Analysis Of The Relationship Between Drought-Flood Disasters And Land-Use Changes In West Jilin, China

Jilin Province is an important grain production base in the country, and has charged withthe mission of ensuring national food safety for a long time. The safety of food production isbarely affectted by relatively natural disturbance, mainly to drought, floods, cold, etc, but theprobability of occurrence is high. Jilin has significant regional differentiation in the aspect ofnatural disaster occurrence: the agricultural natural disaster of eastern mountain area is mainlycold damage, western plains region dominated by natural disasters of drought and floods.Drought and floods cause agricultural production decrease, and are also a threat to the securityof food production in Jilin Province.Administering two prefecture-level cities Baicheng and Songyuan, west Jilin is animportant part of the food production bases in Jilin Province, and also a major grainproduction region to make the province’s food security. Both Baicheng and Songyuan’sagriculture are dominated by farming, their level of agricultural mechanization and irrigationare higher than the average level of Jilin Province, but their grain yield per unit area is lowerthan the average level of Jilin Province. Food production is less restricted by the technicallevel of the west Jilin, but more by natural disasters such as drought and floods. As theconstantly increasing intensity of human activities, land-use changes affected disastersoccurrence significantly, drought-floods disasters and land-use changes become closelyrelated. This paper is to take west Jilin as a typical area to analyze the the relationshipbetween drought-floods disasters and land-use changes, and propose the countermeasures toeffectively mitigate drought and floods disasters.Based on the statistical data, meteorological station statistics, field surveys and testing,using GIS technology, SPSS software, Fragstats software and mathematical methods forspatial and temporal evolution studying of drought-floods disasters in west Jilin, analyzingconversion of land-use types and land-use pattern changes in west Jilin，the linkage betweendrought-floods disasters and land-use changes in west Jilin was analyzed using landscapeindices, and the conclusions were obtained as follows:(1) In west Jilin, the disaster rate decreased from10.95%(1980-1995) to9.27%(1996-2000) and to7.63%(2001-2007), respectively, which showed an obvious decline trend.Overall, it shows that the drought-floods disasters of west Jilin have invaded towards East inthe aspect of spatial distribution. Drought-floods disasters are usually affected by topographyfactors and human factors as well as meteorological factors, which are the most dominant one.In view of a single year, there are some differences in meteorological elements in differentcountries, but in view of multiannual meteorological elements statistics, the result suggestscities and counties have experienced almost the same weather process in this region. Theterrain has aggravated or mitigated effects on the deterioration in the drought-floods disastersoccurrence, but can only affect the regional drought-floods disasters. The study shows thatdifferent land-use pattern has different resilience for drought and floods, combined with thesame unusual weather and stable terrain conditions, and hence, different disaster rates.(2) A reasonable adjustment on land-use type and focus on optimizing the configuration of land-use types in the process of land use transition are helpful to resist or mitigatedrought-floods disasters: keeping a certain quantity of paddy fields and ensure therationalization of spatial configuration will determine their ability of resisting disaster, and itwill has effects on the disaster rate. Deforestation can lead to floods, and ensuring forestownership and implementing Grain-for-Green can resist floods. The implementation ofGrain-for-Green should be adapted to local conditions. Converting grassland for farmlandmay cause drought, and it should ensure the grassland holdings and achieve appropriatepasture. However, it should pay more attentions to the optimization of pasture space. In theconversions between wetlands and farmland, balanced attentions should be paid to both thenumber and the land-use pattern.(3) There is a close relationship between dynamic changes of land-use pattern anddroughts and floods rate. The relationship between landscape scale land-use pattern changesand droughts and floods is limited, and between type-scale land-use pattern changes and theoccurrence of droughts and floods is comparely close. In the mutual transformation process ofdryland and paddy fields, the pattern change of dryland and paddy fields shows more closerelationship with the floods. To defend floods, the shape of new increased patch should beadjusted according to the actual situation.During the transformation process of the pattern offorestland and upland, the shape and connectivity of forest patches should be taken intoconsideration. In the transformation process of dryland to grassland, the relationship betweenthe shape of grassland patch and floods is very close. During the transformation process ofwetlands and farmland, the relationship between the patterns change of wetlands andfarmland and floods is very close. To resist droughts and floods disasters, more attentionsshould be paid to the integrity of landscape patches.(4) Based on the landscape pattern optimization theory and landscape security patterntheory, it can be seen that there is close relationship between land-use type and pattern, anddrought-floods disasters. For the purpose of disaster resisting, proposed grid-style grass fieldis an optimized mode to resist droughts and floods better. To verify the rationality of theland-use configuration screened for defending drought and floods, typical plots in theHalamaodu Town of Qianguo County were selected to compare the differences in soilnutrients, moisture and other indicators in the fields mixed with forestland and grassland andthe pure fields. It shows that the loss of organic carbon content in the fields mixed withforestland and grassland is significantly less than that of pure fields before and after theextreme weather, and the water-holding capacity and effective phosphorus content of thefields mixed with forestland and grassland are significantly higher than those of pure fields.However, effective nitrogen content in the fields mixed with forestland and grassland isgenerally lower than that in pure fields. In addition, soil nutrients are distributed uniformly inthe fields mixed with forestland and grassland, which would be helpful for the growth of crop.