自然-人为双重作用下扎龙湿地水文情势分析

Analysis of the Hydrologic Regime Affected by Natural and Human Factors over the Zhalong Wetland

湿地水文情势制约着湿地环境的生物、物理和化学特征,从而影响到湿地类型分异、湿地生态系统的结构与功能。扎龙湿地是重要的国家级自然保护区,枯水年需要人为补水来维持水文情势。分析人为补水条件下扎龙湿地水文情势,为确定湿地生态补水机制和湿地生态系统的保护和恢复工作提供科学依据。本文选取1971年-1987年和2001年-2008年两个人为补水期,利用收集到的水文气象资料对扎龙湿地水循环要素特征和水量平衡进行计算分析。结果表明:在枯水年,人为补水量是扎龙湿地的重要水源。在自然和人为补水双重作用下,扎龙湿地蓄水量是增加的,有利于维持湿地生态系统平衡。此外,人为补水有利于湿地地下水位的回升和维持地表水位的相对稳定,对于植被的演替与恢复、鹤类种群的繁殖也有显著的作用。

Wetland hydrology,which controls biotic,physical and chemical characteristics of wetlands,is the most critical factor in determining the types,structure,and functions of wetland ecosystems.The Zhalong wetland,an important national nature reserve,is of importance to protect cranes and wetland ecosystems.In addition to precipitation and natural streamflows,the Zhalong wetland requires additional artificial water supply to maintain the hydrologic regime in dry seasons.The hydrologic cycle in the Zhalong wetland is influenced primarily by a combined effect of natural and human-induced factors in dry seasons.Analysis of the mechanisms of how the influence of natural and human factors works on the hydrologic regime would provide a basis for hydrologic budget calculations,being conducive to determining ecological water supply and formulating plans for protecting the wetland ecosystems.In the present work,the authors made an effort to unravel the characteristics of the hydrologic cycle and water balance in the Zhalong wetland using meteorological and hydrologic data for two artificial water supply periods 1971-1987 and 2001-2008.Results of hydrologic budget calculations showed that：1）precipitation and inflow of the upper reaches were the major recharge sources.Artificial water supply was deemed the critical water source into the Zhalong wetland for the two study periods,accounting for approximately 10%and 25%of the total recharge,respectively.Transpiration was found to be the major output,taking up roughly 60%of the total;2）artificial water-supply showed a great effect on the wetland hydrological regime,leading to variations in water level,water area,and water storage.In terms of variations in groundwater level and surface water level,the groundwater level was observed to be increased under the condition of artificial water supply since 2001,returning to the level of 1999.The variation of surface water in the core region of the wetland was within 0.8 m,suggesting a relatively stable level.This was mainly due to the artificial water supply.Meanwhile,the amount of water storage in wetland was increasing because of the artificial water-supply;and 3） the artificial water supply imposed a great effect on the hydrologic regime and wetland ecosystem,being reflected by responses of typical flora and fauna to changes in the hydrologic regime.The increased water storage can maintain the wetland ecosystem balance,particularly benefiting vegetation restoration and growth of animals.It was found that the artificial water supply contributes to an increase in the area of reeds and cranes propagation.