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Northwest A&F University (2017)

Study on Salt Movement in Typical Irrigation Area of Hetao Irrigation District based on Remote Sensing Technology

陈智森;

Titre : Study on Salt Movement in Typical Irrigation Area of Hetao Irrigation District based on Remote Sensing Technology

Auteur : 陈智森;

Grade : Master’s Theses 2017

Université : Northwest A&F University

Résumé
The Hetao irrigation areas in Inner Mongolia are located in the arid and semi-arid areas,and the agriculture development mainly relies on the irrigation water from the Yellow River ;however,the development of irrigation in agriculture is facing many problems.For a long period of time,the relative lack of water and salinization are two main limitations that restrict the sustainable development of Hetao irrigation area.There are about 1.7 million tons of salt input to the irrigated area every year through the irrigation of yellowing,precipitation,and so on.Surprisingly,there has been no significant changes in the salt content of the cultivated land,and the salt wasteland has not increased in recent years.Therefore,it is important to understand that where the salts are,the distributions of different types of ions,and the input and output amounts of the salts.Many studies studied on the water and salt balance of the Hetao irrigation area,but most of them neglected the role of salt in the crops in the salt movement.In addition,it is important to classify the land use types to calculate the salt contents moving out of the irrigation areas by crop harvest,because different types of crops have different capability of carrying salt.In this study,the land use types were classified using the high resolution remote sensing satellite images and land survey data.The typical influencing factors of salt migration in the study area were studied,and the source and discharge characteristics of different salts were analyzed.The following results are obtained :(1)The lands in the study area were divided into three main types(maize,sunflower and non-planting area)using the remote sensing imagines.The results and the accuracies from the image data of 2011,2013 and 2014 were evaluated.The result shows that the areas of non-growing areas in the study area decreased from 34% to 24%,with an average annual decline 2.5% from 2011 to 2014.Therefore,more land was invested in agriculture year by year.The accuracies were evaluated based on the high resolution satellite images and the land survey data.The overall accuracies of the classifications were 93.9%,96.4% and 95.9%,respectively ;and the Kappa coefficients were 0.90,0.94 and 0.94,respectively.It demonstrated that combining the high-resolution remote sensing images with the field surveys can accurately classify the land use types in the township scale ;therefore,facilitate the measurement of the amount of salt produced by different crops in the research area.(2)The factors influencing the salt balance of typical irrigation areas in Hetao Irrigation Area were studied.The analysis of irrigation,precipitation,crop carrying salt and groundwater was carried out.Through the irrigation water from the Yellow River,a total of 5.1297 million m3 of irrigation water with 2667.44 tons of salts flow into the irrigation area,which is the largest source ofthe salt input.The distribution of precipitation during the year is very uneven and the total precipitation is very scarce,bringing the total cation is about 35.50 tons.In 2014,the maize growth area was 13.22km2 in the study area,with 705.95 tons of salt content at harvest.Whereas there were 7.21km2 sunflower with 228.56 tons at harvest.The total amount of salt produced by the crop was about 934.51 tons,which was 35% of the total amount of salt input from the Yellow River Irrigation,which plays a unneglectable role in the regional salt discharge.(3)The salts in the irrigation water were redistributed during the soil profile migration,and the concentrations of Ca2+ and SO42-were the highest in the unsaturated zone,and that of Cl-,SO42-and Na+ were the highest in the groundwater.The main innovation of the study is that the typical crop area in Hetao irrigation area was taken as example to classify and calculate the land use based on the high resolution remote sensing satellite image and land survey.By combining the irrigation,precipitation,groundwater and other factors affecting the salt migration and the regional salt dynamics,it has important practical significance for the scientific adjustment of planting structure and the development of agricultural economy.The study provides some scientific basis for further study on water saving irrigation and soil salinization in Hetao irrigation area

Mots clés : Hetao irrigation area; remote sensing; soil salinization; salt in crop;

Présentation (CNKI)

Page publiée le 4 février 2018