the protection of its green space ecosystem. Under the background of high and cold climate， permafrost is widely distributed in the study area， and the underground ice buried under the geomorphology of permafrost is a special form of water body. It also plays an important role in regulation of regional water resources and plateau ecological environment change. Therefore， the combination of surface water and underground ice storage of permafrost in this paper is helpful to grasp the overall change of water resources in the Qilian Mountains. In this paper， average air temperature， average surface temperature and average thickness of permafrost in the Qilian Mountains are estimated according to the empirical formula of permafrost established by predecessors. The estimated underground ice storage of permafrost in the study area is about 555.76 km³. As warming trend continues in the future， area of the warm permafrost will continue to increase， underground ice of the permafrost will melt at a faster rate， and its internal water storage will decrease accordingly. The study also has important implications for assessment and management of hydrological cycles and ecosystems in the Qilian Mountains.

Key words: Qilian Mountains, water conservation, InVEST model, ecosystem