Ecological Risk Assessment Of Land Reclamation Plan Based On The Relative Risk Model

As a kind of effective means to maintain the balance of cultivated land,coordinate man-land relationship and improve the ecological environment,land reclamation has played a big role in ensuring China's food security and promoting the construction of ecological civilization.At the same time,it also has a negative effect on the planning area and its surrounding environment.In order to avoid or reduce the potential ecological risks of land reclamation,we can make a prediction of the possible ecological risks before the implementation of the plan to realize the maximization of the remediation planning.In this thesis,I took Huachi county of Qingyang city as the research area.Based on the year of 2015,I used the Relative Risk Model to evaluate The Land Reclamation Plan of Huachi County(2016-2020).The main findings of the thesis are as follows:(1)Using Analytic Hierarchy Process(AHP)to determine the weight of 4 kinds of renovation project: farmland management,rural construction land reclamation,land development suitable for ploughing,and land reclamation,Using villages and towns as evaluation unit to calculate comprehensive scores,15 villages and towns of Huachi were divided into four risk area and determine the above four land reclamation projects as risk resources;Combining the distribution of reclamation projects in various land types,select arable land,woodland,grassland,mining land,village and unused land as habitats;According to the impact of land reclamation activities on the natural environment of the project area,the ecology receptors can be identified as soil,water,biological species and landscape pattern.(2)By using Arc GIS,the area of risk sources and habitats in each risk community was obtained,and the density,habitat abundance and exposure coefficient were calculated.The conceptual model of exposure-response is constructed,and exposure-hazard analysis is carried out to determine the response coefficient.According to the relative risk fomula,the relative risk values of each risk community are calculated,and the I to IV area are 1.24,5.50,11.59,3.21 respectively.From the point of risk value of risk resources,the ecological risk of arable land development projects in each risk area is relatively high,from the types of the habitat and the risk values of ecology receptor,the ecological risks in Area II and Area III are relatively high,and that in Area Iand Area IV relatively low;According to the value of the relative ecological risk,the risk level is divided into four levels of Low risk area(Area I),Medium risk area(Area IV),Medium-high risk area(Area II)and high risk area(Area III).(3)According to the risk level and the specific situation of each risk commuinity,the corresponding risk prevention measures are put forward.The comprehensive management of farmland,woodland,and grassland should be implemented.Among them,the cultivated land arrangement should carry out the construction of horizontal terraces fields,within the range of the ecological environment,the scattered parcels should be regularized,and the abandoned land and arable should be cultivated;Basic farmland construction is not only improve farmland accessibility and the level of agricultural mechanization,but also improve the arrangement of the ditch,canal,road,forest and other supporting facilities in the area.Build protective forests along the roads and rivers,change dry lands into irrigated areas in areas where conditions permit,and actively promote water-saving irrigation measures.The main targets of renovation of the rural residential land are waste homesteads and cave dwellings,due to the easy collapse of loess,homestead need constant updating.Because of the fragmented distribution,fewer reclamation scales have been formed,reclamation difficulty increased accordingly,It is suggested to relocate to a nearby village where conditions are better and to reclaim the abandoned homestead;Due to the restrictions of natural conditions such as topography and landform,it is difficult to develop unused land,and the use potential of land to be developed is relatively small.It is suggested to combine the development of such land,reclamation and arable land consolidation;In the process of the reclamation of mining abandoned land,oil exploitation,digging damage and so on destory Vegetation,and change the existing fields,forests,grass ecosystems and polluted groundwater.It's time to take a comprehensive and multi-level consolidation measures in abandonded mining areas restoring native landforms or other suitable vegetation according to local conditions and exerting multiple functions of woodland,grassland,farmland,etc.