基于土壤水分的旱田灌溉用水量估算——以河南省鹤壁市为例

Estimation of irrigation water use of dry farmland by using soil moisture in Hebi city of Henan province

及时、准确地掌握区域灌溉用水量,对水资源管理及其优化配置具有重要的意义。然而,如何有效地获取区域灌溉用水量,仍是农业、水利及地理信息等学科亟需解决的重要问题。鉴于灌溉与土壤水分变化的联系,提出一种利用土壤水分估算灌溉用水量的方法。以鹤壁市16个土壤水分监测站点为研究对象,分别建立线性模型、对数模型和土壤水量平衡模型表达降水量与土壤水分的定量关系。首先,获取站点上的6年逐日气象数据(温度、降水、气压、风速、日照时长)和土壤水分数据,前4年数据用于建模,后2年数据用于模型验证。然后,在每个站点上建立基于土壤水分估算降水量的模型,并利用验证数据进行验证。结果表明:线性模型计算降雨量的RMSE为10.55 mm,对数模型计算结果的RMSE为10.3 mm,土壤水量平衡模型计算结果的RMSE为8.62 mm,基于土壤水量平衡原理的模型能更好地表达土壤水分与降水量之间的定量关系。最后,利用土壤水量平衡模型估算田间的灌溉用水量。与实测的灌溉用水量数据对比,采用水量平衡模型估算的灌溉用水量偏小约14.19%。综上,建立的利用土壤水分估算灌溉用水量方法,对准确获取灌溉用水量具有重要意义。

Acquiring regional irrigation water use is of great significance to agricultural water resources management and its optimal allocation.How to acquire regional irrigation water use is still a great challenge for several disciplines,such as agricultural science,hydraulic science and geography.Considering the relationship between irrigation and soil moisture change,this study proposed a method for estimating irrigation water use by using soil moisture data.To achieve this goal,soil moisture and precipitation were regarded as the objects and their quantitative relationship was analyzed in this study by establishing three models,including linear model,logarithmic model and soil water balance model.After building models on every site,the relationship between soil moisture and precipitation is clear and it is feasible to estimate the irrigation water use on the condition that the soil moisture data is known.Estimation of irrigation water use was realized on the base of three models and soil moisture data.Firstly,the 16 sites which monitor soil moisture conditions in Hebi City were considered as objects of study,then the everyday meteorological data(temperature,precipitation,atmospheric pressure,wind speed,sunshine duration)and soil moisture data on the sites from 2015 to 2020(accumulated six years)were collected.Secondly,the eligible data of the previous four years were sifted and used to establish three models for estimating the quantity of input water on the soil surface based on soil moisture.Thirdly,the eligible data of the last two years were sifted and used to verify the established models on every site then judged the accuracy of the models.Taking site 53990 for instance,the RMSE of linear model,logarithmic model and soil water balance model was 10.55 mm,10.3 mm and 8.62 mm respectively.The results showed that water soil balance model can better express the quantitative relationship between soil moisture and precipitation than linear model and logarithmic model.Depending on this conclusion,finally,the eligible soil moisture data sifted and known in the specific site was used to estimate the irrigation water use in the field by the relationship expressed in the water soil balance model.Consequently,compared with the amount of irrigation water data recorded,the irrigation water use estimated according to the water soil balance in this study was 14.19%lower than those recorded.The method proposed in this study is significant for acquiring regional irrigation water use.