Study On Evolution And Water Sources Of Honghe Wetland

Honghe National Nature Reserve(HNNR) is a typical marsh wetland in northeast Heilongjiang province. In recent decades, there were many problems in the HNNR wetland and its surroundings, such as degradation of wetland and loss of surface-water. It has lead to researchers paying more attention to the evolution of the wetland. In this study, HNNR and its surroundings(including Nongjiang farm, Yaluhe farm, Qianfeng farm and Honghe farm) were taken as the study area to research the evolution of wetland and driving forces for the evolution in the past forty years. To learn about the source of wetland surface water and its effect on evolution of wetland, this study has focused on HNNR to research the surface water-groundwater interrelationship and the source of wetland surface water by investigating, collecting soil and water samples, and analyzing the hydrogeological conditions, water chemistry and isotope datas.In this paper, Thematic Mapper(TM) satellite images of 1975, 1988, 1996, 2002 and 2014 were selected to study the land cover change and evolution of wetland in study area. Wetland area has reduced about 87.67% and meadow area has reduced about 95.29%, while arable land area has increased about 203 times in study area. By adopting land use transfer matrix, there was 1404.0 km2 of wetland and 879.5 km2 of meadow that have transformed into arable land, which accounted for about 94.75% of the degradation of wetland and 91.26% of the degradation of meadow. Clearly, wetland and meadow in the study area have gone through serious degradation from 1975 to 2014, and most of them have transformed into arable land.In HNNR, wetland and meadow are the two main types of land cover and their total area accounted for the proportion about 84.34%~91.66% of HNNR area. What’s more, the area of wetland and meadow has changed a lot and they have mutually transformed in the past forty years. By calculating the landscape index of HNNR, the result showed that landscape fragmentation ascended and plaque area declined. And the shape of plaque has become more irregular and more complicated as well.Agricultural reclamation is a main driving force factor for evolution of wetland in the study area, directly leading to the degradations of wetland and meadow. And natural factors, such as climate warming and rainfall reducing, and human factors, such as the establishing of the systematic irrigation network and groundwater exploitations, have changed the wetland hydrological conditions and the source of surface water. That also has affected the evolution of wetland.The source of surface water in HNNR was study in this paper. It has showed that there is a interaction between surface water and groundwater. And surface water recharges groundwater with limited recharge range. Further more, it is concluded that the main water source of surface water in HNNR is the atmospheric precipitation.