| Ningxia Helan county water-saving irrigation in arid areas,the author of this paper to irrigation area,the influence on the ecological environment,the system of water-saving irrigation were studied on landscape pattern in the irrigation area,appropriate scale,the oasis stability value,ecosystem service value and ecological vulnerability,the influence of the results of the study for the construction and development of modern ecological irrigation area in ningxia.The main research results are as follows:(1)Arcgis10.2 software was used to calculate the comprehensive dynamic attitude of land use types at the two stages of water-saving irrigation in Helan County,which were 0.99%and 0.93%,respectively.The absolute dynamic attitude and relative dynamic attitude of each type of land use were determined to determine the change rule of land use in the irrigated areas in 23 years after water-saving irrigation.By Fragstats 4.2 software,12 landscape index values and landscape pattern change characteristics of two stages of water-saving irrigation were obtained,which revealed the landscape pattern change law of fragmentation degree,complexity degree,landscape heterogeneity,dominant patch dominance influence and diversity degree of Helan County in two stages.(2)The water demand of vegetation was calculated by using area quota method,and the suitable irrigation area was calculated and predicted by using water balance method and water heat balance method.The minimum and suitable ecological water requirements of vegetation in two stages of water-saving irrigation were calculated,among which,in the stage of high-efficiency water-saving irrigation the minimum and suitable ecological water requirements of vegetation in irrigated areas were 123 million m3 and 201 million m3.The suitable irrigation area and oasis stability index H0 of the irrigated area were calculated,and the H0 values in 2008,2010 and 2018 were 0.54,0.51 and 0.58 respectively,indicating that efficient water-saving irrigation prevented the decline of the stability of the irrigated area and prevented the ecological environment degradation of the irrigated area.(3)The value of ecological service(ESV)in irrigated areas was calculated,and the temporal and spatial variation characteristics of the value of ecological service in irrigated areas were determined.The ESV value in high-efficiency water-saving irrigation increased by 15.4%compared with that in water-saving irrigation.After high-efficiency water-saving irrigation,the value of ecological service in irrigated areas tended to move to the west,and the water conservation function tended to decline.Constructed under the condition of water saving irrigation based on "pressure-state-response" criterion of irrigation area ecological environment vulnerability assessment of fuzzy analytic hierarchy process(AHP),a comprehensive model calculated in 2008,2010 and 2018,irrigation area ecological environment comprehensive evaluation value of 3.743,3.794 and 3.909,respectively,are in a class ? general level,fragile ecological environment comprehensive evaluation value increasing trend,show that under the condition of water saving irrigation irrigation area ecological environment evolution in the direction of good. |
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