Cultivated land changes induced water profit and loss characteristics in the main grain-production areas along the Yellow River using MODIS

Yellow River reaches along Henan Province has been one of the most significant core areas to promote ecological protection and high-quality development in the Yellow River Basin. An important role can also be played to enhance the national ecological civilization construction for the commodity grain supply security. However, water resource shortages have been serious threatens to the basic resources in this region. A mismatch between production capacity and water resource distribution has posed a great challenge to local food production, economic development, and ecological environment. Therefore, it is a high demand for the assessment of the water balance to further clarify the effects of water balance under land use, in order to ensure national food security and regional high-quality development. This study aims to reveal the characteristics of water balance under land use in six typical grain-producing counties (such as Yuanyang and Fengqiu). The land use status, MODIS remote sensing data, and conventional meteorological data were also collected in the region from 2000 to 2020. A water balance evaluation model was constructed to reveal the climatic water balance status and the effects of water balance under land use, according to the Priestley-Taylor formula and regional remote sensing evapotranspiration model. The results show that: 1) There was a slow decrease in the area of cultivated land and the subtypes in the six counties along the Yellow River during the study period. Specifically, the cultivation rate decreased from 81.46% in 2000 to 79.34% in 2020. The stable type spectrum accounted for 73.98% of the total change area from the temporal process. The early and late shrinkage types were mainly distributed around the built-up areas of each city and county, whereas, the early addition type was mainly distributed along the Yellow River. The relative area ratios of the three types were 3.97%, 2.63%, and 3.61%, respectively; 2) The annual water balance index in the study area was -0.60, indicating a deficit overall. The key areas of water deficit were found in the southwestern part of Yuanyang County, Huaxian, and Puyang. There were some significant differences in the amount and index of deficit, indicating the varying trend at each time point; 3) The cultivated land in the study area was mostly in a severe climatic drought state, with the water shortage type mainly being moderate, severe, and extremely severe drought. There were no normal and mild drought areas. In terms of the effects of changing states, the stable type cultivated land was in a state of severe drought, while the early and late shrinkage type cultivated land was in a state of severe drought, and the early addition type cultivated land was in a state of extremely severe drought. Considering that most of the cultivated land in the Yellow River region is in a relatively severe climatic drought state, the regional sustainable strategy of cultivated land used can be expected to ensure food security production under the principle of "determining production according to water and conducting production according to the amount of water".