EAGER SitS: Underground Radio Frequency Wireless Network for Measuring Soil Moisture over Large Spatial Scales

确保为日益增长的人口提供足够的食物和水资源是21世纪的主要挑战之一。我们做到这一点的能力在很大程度上取决于土壤和水自然资源的管理效率。此外，储存在土壤中的水分在空间和时间上都有相当大的变化，很难测量这些变化。这一点很重要，因为土壤水库中的水变化会影响地球的气候系统，对云的形成和降水有很大的影响，并影响太阳能量的利用。准确测量地形上土壤水分变化的能力将使我们能够提高农业产量，增加粮食安全，更好地管理降雨(特别是强烈风暴)的水，这在城市规划和管理中非常重要。拟议的研究工作将创建一种廉价的、无线的、可扩展的、完全埋在地下的系统，通过使用地下射频(RF)传输来频繁地测量田间环境中的土壤水分。这项研究汇集了不同学科的科学专业知识，从而使土壤科学家、工程师和计算机科学家之间能够合作创建一个最终用于管理我们有限的水土资源并帮助确保粮食安全和社会福祉的“物联网”。土壤水分是影响植物生产力的重要因素之一。土壤水分监测的重大挑战之一是在1至1000平方米的尺度上捕捉土壤-水文系统的自然异质性。这一介于点尺度和现有遥感测量尺度之间的中间尺度对于确定对生态系统服务的影响以及通过环境可持续管理做法改进水资源的利用十分重要。目前，很少有方法将土壤水分从非常有限的点尺度测量扩展到更大的尺度(从田间、流域到区域)。因此，在地表、水文和植被模型中，以及在确定土壤饱和度和流域降雨径流响应时，都会引入误差和偏差。它还阻碍了精准和可持续农业的发展。我们的目标是探索开发一种廉价的、无线的、可扩展的、完全埋入地下的传感器网络系统，使用地下射频传输来测量超过1到1000平方米的空间尺度和高时间分辨率的土壤水分，并评估该技术作为土壤中的准确传感器的潜力。这项技术如果成功，可以使土壤科学家更好地了解复杂的土壤系统，它的动力学，以及它的生物、化学和物理过程。我们将利用在土壤中传播的射频信号的衰减来推断传感器上方土柱中的水分。在这个项目中，我们将创建一个有大约40个节点的无线控制物理传感器网络，并在伊利诺伊州的一个现场实施，该现场具有高度特征化的土壤，用于评估概念。网络开发包括硬件、固件和用户界面。射频节点将被埋在大约25厘米深的田野中，以感知射频节点与土壤表面之间的水分。数据分析将侧重于土壤水分与无线信号强度传输变化之间的相关性。其他因素，如植物冠层高度和根系条件，将被包括在机器学习算法中，以建立一个稳健的模型。网络物理传感网络将与许多科学和工程应用有关，包括由对陆地-大气相互作用感兴趣的水文气象学家、水文学家用于确定农业用土壤饱和度、干旱监测、灌溉调度和洪水预报、供水管理人员以及参与天气和气候研究的科学家使用。这项研究有可能对未来新传感技术的发展产生影响。这项研究的高度多学科性质将把土壤科学家、计算机科学家和研究工程师聚集在一起，探索开发一种用于受管理和非受管理土壤的新型“物联网”。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Ensuring adequate food and water resources for an increasing population is one of the major challenges of the 21st century. Our abilities to do this are highly dependent on how efficiently soil and water natural resources are managed. In addition, water stored in the soil changes considerably over space and time, and it is difficult to measure these variations. This is important because water variations in soil reservoirs affect the Earth's climate system, have large influences on cloud formation and precipitation, and affect utilization of the Sun's energy. An ability to accurately measure soil water content variations over the landscape will enable us to improve agricultural yields, increase food security, better manage water from rainfall (particularly intensive storms), which is important in urban planning and management. The proposed research work will create an inexpensive, wireless, scalable, fully buried system for frequent measurements of soil water in field environments by using underground radio frequency (RF) transmissions. The research brings together scientific expertise from different disciplines, thus enabling collaboration among soil scientists, engineers, and computer scientists to create an "internet-of-things" for ultimate use in managing our limited water and soil resources and helping ensure food security and societal well-being. Soil water is one of the most important factors that affects plant productivity. One of the grand challenges in soil moisture monitoring is to capture the natural heterogeneity of the soil-hydrological system at scales of 1 to 1000 m2. This intermediate scale between point-scale and available remote sensing measurement scales is important for determining impacts on ecosystem services as well as for improving the use of water resources with environmentally sustainable management practices. Currently, there are few methods for scaling soil moisture from very limited numbers of point-scale measurements to larger scales (field, watershed to regional). As a result, errors and biases are introduced in land surface, hydrological, and vegetation models, and in determining soil saturation and rainfall-runoff responses in catchments. It also handicaps the development of precision and sustainable agriculture. Our objectives are to explore the development of an inexpensive, wireless, scalable, fully buried sensor network system using underground radio frequency (RF) transmission for measurements of soil moisture over 1 to 1000 m2 spatial scales and high temporal resolution and to evaluate the potential for this technology to serve as an accurate sensor in soils. This technology, if successful, could enable soil scientists to gain a better understanding of the complex soil system, its dynamics, and its biological, chemical, and physical processes. We will use the attenuation of RF signal that propagate inside soil to infer water content in the soil column above the sensor. In this project, we will create a wireless cyberphysical sensor network with approximately 40 nodes and implement it at a field site in Illinois with highly-characterized soils for evaluation of concepts. Network development includes hardware, firmware, and user interface. The RF nodes will be buried in the field at about 25 cm deep to sense the water content between the RF node and the soil surface. Data analysis will focus on the correlation between soil moisture and changes in the wireless signal strength transmission. Other factors, such as plant canopy height and root conditions, will be included in machine learning algorithms to establish a robust model. The cyberphysical sensing network will be relevant to many scientific and engineering applications, including use by hydrometeorologists interested in land-atmosphere interactions, by hydrologists for determining soil saturation for agricultural purposes, drought monitoring, irrigation scheduling, and flash flood forecasting, by water supply managers, and by scientists involved in weather and climate research. This research has potential to influence development of new sensing technologies in the future. The highly multidisciplinary nature of the research will bring together soil scientists, computer scientists, and research engineers to explore development of a novel "internet of things" for use in managed and unmanaged soils.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.