Study On Temporal And Spatial Variation Of Rice Irrigation Water Demand In The Northeast Three Provinces Based On Remote Sensing And Meteorological Data

Food security is the basis of national security,social stability and economic development.As a developing country with a population of 1.37 billion,China's food security issue is pretty prominent and important.The northeast of China is the major base of grain production and trading.Japonica cultivation area in the Northeast accounts for 46%of the country's total,and the output is more than 50%.The production process is also a large consumption of agricultural irrigation water.Water resources are the lifelines of agricultural production,and China's agricultural water consumption accounts for about 63%of the total,but the usage efficiency of agricultural water is only 50%.In this paper,we used remote sensing and meteorological data to assess the irrigation water demand of rice in the Northeast,which is of great significance to ensure food security and the sustainable use of agricultural water resources.In this paper,50 representative paddy fields were selected in Northeast China,and the Enhanced Vegetation Index(EVI)and Land Surface Water Index(LSWI)were obtained during the irrigation and transplanting period.We established the relationship between the two indices and constructed algorithm to identify rice-planting areas;The spatial distribution of Evapotranspiration(ET)in Northeast China was extracted using MOD16A2 Data;The Effective Rainfall(ER)was calculated according to the method recommended by the U.S.Department of Agriculture's Soil Conservation Service,and the Deep Percolation(DP)in the field was estimated by simple classification of soil data;With rice-planting area mask,we got the net water demand for rice by subtracting the ET,ER and DP data by the pixels,then we obtained the gross water demand by dividing the canal water loss ?.Main achievements and innovations of this paper were as follows:(1)Rice planting in the Northeast China is mainly distributed in Heilongjiang Province,relatively few in Jilin and Liaoning provinces,and the total errors of area extraction are less than 5%.(2)The distribution of evapotranspiration in the three northeastern provinces is gradually increasing from west to east,showing a regular annular distribution.The mean of the five-year statistics was 329.23 mm.(3)According to the method recommended by the US Department of Agriculture Soil Conservation Service,the effective rainfall interval is roughly 150?800mm,which declines from southeast to northwest spatially.(4)The soil data of the three northeastern provinces were simply classified as clay,loam,and sand.Based on the data of soil geological and leakage conditions,the Deep Percolation was reasonably determined as:clay 2.30mm/day,loam 2.80mm/day,sand 3.40mm/day.(5)The Irrigation Demand Index(IDI)was introduced to reflect the dependence of rice on irrigation during the growth period.The IDI of most areas were above 0.4,which indicated that the demand of irrigation water was higher in Northeast China.The average of total water demand was between 500?600mm.