| Manasi River is a typical inland river in Xinjiang Province. Due to the irrational plantingstructure and the apparent contradiction between water supply and demand in the ManasiRiver Basin, the dissertation studies the relationship between river runoff and irrigation water,and spatial and temporal changes in crop planting structure and the structure of water bycollecting historical data and field trips. Based on the condition of upstream, midstream anddownstream region resources, the paper established the planting structure evaluation andoptimization model and provided some planting solutions considering the food security, waterresource security and ecological protection. The main results were as follows:1) The Mann-Kendall method was used to test the characteristics of river runoff changes.It showed that annual runoff series increase since the1990s and there was a break in1996.The annual irrigation water amount occupies59.63%of the river discharge and this ratio wasrelatively higher. The area of oasis land showed an increase trend from1987to2006and theincreasing rate was103.57km2per year. This aggravated the contradiction of water and landresources. To ensure ecological security and water consumption, the total arable land is32.44×104hm2now and the results of the study suggests that10.70×104hm2farmland whichaccount for about24.80%of the total area should return to woodland.2) The temporal characteristics of the farming structure from water1980to2009wereanalyzed. It showed that the water utilization structure for planting was overall balanced from1980to1989. This balance was broke from1990to1999. From2000to2000, more waterwas consumed by economic crops, and grain crops and other crops consumed a smallerproportion of water. The changes of planting structure and water utilization structural weresimilar. The spatial variations of planting structure and water utilization structure from1980to2009were analyzed. From1980to1989, grain crops were the main crops within the basinand consumed a large part of agricultural water. Thereafter, the downstream planting area ofgrain crops decreased and the grain crops concentrated in the upstream and midstreamirrigation area, the proportion of the overall proportion of water and planting was smaller thanthat in the past. Cotton was mainly distributed in the downstream and the overall percentage became smaller, and water consuming was less. From2000to2009cotton planting waredistributed in the basin and the proportion increased, and the proportion of water dominatedduring this period.3) By the application of water footprint theory, the dissertation analyzed the currentplanting structure of crops. It showed that the utilization of green water was19.34%and bluewater was80.66%. The amount of transferred water is5.30×108m3which accounts for46.54%of total water resource and accounts for62.37%of the water sluice gate, which wasunfavorable to the security of water resources. It required an increase of planting proportionof winter wheat in order to make full use of green water.4) The features of climate changes in the watershed were analyzed. The ET0over the past50years showed an increase trend. In further details, it was found that the effect of climatechange on the planting proportion of cotton was weak while it was relatively apparent overthe years from1980to2008. Under the background of global warming in the future, theincrease of air temperature will increase the water demand and the effect on ET0was mostapparent in June. If the temperature increase by one degree, the amount of irrigation waterwill increase by6.55%while if the temperature increase by two degrees, the amount ofirrigation water will increase by13.54%.5) The effects of production input factors and meteorological factors on grain productionwere analyzed using path analysis. The results showed that the direct coefficient of productioninput factors on per unit yield of cotton, wheat and corn were0.8070,0.8418, and0.8095,respectively, while those for meteorological factors were0.1931,0.1396, and0.1906,respectively. This indicated that the direct effect of production input factors was great thanmeteorological factors.6) The evaluation model for planting structure was established by the Orientor starsmethod. By considering food security, water resource security, ecological security, andeconomic benefit, the optimizing model for coordinating planting structure was developed.And the optimizing planting structures at50%and75%probability of water assurance werederived. It indicated that the proportion of grain crops at these two probabilities was21.38%and21.15%, respectively. It was40.79%and40.38%for cotton, respectively. For pastures, itwas21.04%and19.90%, respectively. For protection forest, it was8%. In addition, theproportion of economic forest was7.61%in middle stream and the proportion of Haloxylonammodendron and Chinese tamarisk was3.70%. The under mulched drip irrigation hadimportant effects on water utilization of plantation and the adjustment of planting structure.The evaluation from society, economics and ecology showed that the under mulched dripirrigation was favorable to the increase of WUE of crops and reduced water consumption. Theunder mulched drip irrigation provide technical support for the implementation scheme of theplanting structure in the future.Taking these findings, it is recommended that developing limited agriculture, improvingirrigation rate guarantee, adjusting planting structure and popularizing water-saving technologies would fundamentally achieve the purpose of the sustainable development ofwater-saving and production-increasing in the arid inland river basin. |
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