Ecosystem Services Evaluation Of Nanliujiang River Basin Based On GIS And InVEST Model

The Nanliujiang river basin is located on the southeast coast of Guangxi low latitude region,In southern Guangxi alone to flow into the sea is the longest,most extensive drainage area,river water is the biggest,With the continuous development of the Beibu Gulf Economic Zone,the importance of ecosystem services in the basin is also rising.In recent years,with the continuous development of social economy,the adjustment of industrial structure,and continuously enhance the types of land use change and other human activities,at the same time because of the uneven distribution of rainfall,resulting in the emergence of a series of environmental problems in the river basin ecosystem,Such as increasing soil erosion,water pollution,air pollution and so on.The quantitative evaluation and the importance of the distribution of ecosystem services can make people more aware of the importance of the natural environment of the ecological system,the development of science resources,protect the ecological environment,realize the sustainable development of natural resources and human beings.InVEST model is widely used,mature model,quantitative and space can be achieved in a region or watershed ecological service function,and calculated the ecosystem service function,to carry out dynamic management of ecological system.Based on the InVEST model,to get the basic data in the field of verification and,using the meteorological data of Nanliujiang River Basin,soil type data,DEM data,land use data of two,using the SDR module model,Water Yield module of Nanliujiang river basin sediment retention,water production evaluation two for ecosystem service quantitatively,and the distribution of the ecosystem services space were analyzed,and two kinds of ecosystem services through overlay analysis of ecosystem services function importance evaluation,functional areas of ecosystemservices,and identify the most Excellent reserve.Through research and analysis,this paper draws a conclusion:(1)Take advantage of watershed hydrological stations(Changle station)service supply water sediment retention and ecological system of sediment and flow measurement data obtained using the model of calculation is verified,The statistical control within the scope of the sediment and the same period of the south flow observation statistics Changle hydrological stations in the river basin are the total sediment quantity is only 4 thousand and 900 tons of Changle station;and statistics Changle station control within the scope of the total flow and the same period of the Nanliujiang river basin hydrological observation station Changle statistics the total flow is relatively close,so the results calculated by the SDR module of InVEST model and water production module is accurate and reliable.(2)The SDR model takes into account the ability to intercept sediment of the upper reaches of the land itself,calculated by the model of soil conservation of a total of 190 million 433 thousand and 670 tons,the average quantity of soil conservation is209.050t/hm2;the average soil erosion modulus is 6.753t/(hm2.a),total annual erosion amount is 626.45*104t/a,mainly for the slight erosion and light erosion deposition.The amount of reserves are mainly distributed in a large amount of Beiliu City,Xingye County,Bobai county and Pubei County,the terrain is relatively large,high vegetation coverage and slope land distribution in few regions.(3)The main distribution of sediment retention and water supply in high land,paddy field,orchard;sediment retention per unit area the largest distribution in yellow soil and red soil,the water yield per unit area the largest distribution in Latosol type;with the increase of vegetation coverage,sediment per unit area of the reservation is also increasing yield per unit area of the largest distribution in vegetation coverage area is 80%-90% per unit area;sediment retention increased with the increase of watershed topographic slope and gradually become larger,not linked to water production per unit area value and slope grade,its value has little difference.(4)Through the quantitative analysis,which shows the spatial distribution of ecosystem services,the spatial distribution characteristics of Nanliujiang River Basin,spatial distribution of ecosystem services were different,on sediment retention and water supply Nanliujiang River Basin in 2014 of ecosystem services of cold and hot spots of spatial distribution spatial statistics,analysis and calculation of different service hot regional spatial distribution of sediment retention,hot zone ecosystem services are scattered,hot spots distribution showed a "north south,in the upstream,downstream characteristics of low water supply;distribution of hot zone ecosystem services are presented "North South low downstream,characteristics from north to south from cold to hot".Outside the ecosystem services excluding significant area,service space of 2 kinds of ecological system differentiation showed low-set oligomeric.(5)Overlay analysis of the calculated ecosystem services,ecological system within the basin comprehensive importance of service distribution,results show that only consider this important level without considering the important general level,for a single ecosystem service function,sediment retention of ecosystem services and ecosystem services are the distribution of water supply the sediment concentration,retain the northwestern and eastern basin ecosystem service distribution in the area,and the water supply of ecosystem services are mainly distributed in the southwest part of the basin;on the whole basin and said,Lu Chuan County,Bobai County,Pubei county and Hepu County in the south of the ecological system in these areas The service function of ecosystem services is poor,not in an important level of scattered distribution in these regions.