Based On HJ-1A/1B Data Of Real Water-Saving Potential Analysis To Hetao Irrigation In Inner Mongolia

The Hetao Irrigation District locates in western Inner Mongolia, it is the one of the three largest first order irrigation districts in China. Besides, the soil salinization in this district is heavy and the economic development mainly depends on agriculture. What’s more, the agricultural water consumption occupies70%of the total one. Currently, the water resource in Hetao Irrigation District is becoming exiguous under conditions of the climatic changes and human activities. It has become a sole parameter in limiting the economic development of Hetao Irrigation District. The total amount of intaking water in this district has decreased from the original5billion m3to4billion m, and the irrigation form herein is always the extensive one, leading to the severe waste of water resource. Hence, it is of dominant importance to study the water-saving potential of this irrigation district and, this is of far-reaching significance.Nowadays, the calculation of agricultural water-saving potential is mainly based on the water saving measures but, ignoring the existence of return water contained in the farmland water cycle system, resulting in the effect problems of water-saving potential scales. All the field consumpted water can be reued except for the evapotranspiration one. Thus, the reduction of evapotranspiration water is usually called the resource water saving or the the real water saving. Therefore, the calculation of agricultural water-saving potential basing on the reduction of evapotranspiration water consumption can avoid the problem of return water, causing a real assessment on the water-saving potential in irrgation district at a wider range.With the development of technology, the applications of remote sensing to calculate the evapotranspiration at a wide range inversely and the related technological theories to moniter the yield of crops are acceptable in productive practice, making the analysis and assessment on water-saving potential into possibility.Firstly, the HJ satellite was applied to classify the planting structures for the three main crops in Hetao Irrigation District, and the terrain classification is a key parameter in remote sensing technology, which accounts for the accuracy of the explained recults. The decision tree classification method, and the measured data in Hetao Irrigation District of2011, as well as the remote sensing images in the corresponding time periods were adopted for the determination on the ND VI value ranges for the three crops. The data in two time points were utilized for the classification of the final planting structures.This paper is based on the previous regional water-saving potential associated studies through remote sensing technology, accompanied by the environmental satellite to yield models of HJ-SEBAL and HJ. Thus, the three main crops related water consumption and yield in the growth period were computed inversely, then, the cumulative frequency curves were built. With the short-term objective of the water productivity in the whole irrigation district reached the half of the general productivity level, i.e., the cumulative frequency equals to50%; as well as the long-term objective which exceeds the half of the general productivity level, i.e., the cumulative frequency equals to70%; so as to assess the water-saving potential in Hetao Irrigation District. Results indicated that:(1) The application of remote sensing technology to analyse the water-saving potential of irrigation district is acceptable, the technological theories are practical and the results are capable of certain reference value(2) Results for the planting structures classification show that the chief crop in Hetao Irrigation District of2013is sunflower, with the acreage occupying50%of the total planting area, which is larger than before. While the planting acreage of maize and wheat is decreased.(3) Compared to the former years, the water consumption in Hetao Irrigation District of2013is larger which exceeds the normal level. The spatial patterns depict that the southern part is larger than the north part, while the central area is larger than the both ends, as well as the Yellow River nearby areas significantly larger than the other ones.(4) The crop yield in Hetao Irrigation District of2013is smaller than the former years, especially for wheat and maize. The spatial patterns illustrate that the yield of central part and Yellow River nearby areas are larger, which might be related to the spatial patterns of evapotranspiration in the irrigation district.(5) The crop water utilization efficiency in Hetao Irrigation District is quite low, which is capable of great water-saving potential, this is resulted from the extensive irrigation form. Hence, it is extremely necessary to develop new water saving irrigation forms for the district.(6) The short-term total water-saving potential for the three main crops is0.522billion m3, and the long-term one is1.845billion m, showing a huge water-saving potential. (7) Through the classification of water-saving regions in this irrigation district, it is revealed that the main attention of water-saving projects and measures should be putted on the northern and western regions.