Response of Rise and Fall in Hulun Lake Wetland to Meteorological and Hydrological Factor Change

With meteorological and hydrological data from 1961 to 2005 in Hulun Lake Wetland, based on gray correlation analysis, Mann-Kendall test, regressive statistics, and wavelet analysis methods, the response models of rise and fall in Hulun Lake Wetland are established by meteorological and hydrological factors. The response characteristics of rise and fall are analyzed under meteorological and hydrological factors change in Hulun Lake Wetland, and references are provided for Hunlun Lake Wetland protecting, resuming and utilizing.Year and summer climate are major roles for the wetland rise and fall, but the water budget of the wetland rise and fall could be reflected completely by year climate. With annual evaporation and runoff fixed, water area and water level depth will respectively increase by 2.6 km² and 1.6 cm if yearly precipitation increases by 10 mm. Runoff increase of 1×10⁸m³ will lead the water area and water level depth to increase by 4.8 km² and 3.0 cm respectively, given the evaporation and precipitation unchanged.The coincidence response characteristics are prominent between the wetland rise and fall and the continuous change process of the influential factors from 1961 to 2005.The response is more prominent after the 1990s in particular, when the water resource shortness of the wetland become serious, because the hydrologic environment of the wetland is worsening and the wetland atrophy is faster. The impacting rates of air temperature and precipitation changes on the rise and fall of water area and water level depth are respectively 33.1% and 66.9%, 22.5% and 77.5%, and the precipitation change are dominant.The response of multi-time scale periodic characteristics is prominent between the wetland rise and fall and the influential factors. Their chief periods are all 27 years on the inter-decadal timescale. At the same time, the secondary period (11—13 years) on the inter-decadal timescale and the quasi-period (5—10 years) on the inter-annual timescale are the same for annual precipitation and annual runoff, the secondary period (14—16 years) and the quasi-period (2—7 years) are the same too for annual average air temperature and annual evaporation. Under the overlying action with the chief period and the secondary period, the wetland rise and fall is displayed the period processes of twice increasings and once decreasing from 1961 to 2005. The short period response about quasi-period is prominent between the wetland rise and fall and the influential factors, the wetland rise and fall take on the wave characteristics from 1985 to 2000 in Hulun Lake Wetland.