Study On Suitable Scale Of Oasis In Middle Reaches Of Heihe River Based On Water Resources Change

Oasis is the basis of human survival in arid areas.The suitable scale of oasis is an important index to maintain the balance of ecosystem and the development of human society.In this paper,the oasis in the middle reaches of Heihe River is taken as the research object.Oasis and cultivated land area in 2025 and 2030 will be predicted by using Arc GIS software and Markov model.The characteristics and rules of water resources change in the basin are analyzed by using runoff data of nearly 76 years.The grey model is used to predict the changes of surface runoff and non-plant water consumption in the future.Based on the principle of water and heat balance,the calculation model of oasis suitable scale in study area is established.The suitable scale of oasis and cultivated land in 2010,2015,2025 and 2030 are calculated and compare it to the actual area.The research results can provide targeted strategies for maintaining the sustainable development of oasis in the study area.The main conclusions are as follows:(1)In 2010,the area of cultivated land and oasis were 2129.24km~2 and 4184.16km~2respectively;In 2015,the cultivated land area was 2172.61km~2,and the oasis area was 4245.23km~2.Oasis scale presents a single growth trend.It is estimated that the cultivated land area will be2257.59km~2 in 2025;In 2030,the cultivated land area will be 2299.11km~2.It is estimated that the oasis area will be 4364.97km~2 in 2025 and 4423.56km~2 in 2030 respectively.(2)Over the past 76 years,the annual runoff of Yingluoxia in the middle reaches of Heihe has been unevenly distributed and has no significant increasing trend.In 2025 and 2030,the annual runoff of Yingluoxia gorge in Heihe River will be 23.68×10~8m~3?25.34×10~8m~3,the annual runoff of zhengyixia gorge in Heihe River will be 14.5×10~8m~3?15.73×10~8m~3.(3)In 2010,the suitable oasis area is 1759.12 to 2345.5km~2,and the suitable farmland area is 703.65 to 938.2km~2.In 2015,the suitable oasis scale is 1836.26 to 2486.01km~2 and the suitable cultivated area are 734.5 to 994.4km~2.In 2025,the suitable oasis area in the middle reaches is2224.27 to 3011.31km~2,and the suitable cultivated area is 889.71 to 1204.53km~2.In 2030,the suitable oasis scale is 2329.65 to 3153.99km~2 and the suitable cultivated area are 931.86 to1261.6km~2.The actual oasis area and farmland area are all beyond the suitable scope,the water resources can not maintain the oasis demand of oasis.For preserving the stability of oasis,the size of oasis should be reduced and the continuous increase of cultivated land should be strictly controlled.